Influence of substrate and relative humidity on the efficacy of three entomopathogenic fungi for the hide beetle, Dermestes maculatus (Coleoptera, Dermestidae)

Dermestes maculatus De Geer (Coleoptera: Dermestidae) is a carrion feeder that is also a pest of poultry houses, museums, silkworm culture, and many stored foods. The Hypocreales, Beauveria bassiana (Balsamo) Vuillemin, Metarhizium anisopliae (Metschnikoff), and Isaria fumosorosea Wize, were tested for efficacy against D. maculatus larvae on concrete, plastic, leather, and wood surfaces. Only wood had a significant negative effect on efficacy, and B. bassiana was the most efficacious species. The conidia of all three species lost viability quickly on wood with various responses on the other surfaces. When beetle larvae were exposed to deposited B. bassiana and incubated at 43, 56, 75, or 82% relative humidity, mortality was greatest at the lowest humidity suggesting enhancement of fungal infection by desiccation stress. The results indicate that entomopathogenic Hypocreales, especially B. bassiana, may be useful for control of hide beetles when applied at a low dose to surfaces that do not impact the viability of conidia.