RAPID SEROLOGICAL DETECTION OF TOMATO SPOTTED WILT VIRUS IN INDIVIDUAL THRIPS BY SQUASH-BLOT ASSAY FOR USE IN EPIDEMIOLOGIC STUDIES

Squash blotting on nitrocellulose membranes was used to detect tomato spotted wilt virus (TSWV) in individual Frankliniella occidentalis adu lt thrips using a specific polyclonal antiserum. This method offers a simple and reliable procedure to test a large number of thrips and was less time-consuming than alternative techniques available. A 95% agre ement was found between the results of squash-blot and plant transmiss ion assay. Based on this agreement, this technique was used to study t he relative number of viruliferous thrips in F. occidentalis field pop ulations collected from a farm in Catalonia where TSWV causes importan t economic losses. The percentages of viruliferous individuals detecte d from a total of 1509 collected thrips increased from 0% to 2% in the different surveys conducted in the 1993 growing season. Squash-blot p roved to be a rapid and inexpensive technique to screen TSWV virulifer ous thrips from field populations. The results obtained by this method could be used together with other epidemiological data to forecast TS WV-induced diseases.