BEHAVIORAL-EFFECTS OF IMIDACLOPRID, A NEW NICOTINYL INSECTICIDE, ON THE POTATO APHID, MACROSIPHUM-EUPHORBIA (THOMAS) (HOMOPTERA, APHIDIDAE)

Adult potato aphids, Macrosiphum euphorbiae (Thomas), caged on potato terminal leaflets treated systemically with imidacloprid solutions ran ging between 5.4 x 10(-4) and 5.4 x 10(-8) mt per mt water showed a si gnificant reduction in the distance they travelled, time taken to trav el a given distance, and flight propensity but no significant differen ces in the frequency or duration of short probing behaviour. The frequ ency of adult apterous potato aphids colonizing untreated potato leafl ets or leaflets treated with an imidacloprid solution (5.4 x 10(-4) mt per mt water) was not significantly different, indicating no repellen cy. Potato aphids moving from systemically treated to untreated leafle ts did not recover much and their reduced walking ability was maintain ed for days. A 3-day exposure to vapour from an imidacloprid solution (5.4 x 10(-4) mt per mt water) did not produce significant mortality o r changes in nymphal production. The daily cumulative mortality obtain ed by caging potato aphids on potato leaflets placed in an imidaclopri d solution (5.4 x 10(-7) mL per mL water) was similar to that obtained in the field, on 20-day-old plants treated at planting with imidaclop rid applied at 0.02 g AI/m. None of the rates of imidacloprid tested s timulated the dispersal of apterous or alate potato aphids.