Alok Krishna

Potential toxicity of new genotypes of Tagetes (Asteraceae) species against stored grain insect pests

Essential oils of three genotypes of Tagetes minuta, six of Tagetes patula and 15 of Tagetes erecta were screened for potential fumigant and contact toxicity against three stored product beetle species, Callosobruchus maculatus (Fabricius), Sitophilus oryzae (Linnaeus) and Tribolium castaneum (Herbst). Genotype 1 of T. minuta (TM-1), genotype 2 of T patula (TP-2) and genotype 13 of T erecta (TE-13) were the most toxic. These three genotypes were then evaluated for adult toxicity, oviposition deterrence, and ovicidal and population reduction activities. Essential oils of genotypes TM-1 and TP-2 induced 100% adult mortality for all three insect species at dosages of 50,000 ppm and 500 μgg/insect in fumigant and contact toxicity bioassays, respectively. Adults of C. maculatus and S. oryzae were highly susceptible to the essential oils of the three genotypes in both fumigant and contact toxicity bioassays. The essential oil of genotype TM-1 deterred oviposition in T. castaneum by 81% and suppressed its egg hatchability by 91% when applied at a dosage of 70,000 ppm on filter paper.RésuméDes huiles essentielles extraites des trois génotypes de Tagetes minuta, six de Tagetes patula et quinze de Tagetes erecta ont été évaluée pour leur toxicité par fumigation ou contact, envers les bruches Callosobruchus maculatus (Fabricius), Sitophilus oryzae (Linnaeus) et Tribolium castaneum (Herbst). Les génotypes TM-1 de T. minuta, TP-2 de T. patula et TE-13 de T. erecta étaient les plus toxiques. Les trois génotypes ont été ensuite évalués pour leur toxicité envers les adultes, leurs effets sur l’oviposition et le pouvoir ovicide, et la réduction de la population chez T. castaneum. Les huiles essentielles des génotypes TM-1 et TP-2 ont provoqué une mortalité totale chez les adultes des trois insectes, à la dose de 50,000 ppm dans des essais de fumigation et à la dose de 500 μg/insecte dans les tests de toxicité par contact. Les adultes de C. maculatus et S. oryzae étaient les plus sensibles à l’effet des huiles essentielles des trois génotypes, à la fois dans les essais de fumigation et de toxicité par contact. Les huiles essentielles de TM-1 ont réduit de 81% l’oviposition et de 91% le taux d’éclosion à la dose de 70,000 ppm appliquée sur du papier-filtre.

Volatile Oil Constituents of the Capitula, Leaves and Shoots of Tagetes patula L.

Abstract The hydrodistilled oils of the capitula, leaves and shoots ofTagetes patula L. were analyzed by GC and GC/MS. The main constituents of the oil of the capitula were identified as (Z)-β-ocimene (19.9%), (Z)-tagetenone (12.4%), (E)-tagetenone (10.4%), piperitenone (5.8%) and β-caryophyllene (15.1%). The oil of the leaves contained limonene (6.5%), terpinolene (16.2%), (Z)-tagetone (13.0%), (Z)-tagetenone (5.5%), (E)-tagetenone (8.2%), piperitone (10.2%) and piperitenone (12.5%) as the main constituents. The oil of the shoots was found to have limonene (6.8%), (Z)-β-ocimene (13.7%), terpinolene (12.0%), piperitone (5.8%) and β-caryophyllene (10.5%) as the major constituents.

Composition of the Essential Oils of the Leaves and Flowers of Tagetes erecta L.

Abstract The essential oils of Tagetes erecta L. leaves and flowers were analyzed by GC and GC/MS. Forty-four constituents representing 94.1% of the leaf oil and 45 constituents of the flower oil accounting for 94.0% were identified. The major constituents of the leaf oil were limonene (7.6%), terpinolene (11.2%), (Z)-myroxide (4.2%), piperitone (52.4%) and piperitenone (5.0%). The oil of the flowers contained limonene (6.9%), terpinolene (4.7%), (Z)-myroxide (7.9%), piperitone (28.5%), piperitenone (10.9%), piperitenone oxide (7.2%) and β-caryophyllene (7.0%) as the major constituents.