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BACKGROUND: Widespread reports of reduced efficacy of imidacloprid for managing cotton aphids (Aphis gossypii Glover) in cotton (Gossypium hirsutum L.) prompted an investigation to characterize the susceptibility of 43 populations over a 2‐year period. The susceptibility of A. gossypii populations to imidacloprid was examined by calculating LC50 values. Further analyses related resistance assay results to a gradient of cotton production intensity. RESULTS: Concentration‐mortality bioassays documencted populations that were 4.26–607.16 times more resistant than the susceptible laboratory population. There was a significant positive relationship between LC50 values and percentage of cotton within 2.5‐ and 5‐km buffers surrounding collection sites. No significant relationship was detected between LC50 values and the percentage of alternative crop and noncrop hosts. CONCLUSION: Variable and high levels of resistance were detected in A. gossypii populations, and this variation was positively associated with cotton production intensity. Cotton is a host that may receive multiple applications of neonicotinoids (via seed treatment and foliar sprays) annually for seedling and mid‐season pests. Rotating modes of action and limiting insecticide use should be implemented to delay the evolution of insecticide resistance in A. gossypii populations. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Foliar-applied insecticide treatments may be necessary to manage thrips in cotton (Gossypium hirsutum L.) under severe infestations or when at-planting insecticide seed treatments do not provide satisfactory protection. The most common foliar-applied insecticide is acephate. Field observations in Tennessee suggest that the performance of acephate has declined. Thus, the first objective was to perform leaf-dip bioassays to assess if tobacco thrips, Frankliniella fusca (Hinds) (Thysanoptera: Thripidae), in cotton production regions have evolved resistance to foliar-applied insecticides. A second objective was to assess the performance of commonly applied foliar insecticides for managing thrips in standardized field trials in Arkansas, Tennessee, Mississippi, and Texas. For both objectives, several insecticides were evaluated including acephate, dicrotophos, dimethoate, lambda-cyhalothrin, imidacloprid, and spinetoram. Field trials and bioassays were completed from 2018 to 2021. Dose-response bioassays with acephate were performed on tobacco thrips field populations and a susceptible laboratory population. Bioassay results suggest that tobacco thrips have developed resistance to acephate and other organophosphate insecticides; however, this resistance seems to be most severe in Arkansas, Tennessee, and the Delta region of Mississippi. Resistance to other classes of insecticides were perhaps even more evident in these bioassays. The performance of these insecticides in field trials was variable, with tobacco thrips only showing consistent signs of resistance to lambda-cyhalothrin. However, it is evident that many populations of tobacco thrips are resistant to multiple classes of insecticides. Further research is needed to determine heritability and resistance mechanism(s). [ABSTRACT FROM AUTHOR]

Melanotus communis Gyllenhal (Coleoptera: Elateridae) larvae are a common soil-dwelling pest of many crops, including sweet potato, grains, and tobacco. Although many studies have focused on the larval stage of this pest, the seasonal activity and ecology of the adults (click beetles) are not well understood. The overarching goal of this study was to relate M. communis adult activity to host crops in the North Carolina row-crop agroecosystem. To do this, we conducted a two-year study documenting male M. communis activity, using a recently identified sex attractant pheromone, 13-tetradecenyl acetate. This project was divided into two parts: 1) a pheromone assessment study testing the efficacy and specificity of 13-tetradecenyl acetate, and two analogs, 13-tetradecenyl butyrate and 13-tetradecenyl hexanoate, and 2) a landscape survey using traps baited with 13-tetradecenyl acetate. Results of the efficacy study showed that 13-tetradecenyl acetate was the most effective M. communis lure when compared to non-baited control traps or traps baited with the two homologs. The landscape study documented a strong association between M. communis catch and the adjacent crop type. We found that adult M. communis abundance was greatest near corn, followed by sweet potato, and then cotton. Analysis of activity over time found that the peak activity occurred during July. Overall, this project demonstrates the usefulness of pheromone-baited traps in providing new information about M. communis activity. [ABSTRACT FROM AUTHOR]

