A Novel Method for Tospovirus Acquisition by Thrips

Abstract

An in vitro feeding method for the acquisition of impatiens necrotic spot tospovirus (INSV) and tomato spotted wilt tospovirus (TSWV) by western flower thrips (Frankliniella occidentalis (Pergande) was developed. This is the first system developed in which tospovirus viability was maintained in an in vitro technique specifically designed for thrips feeding. Three-day-old larvae of western flower thrips were caged in a cylindrical plastic tube with Parafilm membrane covering both ends. Leaf extracts from INSV- and TSWV-infected Nicotiana benthamiana or Datura stramonium were prepared. Following one cycle of differential centrifugation, the extract was placed on the membrane on one end of the cage. A second membrane was placed over the first membrane thus covering the extract. After a 24-h acquisition access feeding period, thrips were kept on green-bean pods in a container until they were 10-dayold adults. Enzyme-linked immunosorbent assays (ELISA) showed that acquisition feeding of virus suspensions prepared from infected plant hosts resulted in thrips testing positive for viruses. Cohorts from these ELISA-positive thrips were shown to be viruliferous when placed onto virus-susceptible host plants. This in vitro method is an important tool in the study of tospovirus/thrips interactions