SEARCHING EFFICIENCY OF TRICHOGRAMMA-NUBILALE (HYMENOPTERA, TRICHOGRAMMATIDAE)

The influence of seasonal increases in plant-leaf surface area on the searching efficiency of Trichogramma nubilale Eitle and Davis was investigated in field and laboratory studies. Parasitoids were released continuously in corn throughout' the weeks of plant growth and their success in discovering European corn borer (Ostrinia nubilalis (Hbn.)) egg masses was measured. In the laboratory, single female parasitoids were placed with a host egg mass within different sized arenas to measure the effect of an increase in area on the searching efficiency of the parasitoid. Increases in the leaf surface area or in searching arena size showed an inverse response in percent discovery by the parasitoid of O. nubilalis. Field and laboratory studies support Knipling and McGuire's (1968) theoretical model where an increase in searching area results in a decrease in host discovery, when the searching pattern of the parasitoid is random. © 1979 Entomological Society of America.