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In Iran, there are four pest domestic species of cockroaches: Periplaneta americana (Linnaeus, Blattodea: Blattidae), Blatta orientalis (Linnaeus, Blattodea: Blattidae), Blattella germanica (Linnaeus, Blattodea: Blattidae), and Supella longipalpa (Fabricius, Blattodea: Blattellidae). The aim of this study was to compile and review studies conducted on insecticide resistance of domestic cockroaches in Iran to assess the current knowledge and gaps. Twenty insecticides were used in susceptibility testing of cockroaches. The bioassay methods varied, and included surface contact (exposure tests), topical applications and feeding studies on baits. Resistance ratio (RR) stated in the reviewed studies showed that B. germanica was resistant (RR > 10) to DDT, permethrin, and cypermethrin, while P. americana and S. longipalpa were categorized as low levels of resistance (RR = 1–2). S. longipalpa is newly reported from houses in some areas of Iran, includingTehran, and there are very few studies on its' biology, ecology and insecticidal resistance. Most studies used adult cockroaches, while the susceptibility status of nymphs was evaluated only in few studies. Use of different test methods and lack of a World Health Organization (WHO) updated procedure, including revised/updated insecticide diagnostic dosages and test kits. The lack of susceptible strains of cockroaches was a major challenge in the assessment of data. A comprehensive national program for monitoring susceptibility of household pests to insecticides in Iran is of great concern and is highly recommended.
Deformed wing virus (DWV) is one of the most widespread viruses that infect honey bee colonies.The route of infection is directly through contaminated food, feces, and air, or indirectly through the varroa mite, which acts as a vector. Positive DWV samples were obtained from Carniolan honey bee (Apis mellifera carnica) colonies and of varroa mites from the whole territory of Slovenia during a survey between 2007 and 2014. Nucleotide sequences of 471 nucleotides for the L protein gene and 573 nucleotides for the helicase gene were compared. High genetic diversity was observed among these Slovenian Carniolan honey bee DWV field samples, as well as with almost all the strains previously found in other countries in Europe. Phylogenetic analyses in two regions of the viral genome show that several of the DWV strains obtained from honey bees and varroa are genetically very closely related, confirming the important role of varroa in the transmission of DWV. Identification of closely related sequences also confirmed that the same strains of DWV have been successfully transmitted between various honey bee colonies and apiaries. It has also been established that simultaneous infection, in one apiary, of honey bees with two or more different strains of DWV is quite frequent. This is phylogenetic study that compares honey bee and varroa DWV strains from Carniolan honeybees.
Rockmelon (Cucumis melo Linnaeus (Cucurbitales: Cucurbitaceae)) is a novel commercialized fruit in Malaysia and has great potential to become an important horticultural crop for the international market. In this study, we investigated the effects of pollination by the Indo-Malaya stingless bee Heterotrigona itama Smith (Hymenoptera: Apidae) on measures of yield and quality of rockmelon cultivated in the greenhouse, compared with hand cross-pollination and self-pollination. Results showed that rockmelon produced from plants pollinated by stingless bees and hand cross-pollination had higher fruit set, were heavier and larger, and contained higher numbers of seed per fruit compared with those produced by self-pollination. Pollination by stingless bees produced fruit with greater sweetness than either hand cross-pollination or self-pollination. This study demonstrated that stingless bee pollination produced rockmelon fruit of similar quality, but better yields compared to the other pollination treatments. We showed that stingless bees should be considered as an alternative, effective pollinator for the improved production of high quality rockmelon in commercial greenhouse cultivation.
The ectoparasitic mite Varroa destructor Anderson and Trueman (Acarina: Varroidae) shifted host from Eastern honeybees Apis cerana Fabricius (Hymenoptera: Apidae) to Western honeybees Apis mellifera Linnaeus (Hymenoptera: Apidae) with disastrous consequences globally. The high genetic diversity of V. destructor and abundant opportunities for cross-species transmission probably promoted this host shift. Whether Varroa underwoodi (Acarina: Varroidae) also exhibits these traits is unknown. Here, we conduct a large-scale survey across China on the occurrence, morphology, reproduction, and genetics of V. underwoodi in A. cerana and A. mellifera colonies to fill gaps in our knowledge of this mite and to determine whether host shifts occurred. Despite the large number of colonies screened, V. underwoodi was exclusively found in A. cerana, where it occurred at low infestation rates. Three genetic clades were detected in the V. underwoodi population, which differed neither in morphology nor in reproductive ability. Nevertheless, the genetic diversity of V. underwoodi is likely to increase chances for host shifts, even though opportunities for cross-species transmission seem low. More studies of the neglected Varroa species seem appropriate to enable a better understanding of host shifts in the Apis spp./Varroa spp. system and evaluate the potential risk they pose to apiculture with A. mellifera.
Honey bee [Apis mellifera L. (Hymenoptera: Apidae)] queens are polyandrous, mating with an average 12 males (drones). Polyandry has been shown to confer benefits to queens and the colonies they head, including avoidance of inviable brood that can arise via sex locus homozygosity, increased resilience to pests and pathogens, and increased survival and productivity, leading to improved colony-level fitness. Queens with an effective mating frequency (ke) greater than 7 are considered adequately mated, whereas queens that fall below this threshold head colonies that have increased likelihood of failure and may be less productive for beekeepers. We determined ke in queens produced in early Spring and Autumn by five Australian commercial queen producers to determine whether the queens they produced were suitably mated. Drone populations are low at these times of year, and therefore, there is an increased risk that queens would fall below the ke > 7 threshold. We found that 33.8% of Autumn-produced queens did not meet the threshold, whereas 93.8% of Spring queens were adequately mated. The number of colonies contributing drones to the mating pool was similarly high in both seasons, suggesting that although many colonies have drones, their numbers may be decreased in Autumn and management strategies may be required to boost drone numbers at this time. Finally, queens had similar levels of homozygosity to workers, and inbreeding coefficients were very low, suggesting that inbreeding is not a problem.
The benefits of insect pollination to crop yields depend on genetic and environmental factors including plant self-fertility, pollinator visitation rates, and pollinator efficacy. While many crops benefit from insect pollination, such variation in pollinator benefits across both plant cultivars and growing regions is not well documented. In this study, across three states in the northern Great Plains, United States, from 2016 to 2017, we evaluated the pollinator-mediated yield increases for 10 varieties of confection sunflowers, Helianthus annuus L. (Asterales: Asteraceae), a plant that is naturally pollinator-dependent but was bred for self-fertility. We additionally measured pollinator visitation rates and compared per-visit seed set across pollinator taxa in order to determine the most efficacious sunflower pollinators. Across all locations and hybrids, insect pollination increased sunflower yields by 45%, which is a regional economic value of over $40 million and a national value of over $56 million.There was, however, some variation in the extent of pollinator benefits across locations and plant genotypes, and such variation was significantly related to pollinator visitation rates, further highlighting the value of pollinators for confection sunflowers. Female Andrena helianthi Robertson (Hymenoptera: Andrenidae) and Melissodes spp. (Hymenoptera: Apidae) were the most common and effective pollinators, while other bees including managed honey bees (Hymenoptera: Halictidae), Apis mellifera L. (Hymenoptera: Apidae), small-bodied sweat bees (Hymenoptera: Halictidae), bumble bees Bombus spp. (Hymenoptera: Apidae), and male bees were either infrequent or less effective on a per-visit basis. Our results illustrate that wild bees, in particular the sunflower specialists A. helianthi and Melissodes spp., provide significant economic benefits to confection sunflower production.
Bee-collected pollen is an essential protein source for honey bee and bumblebee colonies. Its quality directly affects bee health. We estimated the quality of pollen samples using bumblebee microcolonies and high-throughput sequencing for the presence of microorganisms. The tested samples of bee-collected pollen were of different quality, as estimated from their effect on the development of bumblebee microcolonies. Based on the pollen quality, we selected a subset of high-quality and low-quality pollen samples to further analyze them for the presence of microorganisms and pathogens. High-throughput sequencing revealed that the most common microorganisms in the bee-collected pollen were Acinetobacter spp. and bacteria of the genera Lactobacillus and Lactococcus. No pathogenic bacteria infectious for honey bees (e.g., those causing American and European foulbrood) or bumblebees have been identified in the analyzed pollen samples. Among potentially harmful microorganisms, there were bacteria from the Enterobacteriaceae family. The fungal pathogens Nosema apis and Nosema ceranae were detected in four samples; Ascosphaera sp. was found in six samples. Several viruses were found in the pollen samples, such as chronic bee paralysis virus, Israeli acute paralysis virus, deformed wing virus, sacbrood virus, and Kashmir bee virus. No correlation between the presence of these microorganisms or viruses and the impact of low-quality pollen samples on the bumblebee development was found. It is possible that factors affecting pollen quality are the absence of certain biologically active compounds or the presence of pesticides.
Beekeepers commonly supplement honey bee (Apis mellifera L.) colonies' nutrition with commercial pollen and nectar substitutes in an effort to encourage growth and reduce colony losses. However, there is a broad lack of understanding regarding the extent to which supplemental protein feeding affects honey bee colony health. We conducted a field study to determine if feeding protein substitutes affected colony strength and Nosema spp. spore intensity in commercially managed honey bee colonies. Seventy-five honey bee colonies were randomly assigned to one of six treatments (no supplemental protein, one of four commercially available protein supplements, or wildflower pollen supplement).The number of adult bees, the number of capped brood cells, and Nosema intensity were assessed prior to-, 4 wk post-, and 8 wk post-treatment. There was an overall decrease in Nosema intensity across all treatments over time. However, there were no statistically detectable differences in colony strength or Nosema intensity between any of the pollen feeding treatments and those of the negative control treatment. Thus far, multiple investigations regarding supplemental protein feeding have failed to provide a clear consensus on the impact that this practice has on honey bee colony strength or productivity. Additional research is needed to determine the impact, if any, that diet supplementation, including microbial and nutritional supplements, has on colony health, to better inform beekeepers' management decisions.
