KAOLIN AND BENTONITE CLAYS PARTICLE FILMS AS A NEW TREND FOR SUPPRESSION OF CHEWING AND

SUCKING INSECTS OF COTTON PLANTS             

[28]

Shadia¹ E. Abd El-Aziz

Abstract

The effects of two particle films (kaolin and bentonite clays ) on all developmental stages of the cotton leafworm, S.  littoralis, as well as cotton aphids,  Aphis gossypii were studied. There was a positive relationship between the concentration of tested agents and their antifeeding activity . Kaolin and bentonite showed highly significant and moderately antifeedant activities on the 3^rd instar larvae of S. littoralis, respectively . Kaolin particle film was significantly more effective than bentonite on pupal weight and pupal formation . In case of  kaolin ,the deformed pupae were larval-pupal intermediate , while, in case of bentonite treatment they appeared as pupal-adult intermediate. Kaolin treatment at 5 and 3 % concentrations possess  both behavioural characteristies and post  ingestive toxicity  against,  S. littoralis . Females oviposited fewer eggs on cotton plants covered with kaolin particle film with 78.9 % repellency, than on bentonite treatment or untreated cotton plants in free and no choice tests. The tested three day ages of S.littoralis egg masses were highly significantly affected by kaolin than bentonite particle film treatments. Nearly 70 % reduction and lack of nymph production in cotton aphid numbers  occurred within 24 hrs period, when aphid adults were placed onto treated cotton seedling with bentonite . Bentonite completely prevent insect infestations by coating cotton plants with a white natural physical barrier that deters insect infestation , and impedes their movement, feeding, and egg laying.