|Wilson, Elisabeth - North Dakota State University|
|Bowsher, Julia - North Dakota State University|
|Peterson, Steve - Agpollen, Llc|
|Rinehart, Joseph - Joe|
Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/28/2019
Publication Date: 3/30/2019
Citation: Melicher, D.M., Wilson, E.S., Bowsher, J.H., Peterson, S., Yocum, G.D., Rinehart, J.P. 2019. Long-distance transportation causes temperature stress in the honey bee, Apis mellifera (Hymenoptera: Apidae). Environmental Entomology. nvz027. https://doi.org/10.1093/ee/nvz027.
DOI: https://doi.org/10.1093/ee/nvz027 Interpretive Summary: Every year thousands of honey bee hives are transported across the US to pollinate crops, primarily in the central valley of California and in Washington and Oregon. Transporting bees is stressful and the industry reports that 5-10% of bees die each time they are shipped. Bees that survive may be too stressed to recover and transportation may make it more likely for hives to die out in the long term. Researchers from the Insect Genetics and Biochemistry unit from USDA-ARS Fargo, ND in collaboration with North Dakota State University and industry stakeholders want to identify different sources of stress during transportation and quantify them. This allows us to prioritize sources of stress and identify cost-effective measures to improve honey bee health and survival with the goal of developing management strategies during shipping that focus on economic impact and improving pollination services per hive. We used temperature sensors to see how wind and air flow vary between hives in different locations during shipping and found that hives in certain locations on the trailer experience high levels of temperature stress from excessive wind and turbulent air flow. The bees lose their ability to maintain temperature inside the hive for long periods of time, which is very stressful. We also found that hives with fewer bees are at much greater risk of cold stress and rapidly failing after they are shipped. We looked at genes that respond to stress and found that after transportation bees are responding to temperature stress and their immune systems are challenged in the weeks after shipping. This shows that transportation is a significant source of stress that can cause hives to fail and further research is needed to assess the economic impact to determine cost-effective interventions to reduce loss.
Technical Abstract: The pollination services provided by honey bees (Apis mellifera) have broad economic impacts and are necessary for the production of a diversity of important crops. Management practices, including long-distance transportation, contribute to high annual hive losses. Multiple times in a season, hives are transported by truck long distances to locations with highly variant climates and inconsistent resource availability which causes multiple stresses and reduces the health of the colony. To test how temperature may contribute to transportation stress, hives were equipped with internal temperature sensors and placed at different locations and orientations on the trailer during transport. We found that internal hive temperature varies significantly based on hive location and orientation. Hives near the front and rear of the trailer and those oriented toward the center aisle experience much greater variation in internal temperature than those located near the middle. These hives experience significant temperature stress, some lose their ability to thermoregulate temporarily, and a subset does not recover thermoregulation during the duration of transportation. Colony size prior to shipping significantly affects thermoregulation during shipping, bees lost after shipping, and colony survival. Additionally, we profile gene expression in A. mellifera prior to departure, immediately after arrival, and after a recovery period to identify enriched pathways and transcriptional responses to transportation. Functional and enrichment analysis identified an increase in methylation and a corresponding decrease in ribosomal and protein-folding activity. Pheromone and odorant-binding transcripts were up-regulated after transportation. After a recovery period, transcripts corresponding to defense response, immune system activity, and heat shock proteins decreased, while production of antibiotic peptides increased. We conclude that less protected hives experience considerable temperature stress which may be caused by increases in turbulent air flow in the front and rear of the truck. Transportation stress should be considered an important component of annual colony losses which can be mitigated with improved management strategies.