Insecticidal activity of petroleum ether extract and essential oil of Chenopodium ambrosioides L.(Chenopodiaceae) against Anopheles gambiae(Diptera:Culicidae)

Abiodun A. DENLOYE1,Oluwakemi K. AJELARA1,Rasaq A. OLOWU2,Adeolu O. ESHILOKUN3,Winifred A. MAKANJUOLA4(1.Department of Zoology,Lagos State University,Ojo,Lagos,Nigeria; 2.Department of Chemistry Lagos State University,Lagos,Nigeria;3.Department of Chemistry,University of Limpopo,South Africa; 4.Department of Zoology,University of Lagos,Akoka,Lagos,Nigeria)

Malaria; Anopheles gambiae; Chenopodium ambrosioides; insecticidal activity; bioassay; median lethal concentrations; essential oil; petroleum ether extract

Tests were carried out to evaluate the toxicity of Chenopodium ambrosioides (Chenopodiacea) leaf against the 0-2 d old adult,1st,2nd,3rd and 4th instar larvae of Anopheles gambiae (Diptera:Culicidae) as petroleum ether extract and essential oil respectively at ambient laboratory temperature. Thirty larvae at each instar stage were exposed to 50,100,250,500,750 and 1 000 mg/L of extract and essential oil in water,and the number of dead larvae recorded at 24 and 48 h post-exposure. Thirty adults were exposed to C. ambrosioides oil vapour in air-tight rectangular glass cages at 0.8,1.6 and 2.4 μL/L and mortality recorded 24 h after exposure. The results showed that the test extract and essential oil were toxic to all larval stages and adults of An. gambiae. The median lethal concentration after 48 h exposure (48 h-LC50) values show that the extract was most toxic to the 1st instar larvae (14.89 mg/L) followed by the 4th instar (18.90 mg/L) and least toxic to the 3rd instar (183.77 mg/L). The 48 h LC50 values showed that the essential oil was most toxic to the 4th (36.62 mg/L) followed by the 1st instar (90.75 mg/L) larvae. The computed LC50 value of C. ambrosioides oil against adult An. gambiae was 1.01 μL/L. The study highlights the potential of C. ambrosioides for the control An. gambiae.