- Author: Kathy Keatley Garvey
Insects, such as darkling beetles and black soldier flies, can and should be bred to convert organic agricultural waste into usable products--like animal feed, pharmaceutical products, and biofuel, say UC Davis agricultural entomologist Christian Nansen, an associate professor in the Department of Entomology and Nematology and doctoral student Trevor M Fowles of the Nansen lab.
Fowles was recently awarded a grant from the California Department of Food and Agriculture (CDFA) to develop lines of insects for bioconversion of agricultural waste.
“In the 21st Century, we will be breeding insects for their ability to effectively convert agricultural organic waste, and researchers at UC Davis are leading the effort,” Nansen says.
Nansen will be among those speaking at a two-day workshop on “Aligning the Food System for Food Safety in Food Waste Systems,” set May 15-16 in the UC Davis Conference Center and the Walter A. Buehler Alumni Center. Nansen will be part of a panel discussion from 1:30 to 3:35 p.m., Thursday in the Alumni Center on “Composing and Anaerobic Digestion for Nutrient Recycling.” He joins fellow panelists Jenny Stephenson, environmental protection specialist with the U.S. Environmental Protection Agency (EPA), Steve Zacari, director of engineering and research and development, California State Soil; and Robert Horowitz, supervisor, Organic Materials and Construction and Demolition Unit, CalRecycle.
Fowles and Nansen compare insect breeding to livestock breeding. “We are used to thinking of livestock breeding as producing dairy cows with higher milk production or chickens producing more and bigger eggs.”
As part of his PhD project, Fowles applies the concepts of livestock breeding to insects “so that specially adapted lines of insects can be developed and commercialized to manage economically important agricultural organic wastes, such as, skins and stems from wine production and from tomato processing. As the human population continues to grow, so, too, do the concerns regarding the sustainability of waste management from our food production systems. In the U.S. alone, we generate 145-602 gigatons of organic waste annually-- or about nine pounds per day per person! Disposal of these wastes in compost and landfilling operations generates greenhouse gases and other environmental pollutants.”
The Nansen lab research, funded by CDFA and the Western Sustainable Agriculture Research and Education, emphasizes economic feasibility, community engagement, and environmental stewardship.
Fowles and Nansen recently co-authored a paper, "Artificial Selection of Insects to Bioconvert Pre-Consumer Organic Wastes. A Review" in the journal, Agronomy for Sustainable Development (https://link.springer.com/article/10.1007/s13593-019-0577-z).
“The potential for using insects to consume organic waste materials and convert them into feed for animal, biofuels, and other valuable secondary products is gaining momentum as both a research discipline and as a business opportunity,” they wrote in their abstract. They described insects as the ideal bioconverters, as “insects uniquely equipped to convert wastes into biomass and other valuable secondary products, and we present the current knowledge and existing research gaps towards the development of such organisms. We conclude that (1) targeted breeding of insects and their gut microbes can produce tailored insect lineages for bioconversion of specific waste streams; (2) research is needed to take full advantage of the existing insect diversity to identify new candidate species for bioconversion; and (3) further research into insect-gut microbial complexes will likely provide important insight into ways insects can be used as sustainable bioconverters of highly specialized waste streams.”
Currently, only a few insect species are used for bioconversion of organic wastes. They include crickets, locusts, black soldier flies, green bottle flies an several species of mealworms.
In addition to funding from CDFA, Fowles has also secured an EPA grant for his research, “Beetle Larvae as Biodegraders of Styrofoam and Organic Waste,” involving darkling beetles, Tenebrio molitor. In the wild, darkling beetles and larvae are general decomposers, eating decaying leaves, sticks, grasses, and carcasses, but the larvae are also known to eat polystyrene or plastic foam, commonly known as Styrofoam. They can decompose as much as three-fourths of a pound of Styrofoam within a three-week period, Fowles says. After biodegrading the Styrofoam, the beetles can be pelletized for animal feed, and the excrement or frass can be used as “high-value amendment to compost mixtures.”
(News media: you're invited to contact the Nansen lab to see the mass rearing processes and breeding. E-mail Christian Nansen at firstname.lastname@example.org or call the lab at (530)-752-2954.)
