Host specificity of Trichostrongylus tenuis from red grouse and northern bobwhites in experimental infections of northern bobwhites.

The red grouse (Lagopus lagopus scoticus) and northern bobwhite (Colinus virginianus) are parasitized by the cecal nematode, Trichostrongylus tenuis. Our objective was to determine if T. tenuis from red grouse is infective in bobwhites. We inoculated bobwhites with infective-stage T. tenuis larvae that originated from red grouse in northern England and bobwhites in Florida. We also inoculated domestic chickens with larvae from the same sources. None of the 6 bobwhites inoculated with larvae from red grouse became infected. Five of the 6 bobwhites inoculated with larvae of bobwhite origin became infected. All of the chickens were infected. At necropsy, lesions or inflammation of the ceca were not observed either in chickens or bobwhites. The results suggest that Trichostrongylus in red grouse and northern bobwhite are distinct species. Along with absence of gene flow, differences in transmission conditions and infrapopulation levels may have resulted in differences in host specificity.