Seasonal Patterns of Frankliniella spp. (Thysanoptera: Thripidae) in Tomato Flowers

Abstract

Western flower thrips, Frankliniella occidentalis (Pergande), has become a pest of tomato in the Southeast by causing direct cosmetic damage to fruit and by transmitting tomato spotted wilt virus. Other vectors of tomato spotted wilt virus in the region are tobacco thrips, F. fusca (Hinds); and onion thrips, Thrips tabaci Lindeman. Commercial tomato fields were sampled during the spring cropping seasons of 1987, 1988, and 1989, and during the fall cropping seasons of 1987 and 1988 to determine seasonal abundance of thrips inhabiting tomato flowers. Adult F. occidentalis, F. fusca, and F. tritici (Fitch) accounted for ≈88% of the total thrips collected. All species were common between late April and early June, with greatest densities during May. Densities were very low at other times, especially during each fall cropping season. The effects of sample location within a field, sample location on individual tomato plants, and time of day when sampling on density estimates were investigated. Adult F. occidentalis and F. tritid were more abundant on flowers on the upper half of tomato plants compared with flowers on the lower half of plants. Densities of adult F. occidentalis were greater near field margins. Density estimates were not influenced by time of day when sampling.