Development of an IPM Strategy for Thrips and Tomato spotted wilt virus in Processing Tomatoes in the Central Valley of California

Abstract

Tomato spotted wilt virus (TSWV; species Tomato spotted wilt orthotospovirus; genus Orthotospovirus; family Tospoviridae) is a thrips-transmitted virus that can cause substantial economic losses to many crops, including tomato (Solanum lycopersicum). Since 2005, TSWV emerged as an economically important virus of processing tomatoes in the Central Valley of California, in part due to increased populations of the primary thrips vector, western flower thrips (WFT; Frankliniella occidentalis). To develop an understanding of the epidemiology of TSWV in this region, population densities of WFT and incidence of TSWV were monitored in California’s processing tomato transplant-producing greenhouses and associated open fields from 2007 to 2013. Thrips were monitored with yellow sticky cards and in tomato flowers, whereas TSWV incidence was assessed with indicator plants and field surveys for virus symptoms. All thrips identified from processing tomato fields were WFT, and females were three-fold more abundant on sticky cards than males. Symptoms of TSWV infection were observed in all monitored processing tomato fields. Incidences of TSWV ranged from 1 to 20%, with highest incidence found in late-planted fields. There was no single primary inoculum source, and inoculum sources for thrips/TSWV varied depending on the production region. These results allowed us to develop a model for TSWV infection of processing tomatoes in the Central Valley of California. The model predicts that low levels of primary TSWV inoculum are amplified in early-planted tomatoes and other susceptible crops leading to highest levels of infection in later-planted fields, especially those with high thrips populations. Based upon these findings, an integrated pest management (IPM) strategy for TSWV in processing tomatoes in California was devised. This IPM strategy focuses on strategic field placement (identification of high-risk situations), planting TSWV- and thrips-free transplants, planting resistant varieties, monitoring for TSWV symptoms and thrips, roguing infected plants, thrips management targeting early generations, extensive sanitation after harvest, and strategic cropping to avoid overlap with winter bridge crops.

Survey of viruses and vectors in tomato plants, alternative hosts and weeds in the state of Santa Catarina, Brazil

“…Several studies have recommended a series of integrated management strategies for vector‐transmitted viruses in tomato plants, including individual actions such as the choice of planting location (away from alternative hosts and old tomato crops), rotation of different groups of insecticides, use of resistant cultivars and monitoring of infected plants and vectors (Batuman et al., 2020; Gilbertson, 2011).…”

Tomato Spotted Wilt Virus Benefits Its Thrips Vector by Modulating Metabolic and Plant Defense Pathways in Tomato

“…vectors, which in turn could be expected to increase virus secondary spread by thrips dispersal to neighboring plants. While it is well documented that TSWV spread in various vegetable crops grown in Australia (Coutts et al, 2004) and the south-eastern United States (Camann et al, 1995;Gitaitis et al, 1998) is primarily monocyclic in nature, i.e., primary flight of migratory viruliferous adults settling on plants and slow progression of within-field spread during the season, a 6-year epidemiological study of TSWV and F. occidentalis on processing tomatoes grown in the Central Valley of California points to the likelihood and impact of secondary spread of TSWV by viruliferous adults arising from larvae produced on early-season crops to neighboring late-season tomato crops (Batuman et al, 2020). Consistent with this scenario, attraction of female thrips to TSWV-infected plants would promote oviposition on these plants, and emerging larvae, the requisite stage for TSWV acquisition and subsequent plant inoculation as adults, would thrive on these plants, and at or around crop harvest, migrate as adults to inoculate later season crops.…”

Viruses of Economic Impact on Tomato Crops in Mexico: From Diagnosis to Management—A Review

“…TSWV has been involved in severe outbreaks in tomato, causing a 42% reduction in productivity and about a 100% loss in the value of commercial tomato under field conditions [69]. In 2005, around USD 20 million were lost in the Central Valley of California due to a severe epidemic of TSWV and its vector [70].…”