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Chapman, Abigail

University of British Columbia

As the sole female capable of laying fertilized eggs within a colony of thousands, honey bee (Apis mellifera) queens are vital to their colonies. However, the factors contributing to “poor quality queens,” a primary cause of colony loss, remain unclear. Although agrichemical exposure and temperature stress are recognized as detrimental, the impact of viral infections on queen health is just beginning to be investigated. In this work, we initially conducted surveys of honey bee queens from beekeeping operations throughout British Columbia, finding that higher levels of viral infection correlate with decreased ovary mass and beekeeper-identified poor quality queens. We then showed that queens experimentally infected with Israeli acute paralysis virus had significantly smaller ovary masses compared to controls, establishing a causal link between viral infection and ovary size. Next, we performed experiments utilizing a combination of deformed wing virus and black queen cell virus, and an inactivated version of the inoculum to explore a potential trade-off between reproduction and immunity, a concept prevalent in many organisms but not yet fully investigated in honey bees. Infected queens displayed smaller ovaries and a reduced likelihood of egg-laying post-injection relative to controls. In the field, heavily infected queens had smaller ovaries, and infection was a predictor for the presence of supersedure cells in the colony. Immune responses in queens receiving infectious virus were comparable to those receiving inactivated virus, and several of the same immune proteins were negatively associated with ovary mass in the field. Lastly, we examined how maternal viral infections affected the proteomic, metabolomic, and lipidomic composition of eggs laid in controlled experiments and collected from beekeeping operations. Experimentally immune-challenged queens upregulated immune effectors in their eggs and ovaries. However, naturally infected queens showed no significant differences in egg composition linked to viral load or ovary size. Notably, the date of egg collection significantly impacted egg composition, suggesting that transgenerational effects of maternal viral infection on egg proteomes can be overshadowed by seasonal and nutritional factors. This work collectively demonstrates that viral infections impair queen reproductive success, and a reproductive-immunity trade-off likely partially, but not entirely, accounts for these effects.

Text

2024-12-12

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/89858

Biochemistry and Molecular Biology

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/