Effective pest management approaches can reduce impacts of weather on honey bee colony winter survival (Apis mellifera)

Authors: GRAY, DARCY - Pennsylvania State University; Goslee, Sarah; KAMMERER, MELANIE - US Department Of Agriculture (USDA); GROZINGER, CHRISTINA - Pennsylvania State University

Submitted to: Journal of Insect Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/26/2023
Publication Date: 6/15/2024
Citation: Gray, D., Goslee, S.C., Kammerer, M., Grozinger, C. 2024. Effective pest management approaches can reduce impacts of weather on honey bee colony winter survival (Apis mellifera). Journal of Insect Science. 24(3):15. https://doi.org/10.1093/jisesa/ieae043.
DOI: https://doi.org/10.1093/jisesa/ieae043

Interpretive Summary: Honey bee colonies have been dying more often during the winter in recent years. Possible causes include weather during the winter and the previous growing season, changes in land use that reduce flower availability, exposure to pesticides, and disease and parasites. Some of these can be reduced by management interventions such as supplemental feeding and parasite treatments. Management can be effective, so understanding their importance can help beekeepers. We used data from a long-term survey of Pennsylvania beekeepers to identify the most important factors for winter survival. Treating for the parasitic Varroa mite was the most important, especially when more than one kind of treatment was applied. Honey bee colonies where multiple treatments were used could even withstand poorer weather conditions. Reducing the parasite load, a feasible management practice, can reduce the effects of weather, which cannot be controlled.

Technical Abstract: Managed honey bee (Apis mellifera, L.)  colonies have experienced high losses in recent years linked to weather conditions, pesticide exposure, lack of quality forage, and pest and parasite loads, particularly the obligate brood parasite Varroa destructor. These factors may interact at various scales to have compounding effects on honey bee health, but few studies have been able to investigate weather and landscape alongside beekeeping management. We analyzed a dataset of 3,210 survey responses from beekeepers in Pennsylvania from 2017-2022 and combined these with remotely sensed weather variables and novel datasets about seasonal forage availability into a Random Forest model to investigate drivers of winter loss. We found that beekeepers who used treatment against Varroa had higher survival than those who did not treat and furthermore that beekeepers who used multiple types of Varroa treatment had higher colony survival rates than those who used one type of treatment. Our model results also show that weather conditions strongly influenced survival and that the multiple-treatment apiaries had higher survival across a broader range of climate conditions. These findings suggest that the integrated pest management approach of combining treatment types seems to provide a buffer effect, somewhat sheltering apiaries from adverse weather conditions.