INJURIOUS INSECTS AND NEMATODES ON CUCURBITS IN SOUTHERN AFRICA - A RESEARCH REVIEW

A variety of crops belonging to Cucurbitaceae are cultivated in South Africa. They are attacked and damaged by a number of insects, spider mites and nematodes. Larvae of pumpkin flies, Didacus ciliatus, D. vertebratus and other species, develop in cucurbits. In late season plantings, many or all fruits can be infested. Alatae of Aphis gossypii, Myzus persicae and other aphid species transmit watermelon mosaic virus (WMV). In summer when many cucurbit fields have been planted, 80-100 % of plants become infected by WMV and no crop is produced. Larvae of pumpkin stem borer, Apomecyna binubila, develop in stems and laterals of cucumber and watermelon and cause crop failure, but attacks are infrequent. Spider mites, Tetranychus urticae or T. ludeni damage the foliage of cucurbits in fields, and spider mites and whitefly, Trialeurodes vaporariorum damage the leaves of cucumbers in glasshouses or tunnels covered with plastic sheets. Root-knot nematodes, Meloidogyne incognita and M. javanica develop in roots and weaken them when cucurbits are grown on light soils.