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The lychee erinose mite, Aceria litchii (Keifer) (Acari: Eriophyidae), is an important pest of lychee (Litchi chinensis Sonn.; Sapindaceae) trees. This minute mite prefers to feed on young, new flush causing the formation of galls called “erinea.” Chemical control to protect the new flush is the primary management approach that has been used to control this mite. Aceria litchii was detected recently in Lee County, Florida, USA, and there is an urgent need to identify an acaricide that can control mite populations. Among the acaricides registered for use on lychee in Florida, abamectin was reported to be effective against A. litchii from other parts of the world. However, it remains unknown whether this acaricide can control the mites inside the erinea effectively and protect the new flush. We investigated whether abamectin alone or in combination with an organosilicone surfactant could control an existing mite infestation. Lychee leaflets that had erinea were sprayed with acaricides, then placed on uninfested plants and monitored for symptom development. One mo after placing treated leaflets on uninfested plants, the same treatment was applied to the whole plants and monitored for erinea development on the new flush. Our results showed that none of the treatments were able to control the mites inside the erinea and protect the new flush. The methods described here can be used for more precise evaluations of other acaricides that are urgently needed to control A. litchii in Florida.
There are drawbacks associated with current methods used to quantify insect predation. However, there has been relatively little effort to experimentally document the sources of biases associated with different methodologies. In this study, we investigated how methods used experimentally to quantify predation may influence insect antipredator defenses being observed, and thus alter the determination of the number of prey killed by predators, and potentially the conclusions reported in the study. We focused on acclimation period, which represents the time between the point at which a prey individual is made available, for example on a leaf, and when the experiment is initiated. In essence, this is the period of time during which an organism adjusts to the conditions that surround it before a treatment is imposed. We investigated if prey acclimation period on plants influences the antipredator behavior of larval Orgyia leucostigma (J.E. Smith) (Lepidoptera: Lymantriidae), and the number of prey killed in the laboratory by the predatory wasp Polistes fuscatus (Fabricius) (Hymenoptera: Vespidae). The results of this study provide evidence that acclimation time significantly affects the antipredator behavior observed and mortality of caterpillars exposed to predators. The majority of larvae allowed short acclimation periods did not drop in response to the attacks of wasps. These larvae suffered significantly higher mortality compared to caterpillars that were allowed to acclimate for longer periods of time.
KEYWORDS: biological control agents, elongate hemlock scale, interception, plant inspection, agentes de control biológico, insectos escamas, intercepción, inspección de plantas
We characterized the entomopathogenic fungal species, Conoideocrella luteorostrata (Zimm.) D. Johnson, G.H. Sung, Hywel-Jones & Spatafora (Hypocreales: Clavicipitaceae), on the elongate hemlock scale, Fiorinia externa Ferris (Hemiptera: Diaspididae), infesting Fraser fir Christmas tree, Abies fraseri (Pursh) Poir (Pinaceae). Fraser fir Christmas trees that were cultivated in Michigan, North Carolina, and Virginia were intercepted in Florida during plant inspection. This study is based on the isolation in pure culture, and morphological and molecular characterization using a 4-locus (ITS, LSU, SSU, tef1) and represents the first record of C. luteorostrata on F. externa. In addition, we reviewed all previously reported natural enemies of F. externa in the USA, discussed their potential as biological control agents, and concluded the need to explore a new natural enemy of F. externa. We recommend using C. luteorostrata as a biocontrol agent for F. externa. We also suggest that our isolate could be a source of new uncharacterized active compounds and could be used in the biological control of whiteflies and scale insects, as demonstrated in other C. luteorostrata strains. We also discussed the importance of investigating biological control agents in pest and pathogen interception samples.
KEYWORDS: banana stem borer, Saccharum officinarum, soil insect pest, cultural control, gusano tornillo del plátano, Saccharum officinarum, plagas del suelo, control cultural
The giant sugarcane borer, Telchin licus (Drury) (Lepidoptera: Castniidae), also known as the banana stem borer, is an economically important pest of sugarcane in eastern Colombia. The presence of larval and pupal stages within stalks makes biological control of this pest difficult, and growers often resort to insecticide applications. Hilling up the soil around the base of plants, or soil mounding, is a cultural practice sometimes used to improve rooting in sugarcane. Because mature larvae cut holes in stalks close to ground level through which they can emerge as an adult, we hypothesized that soil mounding would impede adult emergence, and thus contribute to population reduction. Two experiments were conducted in fields with significant infestations of this pest in Puerto López, Meta, Colombia, during the seasons of adult emergence in this region (Apr–May and Oct–Nov). Manual mounding of soil to a height of 20 cm was tested in the first trial, and mechanized mounding of soil in the second, which also compared 2 mounding heights (10 and 20 cm). In both cases, 2 m row transects of plants were caged to collect emergent adults. Adult emergence was reduced up to 65% in all mounding treatments, whether manual or mechanical, and regardless of mounding height, demonstrating that this cultural practice could be a useful tactic for inclusion in an integrated management program for this pest. However, as with any other cultural practice in pest management, region-wide implementation likely would be required to impact local population densities, and efficacy will depend further on low levels of moth immigration from alternative host plants.
