Byproduct of biofuel production shows potential for insect pest control

The red flour beetle (Tribolium castaneum), shown here on bleached flour, is a major stored product pest. In new research, very few red flour beetles developed normally into adults after exposure to insecticidal pyrolysis oil derived from biofuel production. (Photo by Rob Morrison, Ph.D.)

By Rob Morrison, Ph.D.

Rob Morrison, Ph.D.

Rob Morrison, Ph.D.

The last 30 years have seen significant progress in the production of biofuels – liquid fuels such as ethanol and biodiesel that can be derived from renewable, non-food and bio-based feedstocks such as lignocellulosic biomass or algae. Part of that progress is finding uses for the byproducts of the biofuel production process, and new research shows some of these byproducts hold promise as insecticides targeting stored product pests.

As part of a multimillion-dollar project funded by the U.S. Department of Energy’s Office of Bioenergy Technologies, my fellow researchers and I from the USDA’s Cereals and Animal Health Research Center- ARS (CGAHR), National Renewable Energy Laboratory (NREL), and Michigan State University to determine if byproducts of cellulosic biofuel production could be used to manage an array of important product insects agricultural and stored. These by-products – or “co-products”, as they are considered equally valuable – are ill-suited to fuel streams, but could increase the profitability and sustainability of biofuel production by being applied to other purposes rather than being wasted. .

One of the main processes for producing biofuels is pyrolysis, in which biomass is deconstructed by high heat in the absence of oxygen. Our research team examined co-products heated to specific temperature ranges, also called “fractions”, from this pyrolysis process and found that they successfully mimic insect growth regulators when applied to a range of stored product insects, including the red flour beetle (Tribolium castaneum) and the confused tribolium (Tribolium confusum). Our findings are published this month in the Journal of Economic Entomology.

Even at low concentrations, oils have been found to cause deformities in normal development, such as incomplete metamorphosis or partial hardening of the pupa. Ultimately, many exposed larvae never became adults. At higher concentrations, there was 100% suppression of the population of red flour beetle larvae and confused flour beetle larvae. In contrast, adults were relatively unaffected.

Additionally, the price of the intermediate pyrolysis oil was very reasonable at less than $1 per kilogram (kg) to be produced, while the final pyrolysis oil cost between $1.41 and $1.70 per kg. This is only 0.9% of the cost of commercially available insect growth regulators for stored product insects.

Finally, a life cycle assessment of greenhouse gas (GHG) emissions was also carried out, and the team found that the use of pyrolysis oil could reduce GHG emissions associated with the chain. production supply of insecticides by 25 to 61% compared to those of a fossil fuel. insecticide or pyrethroid.

Thus, pyrolysis oil is incredibly inexpensive to produce, highly effective against insect larvae, and longer lasting than conventional alternatives. We are encouraged that the adoption of these bio-oils as pest control tools in agriculture will help improve the sustainability of using biofuels to provide at least some of society’s energy, while contributing to global food security.

Rob Morrison, Ph.D., is a research entomologist with the USDA Agricultural Research Service, Cereals and Animal Health Research Center, Insect and Stored Product Engineering Research Unit, Manhattan, Kansas. Web: Twitter: @morrisonlabUSDA. Email: [email protected]