Insecticidal activity of Ageratum conyzoides L., Coleus aromaticus Benth. and Hyptis suaveolens (L.) Poit essential oils as fumigant against storage grain insect Tribolium castaneum Herbst.

Essential oils (EOs) from Ageratum conyzoides L., Coleus aromaticus Benth. and Hyptis suaveolens (L.) Poit were extracted and tested against Tribolium castaneum Herbst, the storage grain insect. The EOs were found effective against Tribolium castaneum during in vitro as well as in vivo fumigant testing. The EOs of H. suaveolens and A. conyzoides showed 100 % mortality of test insect at 250 ppm while C. aromaticus at 350 ppm. During in vivo fumigant testing of wheat samples against Tribolium castaneum, the essential oils of A. conyzoides and C. aromaticus completely checked the damage of wheat grains by the insect at 1000 ppm while essential oil of H. suaveolens checked the grain damage completely even at 500 ppm concentration. There was no adverse effect on seed germination as well as on seedling growth of EOs treated seeds showing non-phytotoxic nature of the oils. Hence, these EOs may be recommended as botanical insecticide against insect invasion of stored food commodities, thereby enhancing their shelf life.