Methanol extract of the dry peels of the common edible plant, Citrus limon (family, Rutaceae), was obtained using a Soxhlet extractor and its larviciding effect evaluated against the larvae of two household mosquitoes: Aedes aegypti and Culex quinquefasciatus. Each batch of larvae (20-30) were treated with 3.90, 15.63, 62.50, 250 and 1000 mg/l of the plant extract in 4 replicates. Application of 3.90 mg/l resulted in 14% mortality in both Aedes aegypti and Culex quinquefasciatus within 24 hours but with a rise in concentration to 250 mg/l, mortality in both reached 66%. At the maximum concentration of 1000 mg/l used, 70% mortality was attained in the case of Ae. aegypti and 86% in Cx. quinquefasciatus. Statistical analysis showed that besides the 1000 mg/l treatment, there was significant difference (Anova, p < 0.05) in larval mortality between the other dosages tested on both species. The log-concentration probit line for C. limon extract against Ae. aegypti and Cx. quinquefasciatus after 24 hrs of treatment indicates that a concentration of 39.81 mg/l proved sufficient in killing 50% of the larvae of the former, while in the case of the latter, 112.20 mg/l was the median lethal dosage. The possible value of C. limon as an anti-mosquito agent is highlighted.


JOURNAL OF AQUATIC SCIENCES Volume 16, Number 2, October 2001, pp. 111-114




KEY WORDS:

Larviciding effects, Lemon peels, mosquito larvae