Characterizing composition and assessing byproducts from biofuel production as potential biorational insecticides to induce lethality in stored product insects

As fumigants face increasing challenges from regulatory restrictions, insecticide resistance, and consumer demand for less harsh alternatives, it is vital to expand the integrated pest management (IPM) chemical toolkit for stored products. The production of biologically-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 115–170°C in one series and 200–255°C in another). Fractions were analyzed using GC-MS, and their differences were visualized using non-metric multi-dimensional scaling. The lethality of these fractions were tested on the red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) and confused flour beetle, Tribolium confusum (L.) (Coleoptera: Tenebrionidae). Fractions were formulated and tested at 80 mg/ml to screen for efficacy. A total of 1.5 ml was evenly sprayed onto a sealed concrete petri dish, and flour was sprinkled evenly in the dish after the fraction had evaporated overnight. A total of 10 adults were added to each dish, and were exposed for either 2, 3, or 8 h. In addition, after 2 weeks, larval emergence was assessed. Controls were treated with distilled water. While adults were largely unaffected, we found that larval emergence was significantly suppressed compared to controls by roughly half. We also determined that there was no repellency in a wind tunnel assay. Several fractions show promise in residual control of both species.