Table 1 Multivariate regression analysis results for the effect of sampling time on resistance ratio (RR) in larval bioassays of Culex pipiens pallens populations. RR was calculated as the ratio of the wild-strain LC₅₀/susceptible-strain LC₅₀

Jining

Acetofenate

y = -0.0525x + 107.7

0.056

0.296

0.609

DDVP

y = 0.1458x - 285.3

0.264

1.789

0.239

Deltamethrin

y = 4.269x - 8488

0.771

16.803

0.009*

Cypermethrin

y = 3.634x - 7209

0.726

7.956

0.067

Propoxur

y = 0.02285x - 49.89

0.018

0.0536

0.832

Zaozhuang

Acetofenate

y = -0.1283x + 260.0

0.194

1.206

0.322

DDVP

y = 0.3005x - 593.0

0.133

0.766

0.422

Deltamethrin

y = 8.260x - 16490

0.621

8.205

0.035*

Cypermethrin

y = 9.306x - 18600

0.807

12.541

0.038*

Propoxur

y = 0.1675x - 331.3

0.434

2.297

0.227

Jinan

Acetofenate

y = -0.0574x + 116.8

0.214

0.545

0.537

DDVP

y = 0.1919x - 398.4

0.135

0.622

0.475

Deltamethrin

y = 9.037x - 18030

0.786

14.721

0.019*

Cypermethrin

y = 5.838x - 11630

0.583

2.795

0.236

Propoxur

y = 0.1781x - 354.6

0.366

1.154

0.395

Taian

Acetofenate

y = -0.02741x + 55.89

0.16

0.571

0.505

DDVP

y = -0.2056x + 418.9

0.605

4.591

0.122

Deltamethrin

y = 8.808x - 17610

0.885

23.047

0.017*

Cypermethrin

y = 12.94x - 25890

0.661

5.860

0.094

Propoxur

y = 0.1037x - 203.7

0.318

1.396

0.322