First Evidence of Western Bean Cutworm (Lepidoptera: Noctuidae) Overwintering in the Province of Québec (Canada)

The western bean cutworm, Striacosta albicosta (Smith), is considered a major corn pest in North America. In 2009, it started invading the province of Québec (northeastern Canada). To our knowledge, there has been no evidence that this pest could overwinter in this province. In the falls of 2017 and 2018, storage totes containing mature western bean cutworm larvae were placed in the soil in three agricultural regions, in Québec, where western bean cutworm invasions are frequent and crop damage is often significant. The goal was to evaluate if western bean cutworm could resist the province’s winter conditions. The storage totes were removed from the soil at different dates to estimate winter survival. Emergence cages were installed over the totes in the spring of the following year to determine whether western bean cutworm could complete its life cycle. In the spring of 2019, car shelters were also installed at two different sites to evaluate natural moth emergences in fields in which numerous mature western bean cutworm larvae and damage were reported in 2018. Western bean cutworm moth emergences occurred in both cases. These experiments constitute the first documented evidence that western bean cutworm can overwinter and complete its life cycle in Québec’s cold climate. It also represents the northernmost overwintering survival for this species ever documented in North America. The western bean cutworm’s ability to overwinter in Québec will have important implications for corn producers. Pest monitoring and management programs in the province of Québec will need to be adapted accordingly.

Contribution of Larvae Developing on Corn and Dry Beans to the Adult Population of Western Bean Cutworm in Michigan

The western bean cutworm, Striacosta albicosta (Smith) (Lepidoptera: Noctuidae), is historically a pest of both corn (Zea mays L. (Poales: Poaceae)) and dry beans (Phaseolus sp. L. (Fabales: Fabaceae)) in the western Great Plains. However, it has recently undergone an eastward range expansion establishing itself across the Corn Belt in 25 states and 4 Canadian provinces. To mitigate the effects of infestation in Michigan, foliar insecticides are used in dry beans, whereas management of the pest in corn relies more heavily on the use of Bt-expressing hybrids. In this study stable carbon isotope analysis was used to determine what crop adult moths developed on as larvae with analysis showing that very few of the adult moths developed on dry beans. These results suggest that beans and corn are not suitable as co-refuges and that mainly adults which developed on corn are contributing to the next generation of western bean cutworm in Michigan.

Geographic Distribution of Bacillus thuringiensis Cry1F Toxin Resistance in Western Bean Cutworm (Lepidoptera: Noctuidae) Populations in the United States

The western bean cutworm (WBC), Striacosta albicosta (Lepidoptera: Noctuidae), can be a severe pest of transgenic corn in the western Plains and Great Lakes regions of North America, including on hybrids expressing the Bacillus thuringiensis (Bt) Cry1F toxin. The level and geographic distribution of Cry1F resistance are not completely known. Neonate S. albicosta from 10 locations between Nebraska and New York state were subjected to dose–response trypsin-activated native Cry1F toxin overlay bioassays. In 2017, the mean estimated lethal concentration causing 50% larval mortality (LC50) ranged from 15.1 to 18.4 µg Cry1F cm−2, and were not significantly different among locations. In 2018, LC50 estimates at Scottsbluff, NE (22.0 µg Cry1F cm−2) and Watertown, NY (21.7 µg Cry1F cm−2) were significantly higher when compared to locations in Michigan (15.8 µg Cry1F cm−2). Significantly lower 14-day larval weight among survivors was correlated with higher Cry1F dose. Results from this study indicate that S. albicosta survivorship on purified Bt Cry1F toxin shows a relatively even distribution across the native and range expansion areas where seasonal field infestations typically occur.

Contribution of larvae developing on corn and dry beans to the adult population of western bean cutworm in Michigan

The western bean cutworm, Striacosta albicosta (Smith) (Lepidoptera: Noctuidae), is historically a pest of both corn (Zea mays L.) and dry beans (Phaseolus sp L.) in the western Great Plains. However, it has recently undergone an eastward range expansion establishing itself across the Corn Belt in twenty-five states and four Canadian provinces. To mitigate the effects of infestation in Michigan, foliar insecticides are used in dry beans whereas management of the pest in corn relies more heavily on the use of Bt-expressing hybrids. In this study stable carbon isotope analysis was used to determine what crop adult moths developed on as larvae with analysis showing that very few of the adult moths developed on dry beans. These results suggest that beans and corn are not suitable as co-refuges and that mainly adults which developed on corn are contributing to the next generation of western bean cutworm in Michigan.

Ecology and Management of the Western Bean Cutworm (Lepidoptera: Noctuidae) in Corn and Dry Beans—Revision With Focus on the Great Lakes Region

The western bean cutworm, Striacosta albicosta (Smith) is a native North American pest of corn and dry beans. The historical geographic range of the western bean cutworm covered the western Great Plains states including Colorado, Nebraska, and Wyoming. Since 1999, the geographic range of the western bean cutworm has rapidly expanded eastward across the U.S. Corn Belt and eastern Canada, causing significant and economic damage to corn Zea mays (L.) and dry edible beans Phaseolus spp., in parts of this region. Since 2010, increasing challenges related to managing this pest in its new range prompted numerous research studies that provided new insights into the biology and management of western bean cutworm. This revision of a previous Journal of IPM profile summarizes new information regarding the ecology and biology of western bean cutworm, and discusses updated recommendations for scouting and management in corn and dry beans, with an emphasis in the expanded geographic range of the Great Lakes region.