The distribution of soybean gall midge (Resseliella maxima) larval cocoons in soil from infested soybean fields

Soybean gall midge (Resseliella maxima Gágne) was a recently identified in 2018 as a new pest in soybean (Glycine max (L.) Merril). As a newly identified species, there are significant gaps in understanding its biology and ecology. To better understand the distribution of the larval cocoons in the soil, samples were collected from four gall midge infested soybean fields in east-central Nebraska (USA) from fall 2019 and spring 2020. A total of 24 soil cores were samples from each field. Each core measured 5 cm in diameter and 12 cm deep. These samples were further divided every 2 cm in depth to determine the distribution of cocoons in the soil profile. Cocoons were separated from soil using a brine extraction method. Results indicated that the majority of cocoons were in the top four cm of soil (91 %). The number of cocoons in soil samples were not a good predictor of adult emergence, however, further analysis is needed. These results provide a foundation for future studies of soybean gall midge and the potential to explore other pest management practices to mitigate soybean gall midge damage to soybean.
Keywords: soybean gall midge, Cecidomyiidae, Diptera, soybean