(2nd Place) Olfactory response and ovipositional preference of Helicoverpa zea and Chloridea virescens to hemp varieties

Production of industrial hemp, Cannabis sativa L., has tremendously increased in the United States since its legalization through the Agricultural Improvement Act of 2018 (a.k.a. 2018 Farm Bill). Larvae of the corn earworm, Helicoverpa zea (Boddie), and tobacco budworm, Chloridea virescens (F.), which feed on developing inflorescences, have negatively impacted this emerging industry. Theories about the evolution of insect host plant choice suggest a close link between oviposition preferences and the nutritional requirements of offspring. However, with polyphagous species, such as H. zea and C. virescens, adult preference and progeny performance is not necessarily linear as larval abundance and survivability vary drastically among host crops. In previous years, larval abundance in field plots has varied among hemp varieties including those sharing the same floral maturity window, indicating that varietal preference may occur during oviposition. The aromatic profiles of Cannabis are generally dominated by monoterpene blends which generate distinct fragrances. Terpene concentrations in Cannabis are known to evolve at different rates among chemotypes throughout the flowering phase. However, the influence of these chemicals on H. zea and C. virescens behavior is not clearly understood. To investigate the role of plant volatiles from hemp inflorescences on the ovipositional behavior of these species, a multi-choice oviposition bioassay and a two-choice oviposition bioassay were performed using several hemp varieties. Results will be presented and discussed. This study aimed to understand the host preference of similar species to potentially select varieties that are productive for growers and less attractive to insect pests.