Project Details:

Development of genetic, chemical and population-based tactics to manage key Kansas soybean insect pests

Parent Project: Development of soybean host plant resistance and other management options for the soybean stem borer
Checkoff Organization:Kansas Soybean Commission
Categories:Breeding & genetics, Insects and pests
NCSRP, USB, QSSB Project Code:1426
Project Year:2015
Lead Principal Investigator:C Michael Smith (Kansas State University)
Co-Principal Investigators:
Brian McCornack (Kansas State University)
William Schapaugh (Kansas State University)
Jeff Whitworth (Kansas State University)
Keywords: Decetes Stem Borer, Soybean Educational Activities, Soybean Germplasm Screening, Soybean Insect - Control, Soybean Variety Testing

Contributing Organizations

Funding Institutions

Information and Results

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Project Summary

Infestations of the soybean stem borer, Dectes texanus, were first reported in Edwards, Barton, Kiowa, Ford and Pawnee counties in 1985. Borer larvae caused severe lodging problems in north-central and southwestern Kansas, where infestations of 50 to 80 % of plants with tunneling are common. In Republic Co., some sites have approached 100% infestation. Damaging populations are expanding westward in soybeans and more recently in sunflowers, with infestations reported in an additional 59 counties. Expansion may be due to reduced availability of alternate host plants such as wild sunflower, increased borer larvae winter survival, increased soybean acreage, or increased adoption of non-tillage practices.

Though interest in management and control of soybean stem borer has increased, strategies remain limited. For example, early harvesting has helped reduce some yield losses if infestations are detected early in the growing season. Commercial insecticides do reduce adult stem borer numbers, but several applications are necessary for better results, making this option cost-prohibitive. Fipronil seed treatments serve to effectively control larvae in the plant stem, but this insecticide remains commercially unregistered for use on soybean stem borer and unavailable.

To date, soybean varieties adapted to the High Plains or Midwestern U.S. contain no genetic traits for resistance to soybean stem borer larval damage. However, our results have provided a source of borer resistance and a reliable method for identifying resistance. Several genes are involved in PI165673 resistance suggesting that breeding for borer resistance will benefit from marker-assisted selection to accurately and efficiently locate the PI165673 resistance genes.

Project Objectives

1. Map the genes contributing to soybean stem borer resistance in PI165673 and determine the effect of PI165673 resistance on borer egg laying, larval survival and plant stem girdling.
2. Improve insecticide efficacy by using host plant developmental stages and other environmental cues or conditions to adjust timing of application.
3. Expand web pages and other educational materials associated with soybean insect pests.

Project Deliverables

Progress of Work

Final Project Results

Field data from the 2014 growing season indicate that PI165673 plants reduce numbers of larvae entering stems, but surviving larva still tunnel into ~40 % of PI165673 stems. Varieties with PI165673 resistance will need to be accompanied by other management methods to prevent stem tunneling and girdling. Research continues to modify methods that exist in the Department of Entomology at K-State to inject or larvae with RNA interference (RNAi) particles that kill larvae before they girdle the stem. When comparing cumulative beetle days (i.e., season-long pressure of adults infesting soybean), there was a weak correlation between adult densities and larval infestations from the previous year. In other words, adults were higher in sweep counts in areas that were heavily infested with larvae. The protein marker data will provide more insight into how much adults are moving from these overwinter areas within a field.

Benefit to Soybean Farmers

Performance Metrics

Project Years