A Survey of the Arthropod Fauna Associated with Hemp (Cannabis sativa L.) Grown in Eastern Colorado

Abstract

A SURVEY OF THE ARTHROPOD FAUNA ASSOCIATED WITH HEMP (CANNABIS SATIVA L.) GROWN IN EASTERN COLORADO Industrial hemp was found to support a diverse complex of arthropods in the surveys of hemp fields in eastern Colorado. Seventy-three families of arthropods were collected from hemp grown in eight counties in Colorado in 2016Colorado in , 2017Colorado in , and 2018. Other important groups found in collections were of the order Diptera, Coleoptera, and Hemiptera. The arthropods present in fields had a range of association with the crop and included herbivores, natural enemies, pollen feeders, and incidental species. Hemp cultivars grown for seed and fiber had higher insect species richness compared to hemp grown for cannabidiol (CBD). This observational field survey of hemp serves as the first checklist of arthropods associated with the crop in eastern Colorado. Emerging key pests of the crop that are described include: corn earworm (Helicoverpa zea (Boddie)), hemp russet mite (Aculops cannibicola (Farkas)), cannabis aphid (Phorodon cannabis (Passerini)), and Eurasian hemp borer (Grapholita delineana (Walker)). Local outbreaks of several species of grasshoppers were observed and produced significant crop injury, particularly twostriped grasshopper (Melanoplus bivittatus (Say)). Approximately half (46%) of the arthropods collected in sweep net samples during the three year sampling period were categorized as predators, natural enemies of arthropods. These findings are of significance considering the expanding cultivation of hemp both within the region of study and across the United States. A website developed to extend the information developed in this project has been accessed over 20,000 times in 28 months, indicating there is wide interest in this subject area.iii ACKNOWLEDGEMENTS I wish to thank my family and friends, for without them I would not have had the support, which I needed to complete this degree. I would like to acknowledge the substantial funding provided by the Western Region IPM Center and the CSU Experiment Station. Thank you to the participating farmers, production farms, and research stations that permitted us to sample arthropods from their facilities across Colorado. Thank you to the Fat Pig Society, Colorado Cultivars, and the Colorado Department of Agriculture for providing resources to conduct local hemp trials, insect collection, and analysis. Thank you to all the lab members:

Bycatch of Common Pollinators in Pheromone Baited Traps for Monitoring Corn Earworm (Lepidoptera: Noctuidae) in Missouri Industrial Hemp

“…Among these pests, H. zea [8], has demonstrated the greatest potential for crop injury in Missouri hemp. This report confirms previous observations by other researchers across several states [9,[11][12][13]. The larvae of H. zea cause significant damage to a diverse array of host plants, including some of the most cultivated crops like corn, tomato, pepper, soybean, etc [14].…”

First Year Survey of Arthropods in California Hemp

“…Lepidopteran larvae and mites are known to be associated with hemp (Lago and Stanford, 1989;McPartland et al, 2000;McPartland and Hillig, 2003;Cranshaw et al, 2019;Schreiner and Cranshaw, 2020;Britt et al, 2021) but this survey recovered very few of both these groups. D-vac sampling is unlikely to recover arthropods which strongly adhere to substrate or are embedded in plant tissue which could include larvae of lepidopterans and others, such as coleopterans (lady beetles) and neuropterans (lacewings).…”

“…The most comprehensive texts thus far are from Cranshaw et al (2019), which focused on hemp production in Colorado, Virginia, and Tennessee, and McPartland et al (2000), which collected reports from various locations throughout the world. To date, the only state-specific studies to catalogue arthropods in Cannabis sativa have been from hemp in Colorado (Schreiner and Cranshaw, 2020) and cannabis (Cannabis sativa L., >0.3% THC) in Mississippi (Lago and Stanford, 1989). There are also several state level Extension guides (Britt et al, 2020;Hansen et al, 2020;Kesheimer et al, 2021), but these texts focus exclusively on pest species (arthropods, pathogens, and weeds) in hemp and guidelines for their management.…”

Biology and management of hemp russet mite (Acari: Eriophyidae)

“…In fact, all treatments slightly improved average root scores relative to the untreated group. This result is notable given the importance of phytotoxicity as a consideration when treating hemp cuttings (Schreiner and Cranshaw 2021).…”