Ecology, epidemiology

• Conservation

The cucurbit transmitted by aphid ( yellows virus Cucurbit aphid-borne yellows virus , CABYV) infects, under natural conditions, cultivated cucurbits but also quite a number of weeds annual that have a winter cycle (capsella, dead nettle, groundsel, ) or perennial (bryone) which can constitute , between two cultures , effective reservoirs of virus but also of vector aphids. This virus can also infect winter crop species (including lettuce), but the frequency of the virus in these crops is not known.
 

• Transmission

CABYV is transmitted in the persistent mode by a few species aphid (including the melon aphid, A phis gossypii , Myzus persicae and Macrosiphum euphorbiae ). CABYV is present only in phloem tissues of infected plants. It is therefore acquired and transmitted during fairly long feeding bites , from a few tens of minutes to a few hours, the time necessary for the aphid's stylet to reach the phloem. Then, the virus will follow a rather complex path in the aphid. It travels through the digestive tract to the intestine, then it crosses the intestinal epithelium, to end up in the hemolymph of the insect before going to accumulate in the accessory salivary glands . This cycle takes place without viral multiplication, but involves specific molecular interactions between the virus and the aphid explaining the specificity of CABYV vection: few aphid species transmit it. This cycle will take between 24 and 48 hours, which corresponds to the latency period, that is to say the time which elapses between the moment when the aphid takes the virus from a virus-infected plant and the moment when it can transmit it to a healthy plant. An aphid that has acquired CABYV can then remain viruliferous, that is, capable of transmitting it throughout its life.

CABYV is not mechanically transmitted in the laboratory or in the field, nor is it by seed. However, it can be during operations grafting .