Comparative demography, population projection, functional response and host age preference behavior of the parasitoid Goniozus legneri on two lepidopterous insect hosts

Abstract

BackgroundThis study was conducted to investigate life table characteristics of the parasitoid species, Goniozus legneri Gordh (Hymenoptera: Bethylidae), a major gregarious larval ecto-parasitoids of the carob moth, Ectomyelois ceratoniae Zeller (Lep.: Pyralidae). Demographic parameters of G. legneri reared on two hosts, the carob moth and the flour moth, Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae), were studied under laboratory conditions using age-stage, two-sex life table. Host stage preference and the functional response of this parasitoid were also determined.ResultsThe duration of the immature period, adult pre-ovipositional period and total pre-ovipositional period of G. legneri reared on E. kuehniella was significantly longer than that of those reared on E. ceratoniae, while fecundity and ovipositional days of the wasp were greater/longer in females reared on E. ceratoniae. There were also significant differences in intrinsic and finite rates of increase and mean generation time between wasp parasitoid reared on two hosts. Moreover, population projection indicated that the G. legneri population can grow swifter when reared on E. ceratoniae than on E. kuehniella. Based on the experiments conducted to determine the larval stage preferences of G. legneri, for both hosts, larger larvae were more preferred stages compared to smaller ones, thereby fulfilling the optimal oviposition theory. The functional responses of G. legneri to different population densities of E. kuehniella two last instar larvae were determined as type III at 25 °C and 60% RH.ConclusionThe results offer valuable information on some life history attributes of G. legneri. Although G. legneri performed better on E. ceratoniae larvae than on E. kuehniella, as the use of E. ceratoniae larvae as the main host in rearing of G. legneri might be a laborious process and can increase the production costs, E. kuehniella can be used as an alternative host. Further studies are required under greenhouse and field conditions for effective use of this biocontrol agent against the carob moth.