New haplotypes of the parasitic mite Varroa destructor on Apis mellifera in Asia: a permanent threat for apiculture
Résumé
The invasion ofApis mellifera by Varroa destructor is attributed to two haplotypes (K and 1) that shifted from A. cerana, in north-east Asia last century. Ofthe eight known haplotypes of V. destructor on A. cerana, only two, the so-called Japan 1 (JI) and Korea 1 (KI) haplotypes, have·colonizedA. mellifera. We have gain further insights into the invasion ofA. mellifèra by V. destructor by identifying and genotyping the mite infesting both A. cerana and A. mellifera in regions where the JI and KI host shifts occurred and in a broader area along the mite geographic range in Asia. Mitochondrial sequences were used and mite samples were first genotyped on the basis of fragment ofthe COI to connect new samples to the known haplotypes. Based on the analysis of expanded mtDNA sequences, new Varroa mitochondriallineages were uncovered. New variants of each ofthe K and J haplotypes were found on Western honeybees and are potential new threats for Western honeybees outside of Asia. The extreme lack of polyniorphism now seen in the K and J haplotypes on Western honeybees outside ofAsia can be plausibly explained from bottlenecks that occurred in Asia before and after mites shifted from their primary host. The presence ofnovel haplotypes of V. destructor parasitizing A. mellifera in Asia highlight the permanent risk that a new Varroa type might extend on A. mellifèra outside Asia, representing a new threat for apiculture.
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