Host range differences between two strains of wheat curl mites (Acari : Eriophyidae)

Previous greenhouse studies to determine the host range of the wheat curl m ite, Aceria tosichella Keifer, sometimes have produced conflicting results. One explanation for the reported differences is that collections of wheat curl mites from different locations may vary in their ability to colonize v arious grasses. Our objective was to test this possibility by comparing two collections of wheat curl mites, one each from Kansas and Nebraska, known to differ in virulence to resistant wheat, for their ability to colonize 28 species of cultivated and wild grasses. Twenty of the 28 grasses were nonh osts based on the criteria of no increase in numbers of wheat curl mites (l ess than the initial infestation of 10 per plant) on these species. Small, but statistically significant, differences in survival between the two coll ections of wheat curl mites occurred on three of these 20 grasses considere d as nonhosts. With the exception of rye, the Kansas and Nebraska wheat cur l mites increased equally on the eight grasses that were considered as host s. The Kansas wheat curl mites increased significantly more on rye than the Nebraska wheat curl mites. This difference may be explained by the develop ment of a Kansas wheat curl mite strain virulent to 'TAM 107' wheat, which has a rye source of resistance. These results provide little support for th e theory that the major differences between previously reported results are due to the use of different collections or strains of wheat curl mite. Fur ther studies are needed to better define the host range of the wheat curl m ite.