LOW-FIELD PERFORMANCE OF AN APHID PARASITOID, APHELINUS-ABDOMINALIS, EFFICIENT IN THE LABORATORY [HYM, APHELINIDAE]

Life history traits of two inbred lines of the aphid parasitoid Apheli nus abdominalis (Dalman) were evaluated in the laboratory. Both lines exhibited high fecundities, produced a high proportion of female offsp ring and showed to be long-lived. However, release experiments in wint er wheat fields failed to achieve establishment of the parasitoids. In addition, the wasps parasitized considerably fewer aphids in two type s of field cages than they did in the laboratory. As A. abdominalis eg gs and/or larvae arrested in development were not found in dissected a phids from field cages, we conclude that the wasps were unable or unwi lling to parasitize high numbers of hosts in the cages. The reason for this odd behaviour is unknown.