Field larvicidal and pupicidal efficacy of the natural insecticide, oxymatrine against Culex species in Beni Suef Governorate, Egypt

Abstract

Oxymatrine is a naturally derived bioinsecticide with an environmentally favorable toxicity profile. So the present study investigated its larvicidal and pupicidal efficacy on Culex species in laboratory, semi-field, and field conditions in Saft, Beni Suef Governorate, Egypt. The results revealed that oxymatrine showed pronounced toxicity against Culex pipiens L. immature stages after 1 h of exposure, with LC50 values (LC50 = 5.73, 8.74 and 16.44 ml/L) for the second larval instar, the fourth larval instar, and pupae, respectively. After 24 h of exposure, complete mortality of the larval and pupal stages was achieved under laboratory conditions. While the semi-field trials showed the mortality percentage of larval and pupal stages of three species of mosquito (C. pipiens L., C. theileri Theobald and C. perexiguus Theobald) increased at a concentration of 20 ml/L with increasing exposure periods of oxymatrine (1, 24, and 48 h). This concentration (20 ml/L) caused complete mortality of immature stages of three Culex species after 48 h. The results also revealed, oxymatrine (20 ml/L) caused higher toxicity against Culex immature stages in most tested breeding habitats (cement irrigation tanks, agricultural canals, and drains). The present study concluded that oxymatrine is a promising larvicide and pupicide that can be used in the treatment of mosquito breeding sites.