DIURNAL RHYTHM OF EMERGENCE FROM PUPAE IN PARASITIC WASP - TRICHOGRAMMA EVANESCENS WESTW (INSECTA, HYMENOPTERA)

Pupal eclosion of Trichogramma evanescens Westw. was studied in differ ent conditions of light-darkness and temperature fluctuations. The res ults revealed that under natural light cycles Trichogramma exhibits a distinct rhythm of emergence from pupae. Maximum emergence takes place in the morning. This rhythm persists in constant dim red light and te mperature, so it is endogenous in nature. The rhythm can be entrained by artificial 24-h temperature cycles or by day-night cycles of light with a very low intensity of illumination (<0.01 lux). Nevertheless a single pulse of bright light or of high temperature is not able to res et the rhythm. The emergence rhythm was also absent if the culture was grown in constant darkness and temperature.