EFFECTS OF PRE-ADULT AND ADULT EXPERIENCE ON HOST ACCEPTANCE IN CHOICE AND NON-CHOICE TESTS IN 2 STRAINS OF TRICHOGRAMMA

The effect of adult learning through an oviposition experience, and pr e-adult learning through development inside a host was investigated in two strains of an Australian egg parasitoid, Trichogramma nr ivelae ( Hymenoptera: Trichogrammatidae). Host response was measured in two typ es of laboratory preference tests. In single host tests, females reare d on three lepidopteran hosts (Heliothis punctigera (Noctuidae), Papil io aegeus (Papilionidae), and Hypolimnas bolina (Nymphalinae)) were pr esented host eggs individually, and allowed two ovipositions. Pre-adul t experience affected host preference in only one strain, while accept ance of a host was increased in both strains when they had previously oviposited in this host species. An oviposition experience had a stron ger effect on host preference than pre-adult experience. In choice tes ts, pairwise combinations of hosts were arranged in an alternating gri d. The ratio of host acceptances to host contacts was computed for the whole test and up to the first oviposition. These indicated that effe cts of rearing host were weak or absent, but the host chosen initially had a strong effect on host preference. Relative size of the hosts ha d a strong effect on choice of the first host. The implications of lea rning in Trichogramma are discussed in relation to host preference tes ting procedures and the selection of candidate strains for mass rearin g and inundative release.