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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]

The invasive Melanaphis sorghi (Theobald; =Melanaphis sacchari Zehntner) is a serious pest of sorghum production in the southern USA. Demonstration of technologies that provide effective control is key to management of this pest. Here, we investigated the effect of host plant resistance (resistant cultivar: DKS37-07 and susceptible cultivar: DKS53-53) and a single foliar insecticide (flupyradifurone: Sivanto Prime) application on M. sorghi infestations and the role of natural enemy populations in grain sorghum production across five locations in four states in southeastern USA. Foliar insecticide application significantly suppressed M. sorghi infestations on both the resistant and susceptible sorghum cultivars across all locations. Planting the host plant resistant cultivar (DKS37-07) significantly reduced aphid infestation across all locations. Plant damage ratings did not vary widely, but there was generally a positive association between aphid counts and observed plant damage, suggesting that increasing aphid numbers resulted in corresponding increase in plant damage. Planting a host plant resistant cultivar and foliar insecticide application generally preserved grain yield. Both sorghum hybrids supported an array of different life stages of natural enemies (predators [lady beetle larvae and adults; hoverfly larvae and lacewing larvae] and parasitoids [a braconid and aphelinid]) for both the sprayed and non-sprayed treatments. We found a strong and significant positive relationship between the natural enemies and the M. sorghi infestation. Results suggest that planting a host plant resistant cultivar and the integration of natural enemies with insecticide control methods in the management of M. sorghi is central to the development of an effective pest management strategy against this invasive pest. [ABSTRACT FROM AUTHOR]

BACKGROUND: Helicoverpa zea (Boddie) damage to Bt cotton and maize has increased as a result of widespread Bt resistance across the USA Cotton Belt. Our objective was to link Bt crop production patterns to cotton damage through a series of spatial and temporal surveys of commercial fields to understand how Bt crop production relates to greater than expected H. zea damage to Bt cotton. To do this, we assembled longitudinal cotton damage data that spanned the Bt adoption period, collected cotton damage data since Bt resistance has been detected, and estimated local population susceptibility using replicated on‐farm studies that included all Bt pyramids marketed in cotton. RESULTS: Significant year effects of H. zea damage frequency in commercial cotton were observed throughout the Bt adoption period, with a recent damage increase after 2012. Landscape‐level Bt crop production intensity over time was positively associated with the risk of H. zea damage in two‐ and three‐toxin pyramided Bt cotton. Helicoverpa zea damage also varied across Bt toxin types in spatially replicated on‐farm studies. CONCLUSIONS: Landscape‐level predictors of H. zea damage in Bt cotton can be used to identify heightened Bt resistance risk areas and serves as a model to understand factors that drive pest resistance evolution to Bt toxins in the southeastern United States. These results provide a framework for more effective insect resistance management strategies to be used in combination with conventional pest management practices that improve Bt trait durability while minimizing the environmental footprint of row crop agriculture. © 2021 Society of Chemical Industry. This article has been contributed to by US Government employees and their work is in the public domain in the USA. [ABSTRACT FROM AUTHOR]

Ceratocystis fimbriata, the causal agent of sweetpotato black rot, is a pathogen capable of developing and spreading within postharvest settings. A survey of North Carolina sweetpotato storage facilities was conducted to determine the arthropods present and identify potential vectors of C. fimbriata. Sixteen taxonomic categories were recovered, and the genus Drosophila (Diptera: Drosophilidae) accounted for 79% of individuals sampled, with Drosophila hydei being the most abundant species. Behavioral assays were conducted to determine if D. hydei is attracted to C. fimbriata-inoculated roots and if the pathogen could be recovered from external or intornal surfaces of the insect. Flles were released in insect-trapping pitchers containing either C. fimbriata-inoculated or noninoculated roots or Petri dishes. No significant differences in fly number were detected in sweetpotato-baited pitchers; however, significant differences were found in the pitcher baited with a mature C. fimbriata culture. Flies were subjected to washes to determine if viable C. fimbriata was present (internally or externally); washes were plated onto carrot agar plates and observed for the presence of C. fimbriata colonies. Both external and internal washes had viable C. fimbriata inocula with no significant differences, and inoculated sweetpotatoes had a significantly higher number of flies carrying C. fimbriata. This study suggests that D. hydei can carry C. fimbriata from infected sweetpotatoes and move viable C. fimbriata inocula both externally and internally, making this the first report of any Drosophila sp. serving as a potential vector for the Ceratocystis genus. [ABSTRACT FROM AUTHOR]