The xylem-limited bacterium Xylella fastidiosa Wells is the causal agent of severe diseases of several cultivated and wild plants. It is transmitted by xylem-sap feeder insects, such as spittlebugs (Hemiptera: Cercopoidea) and sharpshooters (Hemiptera: Cicadellinae). A dramatic epidemic of X. fastidiosa subspecies pauca sequence type 53 is currently affecting a large area of the Apulia Region of Italy, where it is spread by Philaenus spumarius L. adults within olives. In 2015 and 2016, field surveys were carried out in Apulian olive groves to investigate host plant selection of spittlebug nymphs, to identify the main plant species that can act as reservoirs of the vectors. Two different sampling methods were used: randomized plant sampling and quadrats sampling. Host plant selection by P. spumarius and Neophilaenus campestris (Fallén) nymphs was estimated using Manly's selection index. The botanic families presenting the highest number of plants infested by P. spumarius nymphs were Asteraceae, Fabaceae, and Apiaceae. Nymphs of P. spumarius were sampled on 72 plant genera, and among the most common 25 genera, Sonchus, Knautia, Glebionis, Urospermum (Asteraceae), Medicago, Vicia, Melilotus (Fabaceae), and Daucus (Apiaceae) were the ones selected preferentially, according to Manly's index results. Populations of P. spumarius nymphs peak in early April, with densities ranging between 10 and 40 nymph/m2, were about 10-fold those of N. campestris. Plant infestation rate by spittlebug nymphs in 2016 was significantly higher in olive groves located in Lecce province (infected area) than those situated in Bari province (noninfected area).
The tobacco whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is a cryptic species complex with members capable of inducing huge economic losses. Precise identification of members of this complex proves essential in managing existing populations and preventing new incursions. Despite records of serious outbreaks of this pest in Malaysia little is known about species status of B. tabaci in this region.To address this, a comprehensive sampling of B. tabaci from different host plants was conducted in 10 states of Malaysia from 2010 to 2012. Members of the complex were identified by sequencing partial mitochondrial cytochrome oxidase subunit I (mtCOI) gene and constructing a Bayesian phylogenetic tree. Seven putative species were identified including Asia I, Mediterranean (MED), China 1, China 2, Asia II 6, Asia II 7, and Asia II 10.The most important finding of the study is the identification of the invasive MED species from locations without previous records of this species. All putative species except Asia I and MED are recorded from Malaysia for the first time. This study provided the first introductory map of B. tabaci species composition in Malaysia and emphasizes the urgent need for further studies to assess the status of MED invasion in this country.
Many studies have evaluated transmission abilities of laboratory-reared aphids for potato virus Y (PVY), but few have focused on PVY-harboring species of field-collected aphids and the strains of PVY harbored by aphids. In the present study, we collected alate aphids in yellow pan traps in potato fields with Japanese commercial cultivars in Hokkaido, northern Japan in single 24-h periods during the tuber bulking stage and examined whether individual whole aphids harbored PVY by nested RT-PCR. PVY-positive individuals were identified to species using the gene sequence for cytochrome c oxidase subunit I and, when needed, morphological data and distribution records. In addition, individual strains of PVY harbored were determined using partial sequences of coat protein. Among 1,857 aphids trapped, 195 aphids had PVY and comprised 19 species; 17 species were identified to species-group taxa. Most of the aphid species detected as PVY positive colonize weeds that are common around potato fields in Hokkaido. Five species-group taxa had not been reported previously as a vector aphid of PVY and might be new PVY-vector species. PVYNTN was most frequently detected from PVY-positive aphids as found recently in PVY-infected potatoes in commercial fields in Hokkaido. Two or three PVY strains were rarely detected from a single aphid, and no obvious difference was found in the proportion of the harbored PVY strains among positive aphid species. The first documentation of the species composition of PVY-harboring aphids and the strains of PVY harbored in East Asia should aid understanding of the epidemiology of PVY in Japan.
The resistance evolution of Spodoptera frugiperda (J.E. Smith) to insecticides and Bt proteins along with the intensive crop production systems adopted in Brazil make it challenging to implement integrated pest management. The adoption of alternative methods to manage pests is fundamental to the implementation of favorable integrated pest management and insect resistance management. Spodoptera frugiperda multiple nucleopolyhedrovirus (SfMNPV) is a valuable tool for S. frugiperda control. The characterization of the baseline susceptibility of S. frugiperda populations and cross-resistance involving SfMNPV and major insecticides and Bt proteins have not yet been conducted. The objective of this study was to characterize the baseline susceptibility of S. frugiperda populations from five Brazilian States to SfMNPV (Cartugen, AgBiTech, Fort Worth,TX). Possible cross-resistance to insecticides and Bt proteins among resistant S. frugiperda strains was also assessed. There were no differences in the susceptibility of the studied populations to SfMNPV. The estimated diagnostic concentration may be utilized in future monitoring studies to SfMNPV. The SfMNPV presented no cross-resistance to the chemical insecticides and to the Bt proteins tested. Our results provide evidence of the biological activity and high potential of SfMNPV as a distinct insecticidal mode of action for use in rotation with other tools.This biological insecticide is known to have a favorable toxicological and ecotoxicological profile and will be a valuable tool in insect resistance management and integrated pest management programs for control of S. frugiperda.
Fourteen fungal entomopathogenic strains were isolated from soil samples and infected field-collected fall armyworm larvae, in Guanajuato, Mexico. Isolates were identified by morphology and internal transcribed spacers sequencing. Isolates Ma22, Ma41, and Mr8 showed 99% identity with reference strains (RS) of Metarhizium anisopliae. Isolates Bb9, Bb19, Bb21, Bb40, Bb27, Bb23, and Bb39 showed identity between 99 and 100% with RS of Beauveria bassiana. Isolates Nr1, Nr2, Nr3, and Nr4 showed identity between 98 and 100% with RS of Nomuraea rileyi. Qualitative selection used one concentration (1 × 108 conidia/ml) on fall armyworm eggs and neonate larvae. Strains Ma22, Ma41, and Mr8 showed 100%, and strains Bb39, Bb23, Bb9, Bb40, Bb19, and Bb21 showed 92, 89.2, 87.6, 82.8, 58, and 38% egg mortality, respectively. Bioassays on neonate larvae showed 100% mortality with strains Ma22, Ma41, Mr8, and Bb9. Strains Bb39, Bb19, Bb27, Bb23, Bb21, and Bb40 showed 74, 60, 54, 53, 28, and 19% mortality, respectively. Bioassay estimated LC50s for strains Ma41 at 7.4 × 104, Mr8 at 8.9 × 104, and Ma22 at 10 × 104 conidia/ml, on fall armyworm eggs. LC50s on neonate larvae were estimated at 2.8 × 105, 16 × 105, 26 × 105, and 36 × 105 conidia/ml for strains Ma41, Bb9, Ma22, and Mr8, respectively. Virulence genes mad1 and mad2 were found in Mr8, Ma22, and Ma41, whereas the gen gmact was found only in the strain Ma22. Genes hyd1 and hyd2 were identified in Bb9, Bb19, Bb21, and Bb27. No correlation was observed between the virulence gene detection and the estimated LC50s. Strain Ma41 showed the highest potential to be developed as a bioinsecticide.
Lethal and sublethal effects of insecticides used in organic agriculture were tested against Anastatus reduvii and Telenomus podisi, native North American hymenopteran egg parasitoids of the native Euschistus servus Say (Hemiptera: Pentatomidae) and the invasive Halyomorpha halys Stål. Entrust (spinosad), PyGanic (pyrethrin), Neemix (azadirachtin), and Azera (pyrethrin + azadirachtin) were tested at equivalent field rates of 1×, 0.5×, and 0.1×. Bioassays included insecticide exposure to parasitoids through residue on substrate, parasitized host eggs, and their food source. When exposed to dried residues, Entrust caused 100% mortality at the 0.5× rate to both species; PyGanic, Neemix, and Azera exhibited low toxicity. Exposure of parasitized host eggs to Entrust 1× during the egg stage of parasitoid development reduced parasitoid emergence compared to all other treatments in both species. Anastatus reduvii emergence was also reduced by PyGanic at 0.5× and 1×. Parasitoid emergence from host eggs exposed during the pupal stage was more variable than egg stage exposure; emergence of both species was reduced in 0.5× and 1× rates of PyGanic, and A. reduvii was reduced in the 0.5× rate of Entrust compared to controls. Longevity of emerged parasitoids surviving exposure within host eggs showed that Entrust was more deleterious than Neemix or PyGanic. When A. reduvii was fed insecticide-laced honey, all treatments except Neemix at 0.1× reduced adult longevity compared to the control. These studies demonstrated that insecticides commonly used in organic agriculture can negatively affect two common parasitoids of stink bugs; specifically, negative effects were most pronounced with Entrust, and variable with Neemix and Pyganic.
Myzus persicae (Sulzer) (Hemiptera: Aphididae) and Lipaphis erysimi (Kaltenbach) are important pests of Brassica leafy vegetables, especially in Japan, the United States, and India. In Japan, because most of the nonheading Brassica vegetables are considered minor crops, the number of commercially available pesticides against these aphids is limited. Here, we evaluated the effect of releasing adults of a flightless strain of the multicolored Asian ladybird, Harmonia axyridis Pallas, on these aphid species on a nonheading Brassica cultivar in open fields. Three weeks after, ladybirds were released onto aphid-infested plants at a rate of two adults per m2, only 4–12% equal numbers of aphids were found on plants with ladybirds as without ladybirds in all three trials. The result indicates that H. axyridis adults are the effective biocontrol agents against aphids on the plants.
