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Hexane, ethyl acetate, ethanol and methanol extracts of Psidium guajava, Terminalia chebula, Mimusops elengi and Achyranthes aspera were tested against the dental caries causing bacteria Streptococcus mutans and fungus Candida albicans isolated from caries infected patients. All the four extracts of P. guajava showed activity against both S. mutans and C. albicans. Maximum zone of inhibition was observed in ethyl acetate of P. guajava. The four extracts of T. chebula and M. elengi showed antibacterial activity against S. mutans. M. elengi extracts and ethanol extract of T. chebula did not show any antifungal activity against C. albicans. Except for the hexane extract of A. aspera, the other three extracts showed activity against the tested microbes. The ethyl acetate P. guajava leaf extract showed the minimum inhibitory concentration (MIC) against S. mutans to be <0.076 mg/mL in both MHB and BHI. The P. guajava ethyl acetate extract was subjected to GC-MS.

With a view to develop an ecofriendly botanical pesticide, we evaluated the bioeff icacy of crude extracts of Couroupita guianensis against third instar larvae of Helicoverpa armigera. Maximum feeding deterrency (81.67%) and least LC 50 (2.72%) for larval mortality were seen in hexane extract. Hexane extract was subjected to column chromatography using different ratio of hexane-ethyl acetate solvent system. Totally eight fractions were collected. The fractions were screened at 125, 250, 500 and 1,000 mg kg -1 concentrations against H. armigera using no-choice leaf disc method. Fraction eight showed maximum antifeedant (86.24%) and larvicidal (80.88%) activities at 1,000 mg kg -1 concentration. C. guianensis could be utilized in pest control programme. Additional key words: antifeedant, hexane, larvicidal, phytochemicals. ResumenEficacia de Couroupita guianensis (Aubl) frente a larvas de Helicoverpa armiguera (Hub.) (Lepidoptera: Noctuidae) Con el fin de desarrollar un plaguicida ecológico de origen vegetal, se evaluó la eficacia de extractos crudos de Couroupita guianensis frente a larvas de tercer estadio de Helicoverpa armígera. En el extracto de hexano se observó la máxima actividad disuasoria de la alimentación (81,67%) y la menor LC 50 (2,72%) respecto a la mortalidad de las larvas. Se sometió el extracto de hexano a cromatografía en columna, utilizando diferentes proporciones del sistema disolvente hexano-acetato de etilo para eluir ocho fracciones. Las fracciones se evaluaron en concentraciones de 125, 250, 500 y 1.000 mg kg -1 frente a H. armígera, mediante ensayos de no preferencia con discos foliares. La fracción octava mostró la máxima actividad antialimentaria (86,24%) y larvicida (80,88%) a 1.000 mg kg -1 . C. guianensis se podría utilizar por tanto en programas de control de plagas.Palabras clave adicionales: actividad antialimentaria, actividad larvicida, fitoquímicos, hexano.

Larvicidal activity of 12 fractions and a compound of chloroform extract of Clerodendrum phlomidis L. (Lamiaceae) was assayed for their toxicity against the early fourth-instar larvae of the filarial vector Culex quinquefasciatus Say and dengue vector Aedes aegypti L. The fractions were tested at 100-, 50-, 25- and 12.5-ppm concentrations. The compound pectolinaringenin was tested at 5-, 2.5-, 1.0- and 0.5-ppm concentrations. Among the different fractions, fraction 5 recorded the lowest LC(50) and LC(90) values of 5.02, 61.63 ppm and 32.86, 73.62 ppm against C. quinquefasciatus and A. aegypti, respectively. The compound pectolinaringenin showed the lowest LC(50) and LC(90) values of 0.62, 2.87 ppm and 0.79, 5.31 ppm against C. quinquefasciatus and A. aegypti, respectively. This is the first report on the mosquito larvicidal activity of the isolated compound pectolinaringenin from C. phlomidis. The results of this study show that the chloroform extract of C. phlomidis can be used as a potent source and pectolinaringenin as a new natural mosquito larvicidal agent.