|Le Conte, Yves|
Submitted to: Proceedings of the Royal Society of London: Biological Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/1/2004
Publication Date: 12/1/2004
Citation: Solignac, M., Cornuet, J., Vautrin, D., Le Conte, Y., Anderson, D., Evans, J.D., Cros-Arteil, S., Navajas, M. 2005. The invasive korea and japan types of varroa destructor, ectoparasitic mites of the western honey bee (apis mellifera), are two partially isolated clones. Proceedings of the Royal Society, Series B. 272:411-420. Interpretive Summary: Varroa mites are the most important pest of honey bees worldwide. Curiously, only one species of Varroa, Varroa destructor, has been shown to affect the western honey bee (Apis mellifera, the bee most commonly used for pollination and honey production). Within this mite species, only two genetic lines are known to infect A. mellifera and these, too, seem to have different effects on bees. Understanding the genetic basis of these differences offers a route toward understanding how mites can be controlled. This study points to genetic differences between mites that differ in their impact on bees, a start toward identifying the means by which this important pest affects honey bees. This information should prove useful for researchers as well as those regulating the worldwide movement of bees and mites.
Technical Abstract: Varroa destructor, now a major pest of the Western honeybee Apis mellifera, switched from its original host, the Eastern honeybee A. cerana about 50 years ago. To date, only 2 of several known mitochondrial haplotypes of V. destructor have been found to be capable of reproducing on A. mellifera (Korea and Japan). These haplotypes are associated in almost complete cytonuclear disequilibrium to diagnostic alleles at 11 microsatellite loci. By contrast, microsatellite polymorphism within each type is virtually absent, because of a severe bottleneck at the time of host change. Accordingly, 12 mitochondrial sequences of 5,185 nucleotides displayed 0.40 % of nucleotide divergence between haplotypes and no intra-haplotype variation. Hence, each type has a quasi-clonal structure. The nascent intratype variability is subsequent to the clone formation 50 years ago: in both types the variant alleles differ from the most common by one (in 10 cases), 2 (5 cases) or 3 (1 case) repeated motifs. In addition to individuals of the two 'pure' types, five F1 hybrids and 19 recombinant individuals (Japan alleles introgressed into the Korea genetic background) were detected. The existence of F1 and recombinant individuals in admixed populations requires that double infestations of honeybee cells occur in high proportion but the persistence of pure types suggests a postzygotic isolation between the two clones.