This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
Looking for the perfect holiday entrée? Something nutritious yet easy on the Earth? Something with a subtle, yet distinctive, je-ne-sais-quoi flavor? Have you considered the humble mealworm? What about the super superworm?
Before you click away in disgust, remember that the creeping, shelled, 10-legged crustacean we now so lovingly dip in butter (ahem, the lobster) was once considered so repulsive as to be inhumane to feed to prisoners. And in many parts of the world, insects are already a popular—and important—menu item.
A new study, published online December 19 in PLoS ONE, makes the case that the mealworm (Tenebrio molitor) and the superworm (Zophobas morio)—consumed as larval forms before they become beetles—are palatable (ecologically speaking) alternatives to traditional livestock products.
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Rearing cows, pigs and chickens is an intensive ecological endeavor. Currently, more than two thirds of all agricultural land is used for animal production (whether housing the animals themselves or growing feed crops for them). This whole process—from fertilizing grain to raising (farting) cows to shipping milk—produces some 15 percent of all human-generated greenhouse gasses. Many climate-minded researchers have advocated switching to a more plant-based diet as a way to reduce these harmful emissions. But bugs might be an opportunity to keep animal protein on the menu.
Mealworms might be more familiar to pet owners as reptile, fish or bird food. But these insects are already available freeze-dried, canned or live for human consumption and can be baked into breads and cookies, deep fried with potatoes for more nutritious French fries or simply roasted with some salt for a protein-rich snack.
For the new study, researchers examined the process of raising these two insects—the "cradle-to-farm-gate approach," as they noted. Dennis Oonincx, of the Department of Plant Sciences, and Imke de Boer, of the Animal Department of Animal Sciences (both at Wageningen University) studied a Dutch mealworm producer called van de Ven Insectenkwekerij in the town of Deurne. The worms were fed a diet of carrots and mixed grains. The insects also required recycled cardboard egg trays, a climate-controlled rearing station (which requires natural gas and electricity), cages, as well as water.
Nevertheless, they appeared to be a more sustainable source of protein than beef, pork, chicken or milk. To produce one kilogram of protein, including feed growing, the mealworms required just one tenth the amount of land required to produce one kilogram of beef—and much less than chicken, pork and milk, too. Producing one kilogram of mealworms generated about 2.7 kilograms of carbon dioxide equivalent in greenhouse gas (mealworms do not produce earth-warming methane, like gassy ruminants do, although the worms do produce their own tiny manure), which is far less than the standard livestock lineup. The lion's share (42 percent) of the mealworms' greenhouse gas contribution came from producing and transporting grain feed (26 percent of the CO2 came from the heating gas; 17 percent came from the electricity; and 14 percent came from the production and transportation of carrots).
The study authors suspect that with additional research, the bugs could become an even more Earth-friendly option. "Over the last two decades productivity of chickens and pigs has increased annually by 2.3 percent, due to the application of science and new technologies," they wrote in their paper. "Further improvement of the mealworm production system by, for instance, automation, feed optimization or genetic strain selection is expected to increase productivity and decrease environmental impact."
The mealworms are already quite efficient at turning mealworm food into mealworm-based food for humans. They can convert about 2.2 kilograms of food into a kilogram of total bug weight (which is similar to chickens and a much better rate than pigs and cows). They are also proficient reproducers. The female mealworm T. molitor matures in about 10 weeks and will lay some 160 eggs in her short three-month life; and the impressive female superworm Z. morio reaches maturity in three and a half months and can lay some 1,500 eggs in her year of life.
Perhaps most important, the authors concluded, was the mealworm's small land demand. Forest clearing for agricultural use is a major global contributor of greenhouse gas emissions. "Since the population of our planet keeps growing, and the amount of land on this earth is limited, a more efficient, and more sustainable system of food production is needed," Oonincx said in a prepared statement. "Now, for the first time, it has been shown that mealworms, and possibly other edible insects, can aid in achieving such a system."
So perhaps insects will someday graduate from novelty candy and double-dare tequila shots to a meal’s main attraction. Even if they aren't yet replacing many holiday hams.