Abortive Development of the Cynipid Parasite Pseudeucoila bochei (Hymenoptera) in Species of the Drosophila melanica Group1

Abstract

In 6 Nearctic species of the Drosophila melanica group, large numbers of eggs of the cynipid parasite Pseudeucoila bochei Weld failed to hatch, and many of the parasite larvae died in the 1st stage. Microscopic examinations of the dead parasites failed to show any evidence of encapsulation by hemocytes. However, on some dead larvae patches of melanin had been deposited. When host larvae were parasitized at different ages it was found that the parasites were more successful in younger hosts than they were in older hosts. Host immunity, active or passive, appears to be a function of age.