Bioactivity of 1,8-cineole and essential oil of Salvia keerlii (Lamiaceae) against Spodoptera frugiperda.
Fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), infests more than 80 crop species and is the principal pest of maize (Zea mays L.) (Poaceae) in Mexico. Although insecticides are used to control the pest, they can cause environmental damage and negatively affect human health. Essential oils are an alternate for managing the insect. The aim of this study was to investigate insecticidal and insectistatic activities of essential oil of salvia (Salvia keerlii Benth, Lamiaceae) against larval and pupal S. frugiperda. The oil at 400, 600, and 1,000 mg liter-1 killed 65, 55, and 85% of larvae, respectively, with estimated LC50 of 590.2 mg liter-1, but did not adversely affect pupae. Insectistatic activity at concentrations of 600 and 1,000 mg liter-1 delayed larval development as many as 13.8 days (compared to a negative check). The main compounds of essential oil of S. keerlii were identified by GC-MS as 2-pentanone,4-hydroxy-4-methyl, caryophyllene oxide, and 1,8-cineole. The 1,8-cineole at concentrations of 600 and 1,000 mg liter-1 killed all S. frugiperda larvae, with an estimated LC50 of 249.4 mg liter-1.