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Plants present constitutive or induced defense mechanisms against herbivory. In addition, studies show that there are interactions between these different defense mechanisms when multiple species infestations occur. This study investigated the interaction between maize defensive mechanisms to control two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae) under single and double species infestations with this spider mite and fall armyworm, Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae). The experiment was carried out in a greenhouse with the following treatments: uninfested Bt (Bacillus thuringiensis Berliner; Bacillaceae) and conventional maize, single infestation with spider mite on Bt and conventional maize, and both maize types with infestations of spider mite and fall armyworm. Two d after infestation, all treatments were re-infested with spider mite. The number of eggs, immatures, and adult females (alive and dead) were recorded for re-infested populations. In addition, a leaf sample was taken from all maize plants for spectrometric analysis. There was no significant difference of biological variables of spider mite between Bt and conventional plants, as well as the ones from pre-infested and non-infested plants. The same chemical pattern of ions was observed on plants in these 4 groups. In the conventional pre-infested plants with spider mite and fall armyworm, the population of re-infested mite showed reduced survival and fertility. Defensive compounds detected were HMBOA-Glc, Linoleoyl-GPI, and kaempferol rutinose. It was suggested that there is direct induced defense against spider mite in conventional maize in multiple infestations with spider mite and fall armyworm.
This study assessed the biological characteristics of Cotesia flavipes (Cameron) (Hymenoptera: Braconidae) with different densities of female parasitoids with Diatraea saccharalis (Fabricius) (Lepidoptera: Crambidae) caterpillars. Third instar caterpillars of D. saccharalis were exposed to C. flavipes females at parasitoid to host ratios of 1:1, 3:1, 6:1, 9:1, and 12:1, with 5 replications. The parasitism of C. flavipes was 90% at 3:1 ratio, and the emergence was 100% for all densities. The life cycle of C. flavipes ranged from 18.17 ± 0.26 to 18.93 ± 0.50 d with the densities of 12:1 and 1:1 parasitoid to host. The higher progeny of C. flavipes (87.38 ± 2.07 and 67.18 ± 2.57 individuals per D. saccharalis caterpillar) were obtained at the densities of 3:1 and 6:1, respectively. The sex ratio of parasitoid per D. saccharalis caterpillar ranged from 0.12 ± 0.05 to 0.66 ± 0.02 between the parasitoid to host densities of 12:1 and 3:1, respectively. The density of 3:1 C. flavipes females per D. saccharalis caterpillar was found to be optimal for propagation of the parasitoid.
The formicofauna of temperate Mexican ecosystems have been studied poorly. The objective of this study was to document the number of ant species in the protected natural area of La Malinche National Park, which features a temperate ecosystem in central Mexico. Furthermore, this study serves to update the list of species for Tlaxcala State in this area of the country. During 2015 to 2016, samples were collected along six 400 m linear transects in oak forest and agricultural land (2,700, 2,800, and 2,900 masl), using pitfall traps, baits with either protein or sugar, and hand collection from plants (where ants were foraging for floral nectar, extrafloral nectar, or honeydew). Twenty-three ant species belonging to 14 genera, 11 tribes, and 4 subfamilies were collected in La Malinche National Park. One genus (Brachymyrmex Mayr [Hymenoptera: Formicidae]), 7 species in the park, and 5 species in Tlaxcala State were new collection records. In pitfall traps, 23 species were recorded, where Dorymyrmex insanus Buckley, Formica densiventris Viereck, Lasius mexicanus Wheeler, and Brachymyrmex musculus Forel (all Hymenoptera: Formicidae) were collected exclusively from agricultural land. Temnothorax brevispinosus MacKay and Stenamma huachucanum Smith (both Hymenoptera: Formicidae) were collected exclusively in the oak forest, whereas 17 species were recovered from both habitats. Nine species were recorded from either protein or sugar baits; Formica propatula Francoeur and Temnothorax texanus Wheeler (both Hymenoptera: Formicidae) were recorded only in tuna baits, and with the remainder of the species collected with tuna and honey. Seven ant species were recorded from hand collections on plants. We have increased the number of ant species in Tlaxcala State from 53 to 58 (28 of which are present in La Malinche National Park). This faunal survey demonstrated that there is a great diversity of ant species in this temperate ecosystem. It is urgent to document the diversity of formicofauna in these types of ecosystems because they may possibly be the first to be negatively affected by climate change.
