Study on the mortality and repellency effects of three insecticides on Aphelinus mali (Haldeman) (Hym.: Aphelinidae)

In a laboratory study the effect of three insecticides (pirimicarb, pymetrozine and spinosad) was evaluated on Aphelinus mali a parasitoid of woolly apple aphid. To investigate the contact effect, adults were caged for 16 hours in petri-dishes containing apple leaves sprayed with each insecticide. To determine the oral toxicity in the same period of time, other petri-dishes containing filter paper soaked in poisoned solution of 10% sugar were used. To determine the repellency effect of the insecticides in question, we used busvine Y shape tube and host choice experiment between treated and untreated leaf disks was carried out. The results revealed that the rate of mortality was 89.43 and 89.01% spinosad in contact and oral testes respectively. In the case of pymetrozine and in similar tests 78.85 and 62.72% mortality was observed. Moreover, spinosad and pirimicarb showed marked repellency effect on the adult stage of A.mali while pymetrozine didn’t show similar effect.