Potyvirus transmission is not increased by pre-acquisition fasting of aphids reared on artificial diet

Department of Plant Pathology, University of Kentucky, Lexington, KY 40546, USA Aphids ( Myzus persicae ), fasted after removal from healthy rearing plants, transmitted tobacco etch potyvirus (TEV) more efficiently than unfasted aphids whether virus acquisition was from infected leaves or through membranes. There was no difference in uptake of 125 I-labelled TEV by fasted or unfasted aphids as measured by liquid scintillation counting. When aphids acquired 125 I-labelled TEV, label was retained in the stylets (as determined by autoradiographic light microscopy) by 51% of 272 fasted aphids, as against 7·8% of 258 unfasted aphids. There was a close correlation between virus transmission by aphids and virion retention in stylets. The effect of pre-acquisition fasting disappeared when aphids reared on an artificial diet were used in virus transmission tests. The transmission rates obtained with such aphids were similar to the rates with fasted aphids reared on healthy plants. Our results support the hypothesis that fasting eliminates plant component(s) which interfere with the retention of virions in the food canal of aphid stylets. Received 6 June 1996; accepted 22 August 1996.