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We assessed the utility of a Bayesian analysis of dose-mortality curves using probit analysis. A Bayesian equivalent of a conventional single population probit analysis using Abbott's correction demonstrated the ability of the Bayesian model to recover parameters from generative data. We then developed a model that removed Abbott's correction and estimated natural survivorship as part of the overall model fitting process. Based on WAIC (information content) scores, this model was selected over the model using Abbott's corrected data in 196 out of 200 randomly generated datasets. This suggests that considerable information on control survivorship exists in response to treated doses in a bioassay, information that is partially removed when using Abbott's correction. Overdispersion in count data is common in ecological data, and a final model was developed that estimated overdispersion (kappa) as part of the model fitting process. When this model was compared to a model without overdispersion, it was selected as the best model in all 200 randomly generated datasets when kappa was low (5-20, high levels of overdispersion), while the 2 models performed equally well when kappa was large (500-2,000, low levels of overdispersion). The model with overdispersion was used to estimate parameters from bioassays of 10 populations of Helicoverpa zea (Lepidoptera: Noctuidae) exposed to Vip3a toxin, identifying 26 out of 45 pairwise comparisons that showed strong evidence of differences in LC50 estimates, adjusted for multiple comparisons., (© The Author(s) 2024. Published by Oxford University Press on behalf of Entomological Society of America.)

The majority of field corn, Zea mays L., in the southeastern United States has been genetically engineered to express insecticidal toxins produced by the soil bacterium, Bacillus thuringiensis (Bt). Field corn is the most important mid-season host for corn earworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae), which has developed resistance to all Cry toxins in Bt corn. From 2020 to 2023, corn earworm pupae were collected from early- and late-planted pyramided hybrids expressing Bt toxins and non-Bt near-isolines in North and South Carolina (16 trials). A total of 5,856 pupae were collected across all trials, with 55 and 88% more pupae collected in later-planted trials relative to early plantings in North and South Carolina, respectively. Only 20 pupae were collected from hybrids expressing Cry1F + Cry1Ab + Vip3A20 across all trials. Averaged across trials, Cry1A.105 + Cry2Ab2 hybrids reduced pupal weight by 6 and 9% in North and South Carolina, respectively, relative to the non-Bt near-isoline. Cry1F + Cry1Ab hybrids reduced pupal weight on average by 3 and 8% in North and South Carolina, respectively, relative to the non-Bt near-isoline. The impact of the Bt toxins on pupal weight varied among trials. When combined with data from 2014 to 2019 from previous studies, a significant decline in the percent reduction in pupal weight over time was found in both states and hybrid families. This study demonstrates a continued decline in the sublethal impacts of Bt toxins on corn earworm, emphasizing the importance of insect resistance management practices., (© The Author(s) 2024. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Helicoverpa zea (Boddie) is a polyphagous pest that can cause serious damage to crops, including soybeans (Glycine max L.). In soybeans with both determinate and indeterminate growth habits, H. zea larvae are more commonly found on leaves compared to blooms, stems, and pods. Past research demonstrated that H. zea adults tend to oviposit near the upper part of the plant canopy in soybeans with a determinate growth habit. However, ovipositional selection on soybeans with an indeterminate growth habit is unknown. We hypothesized that H. zea would oviposit more uniformly throughout the canopy on indeterminate soybean growth habits due to more diffuse reproductive tissue. We planted field and greenhouse experiments with varieties sharing a similar relative maturity (2 maturity group [MG] 5.2 varieties and 2 MG 5.4/5.5 varieties) but with different growth habits. To test oviposition selection, adult H. zea females were allowed to oviposit under field and caged conditions. We counted the number of H. zea eggs and neonates on each plant tissue type from each of 3 equal parts in the plant canopy: upper, middle, and lower. In both experiments, eggs and neonates were most common on leaves at the top of the plant regardless of soybean growth habit. Consequently, ovipositional selection is likely independent of reproductive tissue availability, and patterns of oviposition through the canopy are similar in growth habits. An improved understanding of H. zea ecology in soybeans relative to indeterminate growth habits may improve recommendations for managing this significant pest of soybean., (© The Author(s) 2024. Published by Oxford University Press on behalf of Entomological Society of America.)

Corn, Zea mays L. (Poales: Poaceae), growers in the US Cotton Belt are required to plant 20% of total corn acres to non-Bt hybrids for resistance management (non-Bt refuge). Most growers do not meet this requirement, in part, because they perceive non-Bt hybrids to yield less than Bt hybrids. We planted multiple non-Bt and Bt hybrids from a single company in small-plot replicated trials at a single location from 2019 to 2023, as well as in small-plot replicated trials at multiple locations during 2022 and 2023. In the single location, we measured kernel injury from corn earworm, Helicoverpa zea Boddie (Lepidoptera: Noctuidae), and we recorded yield at all locations. In the single location trial, yields only separated among hybrids in 3 out of 5 years. In the multiple location trial, yields were variable between both years. We found that Bt hybrids tended to yield higher than non-Bt hybrids overall, but this was influenced by the inclusion of non-Bt hybrids that had a lower overall genetic yield potential in the environments we tested them in. In both tests, when hybrids were analyzed during each year, both Bt and non-Bt hybrids were among the statistically highest yielders. Our study demonstrates the importance of comparing multiple Bt and non-Bt hybrids to draw yield comparisons. This highlights the need for corn seed company breeders to put effort into improving yield for non-Bt hybrids. Hopefully this effort will translate into increased planting of non-Bt refuge corn for growers in the US Cotton Belt., (© The Author(s) 2024. Published by Oxford University Press on behalf of Entomological Society of America.)

