The molecular mechanism of hemp resistance against cannabis aphids (Phorodon cannabis) and its potential for aphid control

Cannabis aphid (Phorodon cannabis) is a newly recognized pest species on hemp in North America. It causes feeding damage by primarily extracting fluids from the plant’s phloem using its piercing-sucking mouthpart, and it may potentially transmit viruses and other pathogens, causing indirect damage. Surveys from our preliminary studies in the greenhouse and field showed that populations of the aphid are higher on fiber hemp cultivars Henola and Bialobrzeskie than on CBD hemp cultivars Citrus and Cherry Dwarf. A major difference between cultivars of fiber and CBD hemp is their CBD content. CBD hemp cultivars contain a significantly higher amount of CBD than fiber hemp cultivars. Thus, we hypothesized that the CBD content of different hemp cultivars mediates the feeding preference that affects gene expression in cannabis aphids. To test this hypothesis, our objectives were to investigate the transcriptional response of cannabis aphids to different hemp cultivars and if CBD hemp triggers higher expression of the genes in cannabis aphids. In this study, adult cannabis aphids were collected from both fiber and CBD hemp cultivars. RNA isolation and RNA-seq analyses were conducted. Specific genes of the cannabis aphid associated with the hemp cultivars were investigated to reveal the potential metabolic and intracellular regulatory molecular mechanisms underlying the different responses of the cannabis aphid to different hemp cultivars. Our research demonstrated that CBD could be a potential botanical insecticide for aphid control.