Corn earworm oviposition preference, larval density and damage on hemp plants

Corn earworm, Helicoverpa zea (Boddie) is a well-known polyphagous and most costly crop pest globally. Due to its polyphagous nature, migrated from other crops and become a key pest to newly reintroduced hemp, Cannabis sativa L. In this study we evaluated the oviposition preference of corn earworm (CEW) between hemp and non-Bt field corn plants in a two-choice experiment under laboratory condition. Moreover, under field condition we assessed the larval density of CEW and plants damage on different hemp cultivars planted in parallel rows. The result from the two-choice oviposition assay showed significantly higher number of CEW eggs laid on the two hemp varieties (Trump and Mountain mango) than corn plant. Additionally, data recorded from the two research fields showed significantly higher larval density on Trump and Cherry wine than Mountain mango varieties. Moreover, lower damage score recorded on Mountain mango variety than the two hemp varieties. Our laboratory and field study provided insight that CEW preferred certain hemp variety for oviposition, therefore, further screening needs to be done on CEW preference among different hemp varieties, furthermore, attractive traits need to be identified and incorporated in to trap crops for the management of CEW.