Biology of Ephedrus plagiator1 on Different Aphid Hosts and at Various Temperatures 2

Host preference, developmental time, fecundity, adult longevity, emergence, and sex ratio of Ephedrus plagiator (Nees) at 3 constant temperatures were studied in the laboratory. The greenbug, Schizaphis graminum (Rondani), corn leaf aphid, Rhopalosiphum maidis (Fitch), oatbird cherry aphid, R. padi (L.), and English grain aphid, Macrosiphum avenae (Fabricius) were preferred over the rusty plum aphid, Hysteroneura setariae Thomas, cotton aphid, Aphis gossypii Glover, yellow sugarcane aphid, Sipha flava (Forbes), and spotted alfalfa aphid, Therioaphis maculata (Buckton). E. plagiator was never observed probing or attempting to parasitize the latter 2 species. Developmental period of E. plagiator varied inversely with the temperature, but was approximately the same in each aphid species at each temperature. The sex ratio averaged 30% female or below on each aphid species and at each temperature. The longevity of E. plagiator (female and male) was greater at 16°C than at 21° or 27°C, and also decreased as temperature increased. The species of aphid host had no apparent effects on either adult longevity or development rate of E. plagiator .