A survey of the mite fauna on citrus was conducted in 550 dooryard trees including 25 varietal trees in Florida, USA, during 2009 to 2014 in the following counties: Broward, Charlotte, Collier, Dade, Indian River, Lee, Manatee, Martin, Palm Beach, Pinellas, Polk, St. Lucie, and Sarasota. One abandoned block of trees was sampled in Highlands County. Seventeen species of Phytoseiidae were identified from 1,982 slide-mounted mites collected from these trees. Euseius ennsi Ueckermann, Moraes & Childers, Euseius ovalis (Evans), Neoseiulus loxus (Schuster & Pritchard), Phytoseius coheni Swirski & Shechter, Typhlodromalus jucundus (Chant), and Typhlodromina johnsoni (Mahr) were new records on Florida citrus. Amblyseius largoensis (Muma) was the most abundant species with 854 of the phytoseiids followed by E. ovalis, Euseius mesembrinus (Dean), E. ennsi, and Iphiseioides quadripilis (Banks) (all Mesostigmata: Phytoseiidae) with 418, 388, 81, and 68 mites, respectively. Amblyseius largoensis was the most frequently collected phytoseiid from 220 of the 550 dooryard and varietal trees, followed by E. ovalis from 97 trees. A total of 787 commercial citrus trees were sampled in Florida from 2009 to 2014 in De Soto, Hardee, Hendry, Highlands, Indian River, Okeechobee, Palm Beach, Polk, and St Lucie counties. One T. jucundus was collected from these trees. Amblyseius largoensis and E. ovalis are recommended for evaluation as general predators of mite and insect pests in enclosed structures of citrus under protective screen (CUPS). Both mites have broad host ranges and are known mite predators, including some insect pests. Both species appear to have some degree of pesticide tolerance and use supplemental plant pollens such as Quercus virginiana Mill. (Fagaceae) or Typha spp. L. (Poaceae). Differences in phytoseiid species in this study and from earlier sampling for mites on citrus in Florida from 1986 to 2003 by the first author, a horticultural mineral oil (HMO) field study during 1994 to 1996, M. H. Muma from 1951 to 1975, and Denmark and Evans (2011) are included for comparison. A combined total of 60 phytoseiid species are reported on Florida citrus for the period of 1951 to 2014.
Food-based traps are an integral component of detection systems for invasive fruit fly (Diptera: Tephritidae) species which pose a serious threat to many agricultural crops. A commonly used bait is torula yeast borax solution; however, it is attractive for relatively short intervals (1–2 wk), necessitating frequent bait replacement. A dry, synthetic food bait that incorporates several components into a single matrix (or food cone) has been developed and appears to be effective for as long as 4 to 10 wk in field trials with the Mediterranean fruit fly (Ceratitis capitata [Wiedemann]) and the Caribbean fruit fly (Anastrepha suspensa [Loew]) (both Diptera: Tephritidae). Based on these results, food cones are used now in several large-scale fruit fly detection programs even though their attractiveness to other economically important tephritids, most notably Bactrocera and Zeugodacus species, has not been well studied. The goal of this study was to compare the captures of oriental fruit fly (Bactrocera dorsalis [Hendel]) and melon fly (Zeugodacus cucurbitae [Coquillett]) (both Diptera: Tephritidae) in traps baited with torula yeast borax solution with captures in traps baited with 3-component (ammonium acetate, putrescine, and trimethylamine) or 2-component (ammonium acetate and putrescine) food cones. Data from wild and released flies of both species showed that captures were significantly higher in traps baited with the torula yeast borax than those with either type of synthetic formulation. Implications of this finding for trapping programs are discussed.
