THE INFLUENCE OF ANT ATTENDANCE ON LARVAL PARASITISM IN HAWTHORN PSYLLIDS (HOMOPTERA, PSYLLIDAE)

The influence of ant attendance on parasitization of the larvae of thr ee hawthorn psyllid species [Cacopsylla peregrina Forster, C. melanone ura Forster, C. crataegi (Schrank)] was studied over 2 years. All thre e psyllid species had low parasitization rates. However, the ant-atten ded C. crataegi was almost exclusively parasitized by Prionomitus mitr atus (Dalman) (Hymenoptera: Encyrtidae) while the unattended C. peregr ina and C. melanoneura were predominantly attacked by P. tiliaris (Dal man). Additionally, C. peregrina and C. melanoneura had significantly higher hyperparasitization rates than the ant-attended C. crataegi, wi th Pachyneuron muscarum as the dominant hyperparasitoid of all three p syllids. The mummies of C. peregrina and C. melanoneura were also heav ily attacked by anthocorids. Both Prionomitus tiliaris and P. mitratus were disturbed and jumped away when encountering foraging ants. Howev er, ant exclusion experiments showed that the primary parasitoid P. mi tratus benefitted from ant attendance of its host C. crataegi as honey dew-collecting ants provided it with protection from hyperparasitoids.