Table 3.
Cypermethrin dose-response results in the susceptible Orlando Normal reference strain and responses of five recently collected B. germanica populations to diagnostic doses of cypermethrin
| Strain | n | Lethal dose LD50 µg/male (95% CI)a |
Slope ± SE | χ² (df) | t-ratiob |
|---|---|---|---|---|---|
| Orlando Normal | 240 | 0.112 (0.090,0.169) | 7.4 ± 0.9 | 14.3 (4) | 7.5* |
| Mean ± SEM % mortality at 48 h (n = 3)c | |||||
|---|---|---|---|---|---|
| Diagnostic dose (µg/insect)d | VS101 | DR2820B | CC29 | ||
| 0.1 (LD50 of Orlando Normal) | 3.3 ± 5.7 | 0 ± 0 | 0 ± 0 | ||
| 1 (10X LD50 of Orlando Normal) | 6.7 ± 5.7 | 0 ± 0 | 3.3 ± 5.8 | ||
| 10 (100X LD50 of Orlando Normal) | 83.3 ± 5.7 | 40.0 ± 10.0 | 80.0 ± 10.0 | ||
Insects were topically treated with cypermethrin (in 1 µl acetone); LD50 was estimated for the Orlando Normal strain from probit analysis. CI is confidence interval. The average mass of B. germanica males is ~50 mg, hence multiply by 20 to obtain approximate µg/g body mass.
t-ratio of the slope. Values >1.96 denote a significant regression (*P < 0.05).
The mean represents the average of 3 replicates with 10 cockroaches assayed in each replicate.
Three diagnostic doses were used, representing the LD50 value (0.1 µg), 10-fold the LD50 (1 µg), and 100-fold the LD50 value (10 µg) of the Orlando Normal strain.