Transgenic cotton expressing Cry51Aa2.834_16 Bt toxin (hereafter referred to as MON 88702) has the potential to be an important tool for pest management due to its unique activity against tobacco thrips, Frankliniella fusca. Unlike other Bt toxins targeting lepidopteran cotton pests, MON 88702 does not cause direct mortality but has an antixenotic effect that suppresses F. fusca oviposition. Previous work has shown neonicotinoid seed treated (NST) crops have similar behavioral effects on thrips. This study used non-choice and common garden experiments to examine how the presence of MON 88702 cotton and soybean (another F. fusca host) with and without NSTs might alter F. fusca infestation distributions. In a no-choice environment, significant larval establishment differences were observed, with untreated soybean plants becoming most heavily infested. In choice experiments, plants expressing MON 88702 or were neonicotinoid treated had significantly lower larval establishment. Larval density decreased as dispersal distance increased, suggesting reproductive decisions were negatively related to distance from the release point. Understanding how F. fusca responds to MON 88702 in an environment where adults can choose among multiple host plants will provide valuable context for projections regarding design of MON 88702 resistance refuges. Reduced larval establishment on NST cotton and soybean suggests that area-wide use of NSTs could reduce the number of susceptible F. fusca generated in unstructured crop refuges for MON 88702. These results also suggest that although the presence of NST MON 88702 could suppress reproduction and resistance selection, over time this benefit could erode resulting in increased larval establishment on NST cotton and soybean due to increased frequency of neonicotinoid resistant F. fusca populations. [ABSTRACT FROM AUTHOR]

BACKGROUND Tobacco thrips, Frankliniella fusca (Hinds), is a pest of cotton. Currently, growers rely on neonicotinoid seed treatments to control F. fusca. However, the occurrence of neonicotinoid‐resistant F. fusca populations has created new challenges for their management. Development of thrips‐active Cry51Aa2.834_16 Bacillus thuringiensis (Bt) toxin expressed in MON 88702 cotton will be an important new tactic for thrips management. Previous studies have shown that MON 88702 causes limited mortality of F. fusca adults and larvae but reduces infestations on seedling cotton by suppressing oviposition from colonizing adults. This suggests that the toxin affects host preference of adult F. fusca. Knowledge of the effect of this trait on F. fusca feeding behavior provides a more complete understanding of MON 88702 activity. Using electropenetrography, we compared the feeding behaviors of adult F. fusca females on MON 88702 cotton and a non‐Bt isoline cotton over 2 h. The number of probes, proportion of probes resulting in ingestion, total duration of ingestion, and duration of ingestion per event were measured. RESULTS: On MON 88702 seedlings, F. fusca probed and ingested fewer times than those on non‐Bt cotton. Probes on MON 88702 were less likely to lead to ingestion than on non‐Bt cotton. The total duration of ingestion and duration of ingestion per event did not differ between treatments. CONCLUSION: The results show that MON 88702 has an antifeedant effect on F. fusca, which provides insight into behavioral responses driving MON 88702 aversion and anti‐oviposition documented in previous studies. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

BACKGROUND: Reports of neonicotinoid seed treatment (NST) failure against Frankliniella fusca in the mid‐south and southeastern USA led to the discovery of widespread resistance in these insect populations. Previous studies of NSTs in other crops have shown the concentration of the insecticide to change over time, which could reduce its efficacy. To understand this temporal effect in cotton with F. fusca, our study examined how plant age alters the effects of NSTs (imidacloprid, imidacloprid + thiodicarb and thiamethoxam) by examining larval establishment at multiple seedling ages during the period of cotton seedling susceptibility to this insect. Additionally, we used F. fusca populations with differing neonicotinoid sensitivity levels to understand how resistance impacts this changing efficacy. RESULTS: Greenhouse studies showed that larval numbers were significantly greater on older NST‐grown cotton seedlings. The population with elevated neonicotinoid resistance had a more rapid increase in larval number on thiamethoxam‐treated plants over time. CONCLUSION: NSTs reduce the number of F. fusca larvae on younger seedlings, but this effect declines as seedlings age. The duration of efficacy is shorter against neonicotinoid‐resistant populations. Neonicotinoid resistance in cotton‐infesting F. fusca populations may be accelerated by this time‐dependent decrease in efficacy, which likely encourages low‐dose exposure to these insecticides. © 2018 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

