Insecticidal and behavioral effects of some plant essential oils against Sitophilus granarius L. and Tribolium castaneum (Herbst)

Insecticidal, repellent and fumigant activities of Rosemary [Rosmarinus officinalis (Lamiaceae)], Daphne [Laurus nobilis (Lauraceae)], Echinacea (Echinacea purpurea (Asteraceae), Marjoram [Origanum majorana (Lamiaceae)], Basil [Ocimum basilicum (Lamiaceae)] and Fennel [Foeniculum vulgare (Apiaceae)] extracts were tested against Sitophilus granarius (Col.: Curculionidae) and Tribolium castaneum (Col.: Tenebrionidae) under laboratory conditions. The composition of essential oils extracted from the plants was also determined. Eucalyptol and Terpinyl acetate were the main components of Daphne oil. Similarly, the main components of Basil oil were Methyl cinnamate, Linalool and Eucalyptol, whereas Camphor and Eucalyptol were the main constituents of Rosemary oil. Likely, γ-Terpinene and β-Terpineol were the main components of Marjoram oil, while Estragole was the main component in Fennel oil. The β-Cubebene and Caryophyllene were the main components of Echinacea oil. Echinacea and Basil oils exhibited high contact toxicity against S. granarius. Basil oil caused 99.59% mortality of S. granarius 24 h after application, whereas Echinacea oil caused 99.59% mortality 72 h after application. In single-dose fumigant toxicity assays, Rosemary oil exhibited 58.41% fumigant activity against S. granarius after 24 h, whereas Fennel oil indicated 100% fumigant toxicity against T. castaneum. All essential oils showed repellent effects against both the pests. The essential oils caused 34.12–95.29% decrease in the progeny production of F1 generation of T. castaneum, while the decrease in the F1 generation of S. granarius ranged between 84.27 and 98.88%. It is concluded that essential oils of Fennel, Rosemary, Echinacea and Basil could potentially be used for the control of studied stored grain pests.