Insecticidal activity of bio-oils and biochar as pyrolysis products and their combination with microbial agents against agrotis ipsilon (Lepidoptera: Noctuidae)

Abstract

Pyrolysis technology for producing biochar and bio-oils can be used as a potential alternative to make biopesticides, which are urgently needed in integrated pest management (IPM). Insecticidal activity of three components of bio-oils: aqueous, organic and their mixture, was evaluated individually and with three different entomopathogens: the baculovirus Agrotis ipsilon nucleopolyhedrovirus (AgipMNPV), bacterium Bacillus thuringensis var. kurstaki (Bt) and fungus Beauveria bassiana (Bb) against black cutworm, Agrotis ipsilon (Hufnagel). The effect of alkaline conditions of spray-dried biochar was studied simultaneously with the microbial pathogens. Our bioassay results indicated that the organic bio-oil phase was the most active, causing 100% mortality after 24 h, when the median lethal toxicity values LC50s (mg/ml) were found. However, the bio-oil fractions applied alone tended to cause higher mortality of the exposed larvae than did either mix with the microbial agents. Also, the results revealed that maximum mortalities were found in spray-dried formulations made with biochar at pH 7.1. It was concluded that pyrolysis oils are effective insecticides, and biochar could be a useful additive in production and formulation of biopesticides. This interesting finding further promotes the use of pyrolysis bio-oils and biochar compounds as eco-friendly alternatives to replace conventional pesticides.