Mohammadali Mirhosseini

Aphidius matricariae (Haliday) (Hymenoptera: Braconidae) is an effective biological control agent that attacks more than 40 aphid species. Despite the importance of biological control as an ecofriendly pest management method, the use of insecticides is often necessary within the integrated pest management (IPM) programs. However, the toxicity of three chemical insecticides including acetamiprid SP20%, pirimicarb WP50%, and chlorpyrifos EC40.8% on A. matricariae were investigated by two methods developed by the IOBC/WPRS with some modifications. The insecticides were tested at the recommended field rates, 250, 500, and 1500 ppm, respectively. Firstly, parasitoid mummies (<48h old) were dipped into aqueous solution of the insecticides for 3 seconds. The mummies were checked daily for adult emergence. Secondly, the tubes (1.5cm diameter and 10cm high) were treated by the insecticide’s solution. After drying the tubes for less than 2h, five adult parasitoids (<24h old) were introduced into each tube. After 24h, the number of dead wasps was recorded. All experiments were performed at the constant environmental conditions (25±1°C; 70±5%; L: D16:8h) and the control was treated with water only. The mean percentage survival (±SE) of parasitoid mummies for acetamiprid, pirimicarb, and chlorpyrifos was evaluated as 18±4.64, 48±5.39, and 3±3.00, respectively. Also, the mean percentage adult mortality (±SE) of A. matricariae for the compounds was obtained 92±4.90, 100, and 100, respectively. Considering the IOBC index, pirimicarb, and chlorpyrifos are categorized as harmful insecticides and acetamiprid is moderately harmful for this parasitoid. Nevertheless, it is important to consider the effect of the insecticides on the parasitoid mummies.