An increased wheat yield potential under changing environmental conditions is a challenge in agriculture. Resistant wheat lines can yield more than susceptible wheat lines in the presence of Russian wheat aphid infestation. There are currently four Russian wheat aphid (RWA) biotypes known in South Africa with different virulence against different wheat cultivars. To keep up with the ever-changing patterns it is necessary to screen the cultivars for resistance against these Russian wheat aphid (RWA) biotypes. All the dryland wheat cultivars on the market were evaluated for resistance against the four known Russian wheat aphid (RWA) biotypes in South Africa. Through this evaluation, the status of Russian wheat aphid (RWA) resistance in South African dryland wheat cultivars can be updated to adapt to environmental changes and the wheat industry can adapt to changes in virulence of Russian wheat aphid (RWA) biotypes that may cause damage to Russian wheat aphid (RWA) resistant cultivars, subsequently affecting yield. Evaluations were done in the glasshouse by screening wheat cultivars against four different South African Russian wheat aphid (RWA) biotypes, RWASA1-RWASA4, under controlled conditions. The glasshouse evaluations showed that out of the 19 dryland wheat cultivars currently on the market in South Africa 16 are resistant against RWASA1, 7 are resistant against RWASA2, 7 are resistant against RWASA3 and 5 are resistant against RWASA4. Dryland wheat cultivars were also evaluated under field conditions at four different field localities. In the field, 5 cultivars were resistant to RWASA3 at two localities, respectively, and 3 and 5 cultivars were resistant to RWASA4 at two localities, respectively. Since Russian wheat aphid (RWA) damage can influence the final yield of a wheat cultivar significantly, changing conditions can influence both resistant cultivars, and the virulence of Russian wheat aphid (RWA). It is advisable to evaluate wheat cultivars on the market under different conditions and with all known Russian wheat aphid (RWA) biotypes in an area.
Morrison, W.P. and Peairs, F.B. (1998) Response Model Concept and Economic Impact. In: Quisenberry, S.S. and Peairs, F.B., Eds., Response Model for Russian Wheat Aphid, Thomas Say Publications in Entomology, Entomological Society of America, Lanham, MD.
Du Toit, F. and Walters, M.C. (1984) Damage Assessment and Economic Threshold Values for the Chemical Control of the Russian Wheat Aphid, Diuraphisnoxia (Mordvilko) on Winter Wheat. In: Walters, M.C., Ed., Progress in Russian Wheat Aphid (Diuraphisnoxia) Research in the Republic of South Africa, Technical Communication No. 191, Republic of South Africa, Department of Agriculture, 58-62.
Lage, J., Skovmand, B. and Andersen, S.B. (2004) Resistance Categories of Synthetic Hexaploid Wheats Resistant to the Russian Wheat Aphid (Diuraphidsnoxia) Euphytica, 136, 291-196. https://doi.org/10.1023/B:EUPH.0000032732.53350.93
Calhoun, D.S., Burnett, P.A., Robinson, J., Vivar, H.E. and Gilchrist, L. (1991) Field Resistance to Russian Wheat Aphid in Barley: II Yield Assessment. Crop Science, 31, 1464-1467. https://doi.org/10.2135/cropsci1991.0011183X003100060014x
Robinson, J. (1994) Identification and Characterization of Resistance to Russian Wheat Aphid in Small Grain Cereals: Investigations at CIMMYT, 1990-92. CIMMYT Research Report No. 3. CIMMYT, Mexico, D.F.
Akhtar, L.H., Hussian, M., Muhammad Iqbal, R., Amer, M. and Hussain Tariq, A. (2010) Losses in Grain Yield Caused by Russian Wheat Aphid Diuraphisnoxia (Mordvilko). Sarhad Journal of Agriculture, 26, 625-628.
Mornhinweg, D.W., Brewer, M.J. and Porter, D.R. (2006) Effect of Russian Wheat Aphid on Yield and Yield Components of Field Grown Susceptible and Resistant Spring Barley. Crop Science, 46, 36-42. https://doi.org/10.2135/cropsci2004.0768
Randolph, T.L., Peairs, F.B., Koch, M.K., Walker, C.B. and Quick, J.S. (2005) Influence of Three Resistance Sources in Winter Wheat Derived from TAM 107 on Yield Response to Russian Wheat Aphid. Journal of Economic Entomology, 98, 389-394. https://doi.org/10.1093/jee/98.2.389
Tolmay, V.L., Lindeque, R.C. and Prinsloo, G.J. (2007) Preliminary Evidence of a Resistance-Breaking Biotype of the Russian Wheat Aphid, Diuraphis noxia (Kurdjumov) (Homoptera: Aphididae), in South Africa. African Entomology, 15, 228-230. https://doi.org/10.4001/1021-3589-15.1.228
Jankielsohn, A. (2011) Distribution and Diversity of Russian Wheat Aphid (Hemiptera: Aphididae) Biotypes in South Africa and Lesotho. Journal of Economic Entomology, 104, 1736-1741. https://doi.org/10.1603/EC11061