Insect crop pests threaten global food security. This threat is amplified through the spread of nonnative species and through adaptation of native pests to control measures. Adaptations such as pesticide resistance can result from selection on variation within a population, or through gene flow from another population. We investigate these processes in an economically important noctuid crop pest, Helicoverpa zea, which has evolved resistance to a wide range of pesticides. Its sister species Helicoverpa armigera, first detected as an invasive species in Brazil in 2013, introduced the pyrethroid-resistance gene CYP337B3 to South American H. zea via adaptive introgression. To understand whether this could contribute to pesticide resistance in North America, we sequenced 237 H. zea genomes across 10 sample sites. We report H. armigera introgression into the North American H. zea population. Two individuals sampled in Texas in 2019 carry H. armigera haplotypes in a 4 Mbp region containing CYP337B3. Next, we identify signatures of selection in the panmictic population of nonadmixed H. zea, identifying a selective sweep at a second cytochrome P450 gene: CYP333B3. We estimate that its derived allele conferred a ∼5% fitness advantage and show that this estimate explains independently observed rare nonsynonymous CYP333B3 mutations approaching fixation over a ∼20-year period. We also detect putative signatures of selection at a kinesin gene associated with Bt resistance. Overall, we document two mechanisms of rapid adaptation: the introduction of fitness-enhancing alleles through interspecific introgression, and selection on intraspecific variation., Competing Interests: Conflict of Interest The authors declare no conflict of interest., (© The Author(s) 2024. Published by Oxford University Press on behalf of Society for Molecular Biology and Evolution.)

Transgenic corn and cotton that produce Cry and Vip3Aa toxins derived from Bacillus thuringiensis (Bt) are widely planted in the United States to control lepidopteran pests. The sustainability of these Bt crops is threatened because the corn earworm/bollworm, Helicoverpa zea (Boddie), is evolving a resistance to these toxins. Using Bt sweet corn as a sentinel plant to monitor the evolution of resistance, collaborators established 146 trials in twenty-five states and five Canadian provinces during 2020-2022. The study evaluated overall changes in the phenotypic frequency of resistance (the ratio of larval densities in Bt ears relative to densities in non-Bt ears) in H. zea populations and the range of resistance allele frequencies for Cry1Ab and Vip3Aa. The results revealed a widespread resistance to Cry1Ab, Cry2Ab2, and Cry1A.105 Cry toxins, with higher numbers of larvae surviving in Bt ears than in non-Bt ears at many trial locations. Depending on assumptions about the inheritance of resistance, allele frequencies for Cry1Ab ranged from 0.465 (dominant resistance) to 0.995 (recessive resistance). Although Vip3Aa provided high control efficacy against H. zea , the results show a notable increase in ear damage and a number of surviving older larvae, particularly at southern locations. Assuming recessive resistance, the estimated resistance allele frequencies for Vip3Aa ranged from 0.115 in the Gulf states to 0.032 at more northern locations. These findings indicate that better resistance management practices are urgently needed to sustain efficacy the of corn and cotton that produce Vip3Aa.

After resistance is first detected, continued resistance monitoring can inform decisions on how to effectively manage resistant populations. We monitored for resistance to Cry1Ac (2018 and 2019) and Cry2Ab2 (2019) from southeastern USA populations of Helicoverpa zea . We collected larvae from various plant hosts, sib-mated the adults, and tested neonates using diet-overlay bioassays and compared them to susceptible populations for resistance estimates. We also compared LC 50 values with larval survival, weight and larval inhibition at the highest dose tested using regression, and found that LC 50 values were negatively correlated with survival for both proteins. Finally, we compared resistance rations between Cry1Ac and Cry2Ab2 during 2019. Some populations were resistant to Cry1Ac, and most were resistant to CryAb2; Cry1Ac resistance ratios were lower than Cry2Ab2 during 2019. Survival was positively correlated with larval weight inhibition for Cry2Ab. This contrasts with other studies in both the mid-southern and southeastern USA, where resistance to Cry1Ac, Cry1A.105, and Cry2Ab2 increased over time and was found in a majority of populations. This indicates that cotton expressing Cry proteins in the southeastern USA was at variable risk for damage in this region.

The use of insect-resistant transgenic crops producing Bacillus thuringiensis protein Cry toxins (Bt) to control caterpillars is wide-spread. Development of a mechanism to prevent Bt from reaching its target site in the digestive system could result in Bt resistance and resistance to other insecticides active per os . Increased feeding rates by increasing temperature in tobacco budworms, Chloridea virescens , and bollworms, Helicoverpa zea , decreased Bt Cry1Ac susceptibility and mortality. The same was found in C. virescens for Bollgard II plant extract containing Bt Cry1Ac and Cry2Ab2 toxins. Furthermore, H. zea from the same inbred laboratory colony that fed faster independent of temperature manipulation were less susceptible to Bt intoxication. A laboratory derived C. virescens Bt resistant strain demonstrated a higher feeding rate on non-Bt artificial diet than the parental, Bt susceptible strain. A laboratory-reared Bt resistant fall armyworm, Spodoptera frugiperda , strain also fed faster on non-Bt diet compared to Bt susceptible caterpillars of the same species, both originally collected from corn. The studies in toto and the literature reviewed support the hypothesis that increased feeding rate is a behavioral mechanism for reducing caterpillar susceptibility to Bt. Its possible role in resistance needs further study.

Soybean (Glycine max L.) is an important row crop in the United States and Helicoverpa zea (Boddie) is one of the most serious insect pests in this system. Economic thresholds for H. zea were developed from soybean varieties with determinate growth habits. However, southern USA farmers have recently planted more soybeans varieties with indeterminate growth habits. Trials were conducted with two determinate and two indeterminate varieties within the same relative maturity group. Levels were compared among groups with differing H. zea pressure (low, medium, high, naturally infested) and manipulated using insecticides. Our objectives were to evaluate yield compensation differences among determinate and indeterminate varieties at these different H. zea pressures and to see if the existing economic threshold should be adjusted between growth habits. Since H. zea larval populations varied across trials, we compared trials with low populations, high populations, and no population. Generally, larval counts did not differ among varieties. We found no yield differences among varieties or between growth habits, regardless of H. zea pressure. In the high population tests, yield was highest in the low population plots, but there was no compensation by the plant in yield components except in number of pods with one seed. In contrast, yield components varied widely across varieties, but these differences were independent of H. zea pressure. These results suggest the economic threshold can be used for determinate and indeterminate growth habits, but more research is needed to confirm this with a larger selection of varieties, planting dates, and maturity groups., (© The Author(s) 2022. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Multiple insect pest species have developed field resistance to Bt-transgenic crops. There has been a significant amount of research on protein-coding genes that contribute to resistance, such as the up-regulation of protease activity or altered receptors. However, our understanding of the role of non-protein-coding mechanisms in Bt-resistance is minimal, as is also the case for resistance to chemical pesticides. To address this problem relative to Bt, RNA-seq was used to examine statistically significant, differential gene expression between a Cry1Ac-resistant (~100-fold resistant) and Cry1Ac-susceptible strain of Helicoverpa zea , a prevalent caterpillar pest in the USA. Significant differential expression of putative long non-coding RNAs (lncRNAs) was found in the Cry1Ac-resistant strain (58 up- and 24 down-regulated gene transcripts with an additional 10 found only in resistant and four only in susceptible caterpillars). These lncRNAs were examined as potential pseudogenes and for their genomic proximity to coding genes, both of which can be indicative of regulatory relationships between a lncRNA and coding gene expression. A possible pseudogenic lncRNA was found with similarities to a cadherin. In addition, putative lncRNAs were found significantly proximal to a serine protease, ABC transporter, and CYP coding genes, potentially involved in the mechanism of Bt and/or chemical insecticide resistance. Characterization of non-coding genetic mechanisms in Helicoverpa zea will improve the understanding of the genomic evolution of insect resistance, improve the identification of specific regulators of coding genes in general (some of which could be important in resistance), and is the first step for potentially targeting these regulators for pest control and resistance management (using molecular approaches, such as RNAi and others).

