Byproducts from the biofuel production process have the potential to be a novel kind of insecticide, according to research funded by the US Government.
It is perhaps unsurprising that fumigants are no longer a desirable solution for the control of stored product pests. With increasing regulatory restrictions alongside consumer pushback and ever increasing insecticide resistance, it is clear that there is a vital need to expand the range of chemical solutions within an integrated pest management program for stored products. Latest research from the US points towards an innovative source of potential new insecticides: biofuels.
Over the past 30 years, new fuels such as ethanol and biodiesel have been produced from renewable, nonfood sources. During the process, a number of byproducts are created. Now, scientists have discovered that these byproducts show promise as potential insecticides.
In a multi-million dollar project funded by the US Government, a team of researchers from the USDA-ARS Center for Grain and Animal Health Research, National Renewable Energy Laboratory, and Michigan State University set out to determine whether byproducts from a particular kind of biofuel production could be used for pest control purposes.1 In particular, they looked at the effect of these byproducts on important agricultural and stored product pests, with the findings being published in the Journal of Economic Entomology in April 2022.
In the study, the researchers took the byproducts created from biofuel production and heated them to specific temperature ranges based on boiling points ranging from 115-230°C in one experiment and 245- 250°C in another. This resulted in different unique fractions (groups of compounds) that were then assessed for their insecticidal efficacy.
Three types of evaluation were carried out to assess their performance as an adulticide, as an insect growth regulator and as a repellent. Three key stored product pests were included in the study: the red flour beetle (Tribolium castaneum), the confused flour beetle (Tribolium confusum) and the sawtoothed grain beetle (Oryzaephilus surinamensis).
Whilst the compounds appeared to have little effect on the adults, these so-called ‘bio-oils’ had a profound effect on the insect larvae, acting as insect growth regulators.
Rob Morrison, research entomologist at the USDAAgricultural Research Service, explained, “Even at low concentrations, the oils were found to cause deformities in normal development such as incomplete metamorphosis or only partial hardening of the pupal case. In the end, many of the exposed larvae never matured to adults. At higher concentrations, there was 100% population suppression of both red flour beetle and confused flour beetle larvae. By contrast, adults were relatively unaffected.”
The researchers also concluded that there was minimal repellency to most substances by most species. This means that the researchers have uncovered a potential new source of non-repellent insecticides, which are inexpensive to produce, highly effective against insect larvae, and more sustainable than conventional alternatives. In fact, the cost of producing one kilogram of the bio-oil was less than US$1.70, which is around 1% of the cost of the commercially available insect growth regulators for stored product insects.
On an environmental note, the researchers noted that if these bio-oils were produced on a large scale, the level of greenhouse gas emissions would be reduced by 25-61% compared with insecticides or pyrethroids produced using fossil fuels. It would be a more climate-friendly alternative that could sit well within IPM programs.
“We are encouraged that adoption of such bio-oils as pest management tools in agriculture will help enhance the sustainability of using biofuels to source at least some of society’s energy, while contributing to global food security,” Mr Morrison said.
He and the US research team believe that the potential benefits of bio-oils are far greater than for the pest control industry alone.
1 Bruce, Alexander & Wilson, A & Ranabhat, Sabita & Montgomery, Jaden & Nicholson, Scott & Harris, Kylee & Morrison, William. (2022). A Biomass Pyrolysis Oil as a Novel Insect Growth Regulator Mimic for a Variety of Stored Product Beetles. Journal of economic entomology. 10.1093/jee/toac017.
Reworked extract from ‘Biofuel Production Shows Potential for Insect Pest Management by Rob Morrison. Entomology Today, April 18, 2022.