Trophic associations of weevils of the genus Tychius Germ. (Coleoptera, Curculionidae) with Astragalus species in the forest-steppe of the middle Volga Area

摘要

Nineteen of the 20 Astragalus species recorded from Ulyanovsk Province have been examined. Eight species of the weevil genus Tychius attack 14 Astragalus species, preferring those without bright (pale purple or violet) coloration of their flowers. This communication is based on the material collected by the author in various landscapes of the Volga-Area Upland and Transvolga Lowland, mainly in Ulyanovsk Province, in 1990-1998. A total of 1000 weevils of the genus Tychius were collected from astragals. For most species of this species-rich weevil genus, trophic associations have been already established (Lohse, 1983; Caldara, 1990; Isaev, 1990, 1994). Nevertheless, the occurrence of Tychius species on particular host plants in a region with transitional environmental conditions is of certain interest.