Beet curly top virus (BCTV) has emerged as a major threat to hemp production in the western United States. Despite this concern, little is known about BCTV biology in hemp. This study investigated the incidence and genetic variability of BCTV strains, as well as the impact of BCTV infection on cannabinoid profiles, potential for seed transmission, and vector survival on hemp. Field surveys across five states revealed four distinct BCTV strains, with BCTV-CO and BCTV-Wor being the most prevalent. In addition, BCTV-PeCT was detected for the first time in hemp samples from Oregon, Colorado, and New Mexico, whereas BCTV-PeYD was detected exclusively in New Mexico. Genetic analysis showed high nucleotide diversity and widespread recombination among hemp-associated BCTV strains, consistent with active genetic exchange in BCTV. Furthermore, BCTV was detected in surface-disinfected seeds (77% in the Elite genotype, 18% in the 791 genotype) and in a small number of seedlings in grow-out experiments (0.98% in Elite, 0.87% in 791). Additional seed dissection experiments in Elite revealed BCTV presence in 41% of embryos, 72% of endosperm, and 5% of seed coats, demonstrating potential for seed transmission in hemp rather than surface contamination. BCTV infection reduced cannabinoid levels in one hemp genotype but not in another, indicating genotype-specific effects of BCTV on cannabinoid production. Finally, beet leafhoppers, the exclusive vector of BCTV, were unable to survive on hemp beyond 7 days, indicating that the insect cannot complete its life cycle on hemp. These findings provide a foundational understanding of BCTV evolutionary dynamics and host interactions in hemp, with implications for disease management. [ ] Copyright © 2026 The Author(s). This is an open access article distributed under the CC BY 4.0 International license .

Background: Cannabis sativa has unique secondary metabolites known as cannabinoids, which include tetrahydrocannabinol (THC) and cannabidiol (CBD) and more than 100 related secondary metabolites. There is increasing evidence that cannabinoids can affect insect fecundity and survival. In this study, we assessed the role of a minor cannabinoid, cannabidivarinic acid (CBDVA) on fecundity and survival of C. sativa-adapted specialist aphid, cannabis aphid (Phorodon cannabis) and non-adapted, generalist aphid, green peach aphid (Myzus persicae). Methods: We evaluated a panel of high and low-CBDVA hemp genotypes obtained from the USDA-ARS Hemp Germplasm Collection at the Plant Genetic Resources Unit for cannabis aphid resistance in greenhouse experiments. Trichome measurements were recorded for genotypes with the highest and lowest aphid counts. To confirm the role of CBDVA, we performed artificial feeding assays by supplementing CBDVA in aphid diets in the laboratory. Results: We found that cannabis populations were significantly higher (Mean ± SE: 221.57 ± 37.27) on a low-CBDVA genotype compared to a high-CBDVA genotype (12.58 ± 3.53) after 14 days of aphid infestation. The high-CBDVA genotype had significantly more trichomes than the low-CBDVA genotype. Supplementation of CBDVA in artificial diets decreased cannabis aphid fecundity from 109.56 ± 10.01 nymphs on diet control and 52.67 ± 7.79 nymphs on DMSO control to 18.71 ± 5.21 nymphs on 1 mM CBDVA + DMSO supplementation after 4 days. CBDVA + DMSO supplementation decreased green peach aphid fecundity from 72.36 ± 6.82 on diet control and 72.50 ± 3.97 on DMSO control to 11.60 ± 2.60 on 0.5 mM CBDVA after 3 days. Conclusions: Our results show that CBDVA has insecticidal activity against cannabis aphids and green peach aphids. CBDVA’s potential as a pure essential oil may be an environmentally sustainable pest management option for organic production systems.