Tospoviruses and thrips
In their paper, Mumford et al. (1996) present the current knowledge on the biology of the tospoviruses: host range and symptomatology, molecular biology, classification, vector relations, control of disease, and detection and diagnosis. Some of these aspects are briefly summarized below. For several years, tomato spotted wilt tospovirus (potential EPPO quarantine pest) has been considered as the only member of the genus tospovirus. Now, several distinct species have been described and separated into 4 serogroups:
- serogroup I: tomato spotted wilt tospovirus (TSWV)
- serogroup II: tomato chlorotic spot tospovirus (TCSV)
groundnut ringspot tospovirus (GRSV)
- serogroup III: impatiens necrotic spot tospovirus (INSV)
- serogroup IV: watermelon silver mottle tospovirus (WSMV)
groundnut bud necrosis tospovirus (GBNV)
melon spotted wilt tospovirus (MSWV)
Among serogroup IV, it appears that groundnut bud necrosis and watermelon silver mottle tospoviruses may be closely related. Additional tospoviruses recently characterized in Brazil are Chry-1, BR-09 (zucchini) and BR-11 (tomato). Chry-1 causes necrotic lesions surrounded by yellow areas followed by stem necrosis on chrysanthemum plants (see EPPO RS 96/082), and because its biological and molecular properties are quite distinct, Bezerra et al. (1996) have proposed to consider it as a new species named chrysanthemum stem necrosis tospovirus (CSNV). Similarly for BR-09 which causes chlorosis and death of zucchini plants, Pozzer et al. (1996) have proposed to consider it as a new species called zucchini lethal chlorotic tospovirus (ZLCV).
Other viruses for which there is currently insufficient data to allow designation as distinct tospoviruses include: groundnut yellow spot virus, BR-10 (onion), Tospo-PD2, TSWV-W (watermelon), TSWV-O (onion) and peanut chlorotic fan virus.
Tospoviruses are transmitted by at least 8 different thrips species, in a persistent way. Taking the example of tomato spotted wilt tospovirus, only larvae can acquire the virus, which will then multiply inside the vector. Adults transmit the virus and remain viruliferous throughout their life. The main thrips species which can transmit tospoviruses are the following:
- Frankliniella fusca ;TSWV, INSV
- F. intonsa TSWV, TCSV
- F. occidentalis (EPPO A2 quarantine pest) TSWV, INSV, GRSV, TCSV
- F. schultzeiTSWV, TCSV, GRSV
- Scirtothrips dorsalis (EPPO A1) GBNV
- Thrips palmi (EPPO A1) WSMV, GBNV, MSWV
- T. setosus ; T. tabaci TSWV
Sources
Mumford, R.A.; Barker, I.; Wood, K.R. (1996) The biology of the Tospoviruses.
Annals of Applied Biology, 128(1), 159-183.
Bezerra, M.I.; Pozzer, L.; Nagata, T.; Lima, M.I.; Kitajima, E.W.; de Avila, A.C.; Resende, R. de O. (1996) Chrysanthemum stem necrosis (CSNV), a proposed new species in the Tospovirus genus.
Fitopatologia Brazileira, 21 (suplemento), p 430.
Abstract of a paper presented at the XXIX Congresso Brasileiro de Fitologia, Campo Grande, MS, 1996-08-11/16.
Pozzer, L.; Resende, R. de O., Bezerra, M.I.; Nagata, T.; Lima, M.I.; Kitajima, E.W.; de Avila, A.C.; (1996) Zucchini lethal chlorotic viurs (ZLCV), a proposed new species in the Tospovirus genus.
Fitopatologia Brazileira, 21 (suplemento), p 432.
Abstract of a paper presented at the XXIX Congresso Brasileiro de Fitologia, Campo Grande, MS, 1996-08-11/16.