International Journal of Plant & Soil Science

Aims: Mosquito-borne diseases still remain a major health problem and their control depends largely on preventive measures against the vectors. The control of mosquito at larvae stage is considered effective way of vector management. Hence, this study aimed at evaluating larvicidal activities of methanol, N-hexane leaf extract and seed oil of castor plant (Ricinus communis Linn) against 2^nd and 4^th instar of Anopheles mosquito larvae.

Place and Duration of Study: This research work was carried out in the Department of Microbiology, Federal University of Technology, Akure, Nigeria.

Methodology: The castor leaf and seed oil were extracted with soxhlet extractor using 98% N-hexane and methanol. Different concentration of the extracts were prepared (10.0-100.0 mg/L), also, a test concentration ranging from 200-1,000 ppm were prepared with distilled water, and mortality was recorded after 24 hours of larvae exposure to extracts.

Results: In 2^nd instar larvae, there was a significant difference (p<0.05) in the LC₈₀ and LC₉₅ values of the extracts, Castor seed oil extract has the lowest values. Castor seed oil extract has the highest mean larval mortalities of 97.60±1.63% and high larvicidal activity at the lowest concentration of 200 mg/l. In 4th instar larvae of Anopheles mosquito after 24 hours of exposure, there was a significant difference (p<0.05) in the LC₈₀ and LC₉₅ values of the extracts, Castor seed oil has the lowest LC₈₀ and LC₉₅ values. Castor oil has the highest mean larvae mortality of 97.60±1.00% and larvicidal activity with high mortality at lowest concentration of 200 mg/l.

Conclusion: Conclusively, the results revealed that extracts of Ricinus communis possesses larvicidal properties against Anopheles mosquito larvae and might be a potential biological control measure.