2016
Development of Genetic, Chemical and Population-Based Tactics to Manage Soybean Stem Borer in Kansas
Contributor/Checkoff:
Category:
Sustainable Production
Keywords:
Crop protectionDiseaseField management
Parent Project:
This is the first year of this project.
Lead Principal Investigator:
C Michael Smith, Kansas State University
Co-Principal Investigators:
Project Code:
1526
Contributing Organization (Checkoff):
Institution Funded:
Brief Project Summary:

Infestations of the soybean stem borer were first reported in 1985 and severity ratings have increased in approximately 30% of Kansas counties. Expansion may be due to reduced availability of alternate host plants, increased larvae winter survival, increased soybean acreage, or increased adoption of non-tillage practices. Project objectives are to create soybeans resistant by inserting borer RNA into soybeans to interfere with borer survival; improve insecticide efficacy by using host plant and other environment cues to adjust application timing and placement; and to expand outreach materials.

Key Benefactors:
farmers, entomologists, extension specialists, breeders

Information And Results
Project Deliverables

The proposed studies will to lead to improved crop protection and management practices that suppress losses caused by soybean stem borer. Commercial insecticides reduce adult stem borer numbers, but several applications are required for effective results, making this option cost-prohibitive. Thus, our efforts for the past several years have focused on identifying plants with heritable resistance to borer stem damage; on monitoring borer movement and distributions in soybean fields to refine an optimum time for insecticide application; and on determining the impact of alternate borer hosts and environmental factors to better predict the appearance of early season adult borer populations.

Final Project Results

Update:
Objective 1: Map the genes contributing to soybean stem borer resistance in PI165673 and determine factors mediating resistance. Lina Aguirre, PhD student, has successfully developed a soybean stem borer colony to supply eggs and larvae for future experiments. Larvae collected in the field from stems of soybean plants in Ashland Bottoms, KS in August, 2015 fed on artificial diet originally developed for larvae of the pink bollworm, Pectinophora gossypiella, and became adults in early 2016. These beetles mated, produced viable eggs that hatched and these larvae now developing on artificial diet. Experiments have developed degenerate PCR primers that successfully amplify the soybean stem borer laccase2 (Lac2) gene required for skin development. Larvae from the colony will be injected with or fed particles of silenced Lac2 to determine the best silencing technique. Future experiments will involve silencing larval gut membrane proteins with RNAi particles to suppress larval development or kill larvae.

Objective 2. Improve insecticide efficacy by using host plant developmental stages and other environmental cues or conditions to adjust timing of application. Alice Harris, the current PhD on this project is working to complete her dissertation by May 2016. Alice finished analyzing her small plot study aimed at quantifying differences infestation rates on soybean plants by measuring changes in near infrared (NIR) imaging using vegetation indices this past month. This included collection of soybean biometric data (e.g., number of pods, seeds per pod, stem diameter, etc.), which she used to compare infested and non-infested plants to better understand yield loss. She found that that larval feeding and subsequent tunneling of the main stem did not alter soybean leaf reflectance. However, soybean significantly responded to D. texanus infestations by producing more nodes and stems with a larger diameter. The results of this study indicate that regardless of infestation level, D. texanus did not alter the leaf reflectance and consequently the GNDVI and VPMs. This study suggests that there is a plant response to D. texanus infestation, with infested plants generally being larger than (stem diameter and number of nodes) than non-infested plants. With further investigation, this information may be able to serve as indicators to at risk areas in the field and possible variety selection in regions known to have heavy D. texanus infestation. We also collected NIR images of a test field using unmanned aerial systems (UASs); orthomosaic images of the field were constructed and are currently being compared to yield monitor data provided by the soybean producer. Alice is diligently writing up her dissertation work with the intention of publishing her results in peer-reviewed journals after her defense in May. For example, Alice’s field study describes for the first time the within-field spatial distribution on adult and larvae D. texanus in Kansas soybean fields. Results from aggregation analyses provide insights into the spatial and temporal distributions of adults and larvae in large, production soybean fields. In addition, spatial distribution patterns show changes in adult activity during the growing season as well as spatial associations between adults and larvae. The results of this study indicate that adults are aggregated along field edges during the growing season. The aggregation occurs during July when adult activity is at its highest, mid-late July. This study suggests that site-specific insecticide applications may be potential methods to control adult and larvae D. texanus populations in soybean.

Objective 3. Expand web pages and other educational materials associated with soybean insect pests. Recent updates by co-PD Whitworth include the 2015 Insecticide Efficacy Trials http://entomology.k-state.edu/extension/efficacy-trials/soybeans.html; the KSU Soybean Insect Management Guide http://www.ksre.ksu.edu/bookstore/pubs/Mf743.pdf; and the 2016 Soybean Production Handbook http://www.ksre.ksu.edu/bookstore/pubs/MF3154.pdf.

View uploaded report Word file

The United Soybean Research Retention policy will display final reports with the project once completed but working files will be purged after three years. And financial information after seven years. All pertinent information is in the final report or if you want more information, please contact the project lead at your state soybean organization or principal investigator listed on the project.