Three species of potato tuber moths, Tecia solanivora Povolny, Symmetrischema tangolias Gyen, and Phthorimaea operculella Zeller (all Lepidoptera: Gelechiidae), attack potato plants in the highlands of Ecuador and cause great economic losses. To understand their ecology and to develop precise integrated pest management strategies, a description of the molecular identification of each species and genetic diversity within populations is needed. In this study, we assessed the genetic diversity of a total of 112 moth samples of these 3 distinct species. Samples were collected from the 4 central provinces (Bolívar, Chimborazo, Cotopaxi, and Tungurahua) in the Ecuadorian highlands, where potato is a major crop for food security. Using polymerase chain reaction (PCR) and Sanger sequencing, we compared mitochondrial gene sequences among conspecific moth samples. Each of the 3 species exhibited different patterns regarding genetic diversity; more than 1 haplotype was present in P. operculella and S. tangolias, whereas all T. solanivora samples were found to be genetically identical. This initial effort of molecular characterization of the potato tuber moths will facilitate identifying incursion and potential migration route of Gelechiidae species as well as prevention of the pest outbreaks.
The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), is a major pest that transmits phloem-limited, gram negative bacteria including ‘Candidatus’ liberibacter asiaticus (Clas), causing huanglongbing. Management of this pest relies primarily on insecticides, such as the neonicotinoid imidacloprid, that may affect secondary pests including the brown citrus aphid, Toxoptera citricida (Kirkaldy) (Hemiptera: Aphididae). Here, we report on direct toxicity and sublethal dose effects of imidacloprid on T. citricida nymphs and adults following direct contact and ingestion. We also examined transgenerational dose-response and hormetic effects following exposure of T. citricida to a sublethal concentration of imidacloprid. Toxicity of imidacloprid was similar for nymphs (0.6 ng per µL) and adults (1 ng per µL) at 72 h. Fecundity and finite rate of increase were greater for populations exposed to systemic and foliar treatments at a sublethal concentration (0.1 ng per µL) compared with untreated controls. Development times of first instar nymphs in the F1 generation and third instar nymphs in the F2 generation were significantly greater for individuals treated with the sublethal dose than an untreated control. Survival of second instar T. citricida on plants treated with a sublethal concentration also was significantly greater than controls. There also was a significant increase in fecundity of F1 and F2 individuals after sublethal treatment compared with controls. Our results indicated that a sublethal concentration of imidacloprid increased the reproductive performance and induced possible physiologically stimulative (hormetic) effects in T. citricida. Hormesis in secondary pests should be considered when developing a management program for pathogen vectors such as D. citri.
Lethal bronzing disease is caused by the 16SrIV-D phytoplasma and is fatal to many palm species. This disease has caused significant economic losses to nursery and landscaping industries in Florida. As is the phloem-limited nature of phytoplasmas, the lethal bronzing disease phytoplasma is transmitted only by phloem-feeding insect vectors. However, the vector remains unconfirmed and this impedes the development of Integrated Pest Management programs that target vector populations. The primary objective of this study was to identify potential vectors of the 16SrIV-D phytoplasma in Florida by surveying auchenorrhynchans using sticky traps at the area where the disease is actively spreading, and screening the specimens for the presence of the phytoplasma. Cixiidae, Cicadellidae, Derbidae, and Membracidae insects were collected consistently during the 1-yr survey. The total number of a cixiid planthopper, Haplaxius crudus (Van Duzee) (Hemiptera: Cixiidae), was significantly higher than other insects that were collected on the traps. Of 3,734 specimens tested by nested polymerase chain reaction, approximately 0.672% of the H. crudus specimens and 1 unidentified leafhopper (Cicadellidae sp.) tested positive for the16SrIV-D phytoplasma. The 16S sequences amplified from the positive specimens were confirmed by sequencing and phylogenetic analysis. Based on the population survey and the polymerase chain reaction assay results, we suggest that H. crudus is the potential vector of the 16SrIV-D phytoplasma. However, the vector competency of H. crudus needs to be further investigated due to the possibility of feeding residue being detected. The study has important implication for current lethal bronzing disease management by monitoring and controlling vector candidates in disease areas.
