Distinct efficiencies of Impatiens necrotic spot virus transmission by five thrips vector species (Thysanoptera: Thripidae) of tospoviruses in Japan

Abstract

Five thrips species known as vectors of tospoviruses in Japan, Frankliniella occidentalis, F. intonsa, Thrips setosus, T. palmi and T. tabaci, were studied for their transmission competence of Impatiens necrotic spot virus (INSV). The competence was examined for adults that acquired the virus as newly hatched larvae using a petunia leaf disk assay. No members of the genus Thrips transmitted the virus; the INSV-N protein was not detected in them by DAS-ELISA. On the other hand, two species of the genus Frankliniella were confirmed as vectors of INSV. Both sexes of F. occidentalis transmitted the virus efficiently (males: 80.5%, females: 78.7%). In F. intonsa, however, the transmission efficiency was relatively low and differed between the sexes (males: 18.3%, females: 3.7%). Most F. occidentalis adults showing ELISA-positive values transmitted INSV; however, only one third of ELISA-positive F. intonsa adults did so. The amounts of the INSV-N protein in ELISA-positive and transmitting adults were larger in F. occidentalis than in F. intonsa by sex. These results show that the transmission of INSV may be characteristic of the genus Frankliniella, and that F. occidentalis is probably the primary vector of INSV in Japan.