Table 2.
Acute toxicity of crude green tea (Camellia sinensis) extract on exposure to L3/L4 instars of A. arabiensis and A. gambiae (s.s.) for 24, 48 and 72 h post-exposure. Summary of percentage mean (± SD) mortality rates of five replicates of mosquito larvae exposed to different concentrations of C. sinensis crude leaf extract for different time periods (24, 48 and 72 h). Half maximal lethal concentrations (LC50) for each dose exposure period have been determined at their 95 % confidence intervals. The mosquito larvae exhibited significant susceptibility to the bioactive fraction at P < 0.05
| Concentration (ppm) | Lethal concentration (ppm) | |||||||
|---|---|---|---|---|---|---|---|---|
| Time | 500 | 250 | 100 | 50 | 25 | Control | LC50 | 95 % CI |
| An. arabiensis* | ||||||||
| 24 h | 86 ± 9.62 | 75 ± 24.75 | 30 ± 19.69 | 0 ± 0.00 | 0 ± 0.00 | 0 ± 0.00 | 154.58 | 152.37–158.22 |
| 48 h | 98 ± 4.47 | 92 ± 5.70 | 53 ± 20.19 | 0 ± 0.00 | 0 ± 0.00 | 0 ± 0.00 | 154.58 | 152.37–158.22 |
| 72 h | 100 ± 0.00 | 95 ± 5.00 | 60 ± 18.03 | 0 ± 0.00 | 0 ± 0.00 | 0 ± 0.00 | 154.58 | 152.37–158.22 |
| An. gambiae (s.s.)* | ||||||||
| 24 h | 100 ± 0.00 | 91 ± 9.62 | 39 ± 6.52 | 0 ± 0.00 | 0 ± 0.00 | 0 ± 0.00 | 117.15 | 112.86–127.04 |
| 48 h | 100 ± 0.00 | 98 ± 2.24 | 62 ± 10.37 | 0 ± 0.00 | 0 ± 0.00 | 0 ± 0.00 | 87.11 | 82.57–112.82 |
| 72 h | 100 ± 0.00 | 100 ± 0.00 | 84 ± 11.94 | 0 ± 0.00 | 0 ± 0.00 | 0 ± 0.00 | 87.11 | 82.57–112.82 |
Data presented as mean ± SD of five replicates
Abbreviations: LC 50 lethal concentration that killed 50 % of test mosquito larvae population, CI confidence interval
*Mean values are not significantly different P ≤ 0.05 (ANOVA)