Trichogramma (Hymenoptera: Trichogrammatidae) are minute polyphagous wasps and endoparasitoids of lepidopteran eggs. The objective of this study was to identify Trichogramma species emerging from the eggs of the Asian corn borer, Ostrinia furnacalis (Guenée) (Lepidoptera: Crambidae) attacking corn, Zea mays L. (Poaceae) in Bunga Raya, Siak, Riau, Sumatra, Indonesia, and individuals from an unidentified species obtained from a commercial laboratory in Jatisari, Karawang, West Java, Java, Indonesia. The emergence rate of Trichogramma yousufi sp. nov. Khan & Ikram (Hymenoptera: Trichogrammatidae) on an infestation containing eggs of both pest species, beet armyworm, Spodoptera exigua (Hübner), and the tobacco cutworm, Spodoptera litura (F.) (both Lepidoptera: Noctuidae), on Acacia crassicarpa A. Cunn ex Benth. (Fabaceae) also was evaluated in a nursery in Pangkalan Kerinci, Riau. Two Trichogramma species, namely Trichogramma chilonis Ishii (Hymenoptera: Trichogrammatidae) and a new species, T. yousufi sp. nov., were recovered from the eggs of O. furnacalis in Bunga Raya. Trichogramma poliae Nagaraja (Hymenoptera: Trichogrammatidae) was identified as the species reared in the laboratory in Jatisari. Trichogramma yousufi sp. nov. was compared and separated from its closer species, Trichogramma latipennis Haliday (Hymenoptera: Trichogrammatidae). Trichogramma species, recovered from corn crops and 1 that also was reared in the laboratory, successfully parasitized the eggs of S. exigua and S. litura under controlled conditions. The emergence rate of T. yousufi sp. nov. was recorded at 24.79 to 40.82%, with the highest percentage for more adults of this parasitoid released per m2 in the nursery, indicating its potential to be employed as a biological control agent of Spodoptera in natural conditions.
Two Fabaceae in the Florida Keys, Pithecellobium keyense Coker and Guilandina bonduc Griseb., have been of interest because they are the larval host plants for the endangered Miami blue butterfly (Cyclargus thomasi bethunebakeri [Comstock & Huntington]; Lepidoptera: Lycaenidae). As a part of ongoing research and conservation for this butterfly, wild host plant material has been periodically collected in order to supplement a captive colony of C. t. bethunebakeri located in Gainesville, Florida, USA. In examining this plant material, 26 lepidopterans were detected, including several host records, a new continental record, and 2 likely undescribed species, 1 Aristotelia (Gelechiidae) and 1 Crocidosema (Tortricidae). Our results expand the geographic, life-history, and taxonomic understanding of lepidopteran herbivores that use P. keyense and G. bonduc in South Florida.
Myriad symbioses exist between insects and orchids, especially in tropical forests where the majority of species are epiphytic. Relationships between ants and rare epiphytic orchids are underrepresented in the scientific literature. The natural history and ecological entomology of Florida's endangered and epiphytic ghost orchid, Dendrophylax lindenii (Lindley) Bentham ex Rolfe (Orchidaceae), remain limited. Widely recognized for long-standing hypotheses concerning the species' pollination ecology, that documentation recently overturned, other interactions between insects and ghost orchids are scarce. Here we describe the first associations between ants, Crematogaster ashmeadi Mayr (Hymenoptera: Formicidae), and D. lindenii. Ghost orchid roots provide facultative and opportunistic structures for arboreal ants to use in nesting. Furthermore, excrement from ant colonies within the root mass can increase nutrient availability in the orchid's nutrient-poor substrate; the proximity of these ants permits patrolling to defend the plant and exert control over possible extra floral nectaries that require further inquiry. This study presents novel observations that expand the known insect associations with ghost orchids, elucidating the complex ecology of one of Florida's rarest and most endangered species.
Ricardo Aquino Borges, Alexander Machado Auad, Marcy Das Graças Fonseca, Cristiano Amancio Vieira Borges, Ana Luisa Sousa Azevedo, Tiago Teixeira De Resende, Gervásio Silva Carvalho, Fernando Rodrigues De Oliveira
This study examines the tegminal coloration pattern and the morphometry of Mahanarva spectabilis (Distant) (Hemiptera: Cercopidae) progeny of crosses between parents with differing wing patterns. Genetic studies were used to investigate whether the different coloration patterns of tegmina have resulted from speciation within the M. spectabilis clade. We crossed M. spectabilis with differing wing patterns to determine percentages of coloration standards of the tegmina and the biometry of the first generation (F1) progeny. DNA of specimens was extracted and analyzed. The results show that parental phenotype was a determining factor in the tegminal coloration pattern of offspring of generation F1. Slight variation exists in the specimens' morphometry; no grouping trend is evident with regard to specimens with different tegminal coloration patterns. Based on the characteristics of the population analyzed herein, it seems that there has been no speciation of M. spectabilis.
Ants can represent a useful model for studies on the impact of forest fragmentation because these organisms are found abundantly in soil and plants sensitive to changes in environmental conditions. Our study characterized the structure of ground foraging ant communities present in 10 fragmented areas of dry forest surrounding areas under soybean and maize cultivation. Using baited pitfall traps, our study identified 60 ant morphospecies, distributed in 21 genera. Species richness of ground foraging ants was not influenced by size of dry forest fragment. Fragment edge traps captured fewer species when compared with traps located in the center of the fragment. Species richness and species composition differed significantly between dry forest fragments and both cultivated crops as well as inter-crop periods. Dry forest fragments had the greatest ant species richness. Integrated knowledge of the mechanisms through which fragmentation effects alter ant communities can be useful for the development of strategies to mitigate harmful effects on those species affected, and to improve methods that can be used to evaluate the conservation value of the remaining natural environment.
Little is known about the community of dragonflies and damselflies in Tampa Bay, Florida, USA. To address this gap, we conducted 2 longitudinal surveys of adult odonates in a natural floodplain of the Hillsborough River in 2013 and 2017. Along with abundance and species diversity, we also measured intraspecific variation in body size, sexual dimorphism, wing-cell asymmetry, and water mite ectoparasitism. Our first weekly survey from Oct 2013 to Oct 2014 sampled 327 adults (230 female, 97 male) from 8 dragonfly species, with the eastern pondhawk (Erythemis simplicicollis Say; Odonata: Libellulidae) representing 79% of captures, followed by the second most abundant (14%), the Florida non-native and neotropical hyacinth glider (Miathyria marcella Selys; Odonata: Libellulidae). Our second weekly survey from Sept to Dec 2017, which focused on both damselflies and dragonflies and captured 205 adults from 8 species, with the fragile forktail (Ischnura posita Hagen; Odonata: Coenagrionidae) being the most abundant with 70% of captures. Female-biased sexual size dimorphism was found in both E. simplicicollis and I. posita; however, both sexes were equally variable in size and symmetric in a meristic trait. Female and male M. marcella were equally variable, monomorphic, and symmetric. Combing symmetry data from each sex, only I. posita damselflies were asymmetric overall. Finally, we did not observe any parasitism by larval water mites in either survey. We aim to continue surveys to track seasonal and climate-driven changes in dragonfly diversity and phenology in this region.
Salvador Ordaz-Silva, Imelda V. López-Sánchez, Macotulio Soto-Hernández, Julio C. Chacón-Hernández, Griselda Gaona-García, Sandra G. Mora-Ravelo, Jorge L. Delgadillo-Ángeles, Ricardo Merino-González
Celery, Apium graveolens L. (Apiaceae), is an essential salad ingredient in different parts of the world, and production is principally destined for the fresh market. Celery hosts several insect species, including the weevil Listroderes costirostris Schoenher (Coleoptera: Curculionidae). Listroderes costirostris currently is present in the San Quintin Valle, Baja California, Mexico, on commercial celery crops. Hypera postica (Gyllenhal) (Coleoptera: Curculionidae) feeds on several plants of the Fabaceae family and is the principal pest affecting Medicago sativa L. (Fabaceae) alfalfa crops. The purpose of this work was to assess the degree of infestation, spatial distribution, and the association between L. costirostris and H. postica on A. graveolens, in Baja California, Mexico. We established 4 quadrants in 1 ha, and we sampled 100 plants per quadrant in each sample. We collected 22 samplings, counting the larvae and adults of both species. Hypera postica was reported herein for the first time feeding on A. graveolens plants. Between 9.57% and 28.68% of the celery plants served as hosts to both species. Listroderes costirostris had the highest percentage of infested plants. The competitive interaction of these 2 species affected H. postica, which showed lesser abundance. Both species were associated in all the sample quadrants. Listroderes costirostris registered an aggregated distribution pattern, whereas H. postica presented a uniform distribution. The spatial distribution of H. postica is the result of competing for food and space with L. costirostris.
