Evidence for Decreasing Corn Earworm Susceptibility to Pyrethroids:

Impact & IPM Recommendations for 2007

W. Hutchison, E. Burkness, B. Jensen, R. Leonard, J. Temple, R. Weinzierl, R. Foster, T. Rabaey, B. Flood, S. Fleischer, P. Pietrantonio, R. Parker, M. Sandstrom, D. Changnon, B. Bishop, C. Welty, E. Roddy, E. Cullen

-University, Industry, Agency Partnership

-N. American Zea-Map Working Group

Great Lakes Expo 2006

Jim Jasinski - Ohio State University Extension

Presentation Overview

• Background on growing pyrethroid resistance

• Testing & Results

• Summary and Recommendations

Why is this Important in the Great Lakes Region?

• H. zea that infest our late season sweet corn, tomatoes, peppers, and snap beans come from southern source regions.

• Primary host crops in those source regions are cotton, sorghum, soybean, and corn.

• These crops receive numerous applications of pyrethroid insecticides.

• Pyrethroid resistance that evolves in southern crops may present a problem in the northern destinations of migrating H. zea

Crops at Risk: Midwest Values (2004)Crop Acres (harvested) Value ($)

Sweet Corn

-Processing 214,000 99.2 M

-Fresh Market 42,400 75.3 M

Snap Beans

-Processing 107,300 59.2 M

-Fresh Market 4,100 8.3 M

Tomatoes

-Processing 18,000 46.3 M

-Fresh Market 10,500 96.9 M

Bell Peppers

-Proc/Fresh Market 3,700 23.7 M

Total 400,000 408.9 M*USDA-NASS Quick Stats (www.nass.usda.gov/index.asp) (RAW roduct)

CEW

CEW

TFW

CEW

Implications for Zea Resistance in the Midwest

• Few to zero alternatives for many crops

• $400 Million at Risk in Midwest

• $ Impact does not yet include potential damage to Seed Corn Production

• Possible return migration in Fall conserves resistance genes? (Johnson 1995)– A function of midwest latitude?

CEW Migration: Classic Summer Scenario

CEW Source Region

LH

Inse

ct P

um

p

DROP ZONE

CEW Reverse Migration Example: Fall

CEW Source Region

HL

Inse

ct P

um

p

DROP ZONE

ZEA-MAP: Multi-state NetworkConnecting Collaborators- first year 2006

http://www.vegedge.umn.edu/ZeaMap/zeamap.htm

ZEA-MAP: Daily Migration Forecasts - 2006Northern Illinois University

(Mike Sandstrom, Dave Changnon, Dept. of Geography)

Types of Resistance Evaluation

• Adult Vial Tests (AVT)– Lab based– Single Dose (x micro grams ai)– Multiple Doses (5-30 micro grams ai)

• Larval Tests– Lab based

• Larval Tests – Field trials (small plots)

0

5

10

15

20

25

30

35

88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03

Year (1988-2003)

Trend for Resistance in the Southern StatesLouisiana: CEW Adult Vial Test (AVT): Cypermethrin

(5 µg/vial)

Roger Leonard, D. Cook, et al. (LSU) -- Southern U.S. --

AV

T S

urv

ival

(%

)

MeanYear

692004

402003

402005

172001

412002

931997

2000

1999

1998 88

49

81

Pyrethroid Efficacy in WI, MN Declines:

% Larval Control (all instars)Sweet corn (Capture/Warrior pooled)

2005 CEW Pyrethroid EfficacyMulti-state Midwest Summary

(Foster, Hutchison, Jensen, Rabaey, Weinzierl)

*Univ. of MN = Percent control is for all CEW instars; approximately 90% of larvae were late instar*MN Green Giant = all percent control values are for 3-6 th instar CEW only*Univ. of WI = Percent control is for all CEW instars; approximately 75% of larvae were late instar*IN Purdue = Percent control is for all CEW instars; approximately 80-90% of larvae were late instar*Univ. of IL = Percent control is for all CEW instarsNOTE: Slightly better results in 2006; Overall Mean of ca. 40-55% control

InsecticideRate

(oz/ac)Overall efficacy (% control)

