No abstract

The effect of sub lethal doses of six compounds, three acaricides (abamectin, ethion and chorfenapyr),one pyrethroid (cyhalothrin),one mineral oil (Nat-1) and one plant extract (Allium sativum)on some biological and behavioral characteristics of the two spotted spider mite,Tetranychus urticae and adult female of predators Stethorus gilvifrons, Amblyseius gossipi, and Phytoseiulus macropilis was examined. The results indicated that Cyhalothrin was the most effective compound tested on egg deposition, which is beneficial for some IPM programs away from predators' employments. A. sativum extract has the least effect on egg deposition that confers a chance to produce eggs enough for predation including egg mite, the preferable stage, for some predators. Ethion, chlorfenapyr and abamectin are considered ideal from the biological point of view since they decreased egg deposition to a suitable level and the character is needed for any integrated mite management program. Nat-1 is the best compound that has a moderate effect on egg deposition of spider mite which gave these compound special importance in integrated mite management. Nat-1 and A.sativum extract exhibited the least effective ovicidal action. The ovicidal effect of Chlorfenapyr and abamectin were about the same against the egg stage of spider mite. Cyhalothrin and ethion were highly toxic compounds that caused the highest decrease in egg hatchability. Cyhalothrin and abamectin were the most effective on prey egg consumption, predator egg production and predator's egg hatchability of three predators. Ethion and chlorfenapyr occupy the next position in prey egg consumption, predator egg deposition and predator's egg hatchability of three predators. Nat-1 and A. sativum extract were the least effective compound in prey egg consumption, predator egg deposition and predator's egg hatchability of three predators. Also, Nat-1 and A.sativum extract were the safest compounds that allowed the predator's egg to hatch producing the next stages necessary to the biological agent to minimize prey populations.

Due to the harmful effects of synthetic chemical acaricides on ecosystems and human health, there is increasing interest in the use of nanotechnology to fabricate eco-friendly nanoemulsions based on plant oils in the field of spider mite control. In this study, nanoemulsions of abamectin, garlic, and neem oils were prepared by a high-energy approach and characterized by transmission electron microscopy. The droplet sizes of all tested nanoemulsions were less than 100 nm. The acaricidal activities of the prepared nanoemulsions compared to abamectin were evaluated against a susceptible laboratory strain of Tetranychus urticae Koch (Acari: Tetranychidae) under laboratory and field conditions. The results showed that abamectin nanoemulsion was the most toxic compound against adult females of T. urticae followed by abamectin emulsion. Neem nanoemulsion had moderate toxicity and garlic nanoemulsion had the lowest toxicity. The effects of tested compound residues on egg deposition and egg hatching in descending order were as follows: abamectin nanoemulsion > abamectin emulsion > neem oil nanoemulsion < garlic oil nanoemulsion. In the field experiment, all tested compounds were effective in reducing the population density of T. urticae in the motile stage, with mean reductions ranging between 66.08% and 95.24% for all compounds. The most effective compound was abamectin nanoemulsion. The results of the present study demonstrate that nanoemulsion enhanced the biological activity of abamectin. Further, neem and garlic oil nanoemulsions have potential utility as environmentally friendly acaricides in integrated pest management programs.

No abstract