Preliminary evidence of a resistance-breaking biotype of the Russian wheat aphid, Diuraphis noxia (Kurdjumov) (Homoptera : Aphididae), in South Africa : short communications

Diuraphis noxia (Kurdjumov) (Homoptera: Aphididae) has been the most important pest of wheat, Triticum aestivum, in the summer rainfall production areas of South Africa since its first report as pest in 1978 (Walters 1984). This aphid is endemic to central Asia, southern Russia, countries bordering the Mediterranean Sea, Iran and Afghanistan (Durr 1983; Hewitt et al. 1984; Dolatii et al. 2005) but now occurs in all major small grain production regions of the world except northeastern China (Robinson 1992) and Australia (Botha & Hardie 2000).