Ecology, epidemiology

- Storage, virus reservoirs

As we suggested earlier, Tomato spotted wilt virus (TSWV) infects many or no cultivated hosts. More than a thousand have been inventoried. It is therefore easily preserved in the environment of salad crops, especially on various weeds such as Amaranthus spp., Anagallis arvensis , Capsella bursa-pastoris , Chenopodium amaranticolor , Convolvulus arvensis , Fumaria officinalis , Oxalis corniculata , Picris echioides , Poa annua , Solanum nigrum , Sonchus spp., Stellaria media , Taraxacum officinale , Veronica spp.

Many cultivated plants host it, 107 have been identified in France:
- vegetable, aromatic or industrial species (eggplant, tomato, pepper, beans, peas, melon, cucumber, squash, spinach, potato, cabbage, artichoke, chard, parsley, lavandin, coriander, tarragon, basil, tobacco ... .);
- ornamental species - daisy, anemone, aroma, begonia, marigold, chrysanthemum, dahlia, zinnia, cyclamen, gladiolus, gerbera, lily, petunia, ranunculus, jasmine ...

It is also found on certain food crops in hot areas: vine, peanuts, chayote, pineapple ...

These numerous plants are reservoirs for viruses which make the control of TSWV extremely difficult.


- Transmission, dissemination

TSWV can be transmitted by several species of thrips in the persistent (circulatory-propagative) mode. In France, only Frankliniella occidentalis seems to intervene. The latter is a very efficient vector, much more than Thrips tabaci , in which biotypes incapable of transmitting this virus to other plants have been detected. Frankliniella shultzei and Frankliniella fusca also transmit TSWV in other countries where it occurs. Recently this virus was experimentally transmitted to peanuts by two other thrips: Thrips palmi and Scirtothrips dorsalis . Only the larvae are likely to acquire the virus in at least 15 minutes. Inoculations take place mainly during the feeding of adults. The latter bite the epidermal cells, inject saliva causing the lysis of the cell content and suck it. They only need 5 to 15 minutes to complete them. The latency period lasts at least four days. Thrips, which are small in size, travel short distances. They are sometimes carried away by ascending air currents which passively carry them several hundred meters, or even more in certain situations. Adults, whose lifespan varies from 30 to 45 days, are viruliferous until their death. Symptoms may appear 7 to 14 days after inoculation.

TSWV is also transmitted by seeds and vegetative reproductive organs in several plants, but not in lettuce. Be wary of plants that may have been contaminated in the nursery.