The revocation of chlorpyrifos tolerances in 2022 left sweetpotato growers without their most important tool to combat a complex of soil-borne root pests that includes wireworms (Coleoptera: Elateridae). Since then, growers have reported increased root damage despite a rapid pivot to pyrethroid-based management systems to replace mechanically incorporated preplant chlorpyrifos broadcast sprays. Our goal was to evaluate the efficacy of alternative insecticide chemistries and application methods to expand the portfolio of management options for wireworms, specifically Conoderus spp. and Melanotus communis (Gyllenhal). We tested (i) insecticidal transplant water drenches and (ii) a foliar spray program targeting adult elaterids. We found that incorporating insecticides into transplant water reduced wireworm damage when compared to untreated transplant water. Our treatments included a recently registered meta-diamide, broflanilide, which represents a promising path to diversify active ingredients and shift away from an overreliance on preplant and post-directed pyrethroid soil sprays. Foliar spray plots had less damage than plots that did not receive foliar sprays. One benefit of adult-focused management is the availability of effective monitoring tools such as sex pheromones and blacklight trapping. Developing a robust adult monitoring program would enable more precise applications of foliar insecticides versus season-long prophylactic soil sprays targeting larvae. Our results demonstrated a significant benefit to both alternative delivery methods. These management alternatives could expand treatment options beyond traditional preplant and post-directed pyrethroid sprays., (© 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.)

We describe experiments that evaluated potential sex pheromone components for 6 North American click beetle species. In field trials in Illinois, South Carolina, North Carolina, and Virginia, male beetles of 6 species were strongly attracted to geranyl butyrate (Agriotes insanus Candèze), 5-methylhexyl (Z)-4-decenoate (Elater abruptus Say), 11-dodecenyl butyrate (Melanotus ignobilis Melsheimer), and limoniic acid (Gambrinus griseus [Palisot de Beauvois], G. rudis [Brown], and G. plebejus [Say]). Collection of E. abruptus in South Carolina represents a new state record. For each species, capture rates varied geographically and temporally, possibly due to differences in local population densities and regional phenology, or the efficiency of different trap designs or trap placement. Structural similarities were observed between the tested attractants and previously identified pheromones of closely related species. For example, males of A. insanus were attracted to geranyl butyrate, analogous to the terpenoid ester pheromones of a number of European congeners. The attractant for E. abruptus, 5-methylhexyl (Z)-4-decenoate, is an analog of the pheromone of its European congener E. ferrugineus L., and the attractant for M. ignobilis, 11-dodecenyl butyrate, is an analog of attractants of European and Asian congeners. Attraction of the 3 Gambrinus species to limoniic acid parallels recent reports of attraction of the congeners G. seminudus (Van Dyke) and G. ursinus (Van Dyke) to this compound, which was originally identified from closely related species of Limonius. Full identifications of additional sex pheromones for elaterid species should provide a more complete picture of the diversities/similarities of the semiochemicals mediating reproductive behaviors of this biologically diverse and taxonomically complex group., (© 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.)

Root-knot nematodes (RKNs, Meloidogyne spp.) are some of the most economically important and common plant parasitic nematodes in North Carolina (NC) cropping systems. Soil samples collected from fields planted with crops rotated with sweetpotato ( Ipomoea batatas [L.] Lam.) in 39 NC counties in 2015 to 2018 were processed at the NC Nematode Assay Laboratory. The occurrence of second-stage juvenile (J2) RKN populations was examined based on collection year, month, county, and previous planted crop. The highest number of RKN-positive samples originated from Cumberland (53%), Sampson (48%), and Johnston (48%) counties. The highest average RKN population density was detected in Sampson (147 J2/500 cm 3 of soil) and Nash (135 J2/500 cm 3 of soil) counties, while Wayne (7 J2/500 cm 3 of soil) and Greene (11 J2/500 cm 3 of soil) counties had the lowest average RKN population density. Meloidogyne enterolobii is a new invasive species that is impacting sweetpotato growers of NC. The host status of an NC population of M. enterolobii , the guava RKN, was determined by examining eggs per gram of fresh root (ER) and the final nematode egg population divided by the initial population egg count (reproductive factor, RF) in greenhouse experiments. This included 18 vegetable, field, and cover crops and weed species. The tomato 'Rutgers' was used as a susceptible control. Cabbage 'Stonehead', pepper 'Red Bull', and watermelon 'Charleston Gray' and 'Fascination' were hosts and had similar mean ER values to the positive control, ranging from 64 to 18,717. Among field crops, cotton, soybean 'P5018RX', and tobacco were hosts with ER values that ranged from 185 to 706. Members of the Poaceae family such as sweet corn ( Zea mays ) and sudangrass ( Sorghum × drummondii ) were nonhosts to M. enterolobii , and the mean ER values ranged from 1.85 to 7. The peanut 'Tifguard' and winter wheat ( Triticum aestivum ) also had lower ER values than the vegetable hosts. Growers should consider planting less susceptible hosts or nonhosts such as peanut, sudangrass, sweet corn, and winter wheat in 2- to 3-year crop rotations to lower populations of this invasive nematode., Competing Interests: The author(s) declare no conflict of interest.