Research Associate II Colorado State University Fort Collins, Colorado
Plants protect themselves with a vast array of toxic secondary metabolites, and insects, in turn, are always ready to develop counter-adaptations. While our understanding of plant-herbivore interactions has steadily increased over the past several decades, there is a lack of information on the most publicized, “new” plant species, hemp (Cannabis sativa). In the U.S. Hemp is a multifunctional plant grown for a diversity uses, including the production of genus specific secondary metabolites known as cannabinoids. This long absence of production has left huge knowledge gaps including hemp responses to herbivores, specifically cannabis aphid (Phorodon cannabis) and hemp russet mite (Aculops cannibicola). It is known from other plant – herbivore interactions that different feeding strategies lead to different plant responses and signaling pathways. To identify the effect cannabinoids, have on these different herbivores, the herbivore performances were studied on different lines of hemp (high and low CBD). Both cannabis aphid and hemp russet mite performed better on hemp with low CBD compared to high CBD. Tissue collection and cannabinoid analysis of herbivore infested plants revealed differences in cannabinoid levels from the different herbivores. Cannabis aphid infestation generated higher CBD and THC levels while hemp russet mite infestation decreased THC levels. The differences in herbivore performance on high and low CBD hemp and in the cannabinoid levels between the two different type of herbivores indicates cannabinoids are being involved in plant defense strategies and involved in different signaling pathways in hemp.
