D3208: Behavioural responses to volatiles by Varroa destructor mites within a western honey bee (Apis mellifera) colony

Domesticated Western honey bees (Apis mellifera L.) around the world are parasitized by Varroa destructor mites (hereafter, varroa). Adult female mites use chemical cues in a bee colony to navigate towards preferred hosts, male honey bee pupae, known as drone brood. There are many volatile organic compounds (VOCs) within a honey bee colony, ranging from bee pheromones to plant VOCs emitted from collected nectar and pollen. We tested whether VOCs in drone brood elicited an attraction response from adult female varroa. Additionally, we tested the efficacy of VOCs from Common yarrow as mite repellents within the hive. Behavioural assays were first conducted on varroa using four putative attractants and four putative repellents. Once the most effective attractant and repellent were found, field trials began. We used a control colony with an untreated sticky board, and three treatments using VOCs: a colony with only the best repellent applied to the inside of the top board, a colony with the best attractant applied to a sticky bottom board, and a colony with a combination of the two. Twice a week for 8 weeks, sticky boards were replaced, and captured mites counted. This will lead to a novel trap design using VOCs that will be available for beekeepers battling varroa infestations.