Hygienic and grooming behaviors in African and European honeybees-New damage categories in Varroa destructor

PLoS One. 2017 Jun 16;12(6):e0179329. doi: 10.1371/journal.pone.0179329. eCollection 2017.

Abstract

Varroa destructor is an ectoparasitic pest of honeybees, and a threat to the survival of the apiculture industry. Several studies have shown that unlike European honeybees, African honeybee populations appear to be minimally affected when attacked by this mite. However, little is known about the underlying drivers contributing to survival of African honeybee populations against the mite. We hypothesized that resistant behavioral defenses are responsible for the survival of African honeybees against the ectoparasite. We tested this hypothesis by comparing grooming and hygienic behaviors in the African savannah honeybee Apis mellifera scutellata in Kenya and A. mellifera hybrids of European origin in Florida, USA against the mite. Grooming behavior was assessed by determining adult mite infestation levels, daily mite fall per colony and percentage mite damage (as an indicator of adult grooming rate), while hygienic behavior was assessed by determining the brood removal rate after freeze killing a section of the brood. Our results identified two additional undescribed damaged mite categories along with the six previously known damage categories associated with the grooming behavior of both honeybee subspecies. Adult mite infestation level was approximately three-fold higher in A. mellifera hybrids of European origin than in A. m. scutellata, however, brood removal rate, adult grooming rate and daily natural mite fall were similar in both honeybee subspecies. Unlike A. mellifera hybrids of European origin, adult grooming rate and brood removal rate did not correlate with mite infestation levels on adult worker honeybee of A. m. scutellata though they were more aggressive towards the mites than their European counterparts. Our results provide valuable insights into the tolerance mechanisms that contribute to the survival of A. m. scutellata against the mite.

MeSH terms

  • Africa
  • Animals
  • Bees / parasitology*
  • Europe
  • Florida
  • Grooming*
  • Species Specificity
  • Varroidae*

Grants and funding

We gratefully acknowledge the financial support for this research by the following organizations and agencies: United States Department of Agriculture (USDA)/ARS- grant # 58-6615-3-011-f; UK aid from the UK government; Swedish International Development Cooperation Agency (SIDA); the Swiss Agency for Development and Cooperation (SDC); and the Kenyan government. The views expressed herein do not necessarily reflect the official opinion of the donors. Immense gratitude to the German Academic Exchange Service In-Region Scholarship for funding the PhD research work and studies of Beatrice T. Nganso at the International Centre of Insect Physiology and Ecology (ICIPE) and the Office of International Research Programs at USDA-ARS for providing the financial support needed for the research conducted in the USA.