S. Arivoli

Larvicidal activity of Wrightia tinctoria R. BR. (Apocynaceae) fruit and leaf extracts against the filarial vector Culex quinquefasciatus Say (Diptera: Culicidae)

Abstract Objective To determine the larvicidal activity of crude aqueous and petroleum ether extracts of Wrightia tinctoria fruits and leaves against the filarial vector, Culex quinquefasciatus. Methods The larvicidal activity was evaluated at concentrations of 0.06%, 0.12%, 0.25%, 0.50% and 1.00%. Larval mortality was observed for 24 and 48 h. Results Among the plant parts tested, aqueous fruit extract exhibited highest larvicidal activity followed by aqueous leaf extract with LC50 values of 0.17% and 0.09%; 0.21% and 0.11% after 24 and 48 h respectively. Conclusions Further investigations are needed to elucidate this activity against a wide range of all stages of mosquito species and also the active ingredient(s) of the extract responsible for larvicidal activity should be identified.

Larvicidal Efficacy of Jasminum sp. (Oleaceae) Flower Extracts against theDengue and Chikungunya Vector Aedes aegypti L. (Diptera: Culicidae)

Dengue and chikungunya are transmitted by Aedes aegypti and for controlling these diseases, the vector mosquito has to be controlled. Extensive use of synthetic and chemical insecticides has resulted in environmental hazards and also in development of physiological resistance among vector mosquito species. Plant products are considered to be a potential alternative approach as they are environmentally safe, target specific and biodegradable. In the present study, the crude chloroform, methanol and aqueous flower extracts of Jasminum officinale, Jasminum auriculatum and Jasminum grandiflorum were tested for the larvicidal efficacy against the third instar larvae of Aedes aegypti at concentrations of 62.5, 125, 250, 500, 1000, 2000, 4000 and 8000 mg/L. Mortality was recorded after 24 and 48 h. Amongst the extracts of Jasminum species tested, the crude chloroform flower extract of Jasminum grandiflorum was found to be effective showing 100% mortality at 1000 mg/L with LC50 value of 344.01 and 300.47 after 24 and 48 h respectively followed by the crude methanolic flower extracts of Jasminum officinale and Jasminum auriculatum. Further investigations are needed to elucidate the larvicidal activity of Jasminum grandiflorum crude chloroform flower extract against a wide range of all stages of mosquito species and also the active ingredient(s) of the extract responsible for larvicidal activity should be identified.

Evaluation of larvicidal efficacy of Cleome viscosa L. (Capparaceae) aerial extracts against Culex quinquefasciatus Say (Diptera: Culicidae)

Abstract Objective To evaluate the larvicidal efficacy of crude petroleum ether, chloroform, acetone and aqueous aerial extracts of Cleome viscosa against the filarial vector, Culex quinquefasciatus. Methods Standard World Health Organization protocols with minor modifications was adopted for the larvicidal bioassay. Larvicidal activity of exyracts was evaluated at concentrations of 62.5, 125, 250, 500 and 1 000 mg/L. Larval mortality was observed after 24 and 48 h. Results Amongst the solvent extracts tested, petroleum ether exhibited the highest larvicidal activity and LC50 values was 52.62 and 43.16 mg/L followed by acetone, aqueous and chloroform extract with LC50 values of 328.64 and 280.58; 493.44 and 298.76; 509.27 and 434.40 mg/L after 24 and 48 h respectively. Conclusions Further investigations are needed to explore the larvicidal activity of the petroleum ether aerial extract of this plant against a wide range of mosquito species and also the active ingredient(s) of the extract responsible for larvicidal activity should be identified.