Flight activity assessment of the egg parasitoid Trichogramma brassicae (Hym: Trichogrammatidae) in laboratory and field conditions

A laboratory and a field test for flight initiation of Trichogramma brassicae Bezdenko (Hymenoptera, Trichogrammatidae) (synonymous to T. maidis Pintureau et Voegele) were developed with the aim to establish a simple, cheap and quick flight quality control method for Trichogramma producers. The flight quality of four strains of T. brassicae reared on Ephestia kuehniella Zeller eggs were compared. The material tested consisted of four strains: two strains reared for two (F2) and 39 to 42 (F39-42) generations on E. kuehniella eggs without storage treatment, a diapause strain reared six generations (F6) on E. kuehniella eggs and a commercial strain also reared on E. kuehniella eggs whose production and storage conditions were unknown. Clear differences in flight activity among strains were observed. Both, the F2 and commercial strain showed significantly better flight activity under laboratory conditions compared to the other strains. Flight field cage experiments were made for comparison between field and laboratory results. Similar differences among strains in field cage experiments were observed when compared to laboratory tests.