POTYVIRUS TRANSMISSION IS NOT INCREASED BY PRE-ACQUISITION FASTING OFAPHIDS REARED ON ARTIFICIAL DIET

Aphids (Myzus persicae), fasted after removal from healthy rearing pla nts, transmitted tobacco etch potyvirus (TEV) more efficiently than un fasted aphids whether virus acquisition was from infected leaves or th rough membranes. There was no difference in uptake of I-125-labelled T EV by fasted or unfasted aphids as measured by liquid scintillation co unting. When aphids acquired I-125-labelled TEV, label was retained in the stylets (as determined by autoradiographic light microscopy) by 5 1% of 272 fasted aphids, as against 7.8% of 258 unfasted aphids. There was a close correlation between virus transmission by aphids and viri on retention in stylets. The effect of pre-acquisition fasting disappe ared when aphids reared on an artificial diet were used in virus trans mission tests. The transmission rates obtained with such aphids were s imilar to the rates with fasted aphids reared on healthy plants. Our r esults support the hypothesis that fasting eliminates plant component( s) which interfere with the retention of virions in the food canal of aphid stylets.