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Tables 3, 4, and 5 from:


Hutchison, W. D., Burkness, E. C., Jensen, B., Leonard, B. R., Temple, J., Cook, D. R., Weinzierl, R. A., Foster, R. E., Rabaey, T. L., and Flood, B. R. 2007. Evidence for decreasing Helicoverpa zea susceptibility to pyrethroid insecticides in the Midwestern United States. Online. Plant Health Progress doi:10.1094/PHP-2007-0719-02-RV.


Table 3. Efficacy of pyrethroids from 2005 Midwest Multi-state H. zea pyrethroid efficacy trials.u

Insect-
icide
Rate Percent control Overall efficacy
by product
(x SD; range)
n
P/
acre
ai/
acre
MN /
U of MN
v
MN /
Green
Giant
w
WI /
U of WI
x
IN /
Purdue
y
IL
U of IL
z
Lambda-cyhalothrin 2.56-3.2 oz 0.02-0.025 71.4 15.4 0.0 9.9 0.0 19.3 29.8
(0-71.4)
6
Bifenthrin 2.1-2.56 oz 0.033-0.04 78.6 36.7 7.7 26.2 37.3 30.0 (7.7-78.6) 4
Zeta-
cyper-
methrin
3.4-4 oz 0.021-0.025 75.0 64.1 0.0 9.2 18.8 33.4 33.9 (0-75.0) 5
Cyfluthrin 1.6-2.8 oz 0.025-0.044 53.8 5.7 0.0 19.8 29.6 (0-53.8) 3
Untreated check - CEW/ear 0.28 0.39 0.13 1.41 0.16

 u Standard replicated sweet corn trials with randomized complete block design (4 replications) [e.g., (5)].

 v University of Minnesota, W. Hutchison. Percent control is for all CEW instars; approximately 90% of larvae were late instar.

 w General Mills/Green Giant, T. Rabaey. Percent control is for 3-6th instars.

 x University of Wisconsin, B. Jensen. Percent control is for all CEW instars; approximately 75% of larvae were late instars.

 y Purdue University, R. Foster. Percent control is for all CEW instars; approximately 80 to 90% of larvae were late instars.

 z University of Illinois, R. Weinzierl. Percent control is for all CEW instars; majority was late instars (20).


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Table 4. Mortality response (LD50) of H. zea larvae to cypermethrin following larval collections from sweet corn during August-September in selected Midwestern US and Canadian sweet corn, as well as Louisiana locations, 2004, compared with previous reference colonies, 1993-1998.

Colony n LD50 95% CL Slope X2 RR*
Louisiana-1998 160 0.049 0.022 0.066 1.86 0.18 n/a 0-4
Illinois-93 n/a 0.096 0.054 0.171 1.16 0.36 n/a 1-7
Arkansas (ARK-93) n/a 0.159 0.121 0.212 2.02 0.30 n/a 2-12
Champaign, Illinois-04 189 0.061 0.027 0.114 1.31 0.25 6.59 1-5
Wisconsin-04 180 0.099 0.047 0.224 1.63 0.23 17.81   2-8
Minnesota-04 120 0.039 0.021 0.062 1.20 0.29 3.35 0-3
Ontario, Canada-04 180 0.020 0.007 0.033 1.41 0.25 5.44 0-1
St. Joseph, LA-04 150 0.032 0.015 0.052 1.15 0.22 4.93 0-3
Macon Ridge, LA-04  79 0.200 0.142 0.315 2.66 0.51 1.16 3-15

 * Resistance Ratio (RR) calculated from LD50 data (0.013 to 0.065 μg) derived from MO and LA, respectively, 1988.


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Table 5. Mortality response (LD50) of H. zea larvae to λ-cyhalothrin following larval collections from sweet corn during August-September 2004, compared with early (May) and late (August) collections in Louisiana, and a known pyrethroid-resistant colony from South Carolina (Estill-99).

Colony n LD50 95% CL Slope X2 RR*
Champaign, IL 208 0.022 0.014 0.031 1.49 0.22 2.22 11
Arlington, WI 150 0.078 0.059 0.103 2.18 0.31 3.40 39
Ontario, Canada 210 0.018 0.009 0.026 1.29 0.22 5.44 9
LA-Early-Macon Ridge 140 0.016 0.006 0.024 1.65 0.34 6.03 8
LA-Late-St. Joseph 120 0.035 0.024 0.047 2.43 0.43 4.13 17.5
SC-ESTILL-99 100 0.076 0.043 0.151 2.0 0.46 n/a 38

 * Resistance Ratio (RR) calculated from LD50 data (0.002 μg/larva) derived from the Clemson, SC lab, based on field-collected H. zea larvae in S. Carolina cotton, as of 1999 (3).


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