Obtaining large numbers of predatory mites, namely Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae), from cotton fields rich in it, and accumulating them on a few leaves

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Abstract Preliminary studies on the population density of Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae) existing in a cotton field revealed that spraying Chlorpyrifos-methyl 48% E. C. and lambda-cyhalothrin 5% E. C. didn't affect the mite population density significantly. As regards the pesticide-untreated area, the maximum population density was recorded in September; meanwhile, the minimum one was recorded in June. The mites were at the highest population density on the leaves of the middle section of the plants; meanwhile, they were at the lowest population density on the leaves of the top section. The mite population found on the lower surfaces of the leaves was significantly more than the mite population found on the upper ones. The majority of the mite individuals existed at the pleats and the bases of the lower surfaces of the leaves. After spraying a defoliant by a week, the population density of the mites existing on the fresh leaves found beneath the defoliant-treated plants were 13.5 mites per leaf, which is considered to be comparatively high. Hence, large numbers of that mite could be obtained from that leaf category. By collecting 15 fresh leaves from the ground located under the plants treated with the pesticides and the defoliant, and stacking them in a jar, in certain conditions, for three days, most individuals congregated on the upper ones. The average population density of the mites found on the upper three leaves was 39.89 mites per leaf. Hence, large numbers of that mite could be accumulated on a few leaves.

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