Submitted to: Experimental and Applied Acarology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/28/2010
Publication Date: 8/1/2010
Citation: Kanga, L.H., Adamczyk Jr, J.J., Patt, J.M., Cascino, J. 2010. Development of a user-friendly delivery method for the fungus Metarhizium anisopliac to control the ectoparasitic mite Varroa destructor in honey bee, Apis mellifera, colonies. Experimental and Applied Acarology. 52:327-342. Interpretive Summary: One of the key pests of honey bees is a parasitic mite, called Varroa. When left untreated, these infestations of mites can kill an entire bee hive. Luckily, there is a fungus that can kill Varroa mites naturally without harming the actual bee. This fungus is called Metarhizium anisopliae. We tested this fungus among commercial bee hives in south Texas and Flordia. Results indicated that it was critical to have fungal spores with good germination, pathogenicity and virulence. Overall, microbial control of Varroa mite with M. anisopliae is feasible and could be a useful component of an integrated pest management program.
Technical Abstract: A user-friendly method to deliver Metarhizium spores to honey bee colonies for control of Varroa mites was developed and tested. Patty blend formulations protected the fungal spores at brood nest temperatures and served as an improved delivery system of the fungus to bee hives. Field trials conducted in 2006 in Texas using freshly harvested spores indicated that patty blend formulations of 10 g of conidia per hive (applied twice) significantly reduced the numbers of mites per adult bee, mites in sealed brood cells, and residual mites at the end of the 47-day experimental period. Colony development in terms of adult bee populations and brood production also improved. Field trials conducted in 2007 in Florida using less virulent spores produced mixed results. Patty blends of 10 g of conidia per hive (applied twice) were less successful in significantly reducing the number of mites per adult bee. However, hive survivorship and colony strength were improved, and the numbers of residual mites were significantly reduced at the end of the 42-day experimental period. The overall results from 2003 to 2008 field trials indicated that it was critical to have fungal spores with good germination, pathogenicity and virulence. We determined that fungal spores (1 x 1010 viable spores per gram) with 98% germination and high pathogenicity (95% mite mortality at day 7) provided successful control of mite populations in established honey bee colonies at 10 g of conidia per hive (applied twice). Overall, microbial control of Varroa mite with M. anisopliae is feasible and could be a useful component of an integrated pest management program.