There is a risk that Bagrada hilaris will be transported from the southwestern USA and establish in Florida where it could infest Brassica crops. Therefore, new rearing methods were developed to maintain a colony of B. hilaris under quarantine conditions to conduct research on the potential for this pest to become established in Florida. Dental wicks, cotton balls, and Kimwipes™ were evaluated as artificial oviposition substrates. Cotton balls were the preferred oviposition substrate by B. hilaris.
The rose varieties (Rosa spp.; Rosaceae), widely used to decorate urban landscapes, are susceptible to attacks by arthropod pests. The twospotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae) is one of the most economically important pests in roses. The study proposed to evaluate the resistance mechanisms (antixenosis, antibiosis, and tolerance) of 4 rose varieties (‘Ojo de Toro,' ‘Samuray,' ‘Virginia,’ and ‘Keiro') to twospotted spider mite under greenhouse conditions. The antixenosis was evaluated by non-preference of oviposition, and through the number of larvae, nymphs, and adults of twospotted spider mite; antibiosis by the growth rate (r); tolerance by chlorophyll loss and leaf damage index. Twospotted spider mite showed no preference to oviposit on plants of the Samuray variety (3 eggs per leaflet). Larvae, nymphs, and adults showed no preference to feed on Ojo de Toro and Samuray varieties. Twospotted spider mite recorded the lowest values in r (0.2047 d-1) and the percentage of chlorophyll loss (15.64%) in the Samuray variety. The damage caused by twospotted spider mite in the 4 rose varieties was similar. The Samuray variety was the most resistant to twospotted spider mite, whereas the most susceptible varieties were Keiro and Virginia.
Blueberries are a group of several species of shrubs in the genus Vaccinium. It is an important crop worldwide, and its production has been expanded in Mexico in recent yr. Preliminary samplings of thrips in blueberry plots in Michoacan, Mexico, have uncovered an important global pest that was not known to be present in this country, Scirtothrips dorsalis Hood (Thysanoptera: Thripidae). This invasive pest is well known to be highly polyphagous and represents a serious threat to blueberries and many other crops in Mexico.
The invasive mite Phyllocoptes fructiphilus Keifer (Acari: Eriophyidae) feeds on plants in the genus Rosa. Phyllocoptes fructiphilus is associated with the rose rosette emaravirus (rose rosette virus) and acts as the only known vector of rose rosette virus, the causal agent of rose rosette disease (Emaravirus). The mite P. fructiphilus is reported for the first time in the state of Florida, USA. No roses showed signs or symptoms of viral infection, and current molecular methods were unable to detect the virus. Phyllocoptes fructiphilus represents a potential threat to the Florida rose industry if rose rosette disease becomes established.
The tawny crazy ant, Nylanderia fulva (Mayr) (Hymenoptera: Formicidae), is an invasive ant from South America with overwhelming populations that invade structures and overrun landscapes. To contribute to the development of biologically based control strategies for this ant, the seasonal prevalence of queens, males, and brood within colonies of N. fulva was determined from monthly collections of colonies located in north central Florida. The average number of queens per colony was significantly greater in the winter and spring than summer and fall. The fall and winter male counts were significantly higher than the other 2 seasons. Brood was most prevalent in the spring and fall and significantly greater than the brood collected in winter. Comparisons of queen, male, and brood to worker ratios generally had similar results to the average counts of queens and males and brood volume per season. The seasonal fluctuations in levels of queens, males, and brood reflect the winter coalescing of colonies into larger, permanent nest sites, and the summer dispersal of smaller colonies into transient nest sites located throughout landscapes.
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