Catalina Leos Rivas

Coumarin Isolated from Tagetes lucida Cav. Exhibits Larvicidal Activity in Aedes aegypti (L.)

Aedes aegypti (L.) was eradicated successfully in Latin America in the 1950s-1960s, but explosive outbreaks occurred in the 1980s. Environmental, chemical, biological, and integrated control methods were previously used to eradicate this vector (Organizacion Panamericana de la Salud 1995). The control of mosquitoes is complicated by certain species demonstrating resistance to some conventional insecticides, causing indiscriminate use of these insecticides and potentially damaging the environment and thereby requiring alternative control methods (Perich et al. 1995). Additionally, the wide utilization of synthetic insecticides for domestic and agricultural use, as well as for vectors of human diseases, has caused concern because of the toxicity and environmental impact of some of these agents (Mulla and Su 1999). Bautista (1996) demonstrated that products extracted from plants have great potential for being used in alternative control methods for mosquitoes. Some of the most protective extracts are derivatives of plants from the genus Tagetes (Asteraceae). There are about 40 species in the genus, and all species originated in the Americas. Tagetes patula L., T. erecta L., and T. minuta L. possess larvicidal activity against third-instar larvae of Ae. aegypti and Anopheles stephensi Liston (Perich et al. 1994). Insecticidal components of these three Tagetes species were isolated and evaluated, and it was determined that four thiophenes were potentially responsible for the toxicity against mosquitoes. Tagetes lucida A. Cavanilles, native to Mexico and Guatemala, is one of the medicinal plants most frequently reported (Giron et al. 1991), and the smoke resulting from the burning of its leaves is used traditionally in Mexico as a mosquito repellent (Gonzalez 1998). T. lucida has been investigated for its phytochemical and biological properties, and its extracts have been reported to have different activities: as a sedative (Linares 1986), as an enterobactericidal agent, for the treatment of respiratory diseases (Caceres 1990, 1991), and as a bactericidal agent (Salgado 2000). The aim of this study was to evaluate extracts and isolated components of T. lucida for larvicidal activity against Ae. aegypti. ________________________ Laboratorio de Entomologia Medica, Facultad de Ciencias Biologicas, Universidad Autonoma de Nuevo Leon, Mexico. Ap. Postal 109-F, San Nicolas de los Garza, N.L. Mexico, adrflores@fcb.uanl.mx