The mite Varroa destructor lowers the stinging response threshold of honey bees (Apis mellifera)

The ecto-parasitic mite Varroa destructor is an extremely damaging biotic factor of honey bees (Apis mellifera) worldwide. The magnitude of the damage that V. destructor causes to the health of honey bees is well documented, but little is known about how it affects their behavior. For example, it is not known whether parasitism by V. destructor influences the bees' defensive behavior, and since this behavior has evolutionary and practical implications, its study is of importance. In this research, we used a constant-current stimulator to expose worker bees to a 0.5 mA electric stimulus after being parasitized by Varroa mites to test the hypothesis that V. destructor parasitism affects the stinging response threshold of individual honey bees. Bees exposed to V. destructor parasitism stung significantly faster than control bees in each of three trials (p < 0.05) and thus, it is concluded that the irritation caused by V. destructor reduces the stinging response threshold of honey bees. The implications of these findings are discussed, as well as the need for further studies to understand how V. destructor affects neuronal processes in the honey bee to make them more defensive.