It's mid-September and the tenth episode of Season 9! Erin provides a brief update on the newest soybean pest in Iowa - soybean gall midge. Activity has slowed drastically since the last episode and is coordinated with quickly maturing fields in western Iowa. Matt traveled to Brazil for a soybean congress and gave some updates on new invasive in this large soybean-growing country.
This podcasting episode provides a short recap of some early-season pests, like grubs, caterpillars and beetles. Matt is a fan of the Bug Eaters Nebraska soccer team, and lets everyone know their upcoming schedule.
Soybean aphid management has relied heavily on foliar insecticides to protect yield since 2000. In 2016, performance issues have been documented in commercial fields and research plots in northern Iowa counties. With support from the Iowa Soybean Association, we are exploring insecticide resistance for soybean aphid in Iowa and describing the mechanism of resistance. Laboratory bioassays identified field-collected population’s evolved resistance to pyrethroids.
Host plant resistance for soybean aphid is a management tool to protect yield. Our lab has evaluated the efficacy and of host plant resistance but generally with small plot research. Working with Iowan farmers, we evaluated the efficacy of aphid-resistant soybean on commercial farms in Iowa. With funding from the North Central Region – Sustainable Agriculture Research and Education Program, we are studying the potential for aphid-resistant soybeans on a larger scale. We provided farmers with experimental and commercially available soybean varieties containing a 2-gene pyramid (Rag1+2).
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.
Longer rotation schemes require less herbicide and reduce frequency of sudden death syndrome in soybean. Crop rotation can alter the soil environment, affecting plant physiology, and may impact insects, like soybean aphid.
We are exploring how small patches of native, perennial vegetation (i.e., prairie) can increase the abundance and diversity of pollinators within corn and soybean. We observed honey bee colonies in Iowa lose weight beginning in August, when clover and soybean cease blooming. When colonies had access to a prairie from August to October, they were buffered from this late season decline.
In the last episode of the year, Matt and Erin talk about midges in the news and interesting honey bee behavior. Here are links to some of the research Matt mentioned in his re-occurring F.I.T. segment:
Behavioral responses of honey bees to natural and synthetic xenobiotics in food. Liao et al. 2017
Bees prefer foods containing neonicotinoid pesticides. Kessler et al. 2015
NPR story about midges:“Scientists say miniature flies are a big worry for Antarctic island”
The use of insecticides to control the soybean aphid has become a predominant management practice for growers. Before the confirmation of the soybean aphid in 2000, less than 0.1% of soybean was treated with insecticides. However, soybean aphid management has resulted in a 130-fold increase of insecticide applications in less than a decade. An estimated 1,400% increase of Iowa soybean acres were treated with a foliar insecticide in 2009 compared to 2000. Growers are also increasing the use of insecticidal seed treatments to control early-season establishment of insects on soybean.
