Insects Associated with Industrial Hemp, Cannabis sp. L., in Tennessee and Development of Helicoverpa zea (Boddie) on a Hemp-Based Diet

As production of industrial cannabis, or hemp, increases throughout the United States, knowledge on the insect interactions and insect guild communities associated with hemp will be essential to understanding beneficial and pest insects that affect this crop. Licensed farmers and hectarage in Tennessee are at its highest since the 2014 legalization. For the 2019 season approximately 2,800 farmers received a license, an increase of 1,100%+ from 2018. Placing insects into guild categories, such as predator and herbivore, will allow for distinctions to be made between the various insects identified during the two-year study. An insect study was performed in Tennessee during 2017 utilizing visual surveys, beat-sheet sampling techniques and pitfall traps. A similar study was performed again in 2018, but with the omission of pitfall traps. The goals of this research were to 1) determine guild composition and seasonality of insect species on hemp in Tennessee, 2) assess the influence of hemp variety on insect incidence, and 3) determine development and survival of Helicoverpa zea (corn earworm) on hemp plant material. In 2017, three varieties were planted representing a grain variety, fiber variety, and dual-purpose. For 2018, three varieties bred for cannabinoid production were planted in Crossville, TN, and sampled weekly to assess insects and their pressure. Both crops were assessed to determine the most common insects associated both among and between crops. The most abundant guild found to interact with hemp was herbivores. While insect incidence between varieties did not produce significant results, more research into different varieties may prove to show varietal resistance to certain pests. Lepidopteran larvae were observed as the most damaging pest, corn earworm larvae, a commonly observed insect, were chosen for feeding trials involving hemp. Development of corn earworm on hemp was stunted when compared to the artificial diet, with larvae showing lower weights and higher mortality on solely hemp-based diet.Interactions determined from this study can be used to better interpret how pest insects may affect this crop. Understanding the insect pests that need to be mitigated will lead to more robust management plans increasing the yield and quality of hemp crops