Submitted to: Acta Horticulture Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 9/1/2004
Publication Date: 11/25/2005
Citation: Reitz, S.R. 2005. Biology and ecology of flower thrips in relation to tomato spotted wilt virus. Acta Horticulture. 695:75-84.
Interpretive Summary: Thrips are the most significant insect pests of tomatoes in the southeastern USA. Feeding by thrips reduces the quality and yield of crops, and some species, such as the western flower thrips, transmit a devastating plant disease, tomato spotted wilt virus (TSWV). Because TSWV can only be acquired by larvae and transmitted by adults, it is essential to determine the life history and movements of these different life stages to improve management of thrips and TSWV. Scientists at the Center for Medical, Agricultural and Veterinary Entomology have studied several thrips vectors of tomato spotted wilt virus using a complex of native and exotic Frankliniella species that occurs in the southeastern USA as a model. All of these species have a rapid generation time, and adults feed on many plants. Therefore, populations can build rapidly on numerous hosts and then infest tomato fields. Species with high dispersal rates may actually account for a disproportionate amount of virus transmission. More mobile species can also recolonize insecticide treated fields rapidly, which can create an impression that they are less susceptible than more sedentary species to certain insecticides. A better understanding of interspecific variation among vectors will lead to improved management of thrips and TSWV.
Technical Abstract: Tomato Spotted Wilt Virus (TSWV) is transmitted exclusively by certain species of thrips. Because TSWV can only be acquired by larvae and transmitted by adults, it is essential to determine the ecology of these different life stages to improve management of thrips and TSWV. Furthermore, interspecific differences among vector species complicate management issues. Herein, aspects of the biology and ecology of thrips vectors of tomato spotted wilt virus are discussed and an overview of vector-pathogens interaction is given. The complex of native and adventive Frankliniella species that occur in the southeastern USA is used as a model system for comparing and contrasting species-specific behavioral attributes that affect large-scale spatial and temporal population dynamics. The common Frankliniella species in the southeastern USA include Frankliniella occidentalis, F. fusca, F. bispinosa, and F. tritici. The western flower thrips, F. occidentalis, is considered the predominant vector of TSWV, but F. bispinosa and F. fusca are also vectors. These Frankliniella species have rapid generation times, and adults are highly polyphagous. Numerous hosts may serve as sources for thrips entering tomato fields, yet tomato is a poor reproductive host. Therefore, most of the thrips infesting fields are immigrants. Consequently, thrips dispersal behavior is a key component of TSWV epidemiology. F. occidentalis is a less mobile species than either F. bispinosa or F. tritici. These interspecific differences in the activity levels of adults affect how the species colonize plants and the field efficacy of insecticides against each species. These results show the importance of understanding interspecific variation among vectors for management of TSWV.