Factors Influencing the Efficacy of Biological Control Agents Used to Manage Insect Pests in Indoor Cannabis (Cannabis sativa) Cultivation

Abstract

Current biological control strategies in cannabis (Cannabis sativa) cultivation have resulted in poor efficacy for managing certain insect pests. The cannabis industry has grown at a rapid pace, surpassing our ability to develop knowledge on the production systems for this crop. Currently, the research focus is on optimizing agronomic and environmental factors to maximize the yield and quality of cannabis. However, cannabis growers are increasingly challenged by severe insect pest pressure, with few effective options. Decades of research have optimized biological control strategies in other crops. The implementation of effective biological control strategies in cannabis is hindered by a variety of morphological, biochemical, and agronomic factors unique to this crop. Here, we review the rather limited literature relevant to insect pest management in indoor cannabis production. Further, we have identified three factors that we believe are primarily responsible for the ineffectiveness of biological control in cannabis: Plant morphology including trichome density and floral resources, effects of plant biochemistry on prey suitability, and finally the effects of supplemental lighting including photoperiod, intensity, and spectrum. We highlight the importance of prioritizing the evaluation of these factors to improve our understanding of the tritrophic interactions governing the success of biological control in cannabis cultivation. As intensive research efforts are underway to optimize agronomic practices for cannabis, it is also important to consider their relevance to biological control.

Secondary Terpenes in Cannabis sativa L.: Synthesis and Synergy

“…The plant material used was from commercial breeding lines that could not be affiliated to a specific subspecies because of crossings between different cultivars over many generations. Moreover, several factors have been shown to influence terpene diversity, such as plant genetics, pest presence, overall plant health, soil composition, proper drying, curing, and microbiology [ 34 , 50 , 51 , 52 , 53 , 54 , 55 ].…”

Towards dsRNA‐integrated protection of medical Cannabis crops: considering human safety, recent‐ and developing RNAi methods, and research inroads

“…from Golovinomyces infestation) establishment, and spray applications of potassium bicarbonate or giant knotweed ( Reynoutria sachalinensis (F. Schmidt) Nakai) extract can reduce powdery mildew development 20,34 . Integrated pest management (IPM) strategies may be further supplemented with biological control via carnivorous arthropods 35 . Cranshaw et al 18 .…”

“…20,34 Integrated pest management (IPM) strategies may be further supplemented with biological control via carnivorous arthropods. 35 Cranshaw et al 18 discussed the prevalence of numerous predaceous arthropod taxa in the USA, albeit in outdoor industrial hemp crops; the effects of medical Cannabis's resin-rich trichomes on the activity of natural enemies still requires investigation. Lemay et al 35 discussed potential limitations to successful biological control of Cannabis pests.…”

“…35 Cranshaw et al 18 discussed the prevalence of numerous predaceous arthropod taxa in the USA, albeit in outdoor industrial hemp crops; the effects of medical Cannabis's resin-rich trichomes on the activity of natural enemies still requires investigation. Lemay et al 35 discussed potential limitations to successful biological control of Cannabis pests. For example, the authors discussed how secondary metabolites (primarily phytocannabinoids and terpenes) produced by Cannabis may interact negatively with predators and parasitoids, via biomagnification of these compounds when transported to this higher trophic level.…”

“…In particular, glandular and nonglandular trichome structure/density, and the absence of pollen and nectar in medical Cannabis plants (all of which are female), both may represent impediments to obtaining vital food resources. 35 Morphological differences between Cannabis strains also affect pest pressure; for example, strains that produce loosely packed inflorescences develop less Botrytis infection than tightly packed inflorescences, improved air flow being the assumed reason. 20 Britt et al 17 discussed several biorational options that may be useful in managing H. zea in outdoor Cannabis crops; for example, Bacillus thuringiensis Berliner-and/or nucleopolyhedrovirusbased insecticides.…”