Elucidating the relationships between asymptomatic honey bee virus infections, flight, heat stress, and antiviral responses

Montana State University, Bozeman MT

Investigators

Abstract

Honey bees are important pollinators of agricultural crops and plant species that enhance ecosystem biodiversity. Therefore, high annual mortality of US honey bee colonies (averaging 38% since 2008) concern farmers, beekeepers, citizens, and scientists. Multiple factors, including viruses, contribute to honey bee colony deaths. To date, most honey bee virus research has focused on colony health or symptomatic infections in individuals. However, most virus infections appear asymptomatic, even in bees with high viral loads. The investigator will conduct experiments in individual bees to determine the impact of viral infections on overall honey bee health, using flight performance as a health indicator. Additional experiments at the organismal and cellular levels will reveal how honey bee antiviral defense systems combat virus infections. These studies could lead to strategies to reduce virus-related colony losses, benefiting agricultural and ecological systems that depend on honey bee pollination. This project will result in undergraduate and graduate student training via course work and laboratory experiences. Students will be involved in outreach events for learners of all ages and backgrounds and be involved with the production of a short film featuring this project. Together the scientific and educational aims of this project will enhance scientific literacy and underscore the importance of scientific approaches to address global challenges. Viruses are obligate intracellular pathogens that infect all organisms and rely on host resources for replication. While viruses are associated with honey bee colony losses, their effects at the individual and colony (super-organism) levels remain poorly understood. Virus infections in individual honey bees can cause paralysis, deformities, and/or result in death, but most infections are seemingly asymptomatic. Previous studies by the investigator have revealed that virus infections alter honey bee metabolism and trigger an antiviral heat shock response (HSR). The role of HSR varies across species; it is antiviral in fruit flies and honey bees infected with a model virus, but its role in most bee-virus interactions is unknown. Flight is an essential honey bee behavior that is both energetically taxing and heat generating. To test the hypothesis that virus abundance and flight performance are negatively associated and to elucidate the impact of heat stress and the heat shock stress response on the outcome of honey bee virus infections, the investigator will conduct laboratory-based experiments using individual bees and cultured primary cells. Analysis of transcriptional responses to virus infections and/or heat stress, coupled with quantification of overall honey bee health using flight assays, will determine the physiologic consequences of asymptomatic virus infections. This research has implications beyond bees, since flight performance may serve as an indicator of the negative impacts of sublethal virus infections in other organisms (including insects, birds, and bats), as well as an activator of potentially antiviral HSRs in additional species. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.