Thrips tabaci (Thysanoptera: Thripidae) and Iris yellow spot virus (genus: Tospovirus, family: Bunyaviridae) in onions

Abstract

Thrips vectors of tospoviruses were surveyed in onions and other vegetable crops in India and in onions in Georgia, USA. The only known vector species of Iris yellow spot virus (IYSV) collected both in the USA and India was Thrips tabaci (Thysanoptera: Thripidae). In onions in Georgia, the two dominant species of thrips during this survey were Thrips tabaci and Frankliniella fusca. Competition studies between these two thrips species revealed that T. tabaci reproductively outcompeted F. fusca in onions. Distribution studies on T. tabaci in onions indicated that adult settling and oviposition are skewed towards the base of the plant. Field studies on the distribution of thrips and IYSV in onions demonstrated similar distributions of eggs and virus skewed towards the base of the plant. Transmission studies of IYSV indicate that T. tabaci can inoculate onion plants very efficiently, achieving 64% successful transmission in 15 minutes. Thrips tabaci appeared to be the main thrips vector of IYSV in both Georgia and India.