Host plants alter the reproductive behavior of pieris brassicae (Lepidoptera: Pieridae) and its solitary larval endo-parasitoid, hyposoter ebeninus (Hymenoptera: Ichneumonidae) in a cruciferous ecosystem

Abstract

The behavior of most destructive pest of cabbage, Pieris brassicae and that of its potential parasitoid, Hyposoter ebeninus, were studied under the influence of 4 common Brassica host plantspecies, cabbage, broccoli, cauliflower and knol-kohl. These host plant species were found to have considerable influence on egg distribution and leaf surface preference for oviposition and pupation. The number of egg masses was highest on knol-khol; however, the number of eggs per mass was highest on cabbage. Similarly, larval incidence was also highest on cabbage throughout the season, indicating that cabbage is the most preferred host. Natural parasitism on P. brassicae larvae by Hyposoter ebeninus was higher on knol-khol and cabbage. The weight of the third instar parasitized caterpillars was the highest on cabbage, suggesting that cabbage is the most favorable of these 4 hosts of P. brassicae for mass rearing of H. ebeninus. The development time of H. ebeninus was also shortest for cabbagereared larvae. Also the cocoon weight of the parasitoid was significantly higher when its host larvae were reared on cabbage. Overall from this study it can be concluded that, of the host plants evaluated, cabbage was preferred for oviposition by P. brassicae and its parasitoid. In addition, cabbage was found to be the best host plant for producing excellent quality H. ebeninus parasitoids.