Varroa mites (Varroa destructor) are external parasitic mites of honey bees. Varroa is one of the major contributing factors to the recent serious honey bee loss in USA, which endangers bee pollination and honey production. Our research addresses how the mites kill honey bees by investigating the impacts of varroa on honey bee immunity and pathology. We hypothesize that varroa depresses the honey bee immune response to various pathogens. We used E. coli as an immune challenger by injecting it into the bees to determine if varroa affects the survivorship of bees. Wing deformity is the key symptom of varroa infestation. Three types of bees were used: mite-free bees (MF), bees with mites and normal wings (NW), and bees with mites and deformed wings (DW). After challenge with E. coli, NW bees lived a significantly shorter time than MF bees. The DW bees lived the shortest. Given this impact on the survivorship, we tested the impact of varroa upon immunity by measuring the activity and gene expression of two immunologically important enzymes, phenoloxidase (PO) and glucose dehydrogenase (GLD). We also measured the gene expression levels of various antimicrobial peptides, including hymenoptaecin, defensin, apidaecin, abaecin, and lysozyme. The GLD activity of hemocytes in MF bee is significantly higher than that in mite-infested bee. In the bees infested with deformed wing virus, we have detected the expression of hymenoptaecin, defensin, and apidaecin with RT-PCR. We are also determining the levels of viruses and pathogens in varroa-infested versus uninfested bees.
Species 1: Hymenoptera Apidae Apis mellifera (honey bee)
Species 2: Acari Varroidae Varroa destructor (varroa mite)
Keywords: immune response, antimicrobial peptides
Back to Student Competition Display Presentations, Section B. Physiology, Biochemistry, Toxicology, and Molecular Biology
Back to Student Competition Posters
Back to The 2003 ESA Annual Meeting and Exhibition