Monday, 18 November 2002

This presentation is part of : Student Competition Display Presentations, Subsection Cb. Apiculture and Social Insects

Effects of Varroa mites on the immune system of honey bees

Xiaolong Yang, Scott Camazine, and Diana Cox-Foster. The Pennsylvania State University, Department of Entomology, 501 ASI, University Park, PA

We have investigated the immunosuppression of honey bees (Apis mellifera) by Varroa mites. Survivorship can reflect the total ability of the immune system of an organism. We used E. coli as an immune challenger by injecting it into the bees to investigate their survivorship. After challenge with E. coli, Varroa-infested bees with normal wings lived a significantly shorter time than Varroa-free normal bees. This indicates that Varroa mites suppress the immune responses of honey bees. GLD is an important enzyme for insect cellular immune responses related to the production of oxidative free radicals in insect immune system. The GLD activity of hemocytes from Varroa-free bees was higher than that of Varroa-infested bees. Our preliminary study indicated that the hemocytes from Varroa-free bees had a higher encapsulation degree than those from Varroa-infested bees. PO is a critical enzyme and marker of some cellular immune functions. No PO activity was found in newly emerged and immuno-elicitor treated bees at 0 to 24 hrs, suggesting that they are immuno-incompetent at this developmental time point. It is during this immuno-incompetent period that the bees with mites are dying when challenged with bacteria, fungi or viruses. We have also isolated several Varroa salivary proteins. We are investigating the possible immunosuppression ability of the proteins to honey bees, as well as their sequences and structures.

Species 1: Hymenoptera Apidae Apis mellifera (Honey bee)
Species 2: Acari Varroidae Varroa jacobsoni (varroa mite)
Keywords: immunity, protein

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