The bamboo longhorned beetle, Chlorophorus annularis (Fabricius), distributed widely in Asian countries attacking live or postharvest bamboo, is a concern to the international trade of bamboo materials. With the phase out of methyl bromide for quarantine and preshipment use, a reliable, safe, and environmentally friendly phytosanitary treatment is needed as an alternative. In this study, the thermotolerance of C. annularis larvae at atmospheric pressure was examined.The results showed that the thermotolerance increased with instar.The fifth instar was the most thermotolerant stage at 48 and 50°C. A series of vapor heat treatment tests were conducted for bamboo poles infested with C. annularis at the vacuum levels of 15, 30, 50, 70, 90, and 100 kPa at the temperatures of 40, 44, 48, 52, and 56°C with a holding duration of 15 min.The lower pressure or higher temperature increased the mortality of C. annularis. In total 473 larvae were treated at 48°C and 50 kPa for 15 min. Only one larva was found alive, resulting in a mortality rate of 99.7886%. In total 418 larvae were treated at 52°C and 100 kPa for 15 min resulting in 100% mortality. Based on these two results, a heat treatment of 52°C for 15 min at 50 kPa can be used as a low pressure vapor heat treatment for bamboo articles infested with C. annularis. The vapor heat treatment combined with low pressure is an effective alternative phytosanitary measure for bamboo articles.
The Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), is arguably the most significant and studied quarantine pest of fresh fruits. There is well over a century of research observations on its response to cold, first as it pertains to shipment of fruits using cold temperatures to preserve fruit quality and how that may aid the survival and distribution of the pest, and then the use of colder temperatures to kill the pest in fruit shipments. Cold tolerance at 1.1°C in three populations of C. capitata generally increased as the insect developed; therefore, the third instar is the most tolerant of the stages that are found in fruit. The three populations did not differ in cold tolerance, indicating that cold phytosanitary treatments against this pest can be harmonized regardless of country of origin of marketed fruit hosts. This study facilitated the approval of some cold treatment schedules for the International Plant Protection Convention treatment manual that were being held up by concerns of possible differences in cold tolerance among C. capitata populations from different countries and points toward the possibility of generic, broadly applicable phytosanitary cold treatments. Most larvae found alive after 9 d of cold treatment did not pupariate and fewer still emerged as adults, indicating that acute larval mortality need not always be the objective of a cold phytosanitary treatment to be efficacious in preventing the establishment of invasive species.
The mealybug of Dysmicoccus lepelleyi Betrem (Hemiptera: Pseudococcidae) attacks a wide range of fruits, vegetables, and ornamental plants and is categorized as a quarantine pest in China. Utilization of phytosanitary irradiation (PI) as a potential treatment to disinfest agricultural commodities in trade (which has expanded rapidly in the recent years) and preventing the hatch of F1 generation eggs is used as a criterion for the PI treatment of mealybugs. A RS-2000 Pro X-ray irradiator (Rad SourceTechnologies, Inc.) was used to treat the gravid adult females and eggs of the mealybug. The primary tests were conducted to explore the minimum dose for preventing egg-hatch from the irradiated adult females, resulted in a 1.69% of eggs hatched from 100 Gy-irradiated adult females and no crawler developed as treated at the dose of 110 and 120 Gy. To estimate the minimum dose for preventing egg-hatching, the dose–response tests were conducted for 1-, 2-, and 3-d-old eggs at the dose of 20, 40, 60, 80, 100, and 120 Gy, respectively. The results showed that the radio-tolerance increased very slowly with developmental times of eggs, and the estimated dose for 99.9968% mortality at the 95% confidence level (Probit 9) by Probit analysis is 146.2, 155.7, and 156.1 Gy for 1-, 2-, and 3-d-old eggs, respectively. Therefore, dose range between 110 and 160 Gy could be efficient to prevent the reproduction of this mealybug.
Drosophila suzukii (Matsumura) is a pest of small fruits and grapes in the United States and in its home range of Japan. Physiological and morphological laboratory testing was performed on six commonly grown wine grape varieties inVirginia. Skin thickness, penetration force, and °Brix were analyzed to determine ovipositional preferences. Experiments were performed for three consecutive years from grapes collected at one Virginia vineyard. More eggs were laid in intact Viognier grapes than any other variety. Oviposition into intact grapes was not affected by skin thickness or °Brix; however, oviposition increased when penetration force decreased. An ovipositional choice test determined no varietal preferences. Survivorship from egg to adulthood using uninjured and injured grapes was also assessed to determine varietal suitability as D. suzukii hosts, with more flies emerging from injured grapes than uninjured. However, D. suzukii adults did emerge from intact grapes and at higher percentages than previously recorded in other wine grape studies. All varieties had eggs oviposited into them when injured. Determining the time at which each grape variety became susceptible to oviposition was determined using a D. suzukii bioassay spanning 12 wk using grapes from the green pea stage until ripe. Susceptibility to D. suzukii oviposition was based upon ripening period and penetration force. Early ripening varieties may be more susceptible to D. suzukii oviposition in the field with later maturing, harder fleshed-varieties which may escape D. suzukii oviposition.
Behavioral thermoregulation is a key strategy for insects to cope with heat stress.The rice leaf folder Cnaphalocrocis medinalis Guenée (Lepidoptera: Pyralidae) larvae usually fold one leaf to construct a leaf shelter. The larvae are vulnerable to heat stress, and the temperature in summer is often beyond the optimal range of them. Shelters confer protection against environmental stress but unclear whether larvae will alter shelter-building behavior when encountering heat stress. We observed the shelter-building behavior of larvae during and after heat shock, and then examined the shape and structure of shelters. Larvae spent more time in selecting a site and building a shelter during and after heat shock than at the optimal temperature. More than 70% of larvae folded two or three leaves to build a shelter during and after heat shock, but more than 60% of larvae only folded one leaf at the optimal temperature. Larvae built more single-leaf longitudinal shelters at the optimal temperature, but they built more multileaf overlapping shelters during and after heat stress. Larvae constructed a short leaf shelter using a small amount of silk binds when they were exposed to 40°C for 4 h. The rice leaf folder larvae can alter their shelter-building behavior and shelter structure in response to heat stress.
Azuki bean beetle, Callosobruchus chinensis (L.) (Coleoptera: Bruchidae), is a field-to-storage pest of legumes and its females produce sex pheromone components with two isomers: (2Z,6E)-7-ethyl-3,11-dimethyl-2,6,10-dodecatrienal (2Z-homofarnesal) and (2E,6E)-7-ethyl-3,11-dimethyl-2,6,10-dodecatrienal (2E-homofarnesal). Two-day-old virgin adults were treated with different doses (0, 200, 300, 400, 500, and 600 Gy) of gamma radiation and the effects on adult survivorship, fecundity, sterility, and pheromone production were studied. The longevity of both sexes and female fecundity were dose dependently affected by the gamma irradiation revealing that the fecundity was more reduced when the female adults were irradiated. Adults of both sexes were totally sterilized by the doses of gamma radiation tested in this study as depicted by the null hatchability of the laid eggs. The results from analyses by gas chromatography–mass spectrometry for solid phase micro-extraction revealed that both of the female sex pheromone components were significantly reduced by 300 Gy. Though significantly less, there was release of some amount of pheromone components by the irradiated female azuki bean beetles revealing the possibility of pheromonal attraction of males to the irradiated females. It is a pre-requisite for the successful sterile insect technology that the sterility of azuki bean beetle is induced without the total disruption of the calling behavior.
A natural insecticide developed from the mixture of the essential oils (EOs) of Cymbopogon citratus (DC.) Stapf (Poaceae), Cedrus atlantica (Endl.) Manetti ex Carriére (Pinaceae), and Corymbia citriodora (Hook.) K.D. Hill & L.A.S. Johnson (Myrtaceae) was studied. The mixture of oils caused high mortality (LD50 = 0.018 μl/insect) to the Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera:Tephritidae), a globally important pest, after topical application on adults. Based on the chemical characterization of biopesticide using gas chromatography–mass spectrometry (GC-MS) analysis, many of the constituents had known insecticidal properties (the monoterpenes α-citronellal and E-citral and the sesquiterpernes α-himachalene and β-himachalene, all at concentrations above 15%). Phytotoxicity tests on orange trees demonstrated that this natural product was harmless when the mixture was applied diluted in water with a surfactant. The mixture of EOs was also harmless (1, IOBC category) to the biological control agent responsible for reducing populations of tephritids, the parasitoid Psyttalia concolor (Hymenoptera: Braconidae), following exposure to treated orange trees in a semifield assay within a greenhouse, but killed 46.2% of C. capitata (Szépligeti) adults after 72 h. Our results suggest that mixture of EOs has potential for use as an adulticide against medfly, although the production price was exceedingly high compared with that of commercial synthetic insecticides.Therefore, we discuss the advantages and disadvantages related to the potential use of this natural insecticide.
Spotted-wing Drosophila, Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) is a vinegar fly introduced unintentionally into the United States. Since 2008, D. suzukii has reduced annual berry yields from 6 to 100%. Effective control of D. suzukii during harvest requires weekly applications of low-residual, broad-spectrum insecticides that are unavailable for organic farming. A novel ingestible insecticide, a 4-carbon polyol, mesoerythritol (erythritol), was found to kill 75 to 100% of larval and adult D. suzukii. However, mesoerythritol, at effective concentrations (0.5–1.0M), may be cost-prohibitive. Therefore, we conducted laboratory tests to assess the effects of lower cost derivatives of erythritol, namely the pentaerythritol series of 1,3-diols on D. suzukii pupal production, adult production, adult mortality, brood output, and reproductive increase. We then selected the two most promising compounds for a field test on fruiting rabbiteye blueberry. From 90 to 100% of adults died when fed food moistened with 1M solutions of mesoerythritol and pentaerythritol. Mesoerythritol and dipentaerythritol at a concentration of 1M were ovicidal/ larvicidal, killing ≥85% of immatures. Overall, 1M mesoerythritol killed 80% or more larvae and adults, thus bringing populations to near zero. The heaviest compound of this series, tripentaerythritol, at all concentrations, was largely benign to both adults and immatures. Thus, we cannot recommend tripentaerythritol for D. suzukii control. In a blueberry field, 0.5M mesoerythritol and 0.5M pentaerythritol, each by themselves, reduced egg infestation by 64% and larval infestation by 93%; their combination (0.25M mesoerythritol and 0.25M pentaerythritol) achieved even greater egg control with 82% fewer eggs infesting blueberry fruits.
