Single and interactive effects of Varroa destructor, Nosema spp., and imidacloprid on honey bee colonies (Apis mellifera)

Abstract

Citation: van Dooremalen, C., B. Cornelissen, C. Poleij-Hok-Ahin, and T. Blacqui ere. 2018. Single and interactive effects of Varroa destructor, Nosema spp., and imidacloprid on honey bee colonies (Apis mellifera). Ecosphere 9(8):Abstract. High losses of honey bee colonies in recent decades are of great societal and economical concern and experienced as a sign of the vulnerability of the environment, including the service of crop pollination, and of the beekeeping sector. There is no single cause for the colony losses, but many contributing stressors may act in concert. Varroa destructor infestation is acknowledged as an important cause of these losses. The roles of infestation by Nosema ceranae or exposure to insecticides are controversial. Interactions between exposure to pesticides and V. destructor or Nosema spp. have previously been implicated. In two years of field experiments, we studied the effects of and possible interactions between the stressors V. destructor infestation, Nosema spp. infestation, and chronic sublethal exposure to a field-realistic dose of the insecticide imidacloprid on the performance and survival of honey bee colonies. Colonies highly infested by V. destructor were 13% smaller in size and were 59.1 times more likely to die than colonies infested with low levels of V. destructor. Infestation with high levels of Nosema sp. led to 2% decrease in size and 1.4 times higher likelihood to die compared to colonies with low levels of Nosema sp. No effects of chronic sublethal exposure to imidacloprid on colony size or survival were found in this study. Exposure to V. destructor and imidacloprid led to a slightly higher fraction of bees infested with Nosema sp., but in contrast to the expectations, no resulting interactions were found for colony size or survival. Colonies as a superorganism may well be able to compensate at the colony level for sublethal negative effects of stressors on their individuals. In our experimental study under field-realistic exposure to stressors, V. destructor was by far the most lethal one for honey bee colonies.

American foulbrood in a honeybee colony: spore-symptom relationship and feedbacks between disease and colony development

“…The observed increase in the amount of brood in response to a stressor has previously been described for Varroa destructor infested colonies [14], where larger colonies in the autumn were more likely to die the following year. A bee colony is an adaptable unit that uses brood rearing as one of the mechanisms to respond to external and internal stimuli, through both positive and negative feedback loops [60].…”

“…At the same time, beekeepers worldwide are experiencing increased winter and seasonal colony losses [4][5][6][7]. Such losses stem from a combination of parasites and diseases, poor nutrition, inadequate beekeeping management practices and pesticide exposure; both individually and synergistically [8][9][10][11][12][13][14][15][16].…”

Global warming promotes biological invasion of a honey bee pest

“…Amongst the many factors potentially impacting honey bee health and thus pollination services, invasive parasitic species, e.g. introduced by global trade in honey bees and related products such as wax and honey (Chanpanitkitchote et al, ; Krongdang, Evans, Chen, Mookhploy, & Chantawannakul, ; Neumann, Pettis, & Schäfer, ; Ouessou Idrissou, Huang, Yañez, & Neumann, ; Schäfer et al, ), can play a key role (Neumann et al, ; Potts, Biemeijer, et al, ; Rosenkranz, Aumeier, & Ziegelmann, ; van Dooremalen, Cornelissen, Poleij‐Hok‐Ahin, & Blacquière, ). However, knowledge of the potential effects of climate change on such species is currently lacking (Le Conte & Navajas, ).…”

Varroa destructor infestation impairs the improvement of landing performance in foraging honeybees

“…Even though Varroa-infestation rates were moderate (1-2%), the likelihood of these infested colonies to survive winter would have already been compromised [22]. Based on these infestation rates and an assumed doubling of mites between August and September, the likelihood of colony collapse during the following winter would have been 25-60%.…”