Bull. Spec. CORESTA Congress, Brighton, 1998, p. 121, P07

Distribution of thrips on flue-cured tobacco and impact on the incidence of spotted wilt

University of Georgia, Dept. of Entomology and Plant Pathology, Tifton, GA, USA
Flue-cured tobacco fields were surveyed from 1989-91 and 1996-97 to determine the seasonal abundance and species composition of thrips in Georgia, USA. A total of 43 species (including 6 new state records) were recovered from tobacco foliage and blooms. Five species were commonly encountered all five years and accounted for 95% to 98% of all the thrips collected. These included Frankliniella fusca (Hinds), F. occidentalis (Pergande), F. tritici (Fitch), F. bispinosa (Morgan) and Limothrips cerealium (Haliday). F. fusca , F. occidentalis and F. bispinosa are reported vectors of tomato spotted wilt virus (TSWV), a serious threat to tobacco production. Foliage thrips peaked on tobacco in mid-to-late May each year, just prior to the initiation of flowering, then the populations rapidly declined. Flower thrips were present as soon as flowers opened and peaked about a week later. Around 30% of the foliage thrips were vector species in 1989-91; however, in 1996 and 1997 over 90% of the thrips were known vectors. The shift in the species complex was due to a rise in F. fusca (tobacco thrips) populations and a dramatic decline in L. cerealium (Cereal thrips) populations densities. The seasonal incidence of TSWV has been reduced in numerous field trials where acephate has been applied. Imidacloprid treatments have also effectively reduced TSWV.