6: Biological control in odour space: The next frontier

The legalization of recreational cannabis in Canada in 2018 has led to a significant increase in indoor cannabis production. With this high value crop comes high expectations from consumers. Not only must the final product be free of pests, it must also be free of pesticide residues. Growers rely on biological control to manage common greenhouse pests such as aphids, thrips and mites. Cannabis aphid (Phorodon cannabis) is a relatively new pest but is already one of the most common pests in indoor cannabis production facilities. Compared to other aphids and in other crops, parasitoids have been ineffective at controlling cannabis aphid in cannabis. Parasitoids use both host- and plant-derived stimuli to locate hosts. Plant-derived stimuli, also called herbivore induced plant volatiles (HIPV) are specific blends of terpenes used by parasitoids for host location. However, cannabis produces a staggering array of secondary metabolites, including a wide range of volatile terpenes. We are investigating whether constitutive emissions of volatile terpenes by cannabis are interfering with the parasitoids ability to recognize HIPVs used to locate hosts. By comparing the terpene profile of the HIPV to the ambient terpene profile, we hope to identify terpene profiles that could affect the host finding ability of parasitoids, greatly reducing their effectiveness in certain cultivars.