Thrips are early-season pests of cotton and can cause yield and stand losses if not managed. Strip tillage into a winter cover crop, use of a neonicotinoid seed treatment, and foliar insecticide applications are all reliable pest management tactics, but how these methods interact with each other in a thrip–cotton agroecosystem needs to be further understood. A 2-yr field study was conducted to compare thrip counts and thrip-induced plant injury as a function of tillage practice (conventional vs strip tillage with heavy rolled rye), thiamethoxam seed treatment, and foliar insecticide application for managing thrips in cotton. Adult and nymph density, seedling biomass, true leaf formation, stand count, and lint yield were assessed. Results indicate that heavy rolled rye was effective for mitigating thrips on seedling cotton. On conventionally tilled fields, the neonicotinoid seed treatment and a foliar insecticide application were necessary for maximizing yield. Spinetoram was more efficacious than either acephate or cyantraniliprole for management of immature thrips; however, there were no yield effects attributed to foliar insecticide application. These data suggest that growers can mitigate early-season thrips using both cultural and chemically based management tactics.
Mythimna unipuncta (Haworth) (Lepidoptera: Noctuidae) is an important insect pest of corn (Zea mays L.) in North America and can cause severe damage during outbreaks. Insecticides are the main control method; however, development of insecticide resistance poses management challenges and necessitates the use of novel insecticides. A synthetic insecticide, chlorantraniliprole, belonging to the anthranilic diamides, targets insect ryanodine receptors and is a potential alternative to conventional insecticides for management of M. unipuncta. We determined the efficacy of seed treatment with chlorantraniliprole alone compared with a positive control consisting of a neonicitinoid seed treatment of thiamethoxam and combinations of both compounds against M. unipuncta larvae in laboratory bioassays. Bioassays were conducted on two different growth stages of M. unipuncta larvae (instars 3 and 5) and two plant growth stages (V1 and V2 corn) in clip cages and whole plant experiments. Larval mortality, head capsule width, and feeding injury were measured.The chlorantraniliprole seed treatment alone or in combination with thimethoxam at different doses affected survival of M. unipuncta larvae. In all bioassays except one, larval mortality occurred earlier when a combination of chlorantraniliprole and thimethoxam seed treatment was used when compared with a thimethoxam alone seed treatment. Mythimna unipuncta larvae developed faster on the untreated control corn plants compared with corn with insecticide seed treatments. Foliar injury was low in both chlorantraniliprole alone and chlorantraniliprole + thimethoxam treatments compared with the control. Chlorantraniliprole thus offers potential alternative to conventionally used insecticides in the management of M. unipuncta in corn.
The use of foliar insecticide sprays at low temperatures may result in decreased efficacy in grain sorghum, Sorghum bicolor L. Moench, for control of sugarcane aphid, Melanaphis sacchari (Zehntner). Sulfoxaflor and flupyradifurone were evaluated to determine the impact of temperature on their efficacy against sugarcane aphid in grain sorghum. Sorghum was treated at the soft dough growth stage with sulfoxaflor and flupyradifurone, as well as an untreated check. Leaf discs were pulled at various intervals from 0 to 10 d after treatment, placed in water agar plates, infested with aphids, placed in growth chambers at 15.5°C or 29.4°C, and evaluated 48 h after each interval. In 2015, both insecticides resulted in similar levels of sugarcane aphid mortality and efficacy decreased at a similar rate at 15.5°C. At 29.0°C, flupyradifurone resulted in greater mortality of sugarcane aphid than sulfoxaflor as length of time after treatment increased, suggesting that it provides longer residual control than sulfoxaflor. In 2016, both insecticides provided poor control of sugarcane aphid at 15.5°C for all time intervals. At 29.0°C, flupyradifurone provided overall better control than sulfoxaflor. These data suggest that lower temperatures can reduce the efficacy of both sulfoxaflor and flupyradifurone. In addition, flupyradifurone appeared to provide longer residual control and overall better control of sugarcane aphid than sulfoxaflor. If lower temperatures occur when sugarcane aphid populations exceed current thresholds, weather forecast should be considered in pest management decision-making process.
We assessed density of emerald ash borer (Agrilus planipennis Fairmaire) (Coleoptera: Buprestidae) larvae over a 6-yr period by felling and sampling a total of 315 green ash (Fraxinus pennsylvanica Marsh.) trees that were left untreated or treated with imidacloprid, dinotefuran, or emamectin benzoate products at 1-yr, 2-yr, or 3-yr intervals. Our study, conducted across a 32-ha forested area, began soon after emerald ash borer became established and continued through the peak and eventual decline of the emerald ash borer population. Less than half of the 96 trees in the pretreatment sample were infested and larval densities were very low. Densities of emerald ash borer remained low for 3 yr, then increased exponentially, eventually resulting in mortality of most untreated overstory ash. Trees treated with either low or moderate rates of emamectin benzoate applied via trunk injection had few or no emerald ash borer galleries, even 3 yr post-treatment. Basal trunk sprays of dinotefuran applied annually were also effective at preventing larval densities from reaching damaging levels. Average larval densities on trees treated with a trunk injection of imidacloprid were lower but did not differ from untreated trees, regardless of treatment frequency. Larval parasitism was rare, while woodpecker predation was common and accounted for nearly all natural larval mortality, even on trees with very low densities of larvae.
Walking is important to dispersal on plants and colonization of new plants by predatory mites, and this activity is potentially affected by the presence of acaricides. This possibility was investigated in coconut fruits infested with the coconut mite, Aceria guerreronis Keifer (Acari: Eriophyidae), where colonization by the predator Neoseiulus baraki (Athias-Henriot) (Acari: Phytoseiidae) was monitored. The following acaricides were evaluated for influence on the process of colonization by the predatory mite: abamectin, azadirachtin, and fenpyroximate. Water-treated fruits were used for comparison. Experiments were conducted with and without freedom of choice on coconut fruits with the release and recapture of females of N. baraki marked with fluorescent ink. A confinement experiment was also carried out on coconut bunch rachis sprayed or not sprayed with the acaricides. The predatory mite N. baraki avoided contact with acaricide-contaminated areas. After the predators were released on the fruits or bunch rachis, larger numbers were recaptured under the bracts than on the surface of the fruits. The number of predators recaptured in all experiments was lower in the treatments with acaricides than in the control. Among the acaricides tested, azadirachtin least affected N. baraki colonization. Therefore, the presence of the tested acaricides indeed interferes with N. baraki dispersal within plants and the coconut fruit colonization.
The availability of oviposition sites for the predators of arthropod pests is crucial for the success of biological control. The resources for oviposition and offspring survival offered to the predators by crops and the surrounding natural vegetation are relevant in the context of conservation biological control.The endophytic oviposition of Orius insidiosus (Say) depends on the characteristics of the plant tissues. We thus examined, by single- and multiple-choice tests, 1) the oviposition of O. insidiosus in strawberry, analyzing the tissue characteristics of the different plant structures, and 2) the preference for oviposition among strawberry, tomato, bell pepper, eggplant, and the wild South-American poppy Bidens pilosa L. (Asterales: Asteraceae). The calyx and flower petiole received more eggs than the other structures. The thickness of the external tissues did not affect oviposition. All structures of the different plants tested offer sufficient space to house eggs, except for the leaflet lamina. Bidens pilosa was preferred by ovipositing O. insidiosus over the other plants tested.The cultivation of this plant in proximity to strawberry and other horticultural crops could constitute a promising strategy for augmenting the resources for oviposition for this predator.
We evaluated a protein bait based on an enzymatically hydrolyzed beer yeast and two widely used baits including a sugar + vinegar + wine mixture and apple cider vinegar for their ability to trap Drosophila suzukii (Matsumura) in the laboratory and outdoors. The protein bait was a more attractive lure than the other tested baits, with the protein bait capturing significantly more female and male adults at different developmental stages than the other baits. Furthermore, the protein bait with 20% vinegar attracted significantly more adult flies than the other baits, and the protein bait without dilution attracted the most adults. Except for the addition of 0.05% spinosad, increased insecticide content in protein bait reduced its attractiveness to adult flies. Moreover, we found that D. suzukii has a bimodal activity pattern in visiting protein bait, where maximum activity occurs during 8:00–10:00 a.m. and 14:00–16:00 p.m. The antennae and maxillary palpi played an important role in detecting the chemicals emitted from the protein bait, as the number of intact flies that responded to new protein bait was significantly higher than the number of flies without antennae that responded, but almost 15% of defective flies still responded to the protein bait. Our results suggested that the protein bait based on spent brewery yeast could be a promising alternative for D. suzukii population monitoring and for managing this pest when combined with bioinsecticides, providing guidance for using this protein bait as a component of integrated pest management.
Bemisia tabaci MEAM1 (Gennadius), the sweetpotato whitefly, transmits Tomato yellow leaf curl virus (TYLCV), which causes significant yield losses annually in Florida and other tomato-producing regions. Field trials were carried out at the University of Florida's Gulf Coast Research and Education Center to evaluate integration of plastic mulch type, at-plant insecticide, and tomato variety for management of the sweetpotato whitefly and TYLCV. The tomato varieties Charger, Rally, and Tygress had significantly lower season-long densities of whitefly eggs and nymphs than Florida-47 in one or more trials. Aggressive chemical control measures failed to reduce virus incidence in two of the three trials and did not improve yield. In 2013, when virus pressure was extremely high, yield in the susceptible variety was decimated, but virus-tolerant varieties produced a crop. Egg and nymph densities tended to be lowest onTYLCV-tolerant varieties and on tomato grown on metalized mulch. Differences in yield were primarily due to tomato variety and TYLCV incidence. Intensive insecticide use common in Florida tomato production may reduce losses when viral pressure is moderate, but not when migration of viruliferous whiteflies into the field is constant. Without significant winter freezes or a coordinated host-free period to reduce whitefly populations, insecticidal control and repellent-metalized mulches will offer limited protection compared with genetic tolerance to the virus, which may also be overcome under high virus pressure.
