Insecticide susceptibility of the adult darkling beetle, Alphitobius diaperinus (Coleoptera: Tenebrionidae)
Boozer, Whitney Elizabeth
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Alphitobius diaperinus is a worldwide pest of poultry. Loss of insecticide susceptibility has been observed in darkling beetle populations worldwide. Topical bioassays were performed using technical grade spinosad (90% active ingredient by weight), bifenthrin (94.88% active ingredient by weight), and imidacloprid (95% active ingredient by weight) to determine susceptibility status of beetle populations in Georgia. LD50s were determined and compared to the LD50 of a susceptible laboratory colony to ascertain resistance ratios. A discriminating dose based on the LD99.9 of the susceptible population (Denmark) was also estimated. Varying levels of resistance to bifenthrin and imidacloprid were observed, with highest resistance occurring to imidacloprid (>3000-fold). Populations treated with spinosad showed only slight tolerance. Data indicate that resistance to bifenthrin is occurring in populations with prior pyrethroid exposure, and that efficacy of imidacloprid may be severely limited due to significant resistance occurring in beetle populations.