Table 2. Values of 50% lethal concentration (LC₅₀) for the five An. sinensis resistant field populations compared to the susceptible lab strain in response to beta-cypermethrin.

Mosquito Population	LC50(ppm)	95% confidence interval	R/S*
SS	0.001	0.0002–0.001	1
XZ	0.9	0.3–3.5	900
HY	1.3	0.2–11	1300
NJ	1.7	0.4–3.3	1700
CS	2.1	1.3–3.1	2100
SZ	0.7	0.46–1.0	700

*R/S is the ratios of LC50 of the test population to the SS population.