Selectivity of Four Insecticides to Woolly Apple Aphid, Eriosoma Lanigerum (Hausmann) and its Sole Parasitoid, Aphelinus mali (Hald.)

Four insecticides were tested for their suitability to an integrated pest management program of woolly apple aphid (WAA). The tested insecticides were imidacloprid, pirimicarb, cartap and petroleum oil. Three indices were developed to determine the degree of selectivity of studied insecticides and to determine their suitability to WAA IPM program. WAA index used to measure the efficacy of the insecticides against the WAA and showed that imidacloprid was the most efficient in suppressing WAA. Parasitoid index used to measure the negative impact of insecticides on the sole parasitoid of WAA, Aphelinus mali. This index indicated that pirimicarb was the safest insecticide to WAA parasitoid, while imidacloprid caused drastic effect on mummified aphids. Both the WAA and parasitoid indices were integrated in a selectivity index that was used to determine the IPM compatibility of the tested insecticides. Selectivity index indicated that pirimicarb is the most suitable insecticide for controlling WAA as its application resulted in valuable suppression of WAA and very low negative impact to its parasitoid.