ABSTRACT

Field experiments were conducted in 1999-2001 cotton seasons to evaluate the role of the local strain of Trichogramma evanescens Westwood in reducing infestation with pink bollworm, Pectinophora gossypiella (Saund.). The real control effect of T. evanescens was determined through the analysis of the weekly infestation level of green cotton bolls in the release area in relation to the control. The obtained results show that release of T. evanescens to control pink bollworm is biologically effective and could be used as an important agent in integrated pest management programs. When T. evanescens was released in combination with insecticide treatment, resulted in 75.27 and 76.27% reduction in pink bollworm infestation than control in the two seasons, respectively. These levels of control were relatively lower than those determined (82.8 and 83.51%) when this parasitoid was released in cotton earlier in the season withought any other control agents. On the other hand, the lowest reduction rates (65.3 and 68.88%) were achieved when Trichogramma was released lately after the termination of the recommended control program. These results show clearly that the control rates of pink bollworm are very related to the release time of Trichogramma. In conclusion, the local parasitoid, T. evanescens appeared to be highly effective against pink bollworm particularly when released earlier in the season before the formation of cotton bolls.