Challenges for developing biopesticides against Varroa destructor (Mesostigamata: Varroidae)

Authors: Meikle, William; Sammataro, Diana; NEUMANN, P - Swiss Bee Research Center; PFLUGFELDER, J - Rhodes University

Submitted to: Apidologie
Publication Type: Review Article
Publication Acceptance Date: 1/4/2012
Publication Date: 9/1/2012
Citation: Meikle, W.G., Sammataro, D., Neumann, P., Pflugfelder, J. 2012. Challenges for developing biopesticides against Varroa destructor (Mesostigamata: Varroidae). Apidologie. 43: 501-514.

Interpretive Summary: Varroa mites are probably the most important bee pest in the world today. This paper is a review of work done on general biological control of Varroa mites, and particularly on development of biopesticides against Varroa mites. Biopesticides are “pesticides” with a biological, rather than chemical, active ingredient, and that biological active ingredient is usually some kind of microbial pathogen, such as a bacteria or a fungus. Varroa biopesticides have so far just used fungal pathogens. Several groups of researchers have tried to develop an effective and easily-applied biopesticide, but results have differed greatly. Part of the problem is that all the research has been done on only two species of fungi, when there are many species available that have not been tested, and also that research groups have used many different ways to measure the impact of biopesticides on the Varroa mites. More work needs to be done to understand how the biopesticide affects Varroa mite populations, to develop new kinds of formulations, and to try to find other species of fungi that might work.

Technical Abstract: Control of the major pest of apiculture, the ectoparasitic mite Varroa destructor, using biopesticides would resolve many of the problems experienced with other forms of control, such as chemical control, hive manipulation or selection of resistant strains. Several research groups have developed and tested fungus-based biopesticides in laboratory and field experiments, with varying results. While biopesticides have many desirable qualities, including much reduced problems of honey contamination and of pest resistance, future research needs to focus on: 1) identification of the subpopulation(s) of V. destructor affected by biopesticides, and the duration and impact of the application on mite population dynamics; 2) development of an effective, easily-applied formulation and 3) evaluation of possible side or sublethal effects on bees themselves. Biopesticides need to be evaluated on the field (colony) level in addition to the laboratory level. Researchers should consider providing data that can be easily used to evaluate effect, such as mite drop counts onto sticky boards coupled with estimates of phoretic mite density or brood cell mite density. Exploration for naturally-occurring pathogens should be conducted in the native range of V. destructor in Asia.