The invasive brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), is an agricultural and nuisance pest in Georgia and Alabama, USA. Natural enemies may provide significant suppression of the brown marmorated stink bug, and sentinel egg masses are deployed commonly on plants in the field to measure their effects. The objective of this study was to evaluate the effect of deployment duration (2–5 d) on parasitism and predation of brown marmorated stink bug sentinel egg masses in plum, peach, blueberry, tomato, sassafras, corn, and soybean in these 2 states. Retrieved egg masses were processed to quantify rates of predation and parasitism and identify parasitoid species and predation types. Across crops, predation and parasitism were higher significantly in plum at 5 d compared to 2 d deployment but was similar in soybean regardless of exposure time in 2017. Predation and parasitism were higher significantly after 5 d of exposure compared to 2 d and 3 d whereas parasitism was significantly higher at 3 d compared to 2 d exposure in 2018 to 2020. For individual crop trials, though, effects of time of exposure were tested in different yr, sampling dates, and crops with variable results. When significant differences were detected for parasitism in plum, peach, tomato, and sassafras, a 5 d deployment resulted in higher parasitism compared to 2 d. Given the variability of factors that affect parasitism and predation under field conditions, we conclude that a 5 d deployment is optimal and a 3 d exposure time is minimal for assessing predation and parasitism. An additional benefit for a 5 d exposure is that it increases the probability of detecting hyperparasitism.
KEYWORDS: red imported fire ant, insect community, pasture management, grasslands, hormiga roja de fuego importada, comunidad de insectos, manejo de pastos, pastizales
The red imported fire ant, Solenopsis invicta (Buren) (Hymenoptera: Formicidae), is one of the most prolific invasive species in the southeastern US. These invaders preferentially colonize highly disturbed land and grassland habitat. Management of livestock in pasture systems can have a profound impact on the level of disturbance in grassland habitats, and we hypothesized that adaptive multi-paddock pasture management would significantly increase S. invicta abundance in southeastern US pastures where arthropod diversity would decrease as S. invicta abundance increases. We studied the effects that adaptive multi-paddock pasture management systems (based on stocking density, rotation frequency, and insecticide/anthelmintic [wormer] application rates) have on fire ant mound abundance and arthropod diversity for the soil, foliar, and dung communities. Solenopsis invicta mounds and mound areas were documented along transect lines in 6 pastures. Soil and foliar arthropod communities were collected along the same transect lines, and dung communities were sampled from pats within the pasture system. Pastures managed under adaptive multi-paddock practices had 3.4× more S. invicta mounds and 4.6× more mound area than their conventionally managed counterparts. However, arthropod diversity did not correlate with S. invicta abundance in any of the 3 arthropod communities sampled. This study shows adaptive multi-paddock pasture management can increase S. invicta mound abundance, but arthropod communities in adaptive multi-paddock pastures do not suffer decreased diversity from increased abundance of S. invicta.
Pheromone traps play a crucial role in the integrated pest management of the red palm weevil, Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae). The objective of this study was to increase the effectiveness of pheromone traps by evaluating the effects of location, temperature, degree of palm fruit fermentation, and pheromone lure source on red palm weevil capture rates. Traps baited with either Ferrolure or Rhylure were positioned in 3 rows and checked twice per wk for 12 wk starting 20 Apr 2019. Overall weekly capture rate per trap varied from 1.25 to 9.00. Those traps that were placed in the shade near infested date palm trees in areas of relatively high soil moisture captured more red palm weevil (9 adults per trap per wk) than traps exposed to direct sunlight (1.25 adults per trap per wk). Additionally, traps placed at the field edge captured more adults than those in the middle of the field. Capture rates were highly negatively correlated with temperature. Ferrolure traps captured significantly more red palm weevils than Rhylure traps. The sex ratio of captured weevils in all traps was female-biased. Results obtained from Y-tube olfactometer assays indicated that the response of red palm weevil adults to 5- and 8 d old fermented date fruits were relatively high (86.7–100%). In kairomone field tests more red palm weevil adults were attracted to traps with 8 d fermented date fruits compared with 5 d old. Our results indicated that placing traps containing Ferrolure, water, and kairomones in red palm weevil preferred sites near the edges of the orchard in moderate air temperatures (22–33 °C) increased the efficacy of pheromone traps.