(mean ± SD; range) n

Warrior 1CS 2.56-3.2 oz 19.3 ± 29.8 (0-71.4) 6

Capture 2EC 2.1-2.56 oz 37.3 ± 30.0 (7.7-78.6) 4

Mustang Max 0.8 EC 3.4-4 oz 33.4 ± 33.9 (0-75.0) 5

Baythroid 2EC 1.6-2.8 oz 19.8 ± 29.6 (0-53.8) 3

Untreated check - CEW/ear

-- 0.13 – 1.41

Multi-state Insecticide Trial Results - 2006 Rate Percent Control* Insecticide

P/ac

AI/ac

Overall efficacy (x¯±SD; range)

n

BC 0805 Bt -- -- 94.2±4.7 (87 -100) 5

Warrior 1CS 3.2 oz 0.025 57.0±16.5 (32 -75) 5

Warrior 1CS 3.84 oz 0.03 66.8±13.4 (44 -78) 5

Capture 2EC 2.56 oz 0.04 51.6±25.8 (18 -81) 5

Capt. (app. 1, 2) War. (app. 3, 4) 6.4 / 3.84 oz 0.10 / 0.03 64.6±24.4 (29 -94) 5

Coragen SC + MSO** 6.8 oz + 1%v/v 0.088 79.4±19.2 (50-99) 5

Untreated check - CEW/ear -- -- (0.43 -1.41) 5

*Univ. of MN - Bill Hutchison. Percent control is fo r all CEW instars; approximately 60% of larvae in the check were late instar General Mills/ Green Giant - Tom Rabaey. Percent control is for all CEW instars; approximately 85% of larvae in the check were late instar Univ. of WI - Bryan Jensen. Percent co ntrol is for all CEW instars; approximately 50% of larvae in the check were late instar Purdue Univ. - Rick Foster. Percent control is for all CEW instars; approximately 70% of larvae in the check were late instar Univ. of IL - Rick Weinzierl. Percent co ntrol is for late instar CEW; **MSO = Methylated seed oil

Colony n LD50 95% CL Slope X2 RR

SC-ESTILL-99 100 0.062 0.043 – 0.123 2.0 ± 0.46 n/a 31

Champaign 189 0.061 0.027 – 0.114 1.31 ± 0.25 6.59 30

Wisconsin 180 0.099 0.047 – 0.224 1.63 ± 0.23 17.81 49

Ontario 180 0.020 0.007 – 0.033 1.41 ± 0.25 5.44 10

St. Joseph 150 0.032 0.015 – 0.052 1.15 ± 0.22 4.93 16

LD50 Response of CEW Larvae to λ-Cyhalothrin 2004- Resistance response higher with Warrior (R. Leonard, LSU)

Resistance Ratio (RR) calculated from LD50 data (0.002 μg/larva) derived from SC Lab 1999.

Conclusions to date: The more elevated resistance ratios for Warrior may be due to response to a more “refined” pyrethroid isomer; also supports previous work of cross-resistance among pyrethroids. (Results with larvae may be deemed more conclusive than adult assays.)

LD50 Response of CEW Larvae to Cypermethrin 2006 – (J. Temple, R. Leonard; LSU)

Location N LD50 95% CL Slope X2 RR

Wisconsin 271 0.104 0.081-0.140 2.26±0.24 5.60 1-8

Minnesota 220 0.088 0.071-0.108 2.24±0.27 2.37 1-6

Winnsboro LA 220 0.087 0.069-0.109 2.04±0.25 1.46 1-6

Pennsylvania 239 0.036 0.025-0.046 1.60±0.21 1.99 0-3

Illinois 221 0.043 0.029-0.057 1.50±0.22 0.62 0-3

Indiana 200 0.036 0.024-0.049 2.11±0.29 5.38 0-3

Resistance Ratio (RR) calculated from LD50 data (0.013 – 0.065 μg) derived from MO and LA 1988; Cooperators: Jensen; T. Rabaey; S. Fleischer; Weinzierl; Foster.

Conclusions to date: Response of field-collected larvae for MN, WI locations show significant level of resistance; RRs > 5 generally reflect a significant genetic shift in resistance to an insecticide.

Assessing Midwest Level of CEW Resistance

• Currently, resistance remains variable, but trend is major concern…

• “Range of susceptibility”• Within a colony (R. Leonard):

– a) some show avg. resistance,– b) some high susceptibility,– c) some express very high resistance

• (e.g., 50% survival at 20 ug/vial)

Assessing Midwest Level of CEW Resistance (cont.)

• So far, few major control failures, Processing Sweet Corn, (Snap Beans ?)

• “Process Out” CEW; but how much?

