SPECIES COMPOSITION AND SEASONAL ABUNDANCE OF THRIPS (THYSANOPTERA) ON COTTON IN THE NAMOI VALLEY

Data for four seasons are presented on the seasonal abundance and species composition of thrips on cotton in the Namoi Valley, N.S.W. Adult thrips had three peaks of abundance in each season, with the species composition changing from predominantly Thrips tabaci Lindeman early, to T. imaginis Bagnall mid-season and Frankliniella schultzei (Trybom) late season. Both T. tabaci and F. schultzei appear to breed and develop successfully on cotton, with peaks of immatures occurring in line with peaks in adult abundance. In contrast, T. imaginis did not seem to thrive on cotton, as indicated by the low numbers of immatures recorded relative to the other two species, even when it was dominant in adult populations. The data indicate that T. tabaci is the most important early-season thrips species on cotton in the Namoi Valley.