Sublethal effects of clofentezine and flufenzine on preovipositing Tetranychus urticae Koch females

Changes in parameters of Tetranychus urticae Koch population growth were investigated based on the life tables of females treated with acutely non-toxic concentrations of Clofentezine (200 mg/L) and flufenzine (100 mg/L) in preoviposition period. Over the initial four days of reproduction females treated with Clofentezine laid 14% and those treated with flufenzine 16% less eggs than untreated ones. Gross fertility was 14% lower in the female cohort treated with Clofentezine and 24% lower in the one treated with flufenzine, compared to the untreated cohort. In treatment with flufenzine, the difference between the number of eggs laid and gross fertility mostly resulted from a considerably high number of unhatched eggs 35% on the first day of reproduction, 18% on the second, 4% on the third and 3% on the fourth day. Net fertility was 24% lower in females treated with Clofentezine and 28% lower in those treated with flufenzine over the initial four days of reproduction, compared to control, which means that female mortality under treatment additionally decreased fertility. The decreased net fertility in the initial days of reproduction did not result in a statistically significant decrease in growth rates.