Key Message: Hessian fly resistance has centralized around resistance loci that are biotype specific. We show that field resistance is evident and controlled by a single locus on chromosome 7D. Hessian flies (Mayetiola destructor Say) infest and feed upon wheat (Triticum aestivum L) resulting in significant yield loss. Genetically resistant cultivars are the most effective method of Hessian fly management. Wheat breeders in the southern USA have observed cultivars exhibiting a "field resistance" to Hessian fly that is not detectable by greenhouse assay. The resistant breeding line "LA03136E71" and susceptible cultivar "Shirley" were crossed to develop a population of 200 random F 4:5 lines using single seed descent. The population was evaluated in a total of five locations in North Carolina during the 2019, 2020, and 2021 seasons. A subsample of each plot was evaluated for the total number of tillers, number of infested tillers, and total number of larvae/pupae. From these data, the percent infested tillers, number of larvae/pupae per tiller, and the number of larvae/pupae per infested tiller were estimated. In all within and across environment combinations for all traits recorded, the genotype effect was significant (p < 0.05). Interval mapping identified a single large effect QTL distally on the short arm of chromosome 7D for all environment-trait combinations. This locus was identified on a chromosome where no other Hessian fly resistance/tolerance QTL has been previously identified. This novel Hessian fly partial-resistance QTL is termed QHft.nc-7D. Fine mapping must be conducted in this region to narrow down the causal agents responsible for this trait, and investigation into the mode of action is highly suggested., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Previous studies have reported that the corn earworm/bollworm, Helicoverpa zea (Boddie), has developed field resistance to pyramided Bacillus thuringiensis (Bt) Cry1A/Cry2A maize and cotton in certain areas of the southeastern United States. The objective of the current study was to determine the current status and distribution of the resistance to Cry1A.105 and Cry2Ab2 in H. zea. In the study, 31 H. zea populations were collected from major maize planting areas across seven southeastern states of the United States during 2018 and 2019 and assayed against the two Bt proteins. Diet over-lay bioassays showed that most of the populations collected during the two years were significantly resistant to the Cry1A.105 protein. Most of the populations collected during 2019 were also resistant to Cry2Ab2, while significant variances were observed in the susceptibility of the populations collected during 2018 to Cry2Ab2. The results showed that Cry1A.105 and Cry2Ab2 resistance in H. zea is widely distributed in the regions sampled. The resistance to Cry1A.105 appeared to have plateaued, while selection for Cry2Ab2 resistance is likely still occurring. Thus, effective measures for mitigating the Cry1A/Cry2A resistance need to be developed and implemented to ensure the sustainable use of Bt crop biotechnology., (Copyright © 2021 Elsevier Inc. All rights reserved.)

The bollworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae), is an important agricultural pest in U.S. cotton and is managed using transgenic hybrids that produce insecticidal proteins from the bacterium, Bacillus thuringiensis (Bt). The reduced efficacy against H. zea caterpillars of Bt plants expressing Cry toxins is increasing in the field. In a first step towards understanding Bt cotton-bollworm-microbiota interactions, we investigated the internal bacterial microbiota of second-third stadium H. zea collected in the field from non-Bt versus Bt (WideStrike) cotton in close proximity (in North Carolina, USA). The bacterial populations were analyzed using culture-dependent and -independent molecular approaches. We found that WideStrike samples had a higher bacterial density and diversity per larva than insects collected from non-Bt cotton over two field seasons: 8.42 ± 0.23 and 5.36 ± 0.75 (log 10 colony forming units per insect) for WideStrike compared to 6.82 ± 0.20 and 4.30 ± 0.56 for non-Bt cotton for seasons 1 and 2, respectively. Fifteen phyla, 103 families, and 229 genera were identified after performing Illumina sequencing of the 16S rRNA. At the family level, Enterobacteriaceae and Enterococcaceae were the most abundant taxa. The Enterococcaceae family was comprised mostly of Enterococcus species ( E. casseliflavus and another Enterococcus sp.). Members of the Enterococcus genus can acidify their environment and can potentially reduce the alkaline activation of some Bt toxins. These findings argue for more research to better understand the role of cotton-bollworm-bacteria interactions and the impact on Bt toxin caterpillar susceptibility.

Background: The fall armyworm (Spodoptera frugiperda (J.E. Smith)) is a highly polyphagous agricultural pest with long-distance migratory behavior threatening food security worldwide. This pest has a host range of > 80 plant species, but two host strains are recognized based on their association with corn (C-strain) or rice and smaller grasses (R-strain). The population genomics of the United States (USA) fall armyworm remains poorly characterized to date despite its agricultural threat., Results: In this study, the population structure and genetic diversity in 55 S. frugiperda samples from Argentina, Brazil, Kenya, Puerto Rico and USA were surveyed to further our understanding of whole genome nuclear diversity. Comparisons at the genomic level suggest a panmictic S. frugiperda population, with only a minor reduction in gene flow between the two overwintering populations in the continental USA, also corresponding to distinct host strains at the mitochondrial level. Two maternal lines were detected from analysis of mitochondrial genomes. We found members from the Eastern Hemisphere interspersed within both continental USA overwintering subpopulations, suggesting multiple individuals were likely introduced to Africa., Conclusions: Our research is the largest diverse collection of United States S. frugiperda whole genome sequences characterized to date, covering eight continental states and a USA territory (Puerto Rico). The genomic resources presented provide foundational information to understand gene flow at the whole genome level among S. frugiperda populations. Based on the genomic similarities found between host strains and laboratory vs. field samples, our findings validate the experimental use of laboratory strains and the host strain differentiation based on mitochondria and sex-linked genetic markers extends to minor genome wide differences with some exceptions showing mixture between host strains is likely occurring in field populations.

