Nganso Beatrice T, Fombong Ayuka T, Yusuf Abdullahi A, Pirk Christian W W, Stuhl Charles, Torto Baldwyn
International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya.
Social Insects Research Group, Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa.
PLoS One. 2017 Jun 16;12(6):e0179329. doi: 10.1371/journal.pone.0179329. eCollection 2017.
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.
狄斯瓦螨是蜜蜂的一种体外寄生害虫，对养蜂业的生存构成威胁。多项研究表明，与欧洲蜜蜂不同，非洲蜜蜂种群在受到这种螨虫攻击时似乎受影响最小。然而，对于非洲蜜蜂种群抵御螨虫生存的潜在驱动因素知之甚少。我们假设抗性行为防御是非洲蜜蜂抵御这种体外寄生虫生存的原因。我们通过比较肯尼亚的非洲草原蜜蜂（Apis mellifera scutellata）和美国佛罗里达州欧洲血统的意大利蜜蜂（A. mellifera）杂交种针对螨虫的梳理行为和卫生行为来检验这一假设。通过确定成年螨虫感染水平、每个蜂群每天的落螨量和螨虫损伤百分比（作为成年蜜蜂梳理率的指标）来评估梳理行为，而通过确定冷冻杀死一部分幼虫后的幼虫清除率来评估卫生行为。我们的结果确定了另外两种未描述的受损螨虫类别，以及与两种蜜蜂亚种梳理行为相关的六种先前已知的损伤类别。欧洲血统的意大利蜜蜂杂交种的成年螨虫感染水平比非洲草原蜜蜂高出约三倍，然而，两种蜜蜂亚种的幼虫清除率、成年蜜蜂梳理率和每日自然落螨量相似。与欧洲血统的意大利蜜蜂杂交种不同，非洲草原蜜蜂成年蜜蜂的梳理率和幼虫清除率与螨虫感染水平无关，尽管它们比欧洲同类对螨虫更具攻击性。我们的结果为非洲草原蜜蜂抵御螨虫生存的耐受机制提供了有价值的见解。
