Insecticidal activity of the essential oil of Piper corcovadensis leaves and its major compound (1-butyl-3,4-methylenedioxybenzene) against the maize weevil, Sitophilus zeamais

BACKGROUND Sitophilus zeamais is one of the most economically impactful pests, attacking various grains and processed foods. Control of this insect has been achieved using synthetic insecticides, exacerbated and careless use of which has led to the development of resistant insect populations, toxicity to non-target organisms and environmental contamination. In this study, Piper corcovadensis leaf essential oil (PcLEO) and its major compound, 1-butyl-3,4-methylenedioxybenzene (BMDB), were investigated as alternative insecticidal agents against S. zeamais. RESULTS Characterization of PcLEO showed the presence of 40 compounds. The major components were the phenylpropanoid BMDB (35.77%) and the monoterpenes alpha-pinene (14.95%) and terpinolene (6.23%). PcLEO and BMDB were toxic by fumigation (half-maximal lethal concentration [LC50]: 9.46 and 0.85 mu l L-1 of air, respectively), by contact (half-maximal lethal dose [LD50]: 9.38 and 6.16 mu g g(-1) of insect, respectively) and ingestion (LC50: 16.04 and 14.30 mg g(-1), respectively). In the ingestion test, both PcLEO and BMDB promoted the loss of insect biomass and had a strong deterrent effect. In addition, both were able to inhibit trypsin and alpha-amylase activities. CONCLUSION PcLEO and BMDB exhibited insecticidal activity against S. zeamais, with a toxic effect by fumigation, contact and ingestion, in addition to food deterrence and inhibiting trypsin and alpha-amylase activities, suggesting their potential for use in the control of this pest.