Table 1.
Laboratory bioassay results for Bacillus thuringiensis var. israelensis (Bactivec®) and Bacillus sphaericus (Griselesf®) treatments against larvae of Anopheles gambiae complex, Culex quinquefasciatus and Aedes aegypti
| Mosquito species (strain) | Biolarvicide | No. testeda | LC50b (95% CI) | LC95b (95% CI) | Slope ± SE | χ2 (df) | Heterogeneityc |
|---|---|---|---|---|---|---|---|
| An. gambiae (s.s.) (laboratory) | Bti | 1800 | 0.023 (0.022–0.025) | 0.063 (0.056–0.072) | 3.814 ± 0.186 | 2.789 (3) | 0.930 |
| Bs | 2100 | 0.029 (0.021–0.040) | 0.086 (0.058–0.188) | 3.491 ± 0.159 | 38.974 (4) | 9.743 | |
| An. gambiae complex (wild) | Bti | 1800 | 0.029 (0.020–0.042) | 0.096 (0.061–0.244) | 3.167 ± 0.146 | 23.728 (3) | 7.909 |
| Bs | 2100 | 0.022 (0.013–0.034) | 0.071 (0.042–0.292) | 3.204 ± 0.153 | 67.020 (4) | 16.755 | |
| Cx. quinquefasciatus (laboratory) | Bti | 1800 | 0.026 (0.015–0.047) | 0.106 (0.056–0.633) | 2.709 ± 0.108 | 54.817 (3) | 18.272 |
| Bs | 1800 | 0.017 (0.013–0.022) | 0.040 (0.028–0.099) | 4.386 ± 0.227 | 28.194 (3) | 9.398 | |
| Cx. quinquefasciatus (wild) | Bti | 1800 | 0.028 (0.020–0.038) | 0.123 (0.079–0.267) | 2.548 ± 0.100 | 19.956 (3) | 6.652 |
| Bs | 1800 | 0.021 (0.013–0.036) | 0.054 (0.033–0.486) | 3.980 ± 0.192 | 58.924 (3) | 19.641 | |
| Ae. aegypti (laboratory) | Bti | 1800 | 0.018 (0.012–0.027) | 0.052 (0.032–0.265) | 3.545 ± 0.175 | 41.277 (3) | 13.759 |
| Ae. aegypti (wild) | Bti | 1800 | 0.037 (0.033–0.041) | 0.099 (0.083–0.124) | 3.859 ± 0.166 | 4.519 (3) | 1.506 |
Abbreviations: Bti, Bacillus thuringiensis var. israelensis; Bs, Bacillus sphaericus; CI, confidence interval; SE, standard error; df, degrees of freedom.
1500 subjects and 300 controls in all tests except for Bs experiments with An. gambiae complex where there were 1800 subjects and 300 controls (control mortality did not exceed 4% in any experiment).
mg/litre at 24 and 48 h for Bti and Bs, respectively.
Definition: heterogeneity in the context of bioassay is the value of Chi-square divided by the degrees of freedom, a factor used to measure how well the values predicted by the model compared with the actual value observed in bioassay.