As part of an insect resistance management plan to preserve Bt transgenic technology, annual monitoring of target pests is mandated to detect susceptibility changes to Bt toxins. Currently Helicoverpa zea (Boddie) monitoring involves investigating unexpected injury in Bt crop fields and collecting larvae from non-Bt host plants for laboratory diet bioassays to determine mortality responses to diagnostic concentrations of Bt toxins. To date, this monitoring approach has not detected any significant change from the known range of baseline susceptibility to Bt toxins, yet practical field-evolved resistance in H. zea populations and numerous occurrences of unexpected injury occur in Bt crops. In this study, we implemented a network of 73 sentinel sweet corn trials, spanning 16 U.S. states and 4 Canadian provinces, for monitoring changes in H. zea susceptibility to Cry and Vip3A toxins by measuring differences in ear damage and larval infestations between isogenic pairs of non-Bt and Bt hybrids over three years. This approach can monitor susceptibility changes and regional differences in other ear-feeding lepidopteran pests. Temporal changes in the field efficacy of each toxin were evidenced by comparing our current results with earlier published studies, including baseline data for each Bt trait when first commercialized. Changes in amount of ear damage showed significant increases in H. zea resistance to Cry toxins and possibly lower susceptibility to Vip3a. Our findings demonstrate that the sentinel plot approach as an in-field screen can effectively monitor phenotypic resistance and document field-evolved resistance in target pest populations, improving resistance monitoring for Bt crops., (© The Author(s) 2020. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

The corn earworm, Helicoverpa zea (Boddie), is a major pest targeted by pyramided Bacillus thuringiensis (Bt) corn and cotton in the U.S. Cry1Ab is one of the first insecticidal toxins used in Bt crops, while Vip3A is a relatively new toxin that has recently been incorporated into Cry corn with event MIR 162 and Cry cotton varieties to generate pyramided Bt traits targeting lepidopteran pests including H. zea . The objectives of this study were to determine the current status and distribution of the Cry1Ab resistance, and evaluate the susceptibility to Vip3Aa20 expressed in MIR 162 corn in H. zea in the southeastern U.S. During 2018 and 2019, 32 H. zea populations were collected from non-Bt corn (19 populations), Cry corn (12), and Cry/Vip3A cotton (1) across major corn areas in seven southeastern states of the U.S. Susceptibility of these populations to Cry1Ab and Vip3Aa20 was determined using diet-overlay bioassays. Compared to a known susceptible insect strain, 80% of the field populations were 13- to >150-fold resistant to Cry1Ab, while their response to Vip3Aa20 ranged from >11-fold more susceptible to 9-fold more tolerant. Mean susceptibility to each Bt toxin was not significantly different between the two groups of the populations collected from non-Bt and Bt crops, as well as between the two groups of the populations collected during 2018 and 2019. The results show that resistance to Cry1Ab in H. zea is widely distributed across the region. However, the Cry1Ab-resistant populations are not cross-resistant to Vip3Aa20, and H. zea in the region is still susceptible to the Vip3Aa20 toxin. Vip3Aa20 concentrations between 5 and 10 µg/cm 2 may be used as diagnostic concentrations for susceptibility monitoring in future. Additional studies are necessary to elucidate the impact of the selection with Bt corn on resistance evolution in H. zea to Vip3A cotton in the U.S.

Several different agricultural insect pests have developed field resistance to Bt ( Bacillus thuringiensis ) proteins (ex. Cry1Ac, Cry1F, etc.) expressed in crops, including corn and cotton. In the bollworm, Helicoverpa zea , resistance levels are increasing; recent reports in 2019 show up to 1000-fold levels of resistance to Cry1Ac, a major insecticidal protein in Bt-crops. A common method to analyze global differences in gene expression is RNA-seq. This technique was used to measure differences in global gene expression between a Bt-susceptible and Bt-resistant strain of the bollworm, where the differences in susceptibility to Cry1Ac insecticidal proteins were 100-fold. We found expected gene expression differences based on our current understanding of the Bt mode of action, including increased expression of proteases (trypsins and serine proteases) and reduced expression of Bt-interacting receptors (aminopeptidases and cadherins) in resistant bollworms. We also found additional expression differences for transcripts that were not previously investigated, i.e., transcripts from three immune pathways-Jak/STAT, Toll, and IMD. Immune pathway receptors (ex. PGRPs) and the IMD pathway demonstrated the highest differences in expression. Our analysis suggested that multiple mechanisms are involved in the development of Bt-resistance, including potentially unrecognized pathways.

A number of soybean varieties traditionally bred for resistance to various soybean arthropod pests have been identified as resistant to Megacopta cribraria (F.) (Hemiptera: Plataspidae). However, the mechanisms of host-plant resistance (HPR) in this system are not understood. The goal of this study was to identify the mechanisms of resistance by examining the role of plant volatile organic compounds (VOCs) and free amino acids (FAAs) among 16 soybean varieties. Choice and no-choice cage experiments identified several soybean varieties that demonstrated antixenosis as well as antibiosis. However, resistance varied over time in certain soybean varieties, such as N02-7002 and PI567352B. Mean nymph number from choice experiments had positive correlations with the FAAs asparagine, tryptophan, alanine, phenylanaline, and serine; negative correlation with leucine and threonine. Four plant volatiles, hexanal, 2-pentylfuran, beta-cyclocitral, and cis-9-hexadecenal, were positively correlated with subsequent nymph development, whereas n-hexadecenoic acid was negatively correlated with nymph number only, in adult choice cage experiments. This study contributes to understanding the mechanisms of HPR through associations with plant VOCs and FAAs in relation to M. cribraria development and provides useful knowledge for developing soybean varieties for M. cribraria management., (© The Author(s) 2020. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

