Effects of deltamethrin on walking, flight and potato virus Y‐transmission by pyrethroid‐resistant Myzus persicae

SUMMARY In laboratory tests with moderately pyrethroid‐resistant (R1) Myzus persicae, more walked or flew from excised leaves pre‐treated with the pyrethroid deltamethrin, or its aqueous formulation ‘Decis’ at 10 mg a.i. litre‐1 than from untreated leaves. Neither a carbamate (pirimicarb) nor an organophosphate (demeton‐S‐methyl) induced flight. R1 alatae and apterae which had dispersed from deltamethrin‐treated leaves rarely transmitted potato virus Y (PVY); however transmission by the more pyrethroid‐resistant R2 alatae was only halved and that by R2 apterae undiminished. Treatment with deltamethrin decreased spread of PVY both in flight chamber and field experiments.