Sweetpotato weevil, Cylas formicarius elegantulus (Summers) (Coleoptera: Brentidae), an in-field and storage pest of sweetpotato, is the primary insect constraint to sweetpotato production in tropical and subtropical regions. Feeding by adult and larval sweetpotato weevil induces terpenes, rendering storage roots unmarketable. To reduce storage root damage and sweetpotato weevil populations, the present experiment tested the impact of sweetpotato cultivar on developmental time, adult emergence, body length, weight, and supercooling point of sweetpotato weevil. The cultivars tested were ‘Beauregard’ and ‘Evangeline,’ both orange fleshed cultivars susceptible to sweetpotato weevil, and ‘Murasaki,’ a white fleshed cultivar known to be resistant to sweetpotato weevil. There were no differences in developmental time with most adult sweetpotato weevils emerging 34 to 44 d after oviposition. However, the number of adult sweetpotato weevil that emerged from Beauregard (38.9 ± 3.3) and Evangeline (48.4 ± 6.2) roots were greater than numbers emerging from Murasaki (11.1 ± 3.5), indicating resistance is due to antixenosis. Although fewer in number, adults (male and female) emerging from Murasaki were heavier than males and females emerging from Beauregard and males from Evangeline. Supercooling points of sweetpotato weevil males emerging from Murasaki (–17.9 ± 0.4 °C) were significantly lower than Beauregard (–16.3 ± 0.5 °C) but similar to Evangeline (–17.1 ± 0.4 °C). Host plant resistance expressed by Murasaki may reduce sweetpotato weevil populations significantly, but those that emerge may be better suited to survive the cold.
KEYWORDS: fall armyworm, monitoring, pheromone traps, pheromone lures, cropping system, gusano cogollero, monitoreo, trampas de feromonas, señuelos de feromonas, sistema de cultivo
The fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), has now become a pest of global concern. Originally known to be endemic to the Western Hemisphere, its first detection in Africa was followed by spectacular outbreaks and spread to almost all sub-Saharan countries. The rapid incursion of S. frugiperda on maize (Zea mays L.; Poaceae) fields in Africa highlighted a crucial need for a comprehensive assessment of integrated pest management strategies in most smallholder farms. However, these strategies cannot successfully function without efficient monitoring and surveillance efforts. These trapping studies were designed to provide an indication as to whether pheromone trap-lure combinations and simple changes in landscape and agricultural practices might mitigate fall armyworm infestations. Our data show that the commercially available Unitrap was the most effective design for fall armyworm captures among the traps tested. The inexpensive home-made 2 L jar trap was capable of consistently collecting fall armyworm during the first season of relatively moderate fall armyworm density. However, the number of fall armyworm captured by home-made trap were several fold lower than by the Unitrap under all conditions, and almost no fall armyworm was captured during the second season by home-made 2 L jar when fall armyworm density was low. Substantial differences were observed among the pheromone blends with respect to numbers of fall armyworm and non-targets captured. The 4-component blend attracted the most fall armyworm under all conditions. The 2-component blend was the most selective, with no non-target species found during the second season experiments.
Stink bugs (Hemiptera: Pentatomidae) are polyphagous pests that disperse from woodland habitats into crops following food availability. Black cherry (Prunus serotina Ehrh.; Rosaceae) is common in the southeast US. In this 3-yr study, our principal objective was to determine if black cherry acts as a reproductive host as well as a source of food for stink bugs in woodland habitats adjacent to crops in Georgia, USA. Each yr, black cherry trees were examined visually for stink bug species and stages in addition to using pheromone-baited canopy and ground traps to capture them. In 2016, we compared the number of stink bugs captured in canopy traps versus ground-based traps. Chinavia hilaris Say, Euschistus servus (Say), Euschistus tristigmus (Say), and Nezara viridula (L.) (all Hemiptera: Pentatomidae) were detected in traps each yr of the study. Total number of stink bugs was significantly higher in ground traps (1.53 ± 0.07) compared to canopy traps (0.71 ± 0.07) in the 2016 test. Only C. hilaris (99.2%) and N. viridula (0.8%) were found on trees during visual sampling. Over both types of sampling methods, egg masses, most instars, and both sexes of adults of C. hilaris were detected in black cherry. The nymph to adult ratio for this species was 1:1 in traps and nymph biased in visual samples. Anastatus reduvii (Howard) (Hymenoptera: Eupelmidae) (44%), Trissolcus edessae Fouts (Hymenoptera: Scelionidae) (35%), and Ooencyrtus sp. (Hymenoptera: Encyrtidae) (21%) emerged from C. hilaris egg masses. The nymph to adult ratio for N. viridula was adult biased. Both nymphs and adults of E. servus and E. tristigmus were captured in traps; however, the majority of individuals were adults. We conclude that black cherry is a significant reproductive host and a food source for C. hilaris. However, our results indicate that it serves as a food source more so than a reproductive host for the other 3 stink bug species.
