2nd Place: Seasonal dynamics of soybean gall midge cocoons in soil from infested soybean fields

The soybean gall midge (SGM) Resseliella maxima Gagné (Diptera: Cecidomyiidae) was recently identified as new species causing injury to soybean and reducing yields in the Midwestern United States. Adults lay eggs in naturally occurring fissures at the base of soybean, with larval feeding occurring under the epidermis. After the third instar, the larvae migrate to the soil to form a cocoon and later pupate. As SGM is a new species, little is known about its ecology and biology, and management strategies are limited. As a result, a two-year field study was conducted as a randomized complete block design with three replications along the field edge, to evaluate the temporal abundance of SGM cocoons in the soil throughout the crop season. Eighteen soil samples were collected weekly and processed using the brine flotation technique to separate cocoons from the soil and count the number of cocoons per sample. The results showed that the population of SGM cocoons in the soil fluctuated during the growing season. In 2021, two significantly distinct peaks were identified on Aug 8^th, and Aug 20^th (average of 20 and 24 cocoons/plot respectively). Data will be collected during the 2022 season to further the understanding of the seasonal population of SGM cocoons in infested soybean fields. These results are important to better understand the biology of SGM that will help guide future studies and management practices to mitigate SGM injury to soybean crops.