GENETIC DIFFERENTIATION AMONG POPULATIONS OF THE SAWFLY SPECIES PLATYCAMPUS-LURIDIVENTRIS, ASSOCIATED WITH DIFFERENT ALDER SPECIES (HYMENOPTERA, TENTHREDINIDAE)

Populations of Platycampus luridiventris (Fallen 1808) exploiting diff erent host plant species of the genus Alnus exhibit differences in lar val morphology and ecological traits related to host preference. In Ge rmany and Austria the biotypes on A. glutinosa and A. incana are distr ibuted sympatrically and recurrently exist in close neighbourhood, whi le occurrence of populations feeding on Alnus viridis is restricted to the alpine and prealpine regions. Results of allozyme analysis presen ted here suggest that biotypes represent genetically separated host-sp ecific races. Patterns of gene diversity and genetic distances are con gruent with differences in host associations of populations. 3 pairs o f populations collected from adjacent stands of A. glutinosa and A. in cana respectively prove that there are significant genetic differences within the species P. luridiventris. Aspects that support the status of host-specific races are discussed, refering to a connected study on ecological differences among these strains.