A Longitudinal Study of the Principle Factors Leading to Colony Losses in Migratory Beekeeping

Authors: OSHEA-WHELLER, THOMAS - Louisiana State University; Simone-Finstrom, Michael; Danka, Robert; Rinkevich, Frank; HEALY, KRISTEN - Louisiana State University; PENN, HANNAH - Louisiana State University; SWALE, DANIEL - Louisiana State University; LANG, SARAH - Louisiana State University; FELLOWS, C.J. - Louisiana State University

Submitted to: Insects
Publication Type: Proceedings
Publication Acceptance Date: 1/28/2020
Publication Date: 1/29/2020
Citation: Oshea-Wheller, T., Simone-Finstrom, M., Danka, R.G., Rinkevich Jr, F.D., Healy, K., Penn, H., Swale, D., Lang, S., Fellows, C. 2020. A Longitudinal Study of the Principle Factors Leading to Colony Losses in Migratory Beekeeping. Insects. 11(2):1-49. https://doi.org/10.3390/insects11020088.
DOI: https://doi.org/10.3390/insects11020088

Interpretive Summary: This study reports findings of a two-year longitudinal study of colonies involved in a commercial migratory beekeeping operation. Our project aims to identify the key predictors of colony loss and their relative importance under real-world conditions. Additionally, our study incorporates a field test of Pol-Line bees, a stock developed for resistance to Varroa mites. Crucially, we show that Varroa accounts for ~70% of observed colony deaths. Furthermore, Pol-line bees exhibited a marked and significant reduction in mortality, and consistently lower mite levels throughout the year, presenting a viable alternative to current commercial stocks. In sum, our data suggest that Varroa should be the prime concern if colony losses are to be curtailed, and that integrated control methods, principally in the form of mite resistant stocks, are the most effective long-term solution to effectively curtail issues related to Varroa. However, significant colony losses occurred unrelated to Varroa or even when Varroa was under control. Understanding drivers of colony loss outside of Varroa was discussed and is key for continued efforts.

Technical Abstract: Commercial beekeeping in the United States accounts for ~3/4 of all colonies in circulation, with migratory pollination comprising a large proportion of the industry. However, the system simultaneously experiences high overwinter losses on a consistent and yearly basis. Consequently, without substantial improvements in colony health, large-scale migratory pollination is likely to become both biologically unsustainable, and commercially infeasible in its current form. Our project aims to identify the key predictors of colony loss and their relative importance, both at a large spatiotemporal scale, and under real-world conditions. Additionally, our study incorporates a field test of Pol-Line bees, a stock developed for resistance to Varroa mites, which current data implicate as the principle extraneous threat to bee colonies in the United States. Our results demonstrate the relative weightings of parasite, disease, forage and pesticide stressors upon colony health. Crucially, we show that Varroa accounts for ~70% of observed mortality across regions. Furthermore, Pol-line bees were found to experience a marked and significant reduction in mortality, and consistently lower mite levels throughout the year, presenting a viable alternative to current commercial stocks. In sum, our data suggest that Varroa should be the prime concern if colony losses are to be curtailed, and that integrated control methods, principally in the form of mite resistant stocks, are the most effective long-term solution to the current V. destructor pandemic.