D3105: Integrating host plant resistance for Helicoverpa zea management in hemp

Corn earworm (Helicoverpa zea) infestations pose economic concerns to the reintroduction of hemp cultivation in the United States. These pest caterpillars are especially damaging to floral hemp because they feed on flower buds, producing tunneling, lesions, and subsequent bud rot, all of which significantly diminish flower yield and quality levels. The current pest management strategy is mainly based on biological insecticides, but it doesn’t provide full pest control. In this setting, developing the additional pest management tools, such as host plant resistance, can contribute to improving corn earworm management in hemp production. It is classified into three types: antixenosis (which deters pests), antibiosis (which inhibits pest development), and tolerance. The aim of our research is to understand the hemp floral morphology, trichome structure, and chemical content (cannabinoids and terpenes) impacts on corn earworm behavior, fitness and management. As a part of the research, we evaluated eight hemp germplasms (WICW-041, RNRN-0381, SESE-001, NCBD-010, CTCT-0381, SGCW-006, CNCBD-031, ABA-019, and CBGB) for terpene type and content. We observed higher variations in the terpene type and content among the tested germplasms. Specifically, WICW-041 exhibited the highest levels of beta myrcene and limonene, while RNRN-0381 had the lowest concentrations of beta myrcene and beta-caryophyllene. SESE-001 stood out with the highest alpha pinene and alpha humulene levels and was the only germplasm containing valence. Additionally, we also characterized floral morphology and trichome structure of tested germplasms. These preliminary results will be discussed in the presentation.