Dr. Kaira Wagoner (Biology) received new funding from Project Apis m. for the project “Hydrocarbon-induced immune priming to improve honey bee colony Varroa-resistance.”
The health of the honey bee (Apis mellifera) is declining despite the pollinator’s significant contribution to global food security. The primary threat to honey bee health is the parasitic mite Varroa destructor, which completes reproduction inside honey bee brood cells, and is both a physical burden and disease vector to its honey bee host. While numerous solutions have been implemented to reduce the threat of Varroa, no suitable intervention has been discovered, resulting in the continued decline of honey bee health, annual colony loss rates exceeding 34%, and an ongoing search for improved interventions. Hygienic behavior, the ability to detect, uncap, and remove unhealthy brood from the colony, has been selectively bred for over two decades, and continues to be a promising avenue for improved Varroa management.
To address the need for a more effective and efficient selection tool to measure Varroa-specific colony hygiene, the researchers used cuticular hydrocarbons (CHCs) elevated in mite-parasitized and virus-infected brood to develop a 2-hour unhealthy brood odor (UBO) assay. During UBO assay trials in 2019 and 2020, the researchers noticed that colonies tested twice within the same week scored significantly higher in the second assay. Previous work in honey bees has shown that immune-stimulated queens are able to pass pathogen-specific resistance to their progeny, that CHCs can induce queen immune response, and that early-life experiences of workers can confer fitness to similar stimuli later in life.
Thus, the researchers hypothesize that exposure to unhealthy brood odors can improve honey bee Varroa resistance through immune priming. Here, we propose a series of experiments to test our predictions that 1) queens exposed to unhealthy brood odors produce more Varroa-resistant progeny, 2) nurse bees exposed to unhealthy brood odors exhibit augmented hygienic behavior, and 3) effects of UBO immune priming decrease with time since exposure.
Experiments will include exposure to synthetic UBOs as well as extracts from Varroa-parasitized brood. Should UBO exposure improve honey bee Varroa resistance, interventions could be rapidly implemented to sustainably improve honey bee health through enhanced, Varroa-specific hygienic behavior. Such treatments would avoid the risks associated with many current chemical interventions, such as the evolution of pest and pathogen resistance and the contamination of honey bee hive products with harmful miticides. Thus, this research could have major economic significance, with the potential to benefit honey bees, queen breeders, commercial beekeepers, farmers, and consumers.