Rhizoglyphine mites (Acari : Acaridae) infesting rakkyo (Allium Chinense G. Don) and Chinese chive (A. tuberosum Rottler), and their susceptibility to dimethoate and disulfoton

Mites of the subfamily Rhizoglyphinae infesting rakkyo and chinese chive were collected in several districts where these crops are being grown. Mites were identified and their susceptibility to dimethoate and disulfoton was examined in the laboratory. Two species, Rhizoglyphus robini CLAPARÉDE and Caloglyphus sp., were identified in the samples and no individuals belonging to the R. echinopus (FUMOUZE et ROBIN) species were collected. Although the current samples were limited representatives of the districts, the number of either of the two species predominated over the other in most cases. The susceptibility of R. robini to dimethoate and disulfoton showed similar inter-district variations with a resistance factor in the range of 2 to 9. In contrast Caloglyphus sp. showed a low susceptibility to dimethoate without significant variations (resistance factor ranging from 1-3) between the districts. However, the same species showed a potential for high susceptibility to disulfoton and the inter-district difference in the resistance factor was as great as 3 to 25 times.