The corn earworm, Helicoverpa zea, is a major target pest of the insecticidal Vip3Aa protein used in pyramided transgenic Bt corn and cotton with Cry1 and Cry2 proteins in the U.S. The widespread resistance to Cry1 and Cry2 proteins in H. zea will challenge the long-term efficacy of Vip3Aa technology. Determining the frequency of resistant alleles to Vip3Aa in field populations of H. zea is critically important for resistance management. Here, we provided the first F 2 screen study to estimate the resistance allele frequency for Vip3Aa in H. zea populations in Texas, U.S. In 2019, 128 H. zea neonates per isofamily for a total of 114 F 2 families were screened with a diagnostic concentration of 3.0 μg/cm 2 of Vip3Aa39 protein in diet-overlay bioassays. The F 2 screen detected two families carrying a major Vip3Aa resistance allele. The estimated frequency of major resistance alleles against Vip3Aa39 in H. zea in Texas from this study was 0.0065 with a 95% CI of 0.0014-0.0157. A Vip3Aa-resistant strain (RR) derived from the F 2 screen showed a high level of resistance to Vip3Aa39 protein, with a resistance ratio of >588.0-fold relative to a susceptible population (SS) based on diet-overlay bioassays. We provide the first documentation of a major resistance allele conferring high levels of Vip3Aa resistance in a field-derived strain of H. zea in the U.S. Data generated from this study contribute to development of management strategies for the sustainable use of the Vip3Aa technology to control H. zea in the U.S.

Megacopta cribraria (F.) (Hemiptera: Plataspidae) is an invasive pest of soybean that has spread across the southeastern United States since its initial discovery in 2009 in Georgia. Previous studies in the southeastern states have documented both the population dynamics of this pest and host plant resistance (HPR) among soybean varieties, although the specific mechanisms of HPR remain unknown. The objectives of this study were, therefore, to 1) quantify field resistance to M. cribraria in multiple soybean varieties in two states previously affected by severe M. cribraria infestations, North Carolina (NC) and South Carolina (SC); and 2) study the role of soybean trichome density in imparting resistance against M. cribraria. Soybean variety 'Camp' was least attractive to M. cribraria, through time and locations, suggesting consistent resistance. Other varieties showed variable performance among the locations and sampling dates. A significant difference in trichome density was evident. However, there was no correlation between trichome density and M. cribraria infestation. Compared to a previously published study in the same location, when M. cribraria adults emerging from overwintering dispersed into soybeans, in our study only first-generation adults dispersed into soybeans. Considering the current trend of significantly lower M. cribraria infestation rates in North and South Carolina, this pest may be finally succumbing to indigenous natural enemies and should be managed by incorporating integrated pest management tactics, such as HPR, that help conserve natural enemy populations., (© The Author(s) 2020. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Recent studies suggest that resistance in Helicoverpa zea (Boddie) (Lepidoptera, Noctuidae) to Cry1A(b/c) and Cry2Ab2 toxins from the bacterium Bacillus thuringiensis Berliner (Bacillales: Bacillaceae) has increased and field efficacy is impacted in transgenic corn and cotton expressing these toxins. A third toxin, Vip3A, is available in pyramids expressing two or more Bt toxins in corn hybrids and cotton varieties, but uncertainty exists regarding deployment strategies. During a growing season, H. zea infests corn and cotton, and debate arises over use of Vip3A toxin in corn where H. zea is not an economic pest. We used a three-locus, spatially explicit simulation model to evaluate when using Vip3A in corn might hasten evolution of resistance to Vip3A, with implications in cotton where H. zea is a key pest. When using a conventional refuge in corn and initial resistance allele frequencies of Cry1A and Cry2A were 10%, transforming corn with Vip3A slowed resistance to these toxins and delayed resistance evolution to the three-toxin pyramid as a whole. When Cry resistance allele frequencies exceeded 30%, transforming corn with Vip3A hastened the evolution of resistance to the three-toxin pyramid in cotton. When using a seed blend refuge strategy, resistance was delayed longest when Vip3A was not incorporated into corn and used only in cotton. Simulations of conventional refuges were generally more durable than seed blends, even when 75% of the required refuge was not planted. Extended durability of conventional refuges compared to other models of resistance evolution are discussed as well as causes for unusual survivorship in seed blends., (© The Author(s) 2019. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

The primary management tactic for lepidopteran pests of cotton in the United States of America (USA) is the use of transgenic cotton that produces Bacillus thuringiensis Berliner (Bt) toxins. The primary target pests of this technology are Helicoverpa zea (Boddie) and Heliothis virescens (F.) in the eastern and central Cotton Belt of the USA. Concerns over the evolution of resistance in H. zea to Bt toxins and scrutiny of the necessity of Bt crops has escalated. We reviewed published and unpublished data from field trials of Bt cotton in the eastern and central Cotton Belt of the USA through 2015 to evaluate the effectiveness of Bt cotton (Bollgard, Bollgard II, WideStrike, WideStrike 3, and TwinLink). Bt cotton reduced insecticide usage, reduced heliothine pest numbers and damage, and provided a yield benefit, but Bollgard II and WideStrike efficacy declined in the Midsouth over the period evaluated. In the Southeastern region, heliothine damage remained constant through 2015, but yield benefits declined from 2010 until 2015. Resistance of H. zea to several Bt toxins is the most plausible explanation for the observed changes in Bt cotton efficacy. The introduction of new Bt toxins such as found in Widestrike 3 and Twinlink may preserve the benefits of Bt crops. However, while both Widestrike 3 and Twinlink had less damage than Widestrike, damage levels of both were similar to Bollgard II., Competing Interests: While the agriculture industry did not fund the analysis presented in this manuscript, all the authors affiliated with a university routinely conduct research for Monsanto, Bayer CropSciences and Dow Agrosciences as well as other agrichemical companies. Most of the trial data reported in this manuscript was gathered as part of trials that were funded by these biotechnology companies. DF was a post-doc at Mississippi State University when most of the work was done and is currently employed by Provivi, Inc. Beyond providing his salary, Provivi, Inc did not have any role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. These competing interests do not alter the authors’ adherence to PLOS ONE policies on sharing data and materials.

