To Study the Effect of imidacloprid (SC 350) on Parasitoid Wasp Aphidius colemani Viereck under Laboratory Conditions

Melon aphid, Aphis gossypii Golver, is a key pest of greenhouse crops. In the recent years, attention has been paid to the biological control of this pest. The most important natural enemy of this pest is the parasitoid wasp, Aphidius colemani Viereck. In this study, lethal and sublethal effects of imidacloprid (SC 350) applied by two different application methods (irrigation and foliar spraying) were assessed against this parasitoid at three doses (field dose, half of the field dose and one and half times the field dose) in a randomized complete block design with four replications. Due to high mortality rates, bioassay tests on adults were performed using contact method. The LC50 and LC25 values were estimated as 0.028 and 0.012 g ai/l for adults, respectively. The foliar spraying of Imidacloprid at concentrations of 350, 700 and 1000 ppm caused 95, 100 and 100 percent mortality of the adult parasitoids, respectively. Ten percent mortality was observed when these concentrations were applied by the irrigation method. According to IOBC classification imidacloprid was grouped in the slightly-harmful category. Based on the present results, the adult parasitoid showed high susceptibility to imidacloprid; therefore, imidacloprid should not be applied when the population density of this parasitoid is high in the greenhouse.