Ecology and Epidemiology

- Survival and virus reservoir
 
Cucumber mosaic virus (CMV) is an extremely common virus. It is able to infect a large number of hosts, more than 700 plant species belonging to 85 families. This great polyphagia partially explains why the virus  easily survives from one season to another through weeds: Rubia peregrina, Stellaria media, Senecio vulgaris, Mercuriailis annua, Veronica agrestis, amplexicanle Lamium, Ajuga chamaepitys, Achetropeum europeum , Portulaca oleracea, Solanum nigrum ...
 
Many crops also serve as reservoirs for this virus such as spinach and celery in winter and various cucurbits (melon, cucumber, zucchini, figure 1) and other Solanaceae (tomato, pepper) in summer.
 
 
- Transmission and dissemination
 
CMV is transmitted from infected plants to other plants by aphids (figure 2) in a non-persistent manner; aphids, by short "test" bites, very quickly acquire adsorbed virus particles in their stilettos and teguments of their mouthparts. They are able to transmit the virus particles  immediately, but for a short period, not exceeding 2 to 4 hours. About sixty aphid species can transmit CMV.
 
Transmission with seed occurs in about twenty plant species, especially in several weeds. For example in Stellaria media, CMV is transmitted with seed. It is thus transmitted to the progeny, which subsequently will influence the epidemiology of the virus.

 Spread of CMV is mainly achieved by aphids, and it depends on the nature of outbreaks of these insects. Several abiotic factors play a key role on the biology and effectiveness of aphid flights:
- The wind determines their distribution;
- The temperature affects tobacco growth, multiplication of the virus and aphids, in and on plants, respectively;
- The production conditions, such as proximity of other infected crops and presence of many virus-infected weeds that foster contamination;
- Finally, regional factors  can be added to the factors above, such as the layout of the plots, orientation to the wind, possible protection by hedges, conservation of virus reservoir plants ...