Insect symbionts offer an opportunity to deal with the anticipated elevated demand for novel pest management strategies. One approach is the disruption of essential symbionts required by the pests. In the present study, we examined the effects of symbiont elimination strategies, high temperature and sterilization agents, on the fitness of three stink bugs, Brachynema germari Kolenati, Acrosternum heegeri Fieber, and Acrosternum arabicum Wagner by using demographic approach. In the high-temperature experiments, almost all insects exhibited severe fitness defects, including elevated nymphal mortality and reduced population growth parameters (especially intrinsic rate of increase, r), as well as significant reductions in the gut symbiont titers. In the egg surface sterilization assays, we experimentally assessed the effects of sterilization agents on the bugs and their symbionts and observed similar fitness defects to those observed under the high-temperature condition. According to the results, we concluded that the host's defective phenotypes are attributable not to the heat stress itself but to the suppression of the symbiont titer, which highlights the possibility that global warming and elevated temperature may negatively affect this mutualism.Together, the results suggest the biological importance of the bacterial symbiont for the host that might help us for better management of these important pests in the future.
Carposina sasakii Matsumura is one of the most destructive fruit-boring pests of pome and stone fruit trees in eastern Asia. Because larvae complete their development inside a single fruit, larval density per fruit is a critical factor in their survival, development, and fecundity. The effect of larval density was examined to determine the ideal density for devising an economic and sustainable mass-rearing system for harvesting of C. sasakii. Mass production of insects of the same age of a specific stage is not only important in biological control, but also in pheromone extraction, culturing of entomopathogenic nematodes and fungi, etc. Life history data for six larval densities (1–5, 6–10, 11–15, 16–20, 21–30, and 31–40 larvae/apple) were collected at 25.5 ± 0.5°C, 75.0 ± 5.0% RH, and a photoperiod of 15:9 (L: D) h. Data were analyzed using the age-stage, two-sex life table. The results showed that the highest preadult survival rate (42.00%), fecundity (104.70 eggs), and population parameters (intrinsic rate of increase r = 0.0718 d-1, net reproductive rate R0 = 23.03 eggs, and finite rate of increase λ = 1.0744 d-1) were observed at a density of 1–5 larvae/apple. However, when the rearing costs and production rate were considered, the density of 16–20 larvae/apple was the most economical for mass-rearing C. sasakii in order to achieve a daily harvest rate of 1,000 pupae (from 273 apples per day).To ensure the sustainability of the mass-rearing system, we included the life table variability in the harvesting strategy.
The citrus mealybug, Planococcus citri (Risso) (Hemiptera: Pseudococcidae), is a major insect pest of greenhouse-grown horticultural crops. Applications of systemic insecticides as drenches to the growing medium are typically used by greenhouse producers to prevent or suppress citrus mealybug populations. A comprehensive study was conducted that included 11 experimental trials designed to assess the effects of growing medium applications of six systemic insecticides (azadirachtin, dinotefuran, flonicamid, imidacloprid, spirotetramat, and thiamethoxam) in preventing the establishment of and suppressing citrus mealybug populations on different plant species. The experimental trials included four plant species: Solenostemon scutellarioides, Gerbera jamesonii, Begonia × semperflorens-cultorum, and Salvia splendens, with six different cultivars grown in research greenhouses similar to those used in greenhouse production systems. In addition, feeding location (plant stem, leaf top, and leaf bottom) of citrus mealybugs on the various plants was also recorded. Overall, percent citrus mealybug mortality was consistently <50% (n = 255 to 1,598) for any treatment or rate of application; regardless if the systemic insecticides were applied preventatively or curatively. Percent citrus mealybug mortality did reach 78% (n = 36) for thiamethoxam at 8 times the label rate when plants were treated preventatively. Furthermore, none of the treatments prevented development of citrus mealybug F1 individuals to F2 generation egg-laying females on S. scutellarioides or G. jamesonii plants. Citrus mealybugs varied in their spatial distribution on the plant stem, leaf top, and leaf bottom with no noticeable trends. Therefore, based on the results of the study, systemic insecticides are not effective against the citrus mealybug in greenhouse production systems.
Ectropis grisescens Warren 1894 (Lepidopotera: Geometridae) and Ectropis obliqua Prout 1915 (Lepidopotera: Geometridae) are the most destructive chewing pests in China's tea plantations. Ectropis grisescens sex pheromone lures and E. obliqua nucleopolyhedrosis virus (EoNPV) are two species-specific and effective bio-control technologies to control these pests. Because these two species are morphologically similar, tea growers are unable to discriminate them by visual inspection. Hence, determining whether to use E. grisescens sex pheromone lures or EoNPV is difficult without knowledge on the geographical distribution of these two Ectropis species in China. In this study, we developed an efficient identification method, which is considerably cheaper and faster than sequencing the cytochrome c oxidase I gene. Overall, 2,588 E. grisescens and E. obliqua samples, collected from 13 provinces and municipalities in China covering the major regions where these pests have been reported, were identified. All insect samples from southern Jiangsu Province were identified as E. obliqua. Both Ectropis species were mix-distributed at the Anhui–Zhejiang Province border areas, whereas E. grisescens was mostly collected from the other sampling sites. Thus, E. obliqua might be mainly distributed at the junction of Jiangsu, Anhui, and Zhejiang Provinces. In contrast, E. grisescens has a considerably wide distribution area and is the main lepidopteran pest in the tea plantations of China. Our results contribute to improve the management of E. grisescens and E. obliqua populations and provide new insights for further studies on these two species.
The German cockroach, Blattella germanica (L.), is a common pest found in apartment buildings. Prevalence of cockroach infestations is affected by both environmental conditions and building occupant behavior, but their relationships are not well studied. The objective of this study was to analyze the presence of German cockroaches in relation to environmental conditions, resident demographics, and residents' tolerance of cockroaches. We conducted resident interviews, placed sticky traps to detect the presence of German cockroaches, and assessed apartment conditions. A total of 388 apartments from seven low-income apartment buildings, occupied by senior citizens in New Jersey, United States, were included. Among the 344 apartments where trap count data were obtained, 30% had German cockroaches. Among interviewed residents whose apartments had existing cockroach infestations, 36% were unaware of the presence of cockroaches. The odds of having cockroaches in apartments with a ‘poor’ sanitation rating in kitchens and bathrooms was 2.7 times greater than that in apartments with better sanitation conditions. Residents' tolerance to cockroaches is significantly associated with presence of cockroaches and cockroach population size. The median cockroach count when residents were bothered by cockroaches was ≥3, based on deployment of 4 sticky traps per apartment, over a 2-wk period. Assessing and reducing cockroach tolerance thresholds and improving housekeeping through resident education and assistance from community and housing management should be incorporated in future cockroach management programs in order to reduce high cockroach infestation rates found in similar communities.
Moisture conditions of food and soil are essential for the survival and foraging activities of subterranean termites. Polyacrylamide/attapulgite composite is a water-retaining agent that has been applied to increase moisture of agricultural soils. We hypothesize that polyacrylamide/attapulgite composite may increase the moisture of bait matrixes and soil surrounding baiting containers and therefore attract termites and increase their foraging activities. In the present study, aggregation and feeding preferences, survivorship, body water percentage, and wood consumption of Formosan subterranean termites, Coptotermes formosanus Shiraki (Blattodea: Rhinotermitidae), were investigated when responding to polyacrylamide/attapulgite composite that was buried within soil (substrate) or filled in the void volume of baiting containers. Two-choice tests showed that termites consumed significantly more wood when polyacrylamide/attapulgite composite was buried within dry soil (27%-moisture) than the controls (no polyacrylamide/attapulgite composite was provided). However, polyacrylamide/attapulgite composite buried within wet soil (54%-moisture) did not significantly affect foraging behaviors of termites. Multiple-choice tests showed no aggregation or feeding preference of termites in the baiting containers filled with polyacrylamide/attapulgite composite compared with the soil-filled or unfilled ones, whenever the substrate was dry or wet. No-choice tests showed that the presence of polyacrylamide/attapulgite composite (buried within soil or filled in baiting containers) significantly increased wood consumption and body water percentage of termites as well as wood moisture under dry-substrate conditions. Our studies suggest that burying polyacrylamide/attapulgite composite within dry soil may enhance foraging activities of termites, but filling the bait stations with polyacrylamide/attapulgite composite may not effectively attract termites.
Two invasive subterranean termite species, Coptotermes formosanus Shiraki and Coptotermes gestroi Wasmann (Blattodea: Rhinotermitidae), established in South Florida have the potential to hybridize owing to their sympatric distribution, overlapping dispersal flight seasons, and interspecies mating behavior. This study examined the effects of temperature on survivorship and wood-consumption rate (WCR) to determine the potential of such hybrid termites as structural pests. Temperature tolerance was tested using groups of termites from incipient colonies established in the laboratory with four mating types (♀C. gestroi × ♂C. gestroi, ♀C. formosanus × ♂C. formosanus, ♀C. gestroi × ♂C. formosanus, ♀C. formosanus × ♂C. gestroi) in glass screw-top jars placed in incubators at 10, 15, 22, 28, and 35°C in constant darkness for 28 d. Results showed that hybrid termites have a temperature tolerance covering those of both parental species and survived at 15–35°C. WCR was not significantly different among the four mating types, but the WCR in the temperature range of 22–35°C was significantly higher than at temperatures ranging from 10 to 15°C for all mating types. Our results suggest that the potential distribution of the hybrid populations may cover most of the range of both parental species, i.e., 32.5°N and 23.5°S, and they can be as damaging as their parental species, the two most destructive termite pests, C. formosanus and C. gestroi.
