| 研究実績の概要 |
Western honey bee populations continuously fight against tenacious Asian enemies: ectoparasitic Varroa mites. The Western honey bee (A. mellifera) has been introduced into the native range of its sister species, the Eastern honey bee (A. cerana). This new, sudden contact between both species allowed parasite spillover. About 70 years ago, Varroa destructor, took this opportunity and successfully switched hosts from the Eastern to the Western honey bee. This parasite rapidly spread quasi-worldwide and became the main driver of honey bee colony losses. Concerns arise as ten years ago, an emerging threat, V. jacobsoni, also jumped onto the Western honey bee in Papua New Guinea.Despite a reported loss of genetic diversity and quasi-clonality in invasive populations, mites are persisting and evolving new traits such as acaricide resistance.
To help turning the tide in the Varroa-honey bees-beekeepers war, we recently developed new genomic resources to identify the mechanisms behind the mites' success. Here, I will present i) the first genomic insights into the demographic origins of V. destructor and V. jacobsoni jumps. Using mite species collected in their native ranges from both the ancestral and novel hosts, we were able to correctly reconstruct the temporal dynamics of the switch. We further found that hundreds of haplotypes were involved in the initial host switch, and, while greatly reduced, some gene flow between mites adapted to different hosts remains.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
2: おおむね順調に進展している
理由
The samples were largely on hand, and given our previous experience with Varroa genomics, we were able to quickly make libraries for sequencing. In fact, we conducted preliminary investigations by sequencing a representative sub-sample of the total samples to ascertain the viability of this project. There results were surprising, and showed that we can, in fact, reconstruct Varroa biogeography. We presented these preliminary data at two international conferences.
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