Scirtothrips aurantii (South African citrus thrips)

On Citrus, S. aurantii causes silvering of the leaf surface, linear thickenings of the leaf lamina, brown frass markings on the leaves and fruits, grey to black markings on fruits often forming a ring around the apex, and ultimately fruit distortion and early senescence of leaves. If flushes of young leaves are severely attacked later in the season, then the crop of the following season may be reduced (Kamburov, 1991). On mangoes, S. aurantii causes lesions on the fruit, leaf malformation and stunting of new growth (Brink, 1994). It causes fruit spotting on bananas in Yemen.

At least ten Scirtothrips spp. are known as pests of various crops in different parts of the tropics, but most of them have restricted geographic ranges and tropical host plants, such as S. kenyensis which damages tea and coffee in eastern Africa, or S. manihoti which causes serious leaf distortion of cassava in Central and South America. Scirtothrips spp. are particularly associated with plants that grow in warm, dry conditions; they are usually more abundant on terminal shoots rather than within the canopy of a tree. With S. citri and S. dorsalis (EPPO/CABI, 1996), S. aurantii is, as a pest of Citrus, one of the most important Scirtothrips spp. for international agriculture.In South Africa and Zimbabwe, S. aurantii causes reduction in Citrus yields through serious damage to young leaves, and reduces the proportion of export-quality fruits. It is a most serious pest at low altitudes (Hill, 1983). It is not generally regarded as harmful to crops further north in Africa, although this might be due to less intensive cultivation practices. Damage to tea plants has been reported from plantations in Malawi (Rattan, 1992) and losses have been studied (Rattan, 1996). S. aurantii is the primary cause of banana fruit-spotting in Yemen (Nasseh and Mughni, 1990). It is also recorded as the most important thrips species on mangoes in South Africa (Brink, 1995).