Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Investigation into the parasitism of the cabbage seed-pod weevil (Ceuthorrhynchus assimilis Payk.) and the cabbage seed-pod gall-midge (Dasyneura brassicae Winn.) in Schleswig-Holstein.

Abstract

Field investigations were carried out in 1968-70 at four places (with different soils and climate) in Schleswig-Holstein, West Germany, on the parasites of Ceutorhynchus assimilis (Payk.) and Dasineura brassicae (Winn.) on rape. Parasitism of the larvae of C. assimilis by Trichomalus perfectus (Wlk.) averaged 10.8-43.2%; an unidentified species of Necremnus, possibly N. duplicatus Gah., was also found. T. perfectus was more numerous in the middle of the field than at its borders, and adults left the rape pods before harvest. Ten Hymenopterous parasites were reared from cocoons of D. brassicae. The maximum rate of parasitism was 14%, and it is concluded that the effects on populations of the gall-midge were insignificant. Of these parasites of D. brassicae, a species believed to be Prosactogaster (Platygaster) oebalus (Wlk.) was the most frequent, and Aphanogmus abdominalis (Thoms.) was the next commonest. Other parasites obtained were Omphale clypealis (Thoms.), Synopeas thomsoni (Kieff.), Inostemma reticulatum Szelenyi and two other species of the same genus, Ceraphron serraticornis Kieff., C. pallipes Thoms. and Conostigmus rufescens Kieff.