COMPARISON BETWEEN THE EFFICACY OF Trichogramma evanesces RELEAS AND THE INSECTICIDES TREATMENTS ON BOLLWORMS AND WHITEFLY IN RELATION TO THEIR PREDATORS IN COTTON FIELDS

Abstract

Field trials were conducted at Margha district, Sohag Governorate to evaluate the egg parasitoid, Trichogamma evanescens. (West) release for control both pink bollworm, Pectinophora gossypiella (Sound.) and Spiny bollworm, E. insulana in the cotton fields during the two successive seasons of 2006 and 2007. Generally, the egg releases showed higher reduction in the infestations caused by pink bollworm, than the spiny bollworm either in flowers or green boll stages. On the other hand, the numbers of pink bollworm moths as well as the infestation rates caused by both pink and spiny bollworm larvae were higher in the insecticidal plots than the egg parasitoid release plots during the flowering stage infestation rates caused by Earias insulana (Boisd) larvae were higher in the Trichogramma plots than the insecticides plots during bolls stage. Plots received seven Trichogramma release exhibited lower numbers of insecticidal application as compared with the insecticidal plots. Moreover, higher numbers of predators were noticed in the Trichagramma plots in comparable with the plots treated with insecticidal treatments. Also, the numbers of whit fly nymphs were very highin the plots treated with insecticides as compared with those in insecticide treatments.