Evaluation of population parameters of Tetranychus urticae Koch (Acari : Prostigmata : Tetranyciudae) exposed to avermectin

The effect of sublethal concentrations of avermectin on life parameters of the twospotted spider mite, Tetranychus urticae Koch, was assessed in labor atory tests. The results of the toxicity tests indicate that concentrations higher than 2 ppm are lethal for all individuals after 48 hours of exposur e. Based on the mite response data, it was clear that concentrations of 0.0 1, 0.05 and 0.1 ppm avermectin had a significant effect on the mean rime of development of twospotted spider mite females. There was a significant dif ference among proportions of the age-specific survival between each toxic l evel and the control. Age-specific fecundity was markedly lower for 0.05 an d 0.1 ppm treatments compared to 0.01 ppm and the control. in general, life parameters were affected inversely and significantly at doses of 0.05 and 0.1 ppm avermectin.