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Chrysis shanghalensis Smith (Hymenoptera: Chrysididae) is an ectoparasitoid and important natural enemy of Monema flavescens Walker (Lepidoptera: Limacodidae), a serious defoliator of a number of tree species. The external morphology of the antennal sensilla of this parasitoid was examined by scanning electron microscopy, and types and distribution of sensilla were recorded. The antennae of C. shanghalensis were geniculate in shape and composed of a scape with radicula, a pedicel, and a flagellum divided into 11 flagellomeres in males and females. Cuticular pore and 14 types of sensilla were identified on the antennae of both sexes. These included aporous Böhm's bristles, sensilla trichodea 1, 2, and 3 (nonporous), sensilla trichodea 4 (multiporous), two types of sensilla chaetica (nonporous), four morphological types of sensilla basiconica (multiporous), two morphological types of sensilla coeloconica (multiporous), and one type of sensillum campaniforme (nonporous).
Entomopathogenic nematodes (EPNs) are widely used agents of biological control, mainly targeting soil-inhabiting insect pests. Reports indicate that these terrestrial EPNs are also able to infect the aquatic larvae of mosquitoes. We isolated EPN strains (Heterorhabditis bacteriophora Poinar and Steinernema carpocapsae [Weiser]) from local soils at Saltillo, Coahuila state, Mexico. EPNs from these strains were produced in the laboratory in yellow mealworm (Tenebrio molitor L.) larvae, and their pathogenicity as infective juveniles (IJs) was tested against larvae of the yellow fever mosquito Aedes aegypti (L.) Third- and fourth-instar mosquito larvae were exposed to four concentrations of IJs (25, 50, 100, and 200 IJ/larva) of five strains of local EPNs in laboratory assays. All strains of EPN caused lethal infections in larvae (3–100%); in particular, strain M5 of S. carpocapsae caused 100% mortality at the 200 IJ/larva concentration, with a median lethal concentration (LC50) of 42 IJ/larva (LC90 = 91 IJ/larva). Strain M18 of H. bacteriophora caused 73% mortality at 200 IJ/larva, with an LC50 = 72 and LC90 = 319 IJ/larva. IJs were produced by all strains in mosquito larvae, with a range of 66–239 IJ/mosquito larva (inoculated at 100 IJ/larva) across strains, suggesting that horizontal transmission might occur in the field. This represents the first report of native EPN strains from Mexico exhibiting pathogenicity against mosquito larvae. Native EPN strains should be further evaluated as potential biological control agents in mosquito management.
Growth and developmental parameters of the fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), were evaluated on 41 new zoysiagrass taxa (Zoysia spp. Willd.), which belong to an increasingly popular group of warm-season turfgrasses, in comparison with 5 commercially available zoysiagrass taxa and 1 known susceptible Paspalum L. taxon. Results from two no-choice growth chamber trials indicated that the new Zoysia japonica Steud. taxa were unfavorable for the development of fall armyworm larvae in general compared with the susceptible Paspalum taxon. This was evidenced by significantly lower larval and pupal weights and survival and longer time to pupation and adult emergence, pointing to antibiosis in these zoysiagrass taxa. The new Zoysia matrella (L.) Merr., Zoysia macrostachya Franch. & Sav., and Zoysia sinica Hance taxa seemed more favorable than Z. japonica taxa, as evidenced by numerically higher larval and pupal weights and survival and shorter duration to pupation and adult emergence. Taxa that consistently showed low larval survival were identified for further testing.
This study investigated (a) the intraplant distribution of Euschistus heros (F.) (Hemiptera: Pentatomidae) in cotton, (b) its preference for different structures and areas of the cotton plant, and (c) the damage caused at different levels of infestation. Our results determined that, regardless of the time of day, E. heros adults significantly preferred the middle third of cotton plants in comparison to the upper and lower areas (F = 30.221; df = 2; P = 0.001). The adults were present on all cotton structures, and numbers were significantly higher on bolls and leaves/branches (F = 25.333; df = 5; P = 0.001) than on flower buds and flowers. In greenhouse tests, fiber yield, number of bolls per plant, and number of internal punctures in bolls responded significantly to increasing infestation levels of E. heros adults. Damage and yield reduction was observed at 1.5 to 2.0 adults/plant, indicating that an action threshold of 1 adult per plant should be adopted to avoid economic losses. Sampling during boll development should be by either whole-plant inspection or beat cloth methods between 0600 and 1800 h.
