Rearing crickets for insect meal may be an effective means of upcycling grains contaminated with mycotoxins, according to a new study from the U.S. Department of Agriculture (USDA).
In the study, researchers from the USDA intentionally added fumonisin to a mix of grains fed to house crickets in order to evaluate whether the crickets would retain any of the mycotoxin in their tissues, according to Ryan Paulk, a biological science technician for the USDA's Biological Control of Pests Research Unit. But the contaminated diets posed apparently little risk to the crickets — which all thrived and grew at roughly the same rate regardless of how much fumonisin they ate. The crickets did not metabolize or store the fumonisin, but rather appeared to excrete the toxin in their frass, Paulk said.
Insect meal derived from the crickets was suitable for potential inclusion in livestock diets, Paulk said, with trace amounts of fumonisin appearing in the meal only when crickets were fed the highest levels of fumonisin included in the study.
Although the frass contained fumonisin at roughly the same level that was included in the crickets' diet, this should not present barriers to its use as a fertilizer, Paulk said.
“I am hopeful and optimistic that … we are going to be able to recycle a lot of what would otherwise be waste through insects,” Paulk said, adding that although insect meal is not cost competitive against other feed ingredients, it could outperform more common proteins such as fish meal in some circumstances. The study did not evaluate how crickets might stack up economically next to other means of controlling mycotoxins in grain.
Paulk said that he initially began raising questions about the impact of mycotoxins on insects while investigating potential means of controlling common crop pests. He learned there was little reason to believe mycotoxins would impact insects — and later connected with other USDA researchers who are working on issues such as the control of mycotoxins and the production of insects for animal consumption.
“If we could turn bad grain, whether out of the field or due to storage problems, and feed it to an insect and then feed the insects to livestock, that seemed like a good way to go,” Paulk said.
However, the question of whether insects would remain safe to eat after consuming contaminated diets remains an open question. Paulk said he chose to study fumonisin in crickets specifically because there was no data on that particular combination.
But other mycotoxins, Paulk said, could still pose a challenge to insect meal production, as could other contaminants of concern like heavy metals. Additional research is needed to shed light on the extent of the risks associated with raising insects on various kinds of waste, he said.