Two main pests were found attacking purple mombin or Spanish plum, Spondias purpurea (Sapindales: Anacardiaceae) in Homestead, Florida, USA: Tenuipalpus uvae De Leon (Acari: Tenuipalpidae), a flat mite damaging the leaves, and the spondias psyllid, Calophya spondiadis Burkhardt & Mendez (Hemiptera: Psyllidae) feeding on the flowers, fruitlets, and tender expanding leaves. Tenuipalpus uvae populations are composed principally of females. Female longevity was 13.1 ± 2.0 d and unmated females oviposited 5.0 ± 1.0 eggs in their lifetime. On average, eclosure time for eggs from laboratory-reared unmated females was 10.2 ± 0.1 d, and developmental times for the larva, protonymph, and deutonymph were 6.6 ± 0.4 d, 5.7 ± 0.2 d, and 6.8 ± 0.7 d, respectively. In a survey of S. purpurea leaflets, the upper surface had a significantly higher number of nymph and adult mites (6.43 ± 0.60) than the lower surface (2.29 ± 0.35). Calophya spondiadis laid their eggs on flowers at first, because these were the first to sprout in Jan, and they were heavily infested by the end of Mar with an average of 10.9 ± 1.5 eggs and 9.6 ± 1.1 nymphs per flower. Few eggs or nymphs (0.17 ± 0.17 and 0.08 ± 0.08, respectively) were found per fruit; nonetheless, the fruit did have multiple punctures or necrotic spots (16.7 ± 4.3 per fruit), likely acquired as nymphs fed on the flowers and their ovaries. Significantly more eggs were found on the upper surface of the leaves and the petiole portion adjacent to each leaflet than the underside of the leaves, and most nymphs migrated to the undersides. The feeding damage resulted in black, necrotic spots that became brown pits as the leaves matured and hardened.
Ants intercepted by the Hawaii Department of Agriculture in 2018 and 2019 identified as Solenopsis spp., and possibly S. invicta, were submitted to the United States Department of Agriculture-Agricultural Research Service-Center for Medical, Agricultural and Veterinary Entomology, Imported Fire Ant and Household Insects Research Unit for further taxonomic assessment using genetic and chemical methods. The 2018 sample consisted of 1 worker ant, and the 2019 sample consisted of 3 worker ants. Thoraces were used for genetic assessment and gasters were used for venom analyses. It was determined readily from genetic and chemical analyses that the intercepted ants were not S. invicta or S. richteri. Mitochondrial COX1 gene sequences were compared with previously published data from Solenopsis species. The closest match for the 2018 sample was S. xyloni, which is native to the shipment's origin (San Diego, California, USA). The 2 major alkaloids found were characteristic of the S. geminata species group. In addition, the alkaloid ratio closely matched that of S. xyloni. Therefore, the alkaloid analysis of the 2018 intercepted ant concurs with the genetic data that the ant was an S. xyloni worker. The COX1 gene sequences of the 2019 interceptions most closely matched S. geminata. The corresponding venom alkaloid profile also eliminated S. invicta and S. richteri as possibilities. However, 1 major alkaloid was unusual (Fig. 2) and normally is found only in trace amounts. We suggest the 2019 specimens are an unusual variant of S. geminata.
Bahiagrass (Paspalum notatum Flüggé; Poaceae) is primarily a pasture grass in the southern US. It is also lawn grass found in residential settings, public parks, and planted in golf courses. Bahiagrass is principally wind-pollinated, but the pollination contribution of insect pollinators is not documented. A survey was conducted on bahiagrass patches in central Georgia, USA, to determine the visitation of foraging pollinators. The results showed that European honey bees, bumblebees, and sweat bees forage on bahiagrass spikelets. Of the total bees observed, 10.6% (n = 94) were foraging on bahiagrass, compared to 46.8% on white clover, 27.7% on dandelion, and 14.8% on buckhorn plantain. This is the first report showing bee foraging on bahiagrass. The results suggest that bahiagrass spikelets may be a supplemental resource for bees and essential for bee conservation programs in rural and suburban areas. More research is warranted to determine how bahiagrass spikelets play a role in meeting the nutritional needs of bees to help sustain their colony and provide pollination service.
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