Pteromalid fauna (Hymenoptera, Pteromalidae) in oilseed rape (Brassica napus L.) fields in Bulgaria – species composition and perspectives for biological control

Abstract

Parasitoid wasps belonging to the family Pteromalidae are widespread and abundant members of the insect communities in the temperate regions of the world. As many other chalcids do, pteromalids serve as natural enemies of the pests in various crops and play an important role in the biological control of these harmful insects. Here we present the results of a field study in Bulgaria which was focused on the diversity of family Pteromalidae in ten oilseed rape fields. All samples were collected by sweep netting on the border line or inside the crop field. A total of 93 pteromalid specimens belonging to 26 taxa were gathered. The most abundant genus was Mesopolobus – 67% of the sampled pteromalids. The most numerous species in the samples was Mesopolobus morys – a well-known key parasitoid of the cabbage seed weevil, Ceutorhynchus obstrictus, in Europe. One species – Halticoptera patellana, is recorded for the first time in Bulgarian fauna. Clearfield oilseed rape fields had relatively higher parasitoid abundance and richness than the fields treated by conventional technology. In the present work we discuss the overall species composition of Pteromalidae obtained from the studied areas and present our point of view on the perspectives for biological control of oilseed rape pests.