Insecticidal properties of pyrolysis bio-oil from greenhouse tomato residue biomass

• Bio-oil obtained from the residues of greenhouse tomato plants has been investigated as a potential source of bioactive and pesticidal compounds.
• Fast pyrolysis of dried tomato residue biomass was performed in a bubbling bed reactor at 300 and 500 °C.
• Neophytadiene, phytol and a number of fatty acids were identified in the most active bio-oil fraction.
• Samples containing neophytadiene and/or phytol exhibited some degree of toxicity toward Colorado potato beetle.

Fast pyrolysis is a recognized technology for the thermochemical conversion of biomasses into bio-oils that may contain valuable chemicals, including solvents, pharmaceuticals and biopesticides. The composition of the bio-oils is partly determined by the biomass feedstock. Bio-oil produced from the residues of greenhouse tomato plants has been investigated as a potential source of bioactive and pesticidal compounds. Fast pyrolysis of dried tomato residue biomass was performed in a bubbling bed reactor at 300 and 500 °C. The condensable vapors were collected using a condenser followed by an electrostatic precipitator (ESP). Bio-oil collected from the ESP exhibited a much greater insecticidal activity based on tests carried out using the Colorado potato beetle (CPB) Leptinotarsa decemlineata leaf disc bioassay. After an extraction with 1:1 water/dichloromethane, most of the activity remained in the organic phase. To further fractionate the components, amino solid phase extractions (SPE) followed by reversed phase LC separation were performed. Six LC fractions were collected and analyzed by GC–MS. Neophytadiene, phytol and a number of fatty acids were identified in the most active fraction, but only with combinations of these compounds was the greatest insecticidal activity obtained. Pyrolysis of tomato plant biomass affords a cost-effective source of bioactive compounds that can be further developed for biopesticide application.