Small-scale genetic structure of the bulb mite Rhizoglyphus robini populations

Abstract Bulb mites are an economically significant pest of subterranean parts of plants and a versatile laboratory animal. However, genetic structure of their populations remains unknown. To fill this gap in our knowledge of their biology, we set-up field experiment in which we allowed mites to colonize onion bulbs, and then determined genetic structure of colonisers based on a panel of microsatellite loci. We found moderate but significant population structure among sites separated by ca. 20m (F ST range 0.03–0.21), with 7% of genetic variance distributed among sites. Allelic richness within some bulbs was nearly as high as that in the total population, suggesting that colonisation of bulbs was not associated with strong population bottlenecks. The significant genetic structure we observed over small spatial scales seems to reflect limited dispersal of mites in soil.