Mayetiola destructor (Say) is a serious pest of wheat, Triticum aestivum L., in North America, North Africa, and Central Asia. Singly deployed resistance genes in wheat cultivars have provided effective management of Hessian fly populations for >50 yr. Thirty-five H genes have been documented. Defense mediated by the H gene constitutes strong selection on the Hessian fly population, killing 100% of larvae. A mutation in a matching Hessian fly avirulence gene confers virulence to the H gene, leading to survival on the resistant plant. As the frequency of virulence rises in the population, the H gene loses its effectiveness for pest management. Knowing the frequency of virulence in the population is not only important for monitoring but also for decisions about which H gene should be deployed in regional wheat breeding programs. Here, we present a novel assay for detecting virulence in the field. Hessian fly males were collected in Alabama, Georgia, North Carolina, and South Carolina using sticky traps baited with Hessian fly sex pheromone. Utilizing two PCR reactions, diagnostic molecular markers for the six alleles controlling avirulence and virulence to H13 can be scored based on band size. Throughout the southeast, all three avirulence and three virulence alleles can be identified. In South Carolina, the PCR assay was sensitive enough to detect the spread of virulence into two counties previously documented as 100% susceptible to H13. The new assay also indicates that the previous methods overestimated virulence in the field owing to scoring of the plant instead of the insect., (Published by Oxford University Press on behalf of Entomological Society of America 2017. This work is written by US Government employees and is in the public domain in the US.)

Helicoverpa zea (Boddie), corn earworm, is a damaging insect pest of many crops, including soybeans. An economic threshold for soybeans during the pod-filling stages exists to prevent economic damage to seeds. However, the impact of florivory (flower feeding) by H. zea larvae on seed yield is poorly understood and there is no economic threshold for flowering-stage soybeans. Four small plot experiments were conducted in North Carolina during 2011 and 2012 to assess the impact of H. zea feeding during the flowering stages of determinate soybeans on various yield components. Helicoverpa zea densities were manipulated with insecticides and various planting dates of soybeans and monitored weekly. Helicoverpa zea naturally infested the plots after flowering began and were allowed to feed until R3; they were eliminated from all plots from R3 to maturity. In some sites, H. zea densities exceeded the podding economic threshold during the flowering stages, but yield did not differ among treatments. During 2012, florivory from H. zea was measured directly by counting injured flowers. There was a negative yield relationship between both injured flower number and cumulative flower number. Moreover, H. zea densities were related to both a decrease in cumulative flowers and an increase in injured flowers, even though a direct linkage between H. zea density and yield loss was not observed. Without knowing the preferred tissue types and performance of early-instar larvae on soybeans, it is possible that H. zea density may not be the best measurement for developing an economic threshold in flowering soybeans., (© The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Predatory arthropods can be important for preventing insect pests from reaching damaging levels in soybean. However, the predator community can be compromised when pest control strategies include the application of broad-spectrum insecticides. The use of selective insecticides such as diamides could conserve predators while still providing necessary pest control. We evaluated two selective diamide insecticides, chlorantraniliprole and flubendiamide, and a broad-spectrum insecticide, lambda-cyhalothrin in combination with chlorantraniliprole, for impact on predators in soybean. We applied insecticides to field plots and documented predator abundance prior to and up to 3 wk postapplication using sticky card, beat sheet, and sweep net sampling methods. In sweep net samples, total predator abundance in plots treated with the selective insecticides was not significantly different from untreated control plots. For beat sheet samples, there were no significant differences in the abundance of total predators on any day postapplication between the selective diamide insecticides or the untreated control, but abundance decreased after application of lambda-cyhalothrin + chlorantraniliprole and did not recover. For sticky cards, there were no differences in predator abundance among treatments on any day postapplication. Over all, results showed that there were no significant differences in the abundance of total predators, Anthocoridae, Araneae, or Geocoridae after application of flubendiamide or chlorantraniliprole compared with the untreated control for up to 3 wk after application. All insecticides significantly decreased populations of lepidopteran pests compared with the untreated control, but only lambda-cyhalothrin + chlorantraniliprole reduced predatory arthropod abundance., (© The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Blended refuge for transgenic plants expressing Bacillus thuringiensis (Bt) toxins has been approved in the northern United States as a resistance management strategy alternative to a structured refuge. A three-year study (2012-2014) was conducted with 54 trials across nine states in the southern United States to evaluate plant injury from lepidopteran pests of corn and yield in a corn hybrid expressing Cry1F × Cry1Ab × Vip3Aa20 (Pioneer Brand Optimum Leptra) planted as a pure stand and in refuge blends of 5, 10, and 20% in both early and late plantings. Injury by corn earworm, Helicoverpa zea Boddie (Lepidoptera: Noctuidae), and fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), was generally proportional to the percentage of non-Bt corn within each refuge blend. Across locations, ear injury in plots with 100% Cry1F × Cry1Ab × Vip3Aa20 (Optimum Leptra) corn ranged from no injury to a maximum of 0.42 cm(2) per ear in Mississippi in 2013. Leaf injury ratings in 100% non-Bt plots in early and late planted trials in 2014 were 86- and 70-fold greater than in 100% Cry1F × Cry1Ab × Vip3Aa20 (Optimum Leptra) plots. Plants in plots with blended refuges had significantly greater leaf injury in 2012 (5, 10, and 20% refuge blends), in the early-planted corn in 2013 (10 and 20% only), and in both early- and late-planted corn in 2014 (20% only) as compared with leaf injury in a pure stand of Cry1F × Cry1Ab × Vip3Aa20 (Optimum Leptra) seen during these years. Corn ears in plots with blended refuges also had significantly greater area of kernels injured in 2012 (5, 10, and 20%), in early- and late-planted corn in 2013 (5, 10, and 20%), and in early (10 and 20% only)- and late-planted corn (5, 10, and 20%) in 2014 as compared with ear injury in a pure stand of Cry1F × Cry1Ab × Vip3Aa20 (Optimum Leptra) seen during these years. Infestations of southwestern corn borer, Diatraea grandiosella Dyar (Lepidoptera: Crambidae), were also significantly reduced by Cry1F × Cry1Ab × Vip3Aa20 (Optimum Leptra). Despite these differences in injury, yield averaged across locations varied among refuge blends only in the late-planted trials in 2013, with greater yields in the 0% refuge blend than in the 20% blend; however, when examining yield separately by location, only two of nine locations had higher yields in the 100% Bt plots than in any of the blended refuge plots. As a complement to studying the contribution of blended refuge to delaying resistance, quantifying injury and yield in a range of refuge blends is a necessary step to provide management information on the range of lepidopteran pests that occur in the southern United States., (© The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), is a target species of transgenic corn (Zea mays L.) that expresses single and pyramided Bacillus thuringiensis (Bt) toxin. In 2014, S. frugiperda were collected from a light trap in North Carolina, and a total of 212 F1/F2 isofemale lines of S. frugiperda were screened for resistance to Bt and non-Bt corn. All of the 212 isolines were susceptible to corn tissue expressing Cry1A.105 + Cry2Ab, Cry1F + Cry1A.105 + Cry2Ab, and Cry1F + Cry1Ab + Vip3Aa20. Growth rate bioassays were performed to isolate non-recessive Bt resistance alleles. Seven individuals out of the 212 isofemale lines carried major non-recessive alleles conferring resistance to Cry1F. A pooled colony was created from the seven individuals. This colony was 151.21 times more resistant to Cry1F than a known-susceptible population and was also resistant to Cry1A.105, but was not resistant to Cry2Ab and Vip3Aa20. The results demonstrate that field populations of S. frugiperda collected from North Carolina are generally susceptible to Cry1F, but that some individuals carry resistant alleles. The data generated in this study can be used as baseline data for resistance monitoring.

