Abundance of tomato spotted wilt thrips vectors on alternative plant hosts associated with the tobacco farmscape in Georgia, U.S.A
Certain species of insect pests called thrips (Family: Thripidae) are known to transmit, or vector, tomato spotted wilt (TSW), a serious virus of flue-cured tobacco produced in the USA. The weed species present in the tobacco farmscape were sampled during January through May in 2007-2009, to determine thrips abundance and species composition. Nearly 10,000 adult thrips were collected and identified from plant hosts during this study, with the objective to determine if vector species were present, and if so, on what host plants. The tobacco thrips, Frankliniella fusca, was the most common TSW vector present in the tobacco farmscape, and was collected from 19 of the 24 host plants sampled. F. fusca were most numerous on wild radish, nutsedge, primrose, rye cover crop, and volunteer soybeans. The western flower thrips, F. occidentalis , another TSW vector, also was commonly collected from 16 of the host plants in the farmscape. Western flower thrips were most common on blooming wild radish, vetch, clover, nutsedge, and rye cover crop. Other non-vector thrips species were observed on all 24 of the host plants surveyed in the farmscape. The tobacco thrips was the predominant thrips species present on tobacco foliage (85%) during the growing season, while the non-vector flower thrips, F. tritici , was the predominant thrips present on tobacco blooms (93%). Thrips vectors of TSW were collected every month of the survey, and were most abundant during March through May. Most host plants also were suitable for thrips reproduction and development as evidenced by the large numbers of immature thrips observed. These data indicate that numerous plant hosts are available in the tobacco farmscape to maintain TSW innoculum and TSW vectors throughout the winter and early spring months, prior to transplanting the tobacco crop.