- Author: Kathy Keatley Garvey
Fowles, a second-year doctoral student in the UC Davis Department of Entomology and Nematology, just received a $15,000 grant from the Environmental Protection Agency for his research on “Beetle Larvae as Biodegraders of Styrofoam and Organic Waste” and now has an opportunity to score a $75,000 grant.
Meanwhile, his 100,000 mealworms in the Briggs Hall lab of his major professor Christian Nansen, are munching away in a project that Fowles hopes will make a difference in breaking down Styrofoam--especially a problem in the nation's landfills--and offer sustainable environmental solutions.
The larvae of the darkling beetle larvae, Tenebrio molitor, eat polystyrene or plastic foam, generically known as Styrofoam, a fact first revealed in 2015 by Stanford University researchers.
“It's about insects processing waste,” Fowles said of his research. “In three weeks they ate three-fourths of a pound of Styrofoam, converting it into biodegradable waste.”
“Trevor's project should be viewed as an example of what entomological agricultural research is all about in the 21st Century--developing new and highly innovative ways to recycle resources and more sustainable food production systems," said agricultural entomologist Christian Nansen, an associate professor of entomology who specializes in applied insect ecology, integrated pest management (IPM) and remote sensing.
In addition, the project has an applied evolutionary angle, which Fowles intends to explore.
Fowles received one of 31 Phase 1 grants in in the National Student Design Competition for Sustainability Focusing on People Prosperity and the Planet (P3), amounting to $463,000 in funding. His project now advances to the Phase 2 level, to take place April 7-8 at the National Sustainable Design Expo at the Science and Engineering Festival in Washington, DC.
In his research project, Fowles seeks to design a pilot-scale styrofoam biodegradation unit to take in regional styrofoam and organic waste, and establish a high-performance beetle lineage, or the “best beetle larvae to do the job.” The adult beetles also eat Styrofoam, but not as much.
“Organization of our food systems will be a defining challenge in the upcoming century and I believe insects will play a significant role in transforming our agricultural sectors,” Fowles said.
His design emphasizes economic feasibility, community engagement, and environmental stewardship. To be sustainable, the project is aimed at connecting local community stakeholders with research expertise to produce an ecofriendly alternative for styrofoam disposal. Fowles is zeroing in on four components to meet these objectives:
- optimizing parameters influencing styrofoam biodegradation
- modeling and designing a pilot system that maximizes degradation and nutritional value of beetle larvae
- project integration in collaboration with local agricultural producers and waste management to meet real world waste demands and
- community engagement to share the novel aspect of this concept and educate local school children about the concepts of sustainability.
After biodegrading the styrofoam, the beetles can be pelletized for animal feed, Fowles said, and the excrement or frass can be used as “high-value amendment to compost mixtures.” He figures that that since Styrofoam by itself is a poor nutrient source for the beetle larvae, he eventually will mix it with organic waste materials, such as, pulp from wine and tomato industries, to optimize beetle development.
The darkling beetles and larvae are pests of stored grains, but the larvae are widely used throughout the world as food for humans; for captive pets, including fish, reptiles and birds; and as fish bait. They are reared commercially on fresh oats, wheat bran or grain, and often with sliced potato, carrots, or apple as a moisture source.
In the wild, darkling beetles and larvae are general decomposers, eating decaying leaves, sticks, grasses, and carcasses.
Fowles said he received his first colony of mealworms in 2016 from then graduate student Tom Nguyen at the Bohart Museum of Entomology, now a researcher at the Smithsonian Institution. Fowles purchased his 100,000 mealworms from the insect farm, Rainbow Mealworms and Crickets in Compton.
Fowles, who grew up in West Sacramento, received his bachelor's degree in biology in 2011 from San Diego State University. Before entering the UC Davis graduate student program, he served as a lab manager for five years for Carroll/Loye Biological Research, launched by the UC Davis entomological team of Scott Carroll and Jenella Loye.
In a news release, EPA Administrator Scott Pruitt said: “This year's P3 teams are applying their classroom learning to create valuable, cutting-edge technologies. This next generation of scientists is designing sustainable solutions that will help protect public health and the environment and ensure America continues to lead the world in innovation and science for decades to come.”