D3048: Does variety of hemp, Cannabis sativa, affect development of corn earworm, Helicoverpa zea, larvae?

In 2018, the Agriculture Improvement Act, aka Farm Bill, permitted industrial hemp, Cannabis sativa, production in the U.S. Interests in therapeutic benefits of cannabinoids, specifically cannabidiol, skyrocketed and, in 2020, nearly 190k hectares (470k acres) were licensed for hemp production across the country. By grower numbers, in 2020, Tennessee was the nation’s largest hemp program with over 1,800 producers licensed to grow up to 6,500 hectares (16,000 acres) according to the Tennessee Department of Agriculture. Though fiber and seed have a role in the industry, most growers (ca. 98%) concentrated on cannabidiol production because of expected higher cash value potential per hectare. Every new crop has a new insect that follows, and for hemp the corn earworm, Helicoverpa zea Boddie, is generally considered to be the most destructive insect pest of hemp grown outdoors. Young larvae feed on developing inflorescences, where cannabidiol concentrations are highest, with some growers reporting entire crops lost due to larval damage. Adult moths, searching for suitable oviposition sites once primary hosts such as corn and soybean are no longer available, find hemp to be a satisfactory secondary host. Previous data suggest variety and plant maturity are highly correlated to larval damage. Larvae may develop differently depending on secondary metabolites produced by different varieties of hemp. This poster will summarize developmental differences of corn earworm when reared using artificial diet incorporated with dried floral material from several hemp varieties. Determining resistant varieties may provide an important step in an IPM plan to manage this destructive pest.