Table 3. Susceptibility (± 95% Confidence Interval) of western corn rootworm neonates by contact to bifenthrin of laboratory colonies from Brookings, SD, including one from a commercial vendor, and from field populations.
Resistance ratios compared with lowest non-diapause LC50; bioassays conducted in 2014, except Kansas populations were conducted in 2015.
| Populations | N a | Slope (±SE) | LC50 (95% CI)ng/cm2 | RR50(95% CI) | LC90 (95% CI)ng/cm2 | RR90(95% CI) | X 2 (d.f.) |
|---|---|---|---|---|---|---|---|
| Wenz | 1456 | 1.91 (0.11) | 0.42 (0.37–0.48) | 1.60 (1.36–1.88) | 1.97 (1.67–2.38) | 2.63 (2.08–3.34) | 4.76 (5) |
| Kansas | 1452 | 1.66 (0.10) | 0.47 (0.36–0.59) | 1.77 (1.48–2.11) | 2.75 (2.02–4.19) | 3.68 (2.83–4.80) | 8.34 (5) |
| Linwood | 1482 | 1.74 (0.09) | 0.54 (0.48–0.61) | 2.06 (1.75–2.41) | 2.97 (2.48–3.67) | 3.97 (3.08–5.11) | 2.70 (5) |
| Dey | 1462 | 2.24 (0.15) | 0.57 (0.46–0.68) | 2.16 (1.84–2.55) | 2.13 (1.72–2.85) | 2.86 (2.27–3.59) | 6.50 (5) |
| S Dakota | 1452 | 1.64 (0.10) | 0.64 (0.50–0.81) | 2.44 (2.05–2.90) | 3.87 (2.78–6.13) | 5.18 (3.92–6.85) | 8.29 (5) |
| Penn #1 | 1462 | 1.51 (0.08) | 0.65 (0.43–0.97) | 2.45 (2.07–2.90) | 4.58 (2.57–12.48) | 6.13 (4.56–8.23) | 25.21 (5) |
| Non-diapause b | 960 | 2.83 (0.16) | 0.26 (0.20–0.36) | - | 0.75 (0.52–1.33) | - | 22.85 (5) |
| Non-diapause c | 956 | 1.74 (0.11) | 0.39 (0.32–0.47) | - | 2.13 (1.62–3.06) | - | 7.49 (6) |
| Saline Co-KS * | 400 | 2.73 (0.37) | 0.75 (0.34–1.37) | 2.86 (2.27–3.60) | 2.22 (1.26–17.81) | 2.97 (2.07–4.27) | 12.85 (4) |
| Sherman Co-KS * | 540 | 2.85 (0.32) | 1.76 (0.87–2.79) | 6.66 (5.46–8.14) | 4.95 (3.06–20.48) | 6.63 (4.94–8.89) | 28.40 (6) |
| Finney Co 1-KS * | 480 | 2.39 (0.34) | 1.59 (0.96–2.47) | 6.03 (4.82–7.55) | 5.45 (3.23–25.44) | 7.29 (4.83–11.0) | 11.75 (5) |
| Finney Co 2- KS * | 925 | 2.24 (0.16) | 2.19 (1.58–2.99) | 8.31 (7.02–9.85) | 8.19 (5.46–16.39) | 10.96 (8.34–14.4) | 15.30 (5) |
| Clay Co-NE * | 1630 | 1.88 (0.08) | 1.16 (0.97–1.38) | 4.39 (3.79–5.08) | 5.55 (4.25–7.77) | 7.42 (5.85–9.42) | 10.90 (6) |
| Perkins Co 1-NE * | 1410 | 1.94 (0.11) | 1.24 (0.85–1.72) | 4.71 (4.00–5.56) | 5.96 (3.84–10.38) | 7.62 (6.00–9.66) | 27.23 (6) |
| Perkins Co 2-NE * | 1438 | 1.87 (0.10) | 1.57 (1.24–2.00) | 5.97 (5.13–6.95) | 7.95 (5.59–13.10) | 10.17 (7.89–13.1) | 13.08 (5) |
| Perkins Co 3-NE * | 960 | 1.97 (0.13) | 0.92 (0.74–1.12) | 3.49 (2.90–4.21) | 4.12 (3.19–5.75) | 5.52 (4.21–7.22) | 6.89 (6) |
| Custer Co-NE * | 765 | 1.72 (0.14) | 0.76 (0.46–1.10) | 2.87 (2.28–3.61) | 4.19 (2.72–8.27) | 5.61 (4.14–7.60) | 15.70 (6) |
| Cuming Co-NE * | 480 | 2.09 (0.21) | 0.82 (0.59–1.07) | 3.12 (2.47–3.93) | 3.38 (2.42–5.59) | 4.52 (3.26–6.28) | 7.46 (6) |
| Pierce Co-NE * | 1864 | 1.62 (0.07) | 0.66 (0.53–0.84) | 2.52 (2.17–2.93) | 4.11 (2.93–6.48) | 5.50 (4.31–7.03) | 16.96 (6) |
| Chase Co-NE * | 720 | 1.89 (0.14) | 0.78 (0.60–1.01) | 2.97 (2.45–3.61) | 3.75 (2.59–6.44) | 5.01 (3.62–6.93) | 7.10 (5) |
aTotal number of neonates tested
bWCR lab colony from USDA/ARS North Central Agricultural Research Laboratory, Brookings, SD
cWCR lab colony from Crop Characteristics, Inc., Farmington, MN
*WCR field populations