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 parasitoidAphelinus abdominalis (Dalman) were evaluated in the laboratory. Both lines exhibited high fecundities, produced a high proportion of female offspring and showed to be long-lived. However, release experiments in winter wheat fields failed to achieve establishment of the parasitoids. In addition, the wasps parasitized considerably fewer aphids in two types of field cages than they did in the laboratory. AsA. abdominalis eggs and/or larvae arrested in development were not found in dissected aphids from field cages, we conclude that the wasps were unable or unwilling to parasitize high numbers of hosts in the cages. The reason for this odd behaviour is unknown.