Initially discovered in Georgia in 2009, the exotic invasive plataspid, Megacopta cribraria (F.), has become a serious pest of soybean ( Glycine max (L.) Merrill). Managing M. cribraria in soybean typically involves the application of broad-spectrum insecticides. Soybean host plant resistance is an attractive alternative approach; however, no commercial soybean cultivars have been identified as resistant. During 2013 and 2014, we compared 40 and 44 soybean genotypes, respectively, for resistance to M. cribraria in a split-plot design under natural insect infestation in small-plot experiments. Soybean genotypes were selected to maximize diversity with respect to maturity group, pubescence type, leaf shape, seed size, nitrogen fixation, drought tolerance, seed protein content, and pest resistance. Megacopta cribraria egg masses, nymphs, and adults were counted during the growing season to identify potentially resistant soybean genotypes. Soybean seed yield was measured in insecticide-protected and unprotected conditions to determine tolerance to M. cribraria feeding. In both years, a range of host plant resistance was observed. The fewest M. cribraria adults and nymphs were found on narrow-leaf, small-seeded cultivars 'N7103' and 'Vance,' as well as the nonnodulating cultivar 'Nitrasoy.' Additionally, N7103 and Vance were among the least susceptible genotypes to M. cribraria oviposition in the field. Most 'Benning' cultivar insect-resistant near-isogenic breeding lines also displayed moderate levels of resistance to M. cribraria . Seed yields of Vance and N7103 were less affected by M. cribraria in 2013 than most other soybean genotypes. These results may be useful to soybean breeders to develop cultivars with resistance to M. cribraria., (© The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Nonmanaged plants occurring along forest edges and in suburban settings were sampled for brown marmorated stink bug, Halyomorpha halys (Stål), in North Carolina (NC) and Virginia (VA) over the course of three growing seasons. Commercial soybeans (Glycine max), an attractive cultivated host, were also sampled in 2014 in NC and in VA from 2010-2014. Very few H. halys were found on nonmanaged plants or soybean fields in the coastal plain region of either state, but substantial populations were recorded in the piedmont and mountain regions. From 2011 to 2013, H. halys comprised from 51 to 97% of all stink bug species observed on nonmanaged plants in the piedmont and mountain regions. In VA, the distribution expanded from detection in 12 counties in 2010 to 53 counties in 2014, with economically damaging levels occurring in the piedmont region. During these studies, H. halys were observed to complete one and a partial second generation per year in western NC and southwestern VA, similar to that previously observed in regions farther north. Several plants were identified as preferred hosts, with tree of heaven, catalpa, yellowwood, paulownia, cherry, walnut, redbud, and grape having consistently high numbers of H. halys. Knowing that these plants are preferred by H. halys during certain stages of the insects' development will aid in the search for H. halys in new areas, as well as serve as one predictor of the likelihood of a certain area to attract and sustain large H. halys populations., (© The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae); corn earworm, Helicoverpa zea Boddie (Lepidoptera: Noctuidae); southwestern corn borer, Diatraea grandiosella Dyar (Lepidoptera: Crambidae); sugarcane borer, Diatraea saccharalis F. (Lepidoptera: Crambidae); and lesser cornstalk borer, Elasmopalpus lignosellus Zeller (Lepidoptera: Pyralidae), are lepidopteran pests of corn, Zea mays L., in the southern United States. Blended refuge for transgenic plants expressing the insecticidal protein derivative from Bacillus thuringiensis (Bt) has recently been approved as an alternative resistance management strategy in the northern United States. We conducted a two-year study with 39 experiments across 12 states in the southern United States to evaluate plant injury from these five species of Lepidoptera to corn expressing Cry1F and Cry1Ab, as both single and pyramided traits, a pyramid of Cry1Ab×Vip3Aa20, and a pyramid of Cry1F×Cry1Ab plus non-Bt in a blended refuge. Leaf injury and kernel damage from corn earworm and fall armyworm, and stalking tunneling by southwestern corn borer, were similar in Cry1F×Cry1Ab plants compared with the Cry1F×Cry1Ab plus non-Bt blended refuge averaged across five-plant clusters. When measured on an individual plant basis, leaf injury, kernel damage, stalk tunneling (southwestern corn borer), and dead or injured plants (lesser cornstalk borer) were greater in the blended non-Bt refuge plants compared to Cry1F×Cry1Ab plants in the non-Bt and pyramided Cry1F×Cry1Ab blended refuge treatment. When non-Bt blended refuge plants were compared to a structured refuge of non-Bt plants, no significant difference was detected in leaf injury, kernel damage, or stalk tunneling (southwestern corn borer). Plant stands in the non-Bt and pyramided Cry1F×Cry1Ab blended refuge treatment had more stalk tunneling from sugarcane borer and plant death from lesser cornstalk borer compared to a pyramided Cry1F×Cry1Ab structured refuge treatment. Hybrid plants containing Cry1F×Cry1Ab within the pyramided Cry1F×Cry1Ab blended refuge treatment had significantly less kernel damage than non-Bt structured refuge treatments. Both single and pyramided Bt traits were effective against southwestern corn borer, sugarcane borer, and lesser cornstalk borer., (© The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

