PLANT INFUSIONS MEDIATE OVIPOSITION OF MALARIA, DENGUE AND FILARIASIS VECTORS: PUSH-PULL APPROACH FOR VECTOR SURVEILLANCE AND CONTROL

Abstract

ABSTRACT Semiochemicals are small organic compounds that mediate interactions between organisms by transmitting chemical messages. They are used by insects for intra- and inter-species communication in their ecosystem. Mosquitoes transmit malaria, dengue, West Nile virus, chikungunya, yellow fever, filariasis and encephalitis to human beings across the globe. Mosquitoes perceive semiochemicals in their environment respectively emanating from potential hosts and habitats by the sensory apparatus and act wisely for the benefit of their progeny. Host seeking and/ avoidance, oviposition site seeking behaviors are governed predominantly by chemical stimuli along with visual cues that ensure blood feeding and subsequent egg laying to complete the gonotrophic cycle. Further, plant materials such as neem, tobacco and their infusions are naturally repulsive to mosquitoes while infusions of Bermuda grass could be a promising avenue for exploring natural attractant molecules using gas-chromatography coupled massspectrometry to identify biologically active molecules. In the laboratory studies one week old infusions of neem seed kernel and dried tobacco leaves reduced 90-97% egg deposition by gravid females of Anopheles stephensi, Aedes aegypti, and Culex quinquefasciatus mosquitoes, while oviposition substrates treated with one week old infusion of Bermuda grass, Cynodan dactylon received 40-60% increased egg laying compared to control. Through GC-MS analysis of these plant materials revealed several fatty acids, hydrocarbons, nicotine, thymol, ethyl dithioisoindole, -lactone, -elemene, squalene, eudesmenol and stigmasterol that could be responsible for the attraction and repulsion of mosquitoes to respective extracts. Being biological in origin, these semiochemicals are safe to humans and environment, when judiciously used would manage effectively the mosquito menace and mosquito borne diseases.