The following was presented at the 2010 American Bee Research Conference in Orlando, FL.
2. Alaux, C., J.-L. Brunet, C. Dussaubat, F. Mondetd, S. Tchamitchand, M. Cousind, J. Brillard, A. Baldy, L.P. Belzunces & Y. Le Conte - INTERACTIONS BETWEEN NOSEMA MICROSPORES AND A NEONICOTINOID IN HONEY BEES - Massive honey bee losses have been reported in the world, but the specific causes are still unknown. Single factors, like pesticide impact, or a disease or parasite have not explained this global decline, leading to the hypothesis of a multifactorial syndrome (van Engelsdorp et al., 2009 PLoS One 4:e6481). Consequently, we tested the integrative effects of an infectious organism (Nosema sp) and an insecticide (imidacloprid) on honeybee health. We demonstrated, for the first time, that a synergistic effect between both agents, at concentrations encountered in nature, significantly weakened honey bees. The combination of Nosema, a pathogen whose importance is emerging, with imidacloprid caused a significantly higher rate of individual mortality and energetic stress in the short term than either agent alone. We then quantified the strength of immunity of honey bees. While the single or combined treatments showed no effect on individual immunity (haemocyte number and phenoloxidase activity), a measure of colony level immunity, glucose oxidase activity, was significantly decreased only by the combined treatments, emphasizing their synergistic effects. Glucose oxidase activity enables bees to secrete antiseptics in honey and brood food. This suggests a higher susceptibility of the hive to pathogens. We, thus, provide evidence for integrative effects of different agents on honey bee health, both in the short and long term. By focusing either on the effects of pesticides or parasites alone, previously established synergy has been ignored, despite clear evidence from integrated pest management that entomogenous fungi act synergistically with sub-lethal doses of pesticides to kill insect pests (Alaux et al., 2009 Environ. Microb. doi:10.1111/j.1462-2920.2009.02123.x).
More presentations from this conference can be found at Proceedings of the American Bee Research Conference 2010