Bionomics of Aphelinus asychis (Hymenoptera: Eulophidae) an Introduced Parasite of the Sorghum Greenbug1,2

Abstract

Field studies of Aphelinus asychis (Walker), an introduced parasite of the greenbug, Schizaphis graminum (Rondani) (Homoptera: Aphididae), were conducted during summer and fall of 1969 to determine host preference, adult longevity, developmental time, fecundity, and sex ratio of the parasite in cages in the field. Based on the species and number of aphids parasitized, A. asychis showed a definite preterence for the C-biotype greenbug over the corn leaf aphid, Rhopalosiphum maidis (Fitch); oat-bird cherry aphid, R. padi (L.); and yellow sugarcane aphid, Sipha flava (Forbes). The mean longevity of A. asychis adults was 19.7 days. The field temperature during the study ranged from −10.0 to 37.8°C. Fecundity ranged from 33 to 159 mummies per female parasite, with a mean of 94.5; the sex ratio of emerging adults was about 1:1. The developmental time (egg to adult) varied inversely with the temperature. A. asychis parasitized both apterous and alate aphids.