Aphid damage on Cucurbitaceae

Cucurbitaceae (melon, marrow, cucumber, pumpkin and so on) are affected by numerous viral diseases transmitted by aphids including  cotton aphid  (Aphis gossypii) and green peach aphid (Myzus persicae). The cucumber mosaic virus (CMV) is the most widespread and most serious. It is transmitted through the non-persistent mode. The disease severely damages crops in the South of France where the virus easily becomes permanently established on plant reservoirs located outside the greenhouses. It is so serious that continued summer and autumn cultivation of cucumber and courgette is being called into question. The only means of control (in the absence of tolerant varieties) is to prevent any aphids from entering greenhouses and avoid sowing too late which would lead to exposure of plants during the aphids’ long flight-time periods.. The water melon mosaic viruses (WMV2) and the courgette (zucchini) yellow mosaic virus (ZYMV) are also passed on by aphids. The development of resistant varieties through genetic transfer techniques is one of the methods being implemented against viral transmission, with the aim of limiting the disease. The research projects run by INRA resulted in varieties resistant to the multiplication of Aphis gossypii. This resistance is coupled with ineffectiveness of transmission of CMV and Potyvirus, WMV 2 and ZYMV. This property is linked to the Vat gene found in several varieties of melon.

The -cotton aphid (Aphis gossypii) also provokes direct damage by inducing leaf crinkling and arrested growth. Early attacks can kill off young plants. On melon, the threshold for triggering aphicide control methods is when 10% of leaves are carrying at least one colony.