Farmer's Weekly (South Africa)
Potentially dangerous new wheat aphid found in SA
A new grain and wild grass aphid was recently detected for the first time in South Africa by Dr Astrid Jankielsohn, a senior researcher of entomology at the Agricultural Research Council’s Small Grains Institute. The Sipha maydis aphid was found in a wheat land in the Western Cape’s Swartland region in July.
According to Jankielsohn, the aphid has a wide host range that includes wild grasses and grain crops. As the aphid’s distribution rate can increase under dry conditions and temperatures of 20°C, it could cause damage during early spring when temperatures are on the increase.
“It is therefore important to pay attention to the possible colonisation of new areas by it. Extension agents, producers, consultants and researchers should be on the lookout for this aphid in order to put preventive measures in place as soon as the target insect is identified,” she said. It is widely distributed in Europe, the Middle East, Asia and parts of Africa.
The aphid is black with white hair covering its abdomen, short pore-like cornicles, and a completely sclerotised dorsum. The largest colonies of these aphids around the world have been found on cultivated grains such as barley and bread wheat, while maize seems to be the main host of this species in Africa. “S. maydis causes direct feeding damage as it feeds on mature stages of grains, infesting flag leaves [that] cause a yellowing of the plant leaf at the feeding site. Heavily infested plants often become yellowed, rolled into tubes and desiccated.
“S. maydis also causes indirect damage as a vector of barley, yellow dwarf virus and cucumber mosaic virus,” Jankielsohn said.
She urged farmers to be on the lookout for the pest, and to pay particular attention to its possible colonisation of new regions. Preventative measures still needed to be put in place to control the aphid. – Annelie Coleman
the aphid could cause damage during early spring