Transmission of TSWV in greenhouse crops in Bulgaria
Karadjova O1, Krumov V1, Nikolov P2
1 Plant Protection Institute, 2230 Kostinbrod, Bulgaria
2 National Service for Plant Protection, 55 Hr. Botev Blvd., Sofia, Bulgaria.
Correspondence: oliakaradjova@abv.bg
Since the Western Flower Thrips (Frankliniella occidentalis Perg.) was first reported in Bulgaria in 1991, it has become one of the most important greenhouse crop pests (Trenchev G, Karadjova O. 1992. Plant Protection Journal 3: 26每30; Karadjova O et al. 2003. Acta Entomologica Bulgarica. 9: 22每29). The first TSWV epidemic was recorded in 1993 in many greenhouses across the country (Hristova D et al. 2001. Journal of Phytopathology 149: 1每5). Until now, TSWV is the only tospovirus that has been found on vegetables and ornamental crops in Bulgaria, although INSV has been found on imported planting material especially from Israel and the Netherlands. The absence of INSV Tospovirus, also in ornamentals, indicates that at present the tospovirus population in Bulgaria is indigenous and not contaminated with strains from Western Europe (Hristova et al. 2001). Two different F. occidentalis populations (F.occ. 1 and F.occ. 2) and three TSWV isolates (BR-01, GD from tobacco and KR from greenhouse tomato) were used in this investigation. DAS-ELISA was used to confirm infection in individual thrips. The transmission efficiency of adult Th. tabaci was tested on petunia leaf discs (Wijkamp I. 1995. Virus-vector relationships in the transmission of tospoviruses. Ph. D thesis, Wageningen, the Netherlands). Positive ELISA values were detected in both F. occidentalis populations. The highest percent TSWV positive thrips was established for the combination F. occ. 2 - TSWV KR (Bulgarian greenhouse isolate from tomato). The lowest ELISA values were detected for F.occ.1 - TSWV isolate from tobacco (GD). Insect transmission tests were conducted with the same populations. Our tests demonstrated successful transmission of TSWV by both F. occidentalis populations. The highest transmission rate was observed for the combination F.occ. 2 每 KR isolate (52.08%). Transmission efficiency of F.occ. 1 每 TSWV BR-01 reached 27.08% and the lowest transmission was observed in F.occ. 1 每 GD (6.25%). Results of virus transmission to leaf discs were correlated to the readings in ELISA.
