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BACKGROUND Over the past two decades, neonicotinoid seed treatments have become the primary method to manage tobacco thrips, Frankliniella fusca Hinds, on seedling cotton. Because this insect is highly polyphagous and the window of insecticide exposure is short, neonicotinoid resistance was expected to pose a minimal risk. However, reports of higher than expected F. fusca seedling damage in seed-treated cotton fields throughout the Mid-South and Southeast US production regions suggested neonicotinoid resistance had developed. To document this change, F. fusca populations from 86 different locations in the eastern United States were assayed in 2014 and 2015 for imidacloprid and thiamethoxam resistance to determine the extent of the issue in the region. RESULTS Approximately 57 and 65% of the F. fusca populations surveyed had reduced imidacloprid and thiamethoxam sensitivity respectively. Survivorship in diagnostic bioassays was significantly different at both the state and regional scales. Multiple-dose bioassays conducted on 37 of the populations documented up to 55- and 39-fold resistance ratios for imidacloprid and thiamethoxam respectively. CONCLUSION Estimates of neonicotinoid resistance indicate an emerging issue for management of F. fusca in the eastern United States. Significant variation in survivorship within states and regions indicated that finer-scale surveys were needed to determine factors (genetic, insecticide use) driving resistance evolution. © 2016 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The sugarcane aphid, Melanaphis sacchari is an important pest of grain sorghum (Sorghum bicolor) in the United States. Current M. sacchari management programs aim to control M. sacchari with insecticides while minimizing impacts on natural enemies that contribute to biological control of aphid populations. As a result, balancing both insecticide efficacy on the target pest and preservation of biological control agents remains an important step toward sustainable management of M. sacchari in grain sorghum. To document tradeoffs between M. sacchari control and non-target impacts, we evaluated three common aphicides (afidopyropen, flupyradifurone, and sulfoxaflor) for M. sacchari control and natural enemy safety. Treatments were paired with surfactants when recommended. Insect abundance was measured before and after foliar insecticide application using randomized complete clock design small plot studies during the 2019 and 2020 field seasons. All plots were harvested at maturity to document the relationship between in-season aphid abundance and grain yield. In this two year study, the average aphid abundance three days after insecticide application was lower in some but not all insecticidal treatments when compared to the untreated control, suggesting some insecticides had limited aphid suppression capabilities. Mean cumulative aphid days were lower in all treated plots compared to the untreated control with the exception of Sefina (afidopyropen). Twenty-eight days after foliar insecticide application, there were no differences in total natural enemy abundance in any of the treatments including the untreated control, suggesting that while M. sacchari populations were reduced by foliar insecticide treatments, the insecticides did not have clear adverse effects to natural enemy populations. • The impact of three selective insecticides on Melanaphis sacchari was tested. • Most insecticides significantly reduced aphid populations on Sorghum bicolor. • There were limited negative effects of insecticides to natural enemies of M. sacchari. [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)., (© The Author(s) 2022. Published by Oxford University Press on behalf of Entomological Society of America.)