Transgenic Bt maize expressing Cry insecticidal δ-endotoxins of Bacillus thuringiensis has been cultivated in South Africa for the control of Busseola fusca since 98. Busseola fusca is resistant to Cry1Ab Bt maize at many localities throughout the maize production region. Pre-release evaluation (94–96) of the inherent susceptibility and post-release assessments (98–2011) of resistance status of B. fusca focused on a limited number of pest populations. This study reports the current levels of susceptibility of 10 B. fusca populations evaluated between 2013 and 2017 and compared this data with previously reported data on the survival of this pest on Bt maize, including data of pre-release evaluations done during 94 and 95. Larval feeding bioassays in which plant tissue of maize events expressing either Cry1Ab or Cry1A.105+Cry2Ab2 (stacked event) proteins were conducted and survival and different life history parameters recorded. Results show a shift in levels of susceptibility of B. fusca to Bt maize. Pre-release evaluation of the single-gene event showed very low larval survival on Bt maize leaf tissue while studies 10 yr later and the current study reported survival of up to 40% and 100% on Cry1Ab maize, respectively. While no larvae completed their life cycle on the stacked event, higher LT50 values in this study indicate a shift in susceptibility of B. fusca to the stacked-gene event and highlight the importance of baseline information and monitoring of pest populations for their susceptibility to Bt maize.
Naled-intoxicated methyl eugenol (ME) is commonly used to control oriental fruit flies, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), in Taiwan. However, non-responsiveness to ME and pesticide resistance in oriental fruit flies may reduce control efficacy. In this study, mark-recapture experiments were used to analyze the effects of naled-intoxicated ME on field and naled-resistant fly strains. ME non-responsiveness was tested in field, naled-resistant, and susceptible strains and pyrosequencing techniques were used to detect frequencies of point mutations on organophosphate resistant alleles in field strains. Finally, the effects of fipronil-intoxicated ME were analyzed to determine whether control efficiency could be enhanced through the use of alternate pesticides. Control efficiency of naled-intoxicated ME was found to be significantly lower in the field and resistant strains compared to the susceptible strain. ME non-responsiveness was found to be 1.7–1.9% in our lab-reared strains (both naled-resistant and susceptible) and 3.4–4.3% in field strains. Results of our pyrosequencing study found frequency of resistant alleles in captured male field flies to be significantly lower than that of the original population, indicating that it is highly probable that resistant flies may escape from traps. Finally, capture rates of naled-resistant flies increased when naled was replaced with fipronil in attractants, showing that use of pesticides with different modes of action could possibly increase control efficiency of intoxicated ME attractants.
Field populations of thrips (Scirtothrips dorsalis Hood) from citrus nurseries and psyllids (Diaphorina citri Kuwayama) from commercial citrus orchards of three districts in Maharashtra State in India were evaluated for levels of resistance to organophosphates (acephate, chlorpyrifos, quinalphos, and dimethoate), neonicotinoids (thiamethoxam, imidacloprid), abamectin and spinosad between 2012 and 2017. Leaf dip bioassays for thrips and shoot tip bioassay for nymph and adult psyllids were used to assess levels of insecticide resistance as indicated by resistance ratios (RRs). In general, levels of insecticide resistance were zero (RR = 1) or very low (RR = 2–10); however, we recorded 21.0- and 28.0-fold increase in resistance (RR = 21–50) to spinosad 45SC in S. dorsalis between 2016 and 2017 that may be attributed to the continuous application of the insecticide for the management of various sucking insect pests of citrus. We found that levels of resistance to insecticides in adult and nymph D. citri collected from the three districts were zero to low (RR = 2–10). Our data show there may be a shift in resistance to neonicotinoid insecticides that are widely used among citrus growers in the study region. Results from this study indicate that the evolution of insecticide resistance and cross-resistance may be decelerated by the rotational use of insecticides with different modes of action.
Pyridalyl is an insecticide that shows significant efficacy against Plutella xylostella, a notorious pest insect worldwide. In this study, we monitored resistance of P. xylostella to pyridalyl in China from 2016 to 2017, determined cross-resistance, inheritance, and synergism of pyridalyl resistance in two pyridalyl-resistant populations, one field-evolved resistant population (ZL-PR) and one laboratory-selected resistant population (XY-PR). We found that variation in susceptibility among 15 field populations in China from 2016 to 2017 was high, with mean LC50 values ranging from 1.839 to 1,652 mg/liter. The laboratory-selected XY-PR strain showed 31.3-fold resistance to pyridalyl and moderate cross-resistance to fipronil.The ZL-PR displayed 1,050.2-fold resistance to pyridalyl and high resistance to all tested insecticides. Genetic analysis illustrated that pyridalyl resistance in ZL-PR was autosomally inherited and incompletely recessive. However, pyridalyl resistance in the XY-PR strain was autosomally inherited but incompletely dominant. Moreover, piperonyl butoxide significantly inhibited pyridalyl resistance in the XY-PR strain. In conclusion, P. xylostella field populations from South China have high levels of resistance to pyridalyl and different modes of inheritance of resistance were found in XY-PR and ZL-PR. Moreover, enhanced oxidative metabolism is possibly involved in resistance of the XY-PR strain but not in the ZL-PR strain.
A piezoelectric quartz crystal impedance (PQCI) sensor was used to investigate influences of the insecticide methamidophos on proteinase activity in midguts of the wolf spider, Pardosa pseudoamulata (Araneae: Lycosidae). Results from PQCI indicated that low-concentration dose methamidophos (0.008%) can activate the proteinase but high-concentration dose methamidophos (0.016–0.032%) can inhibit the enzyme activity.The changes in subcellular structure of spider midgut cells were also observed. Electron micrographs of spider midgut epithelial cells showed that the low-dose methamidophos did not visibly impact the structure of these cells. Conversely, high-concentration dose methamidophos led to severe changes in the cell structure, including the karyotheca dissolved, the nucleolus, and the endoplasmic reticulum disappeared. These may contribute to changes in proteinase activity of spider. This work documents a feasible method for rapid and reliable detection of proteinase activity.
Current assessments from the U.S. Environmental Protection Agency suggest that some current insecticides may be lost or severely restricted in the near future. An experiment was conducted from 2014 to 2015 at two locations in Mississippi to determine the impact of losses of insecticide classes on integrated pest management of insect pests in cotton. The treatments included cotton treated with all available classes of insecticides, cotton treated with all classes except neonicotinoids, cotton treated with all classes except pyrethroids, cotton treated with all classes except carbamates and organophosphates, and an untreated control. Plots were scouted weekly and insecticide applications were made with the most efficacious and economical insecticides for each treatment when that treatment reached threshold for a particular insect pest(s). The primary insects at both locations were tobacco thrips and tarnished plant bugs.Thrips pressure was similar at both locations and generally showed that all insecticide treatments provided a similar level of protection compared with the untreated control. At the Stoneville location where tarnished plant bug pressure was greatest, cotton yields and economic returns differed between plots where all classes of insecticides were applied compared with the untreated control and where neonicotinoids were excluded. However, in Starkville where tarnished plant bug pressure was less, there were no differences among treatments. Although yield and economic returns were similar in high tarnished plant bug pressure areas when using all classes compared with managing without pyrethroids or organophosphates, a rotation among all insecticide classes should be beneficial for resistance management in Mid-South cotton production.
The Chrysodeixis includens nucleopolyhedrovirus (ChinNPV: Baculoviridae: Alphabaculovirus) is a registered insecticide for the management of soybean looper, Chrysodeixis includens (Walker, [1858]) (Lepidoptera: Noctuidae) in Brazil. We conducted studies of baseline susceptibility of Brazilian populations of C. includens to the ChinNPV (Chrysogen, AgBiTech, Fort Worth, TX) as valuable knowledge in support of Integrated Pest Management and Insect Resistance Management programs. In bioassays, neonates were infected with different concentrations of ChinNPV using the droplet feeding bioassay method. Larvae were then transferred to artificial diet and mortality was assessed at 7 d. Results confirm that neonates from Brazilian populations of C. includens are susceptible to ChinNPV. Concentrations from 1.0 × 103 to 1.0 × 108 occlusion bodies (OBs) per ml caused mortality from 1.5 to 99%, respectively. The LC50 ranged from 1.4 × 105 to 7.7 × 105 OBs per ml for populations of C. includens (5.5-fold variation). Similar variation was detected for the LC90 which ranged from 1.6 × 107 to 7.7 × 107 OBs per ml (4.8-fold variation). Importantly, the field-collected populations showed equivalent susceptibility to the reference susceptible population.This indicates a low interpopulation variation in susceptibility of Brazilian populations of C. includens to ChinNPV, representing natural geographic variation and not variation caused by previous selection pressure. The candidate diagnostic concentration of 2.9 × 108 OBs per ml was estimated based on the pooled data and caused mortality ranging from 98.6 to 100%. This concentration will be used in proactive resistance monitoring programs. The Chrysogen will be a valuable tool as a new mode of action in C. includens resistance management in Brazil.
The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), can cause direct damage to citrus trees and is the main vector for the devastating disease, citrus greening disease or huanglongbing. Most molecular studies on this important insect pest use real-time reverse-transcription quantitative polymerase chain reaction (RT-qPCR) to quantify gene expression, including analyzing molecular basis for insecticide resistance in field populations. One critical factor to cause inaccuracy in RT-qPCR results is the lack of appropriate internal reference genes for optimal data normalization. In this study, the expression levels of 10 selected reference genes were evaluated in different tissue samples of psyllid adults and in the insects treated with different temperatures and insecticides. Data were analyzed using different computational algorithms, including Delta Ct, BestKeeper, NormFinder, geNorm, and RefFinder. According to our results, at least two reference genes should be used for the normalization of RT-qPCR data in this insect. The best choices of reference genes for different samples are as follows: ACT1 and Ferritin for different tissue samples, RPS20 and Ferritin for samples treated with different temperatures, TBP and EF1α for samples treated with imidacloprid, and Ferritin and TBP for samples treated with beta-cypermethrin. The reference genes identified in this study should be useful for future studies to analyze the expression patterns of target genes, especially for genes linked with temperature adaptability and insecticide resistance in this insect species in the future.
