Laboratory Evaluation ofBeauveria bassiana(Moniliales: Moniliaceae) against the Lesser Mealworm,Alphitobius diaperinus(Coleoptera: Tenebrionidae), in Poultry Litter, Soil, and a Pupal Trap

In forced-contact bioassays in which hosts were vortexed for 5 s in 5 ml of fungal inoculum, young larvae of the lesser mealworm (Alphitobius diaperinus) were highly susceptible to a strain of the fungal pathogenBeauveria bassiana(WV) that was isolated from a natural epizootic inA. diaperinus(5-day-old larvae LC50=1.73×102conidia/ml, LC90=9.86×103; 10-day-old larvae LC50= 2.49 × 102, LC90=4.74×104). Adult beetles were approximately 1000 times less susceptible than young larvae. Mature larvae and adult beetles were more susceptible to WV and to a second beetle-derived strain (NC) than they were to two strains that originated in house flies. Starch dust formulations were more effective than aqueous suspensions when conidia were applied to poultry litter containing manure, chicken feed, and pine shavings. Because the experiments were conducted a single time, small differences among strains, formulations, and life stages should be viewed with caution. Soil treatments with corn starch containing the WV and NC strains provided 100% control of beetle larvae at 2.5 × 1011conidia/m2; aqueous suspensions were less effective. A pupal trap consisting of conidia-treated cardboard provided 100% control of beetle larvae at 4 × 105conidia/cm2of trap surface. An estimated 3 × 1011conidia could be used to treat a 1200-m2poultry house with the pupal traps.