Insecticidal activity of Laureliopsis philippiana (Looser) Schodde (Atherospermataceae) essential oil against Sitophilus spp. (Coleoptera Curculionidae)

Abstract

In Chile, the main Coleopteran species of stored grains are Sitophilus oryzae, S. zeamais, and S. granarius. The aim of this study was to evaluate under laboratory conditions the contact and fumigant insecticidal activity, as well as the repellent and antifeedant effects of Laureliopsis philippiana (Looser) Schodde essential oil against adults of Sitophilus spp. The main compounds identified in this essential oil were methyleugenol (61.38%) and safrole (14.76%). Based on the contact bioassay, the highest toxicity was achieved with the concentration of 4.0% (v/w), and S. oryzae was the most susceptible species. Emergence (F1) was reduced as the concentration of the essential oil increased, reaching maximums of 60% in the case of S. granarius and S. oryzae, and 36% in S. zeamais. Mortality by fumigant activity was 100% for the three species of Sitophilus. All of the treatments had a repellent effect. The highest antifeedant activity (82.9%) was recorded at 4.0% (v/w) concentration. Concentrations below 2.0% (v/w) did not affect germination of maize. Based on these results, L. philippiana essential oil has the potential to control Sitophilus spp. weevils.