BACKGROUND Detection of neonicotinoid resistance in populations of tobacco thrips, Frankliniella fusca Hinds, throughout the southeastern USA has motivated an examination of alternative insecticides to control problematic infestations on seedling cotton. The objective of this study was to refine understanding of stage-specific mortality and reduced oviposition of several common insecticides (acephate, abamectin, cyantraniliprole, spinetoram, imidacloprid, imidacloprid+thiodicarb, thiamethoxam) on neonicotinoid resistant and susceptible F. fusca populations under laboratory and field conditions. RESULTS Laboratory studies revealed that the average number of eggs per female and larval or adult survivorship responses differed by insecticide and were dependent on the resistance status of the population . In the presence of neonicotinoids, the resistant F. fusca populations exhibited lower mortality and higher egg counts than the susceptible population. In the field study, similar patterns of oviposition suppression were observed, indicating that some insecticides may impact reproductive rate. CONCLUSION This study shows that insecticides have different effects on F. fusca oviposition events, larval and adult mortality that are dependent on neonicotinoid resistance status. Because insecticides tested in this study have varied activity on specific F. fusca life stages (e.g. oviposition suppression, larvicidal activity, adulticidal activity), knowledge of stage-specific activity can be used to improve control and enhance long-term product stewardship. © 2017 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Simple Summary: Tarnished plant bugs (Hemiptera: Miridae) are an important agricultural pest in cotton across the United States. Tarnished plant bugs reduce cotton yields and lower lint and seed quality by feeding on reproductive structures. Effective management of this pest requires timely insecticidal control when populations reach established economic thresholds. Reliable determination of the economic threshold in cotton depends on effective scouting. To evaluate the efficacy of current tarnished plant bug scouting strategies, we surveyed 120 commercial cotton fields across the southeastern USA to quantify (1) variation in tarnished plant bug populations across the production region, (2) evaluate current sampling plans for economic threshold determinations, and (3) examine landscape-scale risk factors associated with tarnished plant bug infestations in cotton. We observed the greatest variability in tarnished plant bug density at the field scale followed by within-field variation, emphasizing the importance of scouting individual fields. Additionally, we determined the sampling size needed for accurate threshold estimates for sweep net (8 sample units of 100 sweeps/sample) and drop cloth sampling (23 sampling units of 1.5 row-m/sample). Furthermore, tarnished plant bugs densities were positively related to the proportion of agriculture and double-crop winter wheat and soybeans and negatively related to contiguous cotton. Tarnished plant bug, Lygus lineolaris (Hemiptera: Miridae), is an economically damaging pest in cotton production systems across the southern United States. We systematically scouted 120 commercial cotton fields across five southeastern states during susceptible growth stages in 2019 and 2020 to investigate sampling optimization and the effect of interface crop and landscape composition on L. lineolaris abundance. Variance component analysis determined field and within-field spatial scales, compared with agricultural district and state, accounted for more variation in L. lineolaris density using sweep net and drop cloth sampling. This result highlights the importance of field-level scouting efforts. Using within-field samples, a fixed-precision sampling plan determined 8 and 23 sampling units were needed to determine L. lineolaris population estimates with 0.25 precision for sweep net (100 sweeps per unit) and drop cloth (1.5 row-m per unit) sampling, respectively. A spatial Bayesian hierarchical model was developed to determine local landscape (<0.5 km from field edges) effects on L. lineolaris in cotton. The proportion of agricultural area and double-crop wheat and soybeans were positively associated with L. lineolaris density, and fields with more contiguous cotton areas negatively predicted L. lineolaris populations. These results will improve L. lineolaris monitoring programs and treatment management decisions in southeastern USA cotton. [ABSTRACT FROM AUTHOR]

