The toxicity of six acaricides namely, ethion, bifenazate, chlorfenapyr, abamectin, diafenthiuron and
hexythiazox, presented different chemical groups, were determined on each of the two spotted spider mites Tetranychus
urticae 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) and
diafenthiuron (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 toxicity
ratios were calculated at the same former levels. All the tested acaricides were safe except ethion at LC50 and bifenazate
at LC90 on P.persimilis, bifenazate and hexythiazox were harmful at LC50; whereas chlorfenapyr and abamectin were
safe at LC90 on S. longicornis. Regarding S. gilvifrons, all tested acaricides were safe at LC90 except bifenazate and
diafenthiuron at LC50 and bifenazate at LC90. The selectivity ratios (s.r) at LC50 and LC90 levels were incorporated in one
parameter 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. The
respective 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 and
0.59 for S. gilvifrons.