EFFECTS OF THE REPELLENT POLYGODIAL ON STYLET PENETRATION BEHAVIOR AND NONPERSISTENT TRANSMISSION OF PLANT-VIRUSES BY APHIDS

Behavioural effects of the plant-derived repellent polygodial were inv estigated by video recording aphids during access to potato virus Y (P VY) or cucumber mosaic virus (CMV) infected tobacco leaf material. Sty let penetration of floating leaf discs, assessed using antennal and bo dy movements as behavioural markers, was significantly delayed by poly godial treatment of the leaf surface. This delay may help account for a previously reported reduction of virus transmission caused by polygo dial, although the majority (77%) of aphids on polygodial-treated leaf areas penetrated within the first minute, compared with 100% on solve nt-treated areas. Neither the duration of stylet penetrations, nor sub sequent transmission of PVY or CMV, were affected by the presence of p olygodial on virus-infected plants. Electrical recording of stylet act ivities confirmed that aphid stylets punctured plant cell membranes, r egardless of polygodial treatment of PVY-infected plants.