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

Pathogens ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 636 ◽  
Author(s):  
Ozgur Batuman ◽  
Thomas A. Turini ◽  
Michelle LeStrange ◽  
Scott Stoddard ◽  
Gene Miyao ◽  
...  

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.

Plant Disease ◽  
2000 ◽  
Vol 84 (8) ◽  
pp. 847-852 ◽  
Author(s):  
D. G. Riley ◽  
H. R. Pappu

Two studies were conducted in Georgia during the spring of 1997 and 1998 to evaluate various management practices for reducing thrips and thrips-vectored Tomato spotted wilt virus (TSWV) in tomato. Populations of the two species of thrips responsible for transmitting TSWV in tomato fields, Frankliniella occidentalis and F. fusca, were determined using blossom and sticky trap samples. Management practices evaluated were host plant resistance, insecticide treatments, planting date, and light-reflective mulch. In both years, intensive insecticide treatment had the largest effect in reducing thrips and spotted wilt and increasing marketable yield, compared with host plant resistance and reflective mulch. The effect of planting date was consistent in that the later planting date resulted in higher incidence of TSWV, lower thrips numbers, and lower tomato yields, both in fruit quality and dollar value. Host plant resistance and reflective mulch significantly reduced thrips and TSWV. In both years, early planting on black plastic with an intensive insecticide treatment resulted in the highest yield.


2003 ◽  
Vol 93 (10) ◽  
pp. 1223-1227 ◽  
Author(s):  
P. C. Maris ◽  
N. N. Joosten ◽  
R. W. Goldbach ◽  
D. Peters

Spread of Tomato spotted wilt virus (TSWV) and population development of its vector Frankliniella occidentalis were studied on the pepper accessions CPRO-1 and Pikante Reuzen, which are resistant and susceptible to thrips, respectively. Viruliferous thrips were released on plants of each accession (nonchoice tests) or on plants in a 1:1 mixture of both accessions (choice tests) in small cages containing 8 or 16 plants. Significantly fewer CPRO-1 plants became infected in the primary infection phase in both tests. In the nonchoice test, virus infection of the resistant plants did not increase after the initial infection, but all plants eventually became infected when mixtures of both cultivars were challenged in the secondary infection phase. Secondary spread of TSWV from an infected resistant or susceptible source plant was significantly slower to resistant plants than to susceptible plants, independent of source plant phenotype. The restricted introduction and spread of TSWV in the thrips-resistant cultivar was confirmed in a large-scale greenhouse experiment. The restricted and delayed TSWV spread to plants of the resistant accession in both the cage and the greenhouse experiment was explained by impeded thrips population development. The results obtained indicate that thrips resistance may provide a significant protection to TSWV infection, even when the crop is fully susceptible to the virus.


Author(s):  
Casey L. Ruark-Seward ◽  
Brian Bonville ◽  
George Kennedy ◽  
David A. Rasmussen

AbstractTomato spotted wilt virus (TSWV) is a generalist pathogen with one of the broadest known host ranges among RNA viruses. To understand how TSWV adapts to different hosts, we experimentally passaged viral populations between two alternate hosts, Emilia sochifolia and Datura stramonium, and an obligate vector in which it also replicates, western flower thrips (Frankliniella occidentalis). Deep sequencing viral populations at multiple time points allowed us to track the evolutionary dynamics of viral populations within and between hosts. High levels of viral genetic diversity were maintained in both plants and thrips between transmission events. Rapid fluctuations in the frequency of amino acid variants indicated strong host-specific selection pressures on proteins involved in viral movement (NSm) and replication (RdRp). While several genetic variants showed opposing fitness effects in different hosts, fitness effects were generally positively correlated between hosts indicating that positive rather than antagonistic pleiotropy is pervasive. These results suggest that high levels of genetic diversity together with the positive pleiotropic effects of mutations have allowed TSWV to rapidly adapt to new hosts and expand its host range.


2012 ◽  
Vol 65 ◽  
pp. 120-125 ◽  
Author(s):  
M.M. Davidson ◽  
S.M. Skill ◽  
R.C. Butler ◽  
M-C. Nielsen ◽  
S. Keenan ◽  
...  

The impact of tospovirus infection on the behaviour of western flower thrips (Frankliniella occidentalis) was evaluated in a Ytube olfactometer The response of female western flower thrips with or without a tospovirus (Tomato spotted wilt virus TSWV) to a thrips lure (methyl isonicotinate MI) and chrysanthemum buds was recorded Compared to the blank arm significantly more thrips chose the odourladen arm of the Ytube when it contained MI (65 P016) increase the percentage of thrips that chose the odourladen arm over and above the cleanair arm but thrips (virusfree and infected) moved more quickly to the end of either arm when a bud was present The virus status of thrips was confirmed with RTPCR The presence of the virus in the vector did not substantially affect the behavioural response of the vector to a lure or hostplant material (P>04)


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