Emergence rhythm and quality control in the laboratory and mass rearing of Trichogramma species (Hymenoptera: Trichogrammatidae)

The laboratory experiments showed that various parameters of the “quality” of Trichogramma telengai Sor. females that emerged from a batch of simultaneously parasitized eggs of the grain moth Sitotroga cerealella Oliv. were significantly dependent on the day and circadian time (i.e., time from light-on) of emergence: the later the females emerged, the smaller were their size, fecundity, and life span. The difference in size and in fecundity between individuals emerged on different days constituted up to 20% and 70% of the mean, correspondingly. Differences between the early (emerged during 2 h after the light-on), middle (emerged from 2 to 3 h after the lighton), and late (emerged from 3 to 6 h after the light-on) fractions of females which emerged on the same day were also significant (about 5% in size and about 25% in fecundity). Based on these results, we conclude that the day and circadian time of emergence should be taken into account in elaboration of the methods of laboratory experiments and of the protocols for Trichogramma quality tests in mass rearing.