Since 2013, the sugarcane aphid, Melanaphis sacchari Zehntner, has been a perennial pest to U.S. sorghum, Sorghum bicolor (L.) Moench, production with yield declines in susceptible hybrids ranging from 50 to 100%. Previous studies have found that a single clonal genotype predominates in samples collected from sugarcane (Saccharum spp.), sorghum, and Johnsongrass (Sorghum halepense [L.] Persoon), from 2013 to 2017 in the continental United States. We sought to determine if the “super-clone” persists in sugarcane aphid samples collected in 2018 from five U.S. states and one territory and to identify the multilocus lineage of samples collected in 2018–2019 from a new host, giant miscanthus, Miscanthus sinensis× Miscanthus sacchariflorus Greef & Deuter ex Hodkinson & Renvoize. Thirty-one samples collected from Columbus grass (Sorghum almum Parodi), Johnsongrass, sorghum, and giant miscanthus in 2018 were genotyped using 9 simple sequence repeat markers; 29 samples had identical alleles to the multilocus lineage F super-clone. All samples (n = 7) collected from giant miscanthus in 2018–2019 also had identical alleles to the predominant genotype.
Dastarcus helophoroides (Fairmaire) (Coleoptera: Bothrideridae) is a naturally occurring ectoparasitoid of wood-boring longhorned beetles (Coleoptera: Cerambycidae). To determine mechanisms involved in this host–parasitoid relationship, we extracted and partitioned the proteomes from neonate and the late-stage D. helophoroides larvae using iTRAQ-based HPLC-MS/MS analysis, followed by functional enrichment and protein–protein interaction analyses. In all, 50 putative venom proteins were identified from the proteome of D. helophoroides larvae. Of those, 19 were identified as arginine kinases, 10 were chitinases, and 21 were either proteases or protease inhibitors. These results serve as a major advance in understanding the parasitism mechanism of this ectoparasitoid, as well as the potential for developing environmentally safe chemistries based upon these venom proteins that might be used in cerambycid control in forest management.
The fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), is the most economically important pest of maize (Zea mays L.) grown in Mexico. In order to identify biologically based management tactics for this pest, we determined the concentration–mortality response of 16 S. frugiperda populations collected in Mexico to two commercial formulations of Bacillus thuringiensis Berliner (Bt) (XenTari® [Bt subsp. aizawai] and DiPel® [Bt subsp. kurstaki]; Valent de México SA De CV, Jalisco, México). Laboratory bioassays established median lethal concentrations (LC50s) for each Bt formulation × population combination. We also determined mean larval weight 7 d after exposure and the number of larvae that reached the third instar of development. The populations were susceptible to both Bt formulations but they were, overall, more susceptible to Bt subsp. aizawai (XenTari) than to Bt subsp. kurstaki (DiPel). These results can serve as a reference to detect changes in S. frugiperda response to these Bt commercial products over time.
Gall wasps (Hymenoptera: Cynipidae) have fascinated researchers for centuries due to the elaborate diversity of charismatic galls they produce, the presence of unique reproductive systems (e.g., a form of cyclical parthenogenesis), the possible convergent evolution of semiparasitic gall wasp forms (i.e., “inquilines”), and their multitrophic interactions. While many classifications for gall wasps have been proposed, recent DNA sequence efforts combined with taxonomic revisions are beginning to clarify the evolutionary relationships of this group. To date, however, a well resolved phylogeny is lacking, complicating the study of outbreak-causing pest species. Outbreaks by one such species, the black oak gall wasp, Zapatella davisae Buffington & Melika (Hymenoptera: Cynipidae: Cynipini), have led to extensive damage and mortality of black oaks, Quercus velutina L. (Fagales: Fagaceae), in the northeastern United States. Here we sequenced fragments of the nuclear ribosomal gene 28S, and the nuclear protein coding gene long-wavelength opsin from samples of Z. davisae collected on Cape Cod, MA, and Long Island, NY. Using these sequences and sequences previously published from the mitochondrial locus cytochrome b, we performed Bayesian and maximum likelihood multilocus phylogenetic reconstructions based on a concatenated alignment including species of gall wasps in the tribe Cynipini from which all three loci were present in the GenBank database. Confirming morphological work, we find that Z. davisae is most closely related to species in the genera Callirhytis and Neuroterus, and appears to be a basal member of the “Quercus” section of the tribe Cynipini. We find that recent generic reclassifications within the Cynipini have made great progress towards clarifying the taxonomic relationships of species of gall-inducing wasps in this tribe, and we comment on several classifications that require additional research.
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