GRADUAL CHANGES OF TRICHOGRAMMA IN THE COURSE OF LABORATORY REARING (TRICHOGRAMMA-EVANESCENS - HYMENOPTERA, TRICHOGRAMMATIDAE)

Female's ability to spontaneous jumping and flying as well as their response to the kairomone of the natural host decrease gradually in the course of laboratory rearing. These are the main reasons of the decrease of parasite efficiency in field. The rearing of Trichogramma on eggs of a non-specific host (Sitotroga cerealella Oliv.) is the main cause of the negative changes. These changes are absent in the case of long rearing on eggs of the natural host - Mamestra brassicae L. Moreover the return of Trichogramma culture from the non-specific host to the eggs of Mamestra brassicae restores the females ability for spontaneous jumping.