Can foraging for earthworms significantly reduce global famine in a catastrophe?

Earthworms are a resilient group of species that thrive in a variety of habitats through feeding on decaying organic matter, and are therefore predicted to survive an abrupt sunlight reduction scenario, such as a nuclear winter. In this study, the feasibility and cost-effectiveness of foraging earthworms to reduce global famine following a reduction in sunlight with or without global catastrophic loss of infrastructure was considered. Methods for extracting worms were analysed, along with scalability, climate-related barriers to foraging, and pre-consumption processing requirements. Estimations of the global earthworm resource suggest it could provide three years of the protein needs of the current world population, at a median cost of 353 USD·kg−1 dry carbohydrate equivalent or a mean cost of 1200 (90% confidence interval: 32–8500) USD·kg−1 dry carbohydrate equivalent. This is more expensive than other resilient food options and, moreover, earthworms may bioaccumulate heavy metals and other contaminants, presenting a health risk. While costs appear high, there are a number of uncertainties that remain to be addressed. In particular, earthworm biomass distribution may be higher in specific locations. Real-world news reports of earthworm foraging in China and Vietnam detail high yields, suggesting a targeted approach to foraging in the most abundant regions could provide a more feasible application of earthworms as a resilient food source.