Ecology, epidemiology

• Conservation

The virus pseudo-beet yellows ( Beet pseudoyellows virus , BPYV) infects many species botanical not belonging to Cucurbitaceae, both cultivated (lettuce, beets, spinach, carrot, zinnia, eyelet d India. ..) than spontaneous (groundsel, capselle, dandelion, bryone ). The latter play a very important role in the conservation of the virus during the winter by constituting reservoir plants in the absence of sensitive culture. They could be sources of viruses in the spring.

BPYV is present in many parts of the world, and besides Cucurbits it causes serious disease in covered lettuce crops, in winter as well as in spring. Lettuce / cucumber or lettuce / melon rotations in greenhouses can therefore be very favorable to the maintenance of the virus. 

• Transmission

BPYV is transmitted only by greenhouse whitefly T. vaporariorum in the semi-persistent mode. The vector is capable of acquiring the virus on an infected plant, or of transmitting it to a healthy plant, during fairly long bites ranging from a few tens of minutes to a few hours. The longer the acquisition period, the greater the transmission efficiency. The whitefly remains able to transmit the virus for a few days. This mode of transmission does not appear to be very efficient, as very large vector populations are generally required for an epidemic to be observed in crops. Since T. trialeurodes is not very abundant in the open field, it is mainly under cover crops that are threatened by BPYV.

BPYV is not transmitted by the whitefly B. tabaci . This explains why in the south of Spain where the populations of B. tabaci are gradually replacing the populations of T. vaporariorum , the virus is tending to disappear, whereas it was very common about thirty years ago. years.

BPYV is not transmitted by seed . In the laboratory, it is not transmissible mechanically, but it is by grafting.