BIO-ECOLOGY OF ANGOUMOIS GRAIN MOTH AND ITS EGG PARASITOID TRICHOGRAMMA EVANESCENS AND PARASITIZATION PERFORMANCE OF THE PARASITOID

Abstract

The study was conducted in the laboratory of the Department of Entomology at Sher-e-Bangla Agricultural University, Dhaka, Bangladesh during the period from July, 2010 to January, 2011 to study on the growth and development of the host Angouimos grain moth, Sitotroga cerealella and its egg parasitoid Trichogramma evanescens as well as to find out the performance of T. evanescens egg parasitoid in parasitizing the eggs of S. cerealella and the effect of weather factors on the biology of both host and parasitoid as well as on parasitization. The experiment was laid out in Complete Randomized Design (CRD) with five replications. The incubation, larval, pupal period, egg to adult period, adult longevity and total life span of Angouimos grain moth, S. cerealella were ranged from 6.67 to 7.33 days, 15.67 to 22.67 days, 4.33 to 6.00 days, 26.67 to 36.00 days, 6.0 to 7.33 days and 32.67 to 44.0 days, respectively during the study period from August 2010 to January 2011. Climatic factors such temperature and relative humidity significantly influenced on the growth and development of S. cerealella and all these parameters regarding growth and development were negatively correlated with both temperature and relative humidity, where the rapid growth and development was observed in August 2010 maintaining 30.12oC temperature and 86.52% relative humidity and slow growth was observed in January 2011 maintaining 23.21oC temperature and 67.20% relative humidity. The freshly laid eggs of S. cerealella performed highest hatching rate (87.60%) that was better than long day stored host eggs for using in rearing ofTrichogramma evanescens egg parasitoid. The egg to larval period, pupal period, egg to adult period, adult longevity and total life span of T. evanescens egg parasitoid were ranged from 2.20 to 3.80 days, 2.0 to 3.60 days, 4.20 to 7.40 days, 3.0 days and 7.20 to 10.40 days, respectively during the study period from September 2010 to January 2011. Climatic factors such temperature and relative humidity significantly influenced on the growth and development of T. evanescens and all these parameters were positively correlated with both temperature and relative humidity, where the rapid growth and development was observed in January 2011 maintaining 23.21oC temperature and 67.20% relative humidity and slow growth was observed in January 2011 maintaining 30.12oC temperature and 86.52% relative humidity. The rate of parasitization increased with the increase of the number of Trichogramma release and the maximum parasitization (91.40%) was achieved by the release of 40 Trichogramma released at pupal stage for 100 host eggs. Among different months of the experimental period, the highest parasitization rate (84.00%) was recorded in January 2011 and lowest (65.40%) was recorded in September 2010. Comparatively lower temperature (23.21oC) and relative humidity (67.20%) recorded in January 2011 favored higher parasitization rate than higher temperature (29.05oC) and relative humidity (84.23%) recorded in September 2010.