• Lack of problem in Commercial fields? – Unique mortality effects in big fields? (vs. small plot trials)

• Commercial Fields: allow for adult control

• Adult control helps; but adults are not fully susceptible

CEW Moth Flight Cooperators: Hartstack Trap sites--2006

19

Pheromone Trap Study: Midwest US, 2006 Hartstack vs. Scentry trap

Hartstack

(# of moths)

Scentry

(# of moths)

Location Trapping interval

Total Per trap per night

Total Per trap per night

Polk Co., IA 6/8 – 9/5 352 3.91 135 1.50

Dakota Co., MN 1 6/2 – 9/29 2999 24.99 677 5.64

Dakota Co., MN 2 6/2 – 9/29 2158 17.98 305 2.54

Le Sueur Co., MN 6/2 – 9/29 2588 21.57 338 2.82

Clark Co., OH 7/5 – 9/26 2820 33.57 524 6.24

Franklin Co., OH 6/14 – 10/11 1158 9.65 159 1.33

Conclusions to date: Hartstack more consistent; better for resistance monitoring; provide necessary moth numbers

Pheromone Trap Study: Ohio, 2006 Hartstack vs. Scentry trap

0

100

200

300

400

500

600

700

6/30/067/7/067/14/067/21/067/28/068/4/068/11/068/18/068/25/069/1/069/8/069/15/069/22/069/29/0610/6/06

CEW Moth

HartstackScentry

CEW Adult Vial Test sites - 2006 (Cypermethrin)

10 micro grams

5 - 30 micro grams

Resistance Monitoring Results – 2006‘Standard AVT’ Method (moths from traps)(“results promising based on this method”)

Mean % survival (ug cypermethrin)

State* 5ug (n) 10ug (n)

MN 11 (170) 6.5 (170)

IN 14 (151) 2 (151)

WI 15 (100) 3 (100)

FMC, SD** --- 0.5 (4,760)

*Multi-dose AVT (0-30ug)**Single dose AVT (IA, IL, IN, MI, MN, NE, WI)

Response of Field-collected Larval Colonies to a Diagnostic Dose of Cypermethrin (5 μg/vial)

0

10

20

30

40

50

60

70

80

IL MN WI

% Survivorship

2003

2004

2005

2006

62

48

57 57

62

50

66

49

70

5553

Response of Field-collected Larval Colonies to a Diagnostic Dose of Cypermethrin (10 μg/vial)

0

10

20

30

40

50

60

IL MN WI

% Survivorship

2004

2005

2006

20

4

4345

26

*0*

16

33

56

“Return” Fall Migration in CEW? Can migrants complete egg-adult up north?

•Degree day Calculations started on either Aug. 1st or 15th using a 55F lower and 92F upper threshold.

•Egg to adult = 760 DDs

Chance of CEW “Return-South” Migration? - by Latitude (conserving Rr genes)

Arrival date 8/1 Arrival date 8/15

Latitude State

% chance Emerg.

Mean emerg.

Date

% chance Emerg.

Mean Emerg.

date

44 43’ MN 70 10/8 0 --

43 17’ WI 50 9/26 0 --

42 52’ NY 50 10/2 0 --

42 01’ IA 100 9/21 50 10/9

41 56’ MI 90 10/3 10 10/16

40 04’ IL 100 9/15 60 10/11

39 56’ PA 100 9/17 30 10/4

38 49’ OH 100 9/12 100 10/10

38 40’ IN 100 9/9 100 10/4

37 47’ VA 100 9/11 100 10/10

36 52’ KY 100 9/10 100 10/4

To What Extent Should We Be Concerned?

• Not Advocating Panic

• Increasing Discussions with Southern U.S. Entomologists

• Resistance Monitoring

• Need new resistance management plans

• New chemistries?

NC IPM Guidelines: 2007

• Cannot fully predict the CEW response in space or time • Resistance depends on level of selection in the South:

– a) continued level of pyrethroid use?– b) geographic extent of pyrethroid use?

• *Depends on continued “opportunity” for genetic mixing of moths each fall and spring in the south, prior to re-entry to the Midwest

• Numbers Game and Timing: Number of moths we receive each year; late-flight only vs. July + Aug. flights

NC IPM Guidelines: 2007• Use Pheromone Traps to Detect Flights

– Base spray interval off of trap catch and temperature– Use State recommendations for spray thresholds

• Alternative (experimental) recommendation: – In conjunction with pheromone trapping…– 1st spray applied at 50% silk– 2nd spray applied 3-4 days later– Later sprays @ 5-6 day intervals– Use Bifenthrin at max. rate (e.g, Capture; 0.10 lb ai / A) – Fresh-market, use Bt sweet corn for late plantings– Processors, “Process out” damage

Thanks to ALL Funding Agencies, Cooperators!

• NC IPM Regional Center (Michigan State and Univ. of Illinois)• IRAC-U.S.• University of Minnesota; Rapid Response Fund• Midwest Food Processors Assoc. (MN, WI, IL)• Minn. Dept. of Agric. IPM Fund• DuPont, Dow AgroSciences, FMC

• In-Kind Support; Multiple Sources (FMC; General Mills-Green Giant; WI DTCP; Greg Payne-Univ. of W.Ga; Dept. of Geography, NIU; Great Lakes Veg. Working Group, NC IPM Center)