EFFECT OF EGG AGE AND FERTILITY ON SOME BIOLOGICAL ASPECTS OF THREE TRICHOGRAMMA SPECIES

Abstract

Two laboratory experiments were carried out to determine the effect of egg age and its fertility on fecundity, progeny survival and sex-ratio of three trichogrammatids i.e., Trichogramma evanescens, Trichogrammatoidea bactrae and Trichogramma brassicae. In the first experiment, three different ages (one, two and three days old) of fertile eggs from three lepidopterous hosts (Pectinophora gossypiella Saund., Agrotis ipsilon Hufn. and Sitotroga cerealella Olivier) were introduced to Trichogramma females. In the second experiment, infertile eggs of P. gossypiella and A. ipsilon were introduced to Trichogramma females to test the acceptability of these eggs to be parasitized by those females. The number of parasitized eggs/ female was higher on 0-l day old eggs and decreased significantly as the host eggs became older. Higher percentages of progeny were emerged from all the tested ages of P. gossypiella and S. cerealella eggs. On the other hand, the emerged progeny of the three Trichogramma species was decreased significantly by the progress of embryo development in A. ipsilon eggs. Furthermore, infertile P. gossypiella and A. ipsilon eggs were not accepted by the three Trichogramma species.