Toxicity of Hexanolic Extracts of Piper guineese Schum and Thonn seed oil to larvae of Aedes aegypti (L.) ,
ANYAELE, O.O.; AMUSAN, A.A.S.; OKORIE, T.G. and OKE, O.A.
ABSTRACT: Hexanolic extract of Piper guineense Schum and Thonn (Piperaceae) was tested for acute toxicity on third instar larvae of Aedes aegypti reared in the Advanced Entomology Laboratory of the University of Ibadan, Nigeria. Five graded concentrations 0.9ppm, 1.7ppm, 2.5ppm, 3.3ppm and 4.1ppm, were tested on the larvae. Effects of two physical parameters namely; sunlight and ultra-violet radiation on the potency of the extract was also investigated. The extract showed a high level of toxicity on the 3rd instar larvae of A. aegypti. LC50 of P. guineense on the larvae was 1.7 ± 0.84ppm. The highest concentration of 4.1ppm killed 77% of the population within an hour and 95% in 24 hours while at the least concentration of 0.9ppm no death was recorded but killed 16% of the larvae in 24 hours. The potency of P. guineense on the larvae was drastically reduced when exposed to sunlight However, there was no significant difference between the potency of the U-V exposed extract the untreated, rather the raw data showed some level of activation by ultraviolet