RESUMEN
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.
RESUMEN
BACKGROUND: Economically damaging infestations of the tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), have become more frequent in Virginia and North Carolina cotton since 2013 and 2010, respectively. Foliar insecticide use has increased dramatically in response. Efficacy data (LC50 ) are needed to evaluate L. lineolaris susceptibility and resistance levels (RR50 ) to commonly used and recommended insecticides for managing this pest in the southeastern USA. RESULTS: Elevated resistance levels to acephate and bifenthrin were measured in L. lineolaris populations collected from wild and cultivated hosts in Virginia, North Carolina and northern Alabama when compared to a susceptible laboratory population. High levels of bifenthrin resistance were observed in 2018 and 2019. Mixed-function oxidase and esterase (EST) inhibitors, piperonyl butoxide and S,S,S-Tributyl phosphotrithioate, respectively, had a synergistic effect on bifenthrin with resistant populations of L. lineolaris. Bifenthrin-resistant L. lineolaris populations expressed elevated levels of cytochrome P450 (CYP450 ) monooxygenase and general EST activity. Results suggest that insecticide resistance is present in some locations and that CYP450 and EST activity in L. lineolaris contribute to pyrethroid resistance in the southeastern USA. CONCLUSIONS: Results can serve as a baseline for continued monitoring of L. lineolaris insecticide resistance and inform insecticide resistance management strategies that help southeastern USA cotton producers to minimize inputs and slow resistance development. © 2020 Society of Chemical Industry.
