ARS | Publication request: Evolution of soybean aphid biotypes: understanding and managing virulence to host-plant resistance

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: April 25, 2011
Publication Date: April 30, 2011
Citation: Michel, A.P., Omprakah, M., Mian, R.M. 2011. Evolution of soybean aphid biotypes: understanding and managing virulence to host-plant resistance. In: Sudarec, A. editor. Soybean - Molecular Aspects of Breeding. Rijeka, Croatia: InTech. p. 355-372.

Technical Abstract: As the discovery of soybean aphid biotypes occurred relatively recently and much information is still needed to determine their influence on resistant soybean varieties. Most critical are determining the relative frequencies and distributions of biotypes, and further elucidating the role of the overwintering host in regards to population genetic issues. However, the largest obstacle remains individually diagnosing aphids to biotypes. Using detached leaves may help but this is a laborious process and may not work for all host-plant resistant varieties. Ultimately, diagnosis should rely on molecular methods, but linking molecular markers to biotype designations may take many years and prove difficult in an aphid species where any such genetic markers may disassociate from the virulence trait through recombination in the obligatory sexual phase. Newly developed molecular resources for the soybean aphid should help in the search for diagnostic genetic markers. The question remains, however, as to how durable host-plant resistant soybean varieties against the soybean aphid will remain effective. In other host-plant resistance systems with virulent aphid biotypes, resistant varieties can remain durable for extended periods of time. The presence and evolution of soybean aphid biotypes places great importance on the constant development of new soybean aphid resistant soybean varieties. By having a wide array of potential soybean aphid resistant genes and varieties—including the possibility virulence can likely be managed and the durability of host-plant resistance will be preserved. In addition, the possibility of mixing or gene pyramiding and geographically varying Rag gene deployment may extend the life of host-plant resistance. Furthermore it is important to keep in mind other potential control tactics including insecticidal seed treatments and mid or late season insecticide applications. Through a multi-year and multi-state research collaboration, an economic threshold exists for the soybean aphid which works for the majority of soybean fields. The integration of all tactics will be necessary to slow the evolution of soybean aphid biotypes and extend the durability of host-plant resistance in soybean.