Investigation of Hibiscus sabdariffa as a new eco-friendly photo-larvicidal natural product for the control of mosquitoes

Abstract

The Culex spp. is a vector of several disease-causing organisms including filarial parasites, encephalitis virus and the West Nile Virus; the control of these diseases is hinged on controlling the vector. Synthetic insecticides have previously been applied in the control of Culex spp. which poses a danger to the environment. In the present research, the use of light and a naturally occurring product, methanol extract of Hibiscus sabdariffa calyces (HSME), in controlling the breeding and spread of Culex tritaeniorhynochus was investigated. Third instar larvae of C. tritaeniorhynochus were fed with HSME and exposed to light for 18 hours. Results indicate over 80% mortality of the test sample with LC50 of 528.44 ppm; also increase in percentage mortality with corresponding increase in HSME concentration and longer irradiation time was established. The trend observed in light reactions was not seen in the control and dark reactions, implying that the presence of light and the photosensitizer (HSME) is required to induce mortality in Culex tritaeniorhynochus larvae population.