Several strains of Hirsutella sp. and Metarhizium sp. were evaluated in the laboratory and in the fields against the parasitic mite, Varroa destructor. The entomogenous fungi, H. thompsonii and M. anisopliae were highly pathogenic to Varroa mites at temperatures similar to that maintained by honeybees in a colony. At a concentration of 108 spores/ml, these fungal isolates caused 91-100% mite mortality at 34 ± 1°C in 4-7days after treatment. Lethal time for 90% cumulative mortality of mites (LT90) was 4.16 days for H. thompsonii and 5.47 days for M. anisopliae at 2 x 108 and 4 x108 conidia ml-1, respectively. LD50 s of these isolates were 0.19 x 108 and 13.45 x 108 conidia per milliliter, 7 days after treatment, respectively. More than 98% of dead mites collected from these treatments showed fungal growth. Both hyphomycetes were not only less harmful to honeybee when they were applied to honeybee hives, but also, they were highly pathogenic to the mites inside the bee hives. Because of their pathogenicity and activity at high temperatures, these insect pathogens offer promising new avenues for successful biological control of Varroa mites in honeybee production.
Species 1: Acari Varroidae Varroa destructor (Varroa mite)
Keywords: insect pathogens, control strategy
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA