Insecticidal activity of Schinus terebinthifolius essential oil for the management of permethrin-resistant Sitophilus zeamais (Coleoptera: Curculionidae)

Maize weevil, Sitophilus zeamais, is a major cause of damage to corn. The preventive control of this agricultural pest is performed with permethrin. However, due to the intensive use of insecticides, the population of S. zeamais has developed resistance to more than 10 synthetic insecticides, including the active ingredient permethrin. In the search for techniques aiming to reduction of the use of synthetic pesticides for the integrated management of S. zeamais, the present study was evaluate the effects of Schinus terebinthifolius essential oil – by fumigation, contact and ingestion methods – against populations of S. zeamais, both susceptible and resistant to the insecticide permethrin. Chemical profile identification showed α-pinene, β-myrcene, α-phellandrene, δ-3-carene and β-phellandrene were the major components in S. terebinthifolius essential oil. Permethrin susceptibility of the S. zeamais revealed four resistant populations (STP_R, STP₁, STP₂ and STP₃). But, in the Fumigant bioassay, STP_R and STP₁ permethrin-resistant populations were susceptible to the essential oil. When the insects were put in direct contact with treated maize grains, only STP_R permethrin-resistant population was susceptible this essential oil. Resistance ratio of the permethrin on S. zeamais populations revealed differences of permethrin susceptibility among the groups tested. S terebinthifolius essential oil exhibited high insecticidal activity, reducing the populations of S. zeamais through fumigation and contact/ingestion methods. The present findings suggest that use of permethrin can be substituted with the preparation of botanical insecticide with S. terebinthifolius essential oil.