Graduate Studies
First Advisor
Justin McMechan
Date of this Version
Spring 5-2023
Citation
Lima, M. da S. Understanding the Spatiotemporal Abundance of Soybean Gall Midge in Soil of Infested Soybean Fields. M.S. thesis, University of Nebraska-Lincoln.
Abstract
Soybean gall midge (SGM), Resseliella maxima Gagné (Diptera: Cecidomyiidae), was identified as new species in 2019 injuring soybean in four midwestern U.S. states. Larvae feed under the plant epidermis causing dark discolorations and necrosis of the affected areas. Heavy infestations can result in the total yield loss in the first 30 meters near the field edge. Despite the severity of SGM attacks, knowledge gaps limit management tactics. To address knowledge gaps in SGM biology, field studies were conducted to investigate the spatiotemporal abundance of SGM in soil from infested fields. Undisturbed soil cores (12 cm deep) were collected from four infested fields in 2019, 2021, and 2022 to access overwintering SGM abundance in the soil profile. Cores were divided into six two-cm layers for processing individually and subsequent cocoon counting. Moreover, deformed soil samples were collected weekly in the 2021 and 2022 growing seasons, to access SGM temporal dynamics in the soil. A brine flotation technique was used to separate SGM from the soil in both collections. Results showed the greatest abundance of immature (96.2%) was in the top six cm of soil depth. The majority (75.5%) of those were in the top two centimeters. The temporal access demonstrated that SGM population in the soil differed between fields and collection dates throughout each growing season. The findings here are crucial for understanding the spatiotemporal dynamics of SGM in the soil. This knowledge enables future studies on SGM and guides the development of management practices, to mitigate SGM damage to soybean.
Advisor: Anthony Justin McMechan
Comments
A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Entomology, Under the Supervision of Professor Justin McMechan. Lincoln, Nebraska: May 2023
Copyright © 2023 Mikaelison da Silva Lima