ARS | Publication request: Concurrent infestations by Aethina tumida and Varroa destructor alters thermoregulation in Apis mellifera winter clusters

Submitted to: Apidologie
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 1, 2011
Publication Date: March 20, 2011
Citation: Schaefer, M., Ritter, W., Pettis, J.S., Hartel, S., Neumann, P. 2011. Concurrent infestations by Aethina tumida and Varroa destructor alters thermoregulation in Apis mellifera winter clusters. Apidologie. 104(3):476-482.

Interpretive Summary: Honey bee hives face a major test in survival as they try to live through the winter in colder regions of the world; they must maintain a stable temperature in the cluster of bees in order to survive. Here we tested to see if two pests, the parasitic Varroa mite and the small hive beetle might act alone or in combination to impact the bees’ ability to maintain a constant temperature in the winter. Both pests overwinter in honeybee colonies. Here we show that combined infestations with Varroa mites and small hive beetles results in higher temperature fluctuations in the winter cluster, whereas infestations with one pest alone had no significant effect on the temperatures. Our research indicates that when both pests are present in the winter, colonies may have difficulty maintaining a stable temperature and this instability could lead to winter colony losses. This information will help refine future studies and can be useful for beekeepers to improve winter colony management.

Technical Abstract: The small hive beetle, Aethina tumida, and the ectoparasitic mite, Varroa destructor, are parasites of the honeybee, Apis mellifera. Both parasites overwinter in honeybee colonies. The efficacy of thermoregulation might be reduced in beetle and mite infested clusters, due to altered activity of host workers. Here we show that combined infestations with V. destructor and A. tumida result in higher thermal maxima in the winter cluster cores, whereas infestations with one parasite alone had no significant effect on thermoregulation. No differences in infestation rates with A. tumida were found between colonies with or without V. destructor. Likewise, no differences in mite/bee ratios were found between colonies with or without A. tumida and between the peripheries and the cluster cores. Our data indicate that an altered thermoregulation of heavily infested V. destructor colonies in combination with A. tumida infestation might be another factor contributing to winter losses of honeybee colonies.