Insecticide Resistance in Field Populations of the Tarnished Plant Bug (Heteroptera: Miridae) in Cotton in the Mississippi Delta

Abstract

Adult tarnished plant bugs, Lygus lineolaris (Palisot de Beauvois), collected in July and August from 4 cotton fields in the Mississippi Delta with plant bug control problems were tested with a glass vial bioassay for resistance to insecticides. Resistance levels determined for the different field populations were compared with those found by using the glass vial bioassay and susceptible plant bugs collected from weeds near Crossett, AR. Significantly higher levels of pyrethroid resistance were found in plant bugs from all 4 cotton fields as compared with pyrethroid resistance in bugs from Crossett. Plant bugs from one cotton field near Schlater, MS, were reared through 9 generations in the laboratory and tested in various generations for resistance to 4 pyrethroid, 5 organophosphorus, and 1 cyclodiene insecticide. Plant bugs in this resistant strain had multiple insecticide resistance to all 3 classes of insecticides. The highest levels of insecticide resistance were to pyrethroids, suggesting that the resistance resulted from selection with these insecticides in cotton. High levels of permethrin resistance were unstable and declined in plant bugs reared in the laboratory in the absence of any insecticide selection pressure. When reared in the laboratory, resistant bugs from Schlater had lower fecundity than a susceptible laboratory strain, and survival from egg hatch to adults was lower than in the susceptible strain. The distribution of insecticide resistance in tarnished plant bug populations from the Mississippi Delta is unknown, but control of populations with multiple insecticide resistance will be difficult. Compliance with the insecticide resistance management plan currently recommended for control of the tobacco budworm, Heliothis virescens (F.), in Arkansas, Louisiana, and Mississippi (by not using pyrethroids in cotton until July) is probably the best strategy for preventing the development of plant bug populations with multiple insecticide resistance in July and August.