Side Effect of some Acaricides on Three Predators of Tetranychus urticae Koch

The toxicity of six acaricides namely, ethion, bifenazate, chlorfenapyr, abamectin, diafenthiuron andhexythiazox, presented different chemical groups, were determined on each of the two spotted spider mites Tetranychusurticae Koch (Acari: Tetranychidae) and three of its predators; Phytoseiulus persimilis Athias-Henriot (Acari:Phytoseiidae), Scolothrips longicornis Priesner (Thysanoptera: Thripidae) and Stethorus gilvifrons Mulsant (Coleoptera:Coccinellidae).The obtained results revealed that abamectin (0.53 ppm), ethion (15.2 ppm), abamectin, (19.0 ppm) anddiafenthiuron (14.0 ppm) were the most toxic acaricides on T. urticae, P. persimilis, S. longicornis and S. gilvifrons,respectively at LC50 level. Based on LC50 and LC90 of the tested acaricides on the studied predators, selective toxicityratios were calculated at the same former levels. All the tested acaricides were safe except ethion at LC50 and bifenazateat LC90 on P.persimilis, bifenazate and hexythiazox were harmful at LC50; whereas chlorfenapyr and abamectin weresafe at LC90 on S. longicornis. Regarding S. gilvifrons, all tested acaricides were safe at LC90 except bifenazate anddiafenthiuron at LC50 and bifenazate at LC90. The selectivity ratios (s.r) at LC50 and LC90 levels were incorporated in oneparameter as general selective toxicity ratio. The obtained values were 2.04, 1.35, 0.28, 0.006, 1.74 and 0.41 for P.persimilis inethion, bifenazate, chlorfenapyr, abamectin, diafenthiuron and hexythiazox treatments, respectively. Therespective values were 0.506, 0.715, 4.0, 3.78, 0.025 and 1.496 for S. longicornis and 0.01, 0.53, 1.68, 1.59, 0.04 and0.59 for S. gilvifrons.