A biomass pyrolysis oil as a novel insect growth regulator mimic for a variety of stored product beetles

Authors: BRUCE, ALEXANDER - University Of Tennessee; WILSON, A. NOLAN - US Department Of Energy; RANABHAT, SABITA - Kansas State University; Montgomery, Jaden; NICHOLSON, SCOTT - US Department Of Energy; HARRIS, KYLEE - US Department Of Energy; Morrison, William - Rob

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/28/2022
Publication Date: 4/8/2022
Citation: Bruce, A.I., Wilson, A., Ranabhat, S.R., Montgomery, J., Nicholson, S., Harris, K., Morrison Iii, W.R. 2022. A biomass pyrolysis oil as a novel insect growth regulator mimic for a variety of stored product beetles. Journal of Economic Entomology. 115(3):877-887. https://doi.org/10.1093/jee/toac017.
DOI: https://doi.org/10.1093/jee/toac017

Interpretive Summary: Fumigants or gaseous pesticides are the main chemical tool for managing insect infestation after harvest in stored products, but fumigants face increasing regulatory restrictions, insecticide resistance, and consumer pushback. As a result, it is important to more generally expand the chemical toolkit beyond fumigants for stored product pest management. Meanwhile, biofuel production has been steadily increasing worldwide, and it is possible the value proposition of biofuels could be enhanced by finding applications for the byproducts of biofuel production in pest management of stored products after harvest as biorational bioinsecticides. These potential biofuel bioinsecticides were fractionated based on boiling points, analyzed using gas chromatography and mass spectrometry (GC-MS), and found to be unique in composition. Fractions tested at a range of concentrations had negligible efficacy against adult red flour beetle and confused flour beetle. However, larvae exposed with supplemental food had mortality that ranged from 50-100%, suggesting that these bioinsecticides are affecting development and could be acting as an insect growth regulator. The different bioinsecticide fractions did not demonstrate significant repellency against four stored product insect species. A greenhouse gas (GHG) emissions life cycle assessment was also performed, which found the use of the bioinsecticide could reduce GHG emissions of insecticide use by 25–61% relative to a fossil-fuel based insecticide or pyrethroid. We conclude that the use of bioinsecticides made from biofuel production have potential as a climate-friendly alternative that may support IPM programs for stored product insects.

Technical Abstract: As fumigants face increasing regulatory restrictions, insecticide resistance, and consumer pushback, it is vital to expand the integrated pest management (IPM) chemical toolkit for stored products. The production of biomass derived insecticides (e.g. bioinsecticides) from byproducts of biofuel production may be a promising alternative source of chemistries for controlling stored product insects. These potential bioinsecticides were fractionated based on boiling points (ranging from 115–230°C in one series and 245–250°C in another). Fractions were analyzed using GC-MS, and were found to be unique in composition. The lethality of these fractions were tested on Tribolium castaneum, Tribolium confusum, and Oryzaephilus surinamensis. Fractions were tested at concentrations ranging from 0–260 mg/ml to screen for efficacy against adults for durations of 2–8 h sprayed on concrete arenas. In addition, a separate assay evaluated adult emergence of larvae after 6 weeks with supplemental food in arenas, while repellency was evaluated against four stored product insect species in a laminar flow wind tunnel. A greenhouse gas (GHG) emissions life cycle assessment was also performed, which found the use of the bioinsecticide could reduce GHG emissions of insecticide use by 25–61% relative to a fossil-fuel based insecticide or pyrethroid. While adults were largely unaffected, we found that larval emergence was significantly suppressed compared to controls by roughly half or more. We also determined that there was minimal repellency to most fractions by most species. We conclude that the use of bio-oil fractions are a climate-friendly choice that may support IPM programs.