Functional Response of Two Egg Parasitoids of Trichogramma (Hymenoptera: Trichogrammatidae) Genre on Duponchelia fovealis Zeller (Lepidoptera: Crambidae) Eggs

Abstract

Aims: To evaluate the potential of the parasitoids of the genus Trichogramma on European pepper moth, a functional response bioassay was performed with two Trichogramma lineages and different egg densities of the host. Study Design: Adopting a completely randomized experimental design, 10 replications were done for each species. Place and Duration of Study: The bioassay was conducted at the Entomology Laboratory of the Universidade Federal do Espírito Santo (CCAE-UFES) in Alegre, ES, Brazil, in the year 2017. Methodology: The functional response bioassay was done for the T. pretiosum and T. galloi for the different D. fovealis egg densities (5, 10, 15, 20, 25 and 30 eggs). After the host eggs were glued to a paperboard, it was inserted into a flat bottom glass tube. Next, a parasitoid female was introduced into each tube. The tubes which were sealed with PVC plastic film were then placed in air-conditioned chambers keeping adjusted at 25°C temp., RH at 70 ± 10 % and a photoperiod of 14 h. Then 24 h later, the parasitoid was removed from the tube and the paperboard with the parasitized eggs was left in the tube until the offspring emerged. Results: For both the Trichogramma species, the functional response was confirmed to be type II, with the Rogers model being the most fitting. An interaction between the factors of parasitoid species and host density (F5,102 = 2.756, P = 0.022) was observed. The search efficiency for T. pretiosum and T. galloi were determined as 0.1799 ± 0.025 and 0.0976 ± 0.011 h-1, while the handling time was assessed as 0.9852 ± 0.077 and 0.5751 ± 0.101 h, respectively. Conclusion: The estimated values for the parameters search efficiency and handling time revealed that T. pretiosum and T. galloi are potential candidates for the biological control of D. fovealis.