Lygus bugs are highly polyphagous insect pests. In recent years, Lygus bugs have become more conspicuous on potato, Solanum tuberosum L., fields in the Pacific Northwest, particularly in the Lower Columbia Basin. There are concerns that direct feeding damage or potential pathogen transmission can reduce yield. Lygus species on potatoes in the region are collectively identified as ‘Lygus bugs’. Overlapping physical traits and the fact that the same species exhibit morphological variations across a geographic range makes it difficult to identify Lygus to species level. Thus, in this study we used DNA barcodes in combination with morphological characters to identify Lygus species on potatoes. Three species were identified in the Lower Columbia Basin: Lygus hesperus (Knight) and Lygus elisus L. were the most common, whereas Lygus keltoni L. was the least common. Interspecific genetic distances among Lygus species were relatively low, ranging from 0.013 to 0.004. Neighbor-joining (NJ) tree clustered L. hesperus and L. elisus into two major clades, with L. keltoni forming a subclade within L. hesperus clade. Statistical parsimony analysis corroborated findings from phylogenetic analysis with L. keltoni and L. hesperus sharing one haplotype. Our study demonstrates the utility of integrating morphology and molecular markers in identifying morphologically similar species such as Lygus bugs. The study also serves as a fundamental step in contributing to developing suitable management strategies against Lygus bugs on potato.
Phenacoccus solenopsis, the cotton mealybug (Hemiptera: Pseudococcidae), is one of the major cotton pests in India. Scanty information is available on molecular studies in this insect due to limited genomic or transcriptomic sequence data. With advancement in sequencing technology, enormous genomic and sequencing data are being generated, and RNAi studies are being undertaken in insects, which require reverse transcription quantitative polymerase chain reaction evaluation. These gene expression studies require normalization of mRNA levels with reference genes to account for sample variability. To supplement the molecular studies in this insect, candidate reference genes were identified and evaluated for their expression stability across various developmental stages and starvation stress. Fourteen candidate reference genes including several commonly used ones were investigated across five different stages and under starvation stress using four different statistical algorithms (NormFinder, genNorm, BestKeeper, and RefFinder). Based on this analysis, GST (third, fourth, and adult stage), Actin (Crawler, second instar), TFIID (starvation stress), SDHA, and 28s were identified as best reference genes for expression studies in mealybug.
Many aphids can adapt on plants of differential resistance levels, but molecular interactions underlying host plant utilization and shift of aphids are still not well understood. Here, we sequenced the transcriptome and compared global gene expression profiles of Sitobion avenae (Fabricius) feeding on wheat (i.e., the susceptible plant) and barley (i.e., the resistant plant). In total, 65,200 high-quality unigenes were identified from the merged transcriptomes, and 861 of them were differentially expressed. Relative to their expression on barley, all differentially expressed P450 (cytochrome 450 monooxygenase) genes (e.g., SavCYP6A13, SavCYP4C1, and SavCYP4G15) in S. avenae on wheat were upregulated, suggesting the significance of P450s in xenobiotic metabolism for this aphid on wheat. For S. avenae on barley, some genes encoding for ATP-binding cassette (ABC) transporters (e.g., ABCG1, ABCG4, ABCB7, and ABCA5) and UDP-glucuronosyltransferases (UGTs; e.g., UGT2B1 and UGT2C1) showed a dramatic increase in expression, suggesting that ABC transporters and UGTs could be critical for detoxification metabolism in S. avenae on barley. In addition, the expression for nearly all differentially expressed proteases was upregulated for S. avenae on barley, reflecting xenobiotic challenges facing S. avenae on resistant barley. Thus, various detoxification and other defense-related genes (e.g., proteases and oxidases) showed highly inducible transcript regulation, suggesting great adaptive potential for S. avenae on different plants. All the abovementioned genes will be prime candidates for further studies of molecular interactions underlying host plant use and specialization in this aphid. Our results provide insights into aphids' defenses against variable phytochemicals, and the molecular basis underlying aphid-plant interactions as well.
Sesamia nonagrioides (Lefèbvre) (Lepidoptera: Noctuidae), is a widespread insect pest in Africa, the Middle East, and Europe. However, its pest status varies across its distribution range. It is a major pest of maize in Europe and of sugarcane in Iran. In Africa, it is a major pest of maize in West Africa but not considered as a pest in East Africa. Recent surveys conducted in 2015 recorded S. nonagrioides to be a major pest of sugarcane in Ethiopia and reported the species for the first time in Botswana, outside its known geographic range. The genetic relationship of these records with the previously recorded population of S. nonagrioides was investigated using the cytochrome oxidase subunit I region of the mitochondrial genome. In total, 113 individuals across the geographic range of the species were analyzed and 63 haplotypes were identified. Phylogenetic analysis separated the populations into two clades with no distinct geographic distribution pattern. The genetic differentiation was also not associated with host plants and geographic distances. Results of the molecular analysis revealed the long-time establishment of S. nonagrioides population in Botswana and identified the newly recorded sugarcane population from Ethiopia as part of the wild host population in the country. The phylogeographic patterns observed among population of S. nonagrioides have probably been shaped by Pleistocene's climatic oscillations and geographic range expansions from different refugia with secondary contact and admixture. Possible reasons for the host-plant expansion by the Ethiopian population are discussed.
Kudzu bug, Megacopta cribraria (Fabricius), is mainly distributed in southern China and has been considered an invasive species in the southeastern United States. Megacopta cribraria is a soybean pest with high-temperature resistance, but the molecular mechanisms underlying its thermal adaptation are largely unknown. Here, we performed comparative transcriptome analysis to unravel the molecular response of M. cribraria toward high-temperature stress. Following RNA-seq, we identified 93,959 assembled unigenes, 14,073 of which were annotated in M. cribraria transcriptome libraries. In addition, 127 differentially expressed unigenes (DEGs) were detected, 88 of them were significantly upregulated, whereas the remaining 39 genes were significantly downregulated. Functional classification revealed that the pathways of metabolic process, cellular processes, and single-organism processes were considered to be significantly enriched. In the COG classification, DEGs were mainly localized into O: post-translational modification, protein turnover, chaperone. Moreover, protein processing in endoplasmic reticulum and linoleic acid metabolism were significantly enriched among the 38 KEGG pathways. Further gene annotation analysis indicated that nine heat shock protein-related genes were significantly upregulated. Finally, five HSP DEGs were selected for real-time quantitative polymerase chain reaction validation and demonstrated a similar upregulation trend with RNA-seq expression profiles.Taken altogether, these findings provide new insights into the molecular mechanisms of thermal adaptation in M. cribraria.
The bird cherry-oat aphid, Rhopalosiphum padi (L.), is an insect pest that persistently attacks wheat crops worldwide. Glutathione S-transferases (GSTs) are important detoxification enzymes that play roles in insecticide resistance. In this study, we identified two GST genes (RpGSTS1 and RpGSTS2) from R. padi. Phylogenetic analysis indicated that the genes are associated with the sigma class of insect GSTs. The RpGSTS1 and RpGSTS2 contain nine α-helices and five β-sheets connected by loops, and had 60 and 50% homology with the 3D structure of the Blattella germanica GST5. We tested the toxicity of chlorpyrifos, imidacloprid, isoprocarb, sulfoxaflor, and λ-cyhalothrin to R. padi, and found that the toxicity of five insecticides to the aphid varied.The detoxification activity of GSTs and the expression patterns of RpGSTS1 and RpGSTS2 after insecticide treatments were also analyzed. Compared to the control, the GST activity was increased by 23, 18.5, 13, and 11.5% in aphids treated by LC50 concentrations of chlorpyrifos, isoprocarb, imidacloprid, and sulfoxaflor, respectively. Exposure to different chemical insecticides showed different effects on the expression of RpGSTS1 and RpGSTS2. These results indicate that RpGSTS1 and RpGSTS2 have unique biochemical characteristics and may play roles in resistance to insecticides in R. padi.
Biological invasions have reached large parts of the globe, due to human actions across the planet. Drosophila suzukii (Matsumura, 1931) is a globally invasive species, always associated with enormous and costly damage to agricultural crops. Native to Southeast Asia, D. suzukii recently (i.e., 2013) invaded and is dispersing through South America. Here, we used a phylogeographic approach based on the cytochrome c oxidase subunit I gene fragment to explore the invasion dynamics of D. suzukii populations in Brazil. We identified five haplotypes and moderate genetic diversity in Brazilian populations, which are undergoing demographic and spatial expansion. The analyses of molecular variance indicated a high genetic structure among the populations, which is partially explained by their morphoclimatic origin and invasion history. Drosophila suzukii expanded from southern to southeastern Brazil, aided by human-mediated transport of fruits from region to region. The sharing of haplotypes among Brazilian and other invaded regions of the world suggests a single invasion event of D. suzukii in Brazil, originating from previously invaded areas (e.g., North America and Europe). The rapid geographic dispersal and wide variety of fruits attacked by of D. suzukii require immediate implementation of control strategies (legal and phytosanitary) to manage this pest in Brazil.
Insect neuropeptides represent more than 90% of all insect hormones. The pheromone biosynthesis activating neuropeptide (PBAN)/pyrokinin family is a major group of insect neuropeptides. These neuropeptides regulate a variety of biological functions from embryo to adult in moths including, sex pheromone biosynthesis and diapause. Other functions are yet to be determined.The identification of suitable target genes is most important for the successful application of RNA interference (RNAi) for pest insect control. Insect neuropeptide genes including PBAN are known to have multiple functions and could be a good target for RNAi suppression. In this study, we selected the PBAN gene and its neuropeptide products as an RNAi target for two economically important moth species, the corn earworm, Helicoverpa zea (Boddie), and the tobacco budworm, Heliothis virescens (Fabricius). We investigated RNAi effects on immature moths that had ingested the specific double-stranded RNA (dsRNA) starting at the first instar larva through pupation. We report that RNAi treatments resulted in delay of larval growth, interference of pupal development, and mortality in the two pest moths. In addition, we selected small interfering RNAs (siRNAs) to determine if they have negative phenotypic effects similar to their full-length RNAi parents.This is one of the few examples of negative RNAi effects on lepidopteran pests via feeding and suggests possible RNAi-based control of pest moths.
