Date of this Version
NebGuide G2331 Index: Crops, Insects and Pests
Soybean gall midge (Resseliella maxima Gagné) was described in 2019 as a new insect species in Nebraska, due to observations of widespread early season injury in eastern Nebraska, eastern South Dakota, western Iowa, and southwest Minnesota soybean fields (Gagné et al., 2019). Since its discovery, soybean gall midge has been causing significant injury and yield losses in soybean in eastern Nebraska. Although only recently identified, soybean gall midge is not likely new to the north- central region of the U.S. In 2011, orange larvae were documented in some isolated fields in northeast Nebraska that had received hail damage during the early half of the growing season. Similar reports were made in 2016 and 2017 in eastcentral Nebraska. Prior to 2018, reports of orange larvae in soybean were confined to the late reproductive stages of a few dead or dying plants.
In 2018, several observations were made that raised concerns that soybean gall midge should be designated as a pest of soybean (McMechan et al. 2021). Unlike previous years where damaged plants were found later in the growing season, injured plants were observed in late June and early July. Soybean plants with larval presence exhibit signs of wilting and death, with the greatest frequency of symptomatic plants occurring along field borders adjacent to fields that had been planted to soybean the previous year. In many cases, the presence of dense vegetation (trees, uncut bromegrass, and/or shrubs) along field borders was associated with an increased frequency and intensity of plant injury.
As a new species, several knowledge gaps must be bridged in order to development an integrated pest management strategy for soybean gall midge (McMechan et al. 2021) Year- to- year variability in the duration of emergence and injury from soybean gall midge has made it difficult to identify an effective control strategies. In 2018, soybean plants were hand- harvested from a heavily infested field in Saunders County, Nebraska, where a yield loss of 92%, was estimated for a section of the field in the first 100 feet from the field edge (compared to historical yields). Yield losses of 31% and 20% at 200 and 400 feet into the field, respectively, were also recorded (McMechan et al. 2021). Additional yield loss may also occur from early pod shatter from infested plants that mature ahead of the rest of the crop as well as lodging from weakened stems.
As of 2020, soybean gall midge had been found in 114 counties in five states, with 39 counties infested in eastern Nebraska (Fig. 1). The distribution of soybean gall midge has increased each year since its discovery, although the extent of field injury is typically far less in newly identified counties.