Investigators: Jessica Hohenstein (Post-doctoral Associate), Matt O’Neal (Associate Professor)

With funding from the North Central Soybean Research Program, we are determining if aphid-resistant soybeans can be use with a “refuge-in-a-bag” or RIB. Refuges of pest-susceptible varieties are often included when a pest-resistant variety of a crop is used. By including a refuge, we can produce a population of avirulent aphids so that they can inter-breed and swamp out the genes of virulent aphids that are capable of surviving on the aphid-resistant soybeans. We have completed two field seasons of experiments in which large plots of soybeans comprised of either 100% aphid-susceptible or 100% aphid-resistant isolines are compared to mixtures of susceptible and resistant plants.  These mixtures included 25% or 10% susceptible seeds. Overall, we observed no effect on yield when the aphid susceptible seeds were included. We observed more aphids with an increasing % of susceptible seed. In 2018, survival and reproduction of field-collected aphids generally increased as the proportion of susceptible seed mix decreased. This suggests that plots with susceptible seeds may produce a higher proportion of avirulent individuals than all-resistant fields. Thus, for locations experiencing virulent soybean aphid populations, inclusion of an interspersed refuge may be a viable resistance management strategy.

Beginning in 2019, with support from the North Central Soybean Research Program, we will collaborate with colleagues from Corteva^TM Agriscience (Jessie Alt and David Onstad) to evaluate elite soybean germplasm with aphid-resistant genes. Our goal is to determine if these lines provide optimal yield without insecticide use. These results will allow us to prepare a response for farmers dealing with insecticide-resistant soybean aphids.

What does it mean for farmers: With the growing threat of insecticide-resistant soybean aphids, farmers are in need of novel approaches for managing this pest. We will advance the development of commercially-available, herbicide-tolerant, aphid-resistant soybean. By developing a resistance management plan for aphid-resistant soybeans, we can ensure sustainable use of these traits for farmers.