Comparative biology of gall-formers in the genus Procecidochares (Diptera: Tephritidae) on rabbitbrush in Idaho.

Abstract

Three species of gall-forming Tephritidae in the ge nus Procecidochares were collected from rabbitbrush (Composi tae: Chrysothamnus spp.) in Idaho. Morphologically alike, adults fit the description of P. minuta Snow; however, biological char acteristics clearly differentiate each species. Significant differences exist in regard to 1) host plants, 2) type of gall formation, 3) sea sonal occurrence, 4) larval behavior, and 5) puparium morphology. The life history and habits of each species are discussed with em phasis on the salient features for their identification. Investigations of the gall-forming Tephritidae on rabbitbrush (Composi tae: Chrysothamnus spp.) in Idaho (Wangberg, 1976) revealed the occur rence of 3 sympatric species in the Procecidochares minuta group. Under the current classification each of the 3 species reported here key to P. minuta Snow. Comparison of gross anatomical features of adults is inade quate for separation of species although the occurrence of very subtle dif ferences cannot be excluded (Steyskal, pers. comm.). Their biologies, how ever, reveal widely different habits and hence serve as evidence for the occurrence of sibling species. This paper reviews the biology of each species with emphasis on the distinguishing aspects. Two of the three species have not been previously reported in the literature, while only fragmentary ac counts exist on the biology of the third. Included with a review of their general life histories are new host records, descriptions of immature stages, descriptions of galls, behavioral observations, and lists of insect associates. A forthcoming taxonomic revision of the P. minuta group by Steyskal (pers. comm.) will be based in part on these observations.