Determination of Parasitism Efficacy and Development of Effective Field Release Technique for Trichogramma spp. (Trichogrammatidae: Hymenoptera)

To determine the parasitism efficacy of Trichogramma spp. on the host eggs of Sitotroga cerealella Olivier (Pyralidae: Lepidoptera) and Corcyra cephalonica Stainton (Pyralidae: Lepidoptera) and to develop the effective field release technique for Trichogramma spp., the study was conducted at the IPM Laboratory and Research field of Entomology Division, Bangladesh Agricultural Research Institute, Gazipur, Bangladesh during the period from July to December 2013. Higher parasitism on the eggs of S. cerealella and C.cephalonica was recorded from Trichogramma chilonis Ishii (Trichogrammatidae: Hymenoptera) (85.5%, 93.8% respectively), compared to those of Trichogramma evanescens West (Trichogrammatidae: Hymenoptera) (83.4%, 92.7% respectively). Higher percent adult emergence was recorded from the eggs parasitized by T. evanescens compared to those by T. chilonis. The field release techniques for T. evanescens and T. chilonis on parasitizing the eggs of S. cerealella, C. cephalonica and Leucinodes orbonalisGuenee (Crambidae: Lepidoptera) were also assessed by using paper strip method (released during pupation) and adult release method in both micro-plot and open field conditions. In micro-plot, the results showed that T. evanescens parasitized 75.5% of host eggs (mean of three host eggs) by adult release method and 38.83% only by paper strip method. In case of open field condition, T. chilonis parasitized 78.6% of host eggs by adult release method and 40.2% only by paper strip method. The results indicate that as a field release technique of T. chilonis, the adult release method is superior to paper strip method.