Winter and Early-Spring Survey of Thrips Vectors and Host Plants of Tomato Spotted Wilt Tospovirus in and near a Flue-Cured Tobacco Farmscape

Abstract

The tobacco thrips, Frankliniella fusca (Hinds), is an economic pest of flue-cured tobacco because it vectors tomato spotted wilt tospovirus. Other species of thrips are also vectors of spotted wilt in tobacco, including the western flower thrips, F. occidentalis (Pergande). This study examined the presence of thrips species on alternate plant hosts associated with the tobacco farmscape and surrounding area. Weed hosts were sampled from December through April from 1998 through 2001 to assess which plants provide suitable refuge and nutrients for thrips survival, reproduction, and spotted wilt infection. Thrips were identified to species and confirmed as potential vectors of spotted wilt by using ELISA to test for the presence of a non-structural tomato spotted wilt virus protein. Wild radish (Raphanus raphanistrum L.), broomsedge (Andropogon virginicus L.), and narrowleaf vetch (Vicia sativa L. subsp. nigra (L.) Ehrh.) are common late-winter weeds in the farmscape that harbor spotted wilt vectors. Cutleaf evening primrose, Oenethera laciniata Hill, and volunteer soybean, Glycine max(L.) Merrill, also were hosts of spotted wilt vectors in the tobacco farmscape. Numerous other weed hosts were present in the tobacco farmscape but either had no thrips collected from them or thrips were not confirmed as potential spotted wilt vectors from these host plants. Several other plants near the tobacco farmscape also were infected with spotted wilt, and three of these host plants, common chickweed (Stellaria media (L.) Cyrillo), carrot (Daucus carota L.), and flowering dogwood (Cornus florida L.) had confirmed vectors (ELISA) collected from them. Henbit (Lamium amplexicaule L.), wild radish, cutleaf evening primrose, narrowleaf vetch, carrot, curly dock (Rumex crispus L.), red sorrel (Rumex acetosella L.), and common chickweed were confirmed as positive plant hosts in this study for spotted wilt using ELISA. Frankliniella fusca appears to be the most abundant thrips vector on these alternate plant hosts and is the predominate thrips species collected on the flue-cured tobacco, Nicotiana tabacum L. However, F. occidentalis, Haplothrips graminis Hood, and Chirothrips spp. also were confirmed in this study to be potential vectors in the tobacco farmscape. Weed hosts in the farmscape appear to be influential as refuge and nutrients for vectors and an innoculant source of tomato spotted wilt virus in the flue-cured tobacco farmscape.