الفهرس 
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Abstract
The present study is directed to evaluate the relative toxicity of six chemicals of different mode of action,
four pesticides (fenpyroximate, ethion, chlorfenapyr and cyhalothrin), one mineral oil (Nat-1) and one plant extract
(wormseed extract) against the adult female mites Tetranychus urticae and its predatory mite Amblyseius gossipi
using standardized method for bioassay. The effect of sublethal doses of these chemicals on some biological aspect of
the mite and its predator were also evaluated. The development of resistance in susceptible strains of T. urticae to
chemicals and the mechanism of resistance of T. urticae were investigated. Also, the effectiveness of malathion and
certain botanical oils against two important insects of stored grains was evaluated. Cyhalothrin was found to have a
special position in integrated mite management while fenpyroximate is a promising compound in mite control
programs.
The contaminated prey egg consumption was different according to the chemical used. The pyrethroid
compound cyhalothrin and the acaricide fenpyroximate were the most effective on prey egg consumption, egg
production and egg hatchability of the predatory mite, A. gossipi. Nat1 and wormseed extract were the safest
compounds that allowed the predator’s egg to hatch producing the next stages
Development of resistance in susceptible strain of T. urticae for eight successive generations using thin leaf
discs technique was studied and the resistance level of T. urticae increased gradually to reach its peak in eighth
generation. The assays of certain enzymes (Acetylcholine esterase and Glutathione-s-transferase) were carried out
in mite homogenate prepared from mites, exposed to each of the tested compounds alone. All tested compounds
were bioassayed for their effects on the specific activity of the two enzymes. Chamomilla oil was found to the most
effective agent against R. dominica and T. castinum followed by basil and nigella oils