Studies on the strains of Trichogramma evanescens Westwood (Hym., Trichogrammatidae) collected from different hosts in Northern Maldova

Abstract Biological and morphological characteristics together with electrophoretic patterns were compared for five strains of Trichogramma evanescens W., collected from the eggs of Mamestra brassicae L., Ostrinia nubilalis Hb. and Agrotis segetum Schiff. in northern Maldova. Significant differences were observed in the biological characteristics including the proportion of female progeny, developmental period, longevity and fecundity. The strains also differed in the ratio of antennal hair length to the maximum width of flagellum in males. Patterns of esterase systems indicated that the strains differed in the mobility and intensity of esterase bands. All the strains had a strong preference for the host from which they were collected in the field. Crossing of the strains indicated that one strain was reproductively isolated. The results have application in selecting the strategy for establishing initial colony in mass rearing of parasitoids and for research on Trichogramma ecology and evolution.