The corn- and rice-strains of Spodoptera frugiperda exhibit several genetic and behavioral differences and appear to be undergoing ecological speciation in sympatry. Previous studies reported conflicting results when investigating male attraction to pheromone lures in different regions, but this could have been due to inter-strain and/or geographic differences. Therefore, we investigated whether corn- and rice-strain males differed in their response to different synthetic pheromone blends in different regions in North America, the Caribbean and South America. All trapped males were strain-typed by two strain-specific mitochondrial DNA markers. In the first experiment, we found a nearly similar response of corn- and rice-strain males to two different 4-component blends, resembling the corn- and rice-strain female blend we previously described from females in Florida. This response showed some geographic variation in fields in Canada, North Carolina, Florida, Puerto Rico, and South America (Peru, Argentina). In dose-response experiments with the critical secondary sex pheromone component (Z)-7-dodecenyl acetate (Z7-12:OAc), we found some strain-specific differences in male attraction. While the response to Z7-12:OAc varied geographically in the corn-strain, rice-strain males showed almost no variation. We also found that the minor compound (Z)-11-hexadecenyl acetate (Z11-16:OAc) did not increase attraction of both strains in Florida and of corn-strain males in Peru. In a fourth experiment, where we added the stereo-isomer of the critical sex pheromone component, (E)-7-dodecenyl acetate, to the major pheromone component (Z)-9-tetradecenyl acetate (Z9-14:OAc), we found that this compound was attractive to males in North Carolina, but not to males in Peru. Overall, our results suggest that both strains show rather geographic than strain-specific differences in their response to pheromone lures, and that regional sexual communication differences might cause geographic differentiation between populations.

The nonnative brown marmorated stink bug, Halyomorpha halys Stål (Hemiptera: Pentatomidae), has become an abundant pest of mid-Atlantic soybean since its introduction in the mid-1990s. Currently, there is little information indicating how this new pest should be managed in soybean or if economic thresholds developed for native stink bugs should be adjusted. In 2010 and 2011, field cage studies were conducted in Beltsville, MD, and Suffolk, VA, to evaluate H. halys injury to three different soybean reproductive development stages. Cages were infested for 2 wk using densities of zero, one, two, four, or eight stink bugs (fifth instars and adults) per 0.3 row-m. Cage plots were harvested, and subsamples were taken to determine pod losses and seed quality. Feeding injury to soybean caused by H. halys was similar to that of native stink bugs, as evidenced by seed destruction, punctures, and destroyed pods. Densities of four stink bugs per 0.3 row-m resulted in significant seed damage in three of four experiments. The full flowering (R2) soybean development stage was least affected by H. halys feeding. The full pod (R4) and the full seed (R6) stage were similarly sensitive to injury. There was no significant yield loss was associated with stink bug densities at either location, although there were significant differences among stages in two of four experiments. The data do not indicate that threshold densities for H. halys should be different than for the native stink bugs.

Megacopta cribraria (F.) (Hemiptera: Plataspidae) was first reported in 2009 near Atlanta, GA. The insect undergoes two generations per year. The first-generation is reported mainly in kudzu during May and June, with the second establishing on both kudzu and soybean during July and August. A greenhouse study was conducted to determine the suitability of two legumes as hosts for first generation M. cribraria. First generation M. cribraria successfully developed on caged potted soybean plants. Conversely, snap beans were not a suitable host under the conditions of this study. A range of 45-50 d was needed to transition from the egg to adult on soybean plants. Although this study was limited to the greenhouse, kudzu may not be an obligate host for the development of first-generation M. cribraria. An important implication of this finding is the establishment for this pest on spring-planted soybean and for the possible expanded geographic range for this pest beyond that of kudzu.

Remote sensing is a precision tool that can detect plant health. Ground-based methods in small-scale experiments were used to explore the applicability of this technology for detection of arthropod-damaged cotton and to find useful indices or wavelengths for detecting arthropod-damaged cotton. Individual leaves of greenhouse-grown cotton plants and cotton plants in the field were infested with populations of cotton aphids, spider mites, and aphids + mites. Several sets of reflectance measurements were collected from the adaxial surface of the leaves at various intervals after infestation using a portable hyperspectral spectrometer with an integrating sphere or a contact probe. Vegetation indices were calculated from the reflectance values; these indices and the raw reflectance values, represented by narrow wavelength bands, were tested to see if arthropod damaged cotton could be distinguished from healthy cotton. Results indicated that it was possible to detect cotton aphid- and spider mite-damaged leaves by tracking the spectral changes in the leaf, although the damage type of each arthropod could not be distinguished spectrally. In addition, spider mite- and aphid-infested cotton leaves increased reflectance in the near infrared wavelength at approximately 850 nm in comparison to uninfested leaves.

The expression of glial fibrillary acidic protein (GFAP) by perivascular cells of many mammalian organs suggests an as yet unknown function of this intermediate filament protein in the maintenance of homeostasis and vascular permeability at the blood-tissue interface. Although a similar situation may exist at the air-tissue interface, the cellular distribution of GFAP in skin tissue has never been demonstrated. To approach this issue, we have employed immunofluorescence and Western blotting techniques to detect GFAP in skin sections of young and adult humans, normal rodents, and two types of mutant mice, as well as in rat lung sections, and in cultured human keratinocytes and fibroblasts. Colocalization with antigens known to be associated with GFAP in other tissues was also tested. Epidermal and hair follicle keratinocytes and dermal fibroblasts showed distinct staining for GFAP as well as colocalization with alpha-actin, metallothionein, and antigens of the class-II major histocompatibility complex (MHC II). GFAP was also identified in rat alveolar fibroblasts which, in common with keratinocytes, form part of the air-tissue interface. GFAP was upregulated together with MHC II in nude mice but was barely detectable in the skin of non-obese diabetic severe combined immunodeficiency mice, suggesting a possible involvement in antigen-presenting functions. The intriguing distribution of a common set of antigens both in certain cells of the integumentary system and at the blood-tissue interfaces of internal organs suggests the involvement of these proteins in universal mechanisms controlling tissue homeostasis and protection.