Effectiveness of Trichogramma evanescens westwood, bacterial insecticide and their combination on the cotton bollworms in comparison with chemical insecticides [electronic resource].

Includes references.

Field studies were carried out todetermine the effect of Agerin (a local commercial product of Bacillus thuringiensis), parasitoid release of Trichogramma evanescens alone or with Agerin and the recommended chemical insecticides against the cotton bollworms at Qalubia Governorate in 2001 and 2002 cotton seasons were conducted. The rate of damage caused by bollworms larvae could be arranged in descending order as follows 29.0, 28.38, 26.25, 20.63 and 38.25 in 2001 and by 22.75, 21.88, 19.63, 16.13 and 29.13 in 2002 for the four treatments and control, respectively. The difference was significantly higher in control than in any of the other four treatments, also, significant differences were detected between chemical insecticides and the other four treatments. Ten predaceous insects on cotton plants were counted weekly. Chemical insecticides showed drastic effect on predators (% reduction than control 55.4 & 58.7) while the parasitoid release of T. evanescens had the least effect (2.0 & 0.7%) in 2001 and 2002, respectively. Infested bolls were weekly collected from each treatment and larvae were individually reared until emergence of parasitoids. Three parasitic species were detected in this study; Apanteles sp. and Exeristes robarator from Pectinophora gossypiella larvae and Periboea orbata from Earias insulana larvae. The highest rate of parasitism was recorded in control treatment (7.7 & 6.2) followed by (7.5 & 5.9) in parasitoid release of T. evanescens alone, (7.3 & 5.8) in bioinsecticide with T. evanescens release, (7.1 & 5.4) in bioinsecticide and (1.6 & 1.6) in chemical insecticides treatment in 2001 and 2002 , respectively. The parasitoid release of T. evanescens with bioinsecticide applications were recommended to control the target pests in order to restore the entomophagous insects and obtain better control of cotton bollworms.

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