Varroa sensitive hygiene

About: Varroa sensitive hygiene is a research topic. Over the lifetime, 714 publications have been published within this topic receiving 24928 citations. The topic is also known as: VSH.

The effect of queen pheromone status on Varroa mite removal from honey bee colonies with different grooming ability.

Abstract: The objective of this study was to assess the effects of honey bees (Apis mellifera L.) with different grooming ability and queen pheromone status on mortality rates of Varroa mites (Varroa destructor Anderson and Trueman), mite damage, and mortality rates of honey bees. Twenty-four small queenless colonies containing either stock selected for high rates of mite removal (n = 12) or unselected stock (n = 12) were maintained under constant darkness at 5 °C. Colonies were randomly assigned to be treated with one of three queen pheromone status treatments: (1) caged, mated queen, (2) a synthetic queen mandibular pheromone lure (QMP), or (3) queenless with no queen substitute. The results showed overall mite mortality rate was greater in stock selected for grooming than in unselected stock. There was a short term transitory increase in bee mortality rates in selected stock when compared to unselected stock. The presence of queen pheromone from either caged, mated queens or QMP enhanced mite removal from clusters of bees relative to queenless colonies over short periods of time and increased the variation in mite mortality over time relative to colonies without queen pheromone, but did not affect the proportion of damaged mites. The effects of source of bees on mite damage varied with time but damage to mites was not reliably related to mite mortality. In conclusion, this study showed differential mite removal of different stocks was possible under low temperature. Queen status should be considered when designing experiments using bioassays for grooming response.

A scientific note on the fungus Beauveria bassiana infecting Varroa destructor in worker brood cells in honey bee hives

Abstract: We report on the isolation of the mitosporic fungus Beauveria bassiana from varroa mites, Varroa destructor, in capped worker brood cells of honey bees, Apis mellifera. To our knowledge, this is the first record of B. bassiana from mites collected from bee brood. The brood chamber is the area of the hive where bees maintain high constant temperatures of 33–36 ◦C (Le Conte et al., 1990). An entomopathogenic fungus may be less efficacious because of poor germination at the high temperatures inside brood cells. Natural enemies of the varroa mite are few and, until recently, included no records of fungal pathogens (Chandler et al., 2001). However, a number of studies have shown that varroa mites are highly susceptible to infection by a range of entomopathogenic fungi, including B. bassiana (James, 2009). Many entomopathogenic fungi have a ubiquitous distribution and a wide host range, thus one might expect foraging bees to frequently carry fungus conidia into the bee hive from their environment. The lack of observed natural infections of varroa mites by these fungi could be due to a combination of hygienic behaviour of worker bees and the harsh environmental conditions in bee colonies. Nevertheless, Meikle et al. (2006) isolated B. bassiana from approximately 0.2% of varroa mites collected from a number of apiaries in southern France and documented that natural infections could indeed be found. B. bassiana has also been reported from varroa mites in southern Spain (Garcia-Fernandez et al., 2008).