D3120: Effect of soybean seeding rate on fissure size and the laying preference of soybean gall midge (Diptera: Cecidomyiidae)

Soybean gall midge, Resseliella maxima Gagné (Diptera: Cecidomyiidae), is a newly identified pest of soybean that is found across seven states in the Midwest. While soybean is the main host for soybean gall midge, this pest can also be found on sweet clover, dry bean, alfalfa, and lead plant. Infested soybean fields have the most damage along the field edge, especially edges that are close to last year’s soybean fields. Yield losses of up to 100% in the first 30 meters of the field, which lessens further into the field. Infestation of soybean occurs when adults lay eggs in fissures at the base of the stem, and after hatching, the larvae feed within the stem that can interrupt the flow of nutrients and water. A study was conducted to understand the laying preferences of adult soybean gall midge related to stem and fissure size. Soybean was planted at different planting densities in controlled conditions to understand its effect on soybean stem diameter and fissure size. Infested soybean stems from the fields were introduced to the controlled soybean plots in a greenhouse. After ten days, stem diameter, fissure size, and larvae were counted from randomly selected stems in the different population density plots. This study will aid in understanding the soybean gall midge infestation preferences, thus assisting in the development of effective integrated pest management strategies.