STUDY ON THE MASS REARING, STORAGE DURATION AND FIELD RELEASE TECHNIQUES OF EGG PARASITOID, TRICHOGRAMMA SPP.STUDY ON THE MASS REARING, STORAGE DURATION AND FIELD RELEASE TECHNIQUES OF EGG PARASITOID, TRICHOGRAMMA SPP.

Abstract

The study was conducted to evaluate the parasitism efficacy, storage duration and field release techniques of egg parasitoid, Trichogramma spp. in the IPM laboratory and research field, Entomology Division, Bangladesh Agricultural Research Institute, Gazipur during July-December 2013. The parasitism efficacy of Trichogramma evanescens and T. chilonis on two host eggs, Sitotroga cerealella (Angoumois grain moth) and Corcyra cephalonica (Rice moth) was determined. There was no significant difference in the percent egg parasitism of T. evanescens and T. chilonis on the host eggs, S. cerealella and C. cephalonica. However, the highest parasitism was occurred in T. chilonis as compared with the parasitism of T. evanescens. The highest number of adult emergence was recorded from T. evanescens on the both host eggs compared to T. chilonis. Effect of storage duration on the adult emergence of three parasitoid species T. evanescens, T. chilonis and T. japonicum was evaluated from mass reared parasitized host eggs and fresh host eggs of Sitotroga cerealella. Observation indicated that adult emergence of three species was found higher in stored parasitized host eggs than that of stored fresh host eggs. In all cases only from stored fresh host eggs whereas, up to 20 days more than 90% adult emergence were recorded from stored parasitized host eggs of T. evanescens. Stored parasitized host eggs gave 50% adult emergence up to 60 days. In contrast, in all cases from stored fresh host eggs only up to 30 days more than 50% adult emergence were recorded. In both condition, with the increase of storage period of parasitized eggs and fresh host eggs, adult emergence of the three Trichogramma species reduced gradually. The field release techniques of T. evanescens and T. chilonis on parasitizing the eggs of S. cerealella, C. cephalonica and Leucinodes orbonalis (Brinjal shoot and fruit borer) were assessed through paper strip method (release during pupation) and adult release method in micro plot and open field condition. The results showed that T. evanescens parasitized 75.5% of the host eggs (mean of three host eggs) in micro plot through adult release method and 38.83% through paper strip method. In contrast, T. chilonis parasitized 78.6% of the host eggs by adult release method and 40.2% by paper strip method in micro plot condition. Both the species exhibited a similar trend of parasitism in open field. It is therefore concluded that the adult release of T. evanescens and T. chilonis was an effective technique of attaining the maximum parasitism in both micro plot and open field condition.