Evaluation of the number of releases of the egg parasitoid, trichogramma evanescens West. In suppressing the spiny bollworm, Earias insulana (Boisd.) Infestation in El-Farafra cotton fields, New Valley Governoratem, Egypt

Abstract

Five and six releases of Trichogramma evanescens West. were applied at El-Amal village and El-Masraf localities, respectively in El-Farafra, New Valley Governorate, Egypt, to evaluate their efficacy in suppressing the spiny bollworm Earias insulana (Boisd) infestation during 2004 cotton season. 22 Trichogramma cards were prepared and distributed in cotton fields to produce 17600 adult females in 2 waves/feddan/release. No significant differences were found between the two rates in suppressing bollworm infestation or in crop yield. The five Trichogramma releases presented 76.92% final mean reduction in boll infestation compared with 83.97% resulted from the six releases. Cotton yield loss was 13.17% in the five releases field compared with 12.05% in the six releases one. Accordingly five Trichogramma releases were economically and more acceptable to be used in El-Farafra cotton fields.