• Damaging infestations of Lygus lineolaris in Virginia cotton relate to biotic and abiotic factors. • Higher minimum temperatures are associated with increased L. lineolaris infestations. • Crop production area and forest disturbance drive L. lineolaris infestations detected in cotton. Lygus lineolaris populations have become increasingly problematic in Virginia cotton since 2013. Although production practices have changed, changes in landscape composition and climatic conditions are also anecdotally associated with increasing populations. To better understand the recent increase in L. lineolaris infestations in Virginia cotton, 56 commercial cotton fields were sampled weekly in 2017 and 2018 for a nine-week period during the growing season. Insect density was measured using sweep net and black drop cloth sampling, targeting adult and nymphal populations, respectively. Geospatial crop production and forest disturbance data were used to measure the composition and management history of landscapes adjacent to sample fields. We also used spatial climate data sets to document the relationship between increasing L. lineolaris and temperature variation. We investigated the significance of landscape composition and climatic effects increasing L. lineolaris infestation intensity using a regression modeling approach. We found the best overall predictor of L. lineolaris abundance was higher annual minimum temperatures. Several crop components in the landscape were significant, specifically corn and double-crop winter wheat and soybeans, but these habitat patches did not explain high levels of variability. Results of this study suggest that increasing minimum temperatures will favor L. lineolaris and may translate into elevated infestation intensity and increasing dependence on insecticide inputs to manage this problematic pest of cotton. Results of this study will be important to describe short- and long-term factors driving L. lineolaris infestation risk in cotton agroecosystems. [ABSTRACT FROM AUTHOR]

Geospatial models are crucial for identifying likely 'hot-spots' of Bt resistance evolution in Helicoverpa zea (Lepidoptera: Noctuidae), thereby improving regional insecticide resistance management (IRM) strategies and planted refuge compliance. To characterize H. zea distributions in relation to land use , we used historical trapping data collected from 2008 to 2019 in North Carolina to model the spatial and temporal abundance of H. zea populations across Bt -dominated landscapes. Helicoverpa zea abundance was standardized across site-year observations, and candidate landscape composition and configuration predictors of H. zea abundance were obtained. Spatiotemporal Bayesian hierarchical models were developed to make posterior predictions of H. zea abundance from environmental covariates, and results were used to generate interpolation prediction maps to visualize H. zea abundance across the sampled region. Our results suggest inverse distance weighted (IDW) soybeans is the most important predictor of H. zea abundance through time in row crop agroecosystems in North Carolina. Soybeans in North Carolina and southeastern U.S. likely serves as a critical non- Bt refuge for delaying H. zea resistance to Bt toxins in landscapes dominated by Bt maize and cotton. Moreover, soybean abundance can be used to predict the spatial abundance of H. zea in this region. Results can be applied to understand population dynamics of H. zea in landscapes dominated by genetically engineered (GE) crops expressing Bt toxins and will enable the development of sound insect resistance management strategies of H. zea populations to GE toxins targeting noctuid pests of maize and cotton. This work will also drive future geospatial studies investigating environmental predictors of resistance evolution in arthropod pests to GE technologies in crop production systems. Landscape-level variation in soybeans predicts spatial and temporal Helicoverpa zea abundance and likely serves as important non- Bt refugia in maize and cotton agroecosystems. [Display omitted] • Helicoverpa zea population dynamics in row crops relate to landscape drivers • Landscape-level soybean and cotton variation in the southeastern U.S. associate with increased H. zea abundance through time • Soybeans likely serve as critical non- Bt refugia for delaying H. zea resistance in maize and cotton agroecosystems [ABSTRACT FROM AUTHOR]