Escaping the hot seat: consuming decomposing Cannabis sativa slows weight gain and heat escape behaviour in the earthworm, Eisenia fetida

Given the rise in cannabis ( Cannabis sativa L .) cultivation, and the absence of disposal guidelines in Canada and other countries, the toxicological impacts of its secondary metabolites on non-target organisms via ingestion are important to understand. Due to the unique chemicals found in C. sativa, sublethal effects, such as those on behaviours and growth, must also be considered. We fed a generalist detritivore, the red wiggler earthworm ( Eisenia fetida (Savigny, 1826)), diets composed of hemp or two other crop plants (lettuce or basil), or combinations thereof, over 28 days to measure effects on earthworm survival, growth, and behavioural responses to stressful stimuli (high heat and light). Earthworms fed only hemp gained weight, albeit less than those on other diets, with no effects on their survival or response to light. However, hemp consumption led to slower escape times and speeds from a heat stimulus, indicating potential sublethal effects. By using hemp genotypes with low cannabinoid concentrations, our results offer a conservative estimate of the potential impact of hemp cultivation or disposal of C. sativa on invertebrates such as earthworms. This research underscores the importance of developing accurate risk models for exposure to crop phytochemicals in non-target species.