In vitro rearing of Trichogramma minutum Riley (Hymenoptera: Trichogrammatidae) for ten generations, with quality assessment comparisons of in vitro and in vivo reared adults

Trichogramma minutum Riley were reared for 10 generations on an artificial diet containing a yeast extract, FreeAmine III, nonfat dry milk, chicken egg yolk, chicken embryo extract, and Manduca sexta (L.) egg liquid. Quality control parameters, including adult longevity, sex ratio, pupation rate, percentage of pupae to emerge as adults, adult female body length, number of Helicoverpa tea (Boddie) eggs parasitized by a female, and percentage of deformed females were assessed and compared to insects reared in vivo on irradiated H. tea eggs. The development time was longer for in vitro reared insects, but there were more deformed females in the in vitro culture. The sex ratio, however, was generally not significantly different between the in vitro and in vivo cultures. The in vitro reared females generally were larger, lived longer, and parasitized more H. tea eggs. Emergence of adults was in excess of 75% in all but the first in. vitro generation and was generally not significantly different from adult emergence in the in vivo culture, These findings will be of value in the development of a practical system for in vitro mass rearing of Trichogramma for use in biological control.