STUDIES OF THE MECHANISM OF TRANSMISSION OF POTATO VIRUS Y BY THE GREEN PEACH APHID, MYZUS PERSICAE (SULZ.) (HOMOPTERA: APHIDAE)

Abstract

Wingless adults of Myzus persicae (Sulz.) usually ceased to be infective within minutes and always within hours after leaving tobacco infected with potato virus Y, the time being longer when the aphids were kept from feeding than when they fed, and aphids that were kept from feeding remained infective longer at 2 °C. than at 35 °C. After one to four hours without food, over 80% of M. persicae made initial feeding punctures that lasted less than a minute, and about 70% of these aphids transmitted potato virus Y after one such feeding puncture on an infected plant. Though virus was acquired by aphids during feeding punctures as brief as five seconds, those that made feeding punctures lasting 11–60 sec. were the most likely to become infective. The percentage of aphids that transmitted potato virus Y decreased when the stylets were inserted into infected plants for over a minute, and none of the aphids transmitted the virus after the stylets had been inserted over 20 min. The highest percentage of aphids transmitted potato virus Y when they were transferred to test plants immediately after a single brief feeding puncture on an infected plant. The percentage of aphids that transmitted the virus decreased when they spent 10 min. or longer on infected plants; also, the probability of their becoming infective during a single feeding puncture decreased by about one third during the first 10 min. they fed after one to four hours without food. Even when conditions were suitable, about 25% of M. persicae failed to transmit potato virus Y. Yet those that failed to transmit the virus in one infection trial transmitted it as readily in a second trial as those that transmitted it in the first.