Spring 2021

Field Notes

The two-spotted cricket is the focus of a UW research project on the viability of insect farming as a sustainable source of protein. Paul venter, CC BY-SA 3.0 via Wikimedia Commons


In the Midwest, we’re used to seeing big fields dotted with cattle and steel barns bustling with broiler chickens. Beef, poultry, and pork are common in our daily meals, whether mixed in pasta or placed on a bun.

But in many countries, where food shortages are common, such protein abundance is a luxury. To help alleviate this global food security problem, a group of UW–Madison researchers, led by entomology professor Susan Paskewitz, is turning to an overlooked solution: insect farming.

“[Insects] are an understudied and underutilized food resource,” says Valerie Stull, a postdoc with the UW Global Health Institute (GHI) and co-investigator for the project. “But that doesn’t mean that people aren’t already eating them.”

Cricket-rearing containers inside a farm in Monze, Zambia. Photo by Colleen Henegan

For many cultures, insects are a traditional and revered food source. To date, however, the vast majority are harvested from the wild, which means their availability varies with the seasons. Proper storage of foraged insects can also be tricky, and food safety concerns can arise. Plus, gathering insects in bulk is labor intensive.

Insect farming may be a way around these issues. An added bonus: Insects need less water, feed, and land than conventional livestock, and they emit fewer greenhouse gases, so they can be a more sustainable and environmentally friendly alternative. This is one of the many reasons insect farms keep popping up in the U.S., Europe, and elsewhere.

But is insect agriculture actually viable? Is there enough potential demand? Are the financials and logistics feasible for farmers in low-resource areas? Can it be beneficial for both human and environmental health? These are some of the main questions driving the UW research team.

In their search for answers, they’ve partnered with some like-minded organizations, including GHI, the Mission to Improve Global Health Through Insects (MIGHTi), and an Italian non-profit called NutriPeople. Together, these groups are assessing small-scale cricket farming in the Southern African nation of Zambia.

“Our project is really evaluating the impact of these small farms on the health and wellbeing of people in terms of their perceptions of farmed insects, their livelihoods, their food security, and then — really critically — their access to dietary iron,” Stull says.

Low-iron diets can cause anemia, a lack of healthy red blood cells. Many Zambians are especially vulnerable to this condition because of their corn-based diet, which can be deficient in numerous nutrients. Stull and the team are collaborating with researchers from Colorado State University to assess the bioavailability of iron in crickets relative to iron in other plant and animal food sources. In other words, they’re trying to determine through lab tests how much iron crickets can absorb from their feed and then pass on to the people who in turn eat them.

The researchers have also been surveying two new cricket farms in Zambia over the past year. Their focus: farm productivity, farmer perceptions, and cricket quality in terms of nutrition. Stull and other members of the team were not able to travel this past summer because of the COVID-19 pandemic. But another collaborator, environmental studies graduate student Colleen Henegan, was in Zambia in January 2020 — before widespread travel bans — to collect data from the farmers and keep the project moving.

This DIY pasteurizer allowed graduate student Martin Ventura to continue work in his backyard when lab access was limited during the COVID-19 pandemic. Photo by Martin Ventura

“Eventually, [our] goal is to actually support the cricket farmers so they can consume crickets on a regular basis, and we can measure health outcomes directly,” says Stull.

The farmers have been successful in raising crickets, but not at quantities high enough to make a widespread impact on the health of Zambians. This is one of the reasons why another part of the team, back in Madison, is studying ways to improve cricket farming and boost production without ramping up cost.

Martin Ventura is an entomology graduate student and a member of Paskewitz’s lab. He’s known as the “cricket wrangler” — he cares for the crickets housed in UW’s Russell Laboratories, along with the help of junior entomology major Michael B. Smith.

The cricket in question is Gryllus bimaculatus, more commonly known as the two-spotted cricket, which is native to Zambia.

Ventura is developing “low-cost, low-tech” cricket feed options — essential for minimizing farmers’ start-up and maintenance costs — that are also healthier for the insects. In Zambia, farmers mainly raise crickets on corn and other grain. But there’s a more nutritious option, Ventura says, with potential environmental benefits.

In the wild, two-spotted crickets will eat fungi when more preferred food sources are unavailable. Mushrooms can also break down compounds in corn, such as lignin, that humans and crickets can’t. Lignin is a complex, organic molecule that gives plants their sturdy nature, and a lot of it is found in corn stover, the material left in a cornfield after harvest.

In Zambia, stover is traditionally fed to livestock, removed from fields, or burned. While burning frees up space, the process releases harmful particulates and greenhouse gases into the air. But what if stover could instead be used to grow mushrooms that serve as cricket feed?

Oyster mushrooms grow on a corn stover substrate inside of a large incubator. Photo by Martin Ventura

Ventura’s looking for a way. He keeps a large barrel in his backyard for pasteurizing stover. It “cooks” the stover at 80 °C (176 °F) for about two hours to kill competing organisms and make it easier for mushrooms to digest. Next, the stover is dried and mixed with mushroom spawn in small plastic bags.

About a week later, the first vegetative growth, or mycelium, emerges.

“The mushrooms that we’re using — oyster mushrooms — will go into that maize stover and secrete enzymes to bust apart lignin, which increases available polysaccharides and actually allows the fungus to concentrate amino acids,” Ventura says. “We’re hoping we can turn straw into gold.”

Ventura’s DIY pasteurizer, constructed with help from Russell Labs Hub instrument maker Tim Lorenz, was one way to continue the project while the pandemic limited lab access. This continuity is vital because Ventura and the team need to collect and analyze quite a bit of data before they can determine if the mushroom method is viable for farmers in Zambia. And the crickets did get their first taste of fungus in December, a major step in the process.

“We’re growing mushrooms to feed insects to feed people, all with the idea of improving human health and environmental sustainability,” Stull says. “And we’re really excited about it.”

This article was posted in Changing Climate, Economic and Community Development, Field Notes, Food Systems, Health and Wellness, Spring 2021 and tagged , , , , , , , , , , .