Insecticide Resistance of Alphitobius diaperinus (Coleoptera: Tenebrionidae) to ?-Cyfluthrin And Associated Heat Tolerance



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The lesser mealworm Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae) is an important economic pest to poultry producers globally that cause structural damage and spread pathogens to poultry. Adult lesser mealworms were collected from three farms in Mt. Pleasant, TX, USA (A-C) and three farms in Franklin, TX, USA (D-F) in order to assess insecticide resistance across populations, as well its relationship to heat tolerance. Filter papers were treated with a range of doses of the active ingredient (AI) ?-Cyfluthrin. Farms B and E displayed much higher LD_(50) of 0.320 mg/mL and 0.627 mg/mL respectively compared to the remaining four farms, which ranged from 0.048-0.161mg/mL. In addition, a field bioassay was conducted to determine adult beetle susceptibility to label rates of formulated permethrin, Vector Ban Plus? and a pyrethroid, Tempo SC Ultra?. These insecticides were applied to commonly found surfaces in poultry operations (concrete, wood chip particle board, and pressure treated wood). Adult beetles were exposed to the treated surfaces for 2 h and then placed in untreated sterile petri dishes. ?Mortality? refers to mortality and morbidity recorded together at 2, 24, and 48 h post-exposure for both bioassays. Insecticide resistance varied greatly based on observation period and compound. The range of mean mortalities measured at 2 h regardless of surface type for Tempo SC Ultra? was 58-100% and for Vector Ban Plus? 17-100%. The mean mortality range at 24 h regardless of surface for Tempo SC Ultra? (91-100%) had less than 10% variation, while Vector Ban Plus? (0.00-49.73%) displayed almost 50% variation. The mean mortality range at 48 h regardless of surface for Tempo SC Ultra? (72-100%) showed high knockdown and increased in variation by 30%, and Vector Ban Plus? (0-29%) had a similar variation, but with low knockdown. Mortality was similar for Tempo SC Ultra? for each substrate. ?-Cyfluthrin (AI) had varying effectiveness depending on the population?s resistance levels, however all the farms tested had LD_(50) well above the equivalent formulation dosage of 0.02mg/mL. The ?-Cyfluthrin formulation had high mortality on all the surfaces tested highlighting the importance of the other ingredients in a formulation. Heat tolerance experiments were conducted on the F_(1) progeny of populations B, D, and E (n=14). The heat shock results were inconclusive. Modification to the experimental design may be needed to yield comparable results.