SEPARATING THE EFFECTS OF EXPERIENCE, SIZE, EGG LOAD, AND GENOTYPE ONHOST RESPONSE IN TRICHOGRAMMA (HYMENOPTERA, TRICHOGRAMMATIDAE)

The effects of experience, egg load, and wasp size on the response of four strains of Trichogramma nr. brassicae (Hymenoptera: Trichogrammat idae) to three economically important hosts, Heliothis punctigera (Noc tuidae), Phthorimaea opercullela (Gelechiidae), and Sitotroga cerealle la (Gelechiidae) were investigated. Experience effects due to rearing host and oviposition were considered in all combinations of host speci es. Both these effects altered response levels to low-ranked hosts but not to highly preferred hosts. Size was correlated with host response in some strains; larger females took more encounters with a host befo re accepting it, while egg load was not correlated with number of host encounters. However, egg lend, rearing host, and size all affected ac ceptance of the low-ranked host S. cereallela. Females were more likel y to accept this host if they were reared on S. cereallela, had a smal l size, and had a high egg load. Effects were consistent across strain s, although overall acceptance levels differed among strains.