As interest in production of second-generation biofuels increases, dedicated biomass crops are likely to be called upon to help meet feedstock demands. Switchgrass (Panicum virgatum L.) is a North American native perennial grass that as a candidate biomass crop, combines high biomass yields with other desirable ecosystem services. At present, switchgrass is produced on limited acres in the United States and experiences relatively minor insect pest problems. However, as switchgrass undergoes breeding to increase biomass yield and quality, and is grown on more acres, insect pest pressure will probably increase.To investigate how currently available switchgrass ecotypes and cultivars may influence herbivory by generalist insect herbivores, we performed feeding trials using neonate and late-instar fall armyworm [Spodoptera frugiperda JE Smith (Lepidoptera: Noctuidae)]. No-choice feeding experiments were used to explore how switchgrass varieties influence larval establishment, consumption levels, and life-history traits in contrast to a preferred host, corn (Zea mays L.). Neonate S. frugiperda consumed greater amounts of corn than switchgrass and increased amounts of upland versus lowland ecotypes. Late-instar larvae, which do the majority of the larval feeding, exhibited lower consumption of lowland ecotypes, which led to increased development time and reduced pupal weights. The exception to these trends was the upland cultivar ‘Trailblazer’, which unexpectedly performed similarly to lowland cultivars. These results suggest that both switchgrass ecotype and cultivar can influence feeding damage by a common generalist herbivore. These findings can be used to help inform current switchgrass planting decisions as well as future breeding efforts.
Palpita forficifera Munroe, 1959 (Lepidoptera: Crambidae) is the main pest of the olive tree (Olea europaea L. Oleaceae) in Brazil. This study investigated the biology of P. forficifera reared on different hosts and elaborated the corresponding fertility life table for a better understanding of its development. Biology of P. forficifera was studied using olive cultivars Arbequina, Arbosana and Koroneiki and the alternative host privet (Ligustrum lucidum Ait., Oleaceae), under controlled conditions of temperature (25 ± 2°C), relative humidity (60 ± 10%), and photophase (14 h). We evaluated duration and viability of egg, larva, and pupa stages; number and duration of instars; sex ratio; pupa weight; duration of preoviposition, oviposition, and postoviposition periods; fecundity and longevity. The fertility life table was elaborated from these parameters. Larvae fed with privet had longer larval stage, and consequently, egg-pupa period. Larva viability was lower in cv. Arbosana, which reflected in lower viability in the egg–pupa period. Larvae fed with cv. Koroneiki originated females with higher fecundity. From the joint assessment of the biological parameters and the fertility life tables, cv. Koroneiki provided the greatest population increase, while cv. Arbosana impaired P. forficifera development. Thus, in areas of high occurrence of this species, cv. Arbosana should be considered as the more indicated cultivar for the establishment of new olive groves.
The whitefly Aleyrodes proletella L. (Hemiptera: Aleyrodidae) has become a major agricultural pest on a broad range of Brassica crops in Europe and has spread to North and South America and Australia. In order to understand its present outbreak, information about its life history parameters in relationship to different host plants is needed. Therefore, we tested the reproduction potential of A. proletella on four different host plants under greenhouse conditions: Kohlrabi, kale, white cabbage, and winter oilseed rape. The influence of host plant on preoviposition period, fecundity, survival rate, and sex ratio was examined. Additionally the effect of mating scenario (45-d mated females and males; virgin females and males; 6-d mated females) on life history parameters of A. proletella adults was evaluated. The mating scenario did not significantly influence the survival rate of A. proletella females and males and did not impact female fecundity and preoviposition period. Fecundity of A. proletella was significantly affected by host plant species: the shortest preoviposition period and highest oviposition rate was observed on winter oilseed rape, while the longest and lowest was recorded on white cabbage. The survival rate on white cabbage was significantly lower compared with those reared on the other host plants. The sex ratio of A. proletella progeny was also significantly affected by the host plant species. Our research indicates that winter oilseed rape is a highly suitable host for A. proletella in terms of fecundity, survival rate, and sex ratio, which might explain the current outbreak of A. proletella.
The aim of the study was to explore the acceptability of 14 species, varieties, and cultivars of grain legumes (Fabales: Fabaceae) to the pea aphid, by investigating the aphid probing behavior using the electrical penetration graph (EPG) technique. Phaseolus coccineus L. ‘Felicia’, Pisum sativum L. ‘Medal’, P. sativum arvense (L.) Poir. ‘Fidelia’ and ‘Hubal’, and Vicia faba L. ‘Dragon’ are highly susceptible, with no antixenosis potential against Acyrthosiphon pisum (Harris) (Hemiptera: Aphididae): aphid probing and feeding activities were not impeded. Lathyrus sativus L. ‘Derek’, Lupinus luteus L.’Perkoz’, Vicia faba minor Beck. ‘Sonet’ are moderately susceptible to A. pisum infestation, with minor antixenosis potential and with antixenosis factors in non-phloem tissues. Aphids on these plants had difficulty to attain the phloem phase and phloem sap ingestion phase. During phloem phase, ingestion lasted for long periods of time. Lens culinaris Medik. ‘Green’ and Phaseolus vulgaris L. ‘Boruta’ are moderately susceptible to A. pisum infestation, with minor antixenosis potential and with antixenosis factors in the phloem. Behavior of aphids during pre-phloem phase was similar to that on highly susceptible plants but individual phloem phases and sap ingestion phases were short and contained a high proportion of watery salivation. Glycine max (L.) Merr. ‘Aldana’, L. angustifolius L. ‘Boruta’, P. coccineus ‘Rothbluende’, and P. vulgaris ‘Mamut’ are highly resistant to A. pisum infestation, with high antixenosis potential and with strong antixenosis factors in non-phloem tissues: aphid probing time was shortened, non-probing intervals between probes were long, and the success rate in reaching phloem phase was very low or none.
In recent times, research has focused on integrated pest management approaches using nonchemical alternatives such as mating disruption for the control of stored product insect pests. In this study, we examined the effect of imposed delayed mating on the longevity and reproductive performance of the cigarette beetle, Lasioderma serricorne (F.), a serious insect pest of value added grain-based products, tobacco products, and spices. Delayed mating, progressing 0–14 d, was imposed on both sexes simultaneously, on males only, and on females only. Insects were observed daily for longevity, and F1 progeny was recorded 7–10 wk after mating pairs were placed together. Unmated adults lived significantly longer than mated adults, and mated females lived significantly longer than mated males. However, the length of the period of mating delay did not significantly affect the longevity of mated adults. Progeny production decreased with the age of adults at mating. The number of progeny produced when mating delay was imposed on both sexes simultaneously or on females only was significantly lower than when mating delay was imposed on males only. Hence, females were more adversely affected by delayed mating than males. Findings from this study may provide information for the development of mating disruption techniques that can delay mating and may be effective in keeping populations of L. serricorne below levels that would warrant a control action.
The house fly, Musca domestica L., is a globally distributed nuisance and disease-carrying urban and livestock pest. Control mostly relies on synthetic insecticides but resistance to them has become problematic. p-Anisaldehyde, a compound found in many edible plants, was assessed for its effects on different life stages of M. domestica. Whereas p-anisaldehyde, applied as an adult contact spray, caused >80% mortality by 30 min at a 30% concentration, egg mortality on treated substrate was complete at 0.1%, and the LC90 was 0.024%. Only 0.5 and 1 ml of 1.5% p-anisaldehyde mixed into 100 g of cow manure curtailed pupation. When the amount of p-anisaldehyde was increased to 2 ml, 0.75% p-anisaldehyde reduced pupation by 95.5%. In static air olfactometer tubes, 0.075% p-anisaldehyde repelled substantial numbers of adult M. domestica within 30 min. Repellency of 60–78% was maintained throughout the 4-h bioassay. This study demonstrates that p-anisaldehyde is strongly bioactive against M. domestica in terms of lethal and nonlethal effects.
A comparative study was conducted to test the efficiency of Centers for Disease Control and Prevention (CDC) light traps baited with either dry ice or carbon dioxide (CO2) produced from one of three different sources in collecting mosquitoes (Diptera: Culicidae) in Thailand. Treatments consisted of dry ice pellets, CO2 gas produced from one of three prototype CO2 generator systems (TDA, CUBE, Moustiq-Air Med-e-Cell - MEC), and a CDC light trap without a CO2 source. The best performing prototype from Thailand was then tested in collecting sand flies (Diptera: Psychodidae: Phlebotominae) in Greece. A total of 12,798 mosquitoes and 8,329 sand flies were sampled during the experimentation. The most prevalent mosquito species collected in Thailand were: Culex vishnui Theobald > Anopheles minimus Theobald > Culex tritaeniorhynchus Giles > Anopheles sawadwongporni Rattanarithikul & Green. By far the most prevalent sand fly species collected in Thessaloniki was Phlebotomus perfiliewi Parrot followed by Phlebotomus tobbiAdler andTheodor and Phlebotomus simici Nitzulescu. In general, theTDA treatment was the only treatment with no significant difference from the dry ice-treatment in mean trap catches. Although dry ice-baited traps caught higher numbers of mosquitoes and sand flies than the TDA-baited traps, there was no difference in the number of species collected. Results indicate that the traps baited with theTDA CO2 generator were as attractive as traps supplied with dry ice and, therefore, the TDA CO2 generator is a suitable alternative to dry ice as a source of carbon dioxide for use with adult mosquito and sand fly traps.
Honeybees (Apis mellifera Linnaeus) (Hymenoptera: Apidae) play a major role in the pollination of cranberry (Vaccinium macrocarpon; Ericaceae). However, fungicide applications during cranberry bloom may affect bees foraging behavior. This research reports the amount of cranberry and noncranberry pollen brought back to hives immediately before and after two types of fungicide applications. The amount of cranberry pollen decreased while the amount of noncranberry pollen increased following a fungicide application. However, this relationship differed depending on the type of fungicide applied. Understanding how different fungicides specifically impact bee behavior is essential to minimizing bee exposure to potentially harmful chemicals.
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