Ecological Effects of Ecological Effects of Transgenic Crops: Non-target Transgenic Crops: Non-target

Effects in Effects in BtBt Cotton Cotton

Steven E. NaranjoUSDA-ARS Phoenix, Arizona

&

Peter C. EllsworthUniversity of Arizona, Maricopa, Arizona

This presents the results of research only. Mention of a proprietaryproduct does not constitute endorsement or recommendation for its use by USDA.

Pest Complex - Western U.S. CottonPest Complex - Western U.S. Cotton

Lygus hesperus

Bemisia tabaci

Pectinophora gossypiella

Key Pests Sporadic and Minor Pests

Cotton bollwormTobacco budworm

ArmywormsLoopers

Cotton leafperforatorSaltmarsh caterpillar

Cutworms

FleahoppersPlant bugsStink bugs

Cotton aphidThrips

Spider mites

Insecticide Use PatternsInsecticide Use PatternsArizona CottonArizona Cotton

19901991

19921993

19941995

19961997

19981999

2000

Mea

n a

pp

lica

tio

ns

per

acr

e

0

2

4

6

8

10

12

14

0

2

4

6

8

10

12

14

Pink bollwormWhiteflyLygus Other

Bt cottonInsect growth regulators

Ellsworth and Jones 2000

Selective Insecticide UseSelective Insecticide UseArizona CottonArizona Cotton

1996 1997 1998 1999 2000

% A

crea

ge

trea

ted

0

10

20

30

40

50

60

70

80

Bt cotton Pyriproxyfen Buprofezin

Natural Enemy Complex -Western U.S.Natural Enemy Complex -Western U.S.Parasitoids Predators

30+ species

HyposterCopidosomaMicroplitis

LysiphlebusChelonusLespesia

EretmocerusEncarsiaAnaphes

Leiophron

50+ species

GeocorisOriusNabisZelus

CollopsHippodamia

DrapetisChrysoperla

LabiduraMisumenops

Natural Enemies – Pectinophora gossypiellaNatural Enemies – Pectinophora gossypiella

Predators

23 species described9 species (immunological ID)

Parasitoids

4 native species described (rare)16 exotic species introduced

(0 established)

Non-Target Effects(Arthropods)

Abundance Diversity

Function

General MethodsGeneral MethodsNon-target abundance/diversityNon-target abundance/diversity

Replicated experimental studies at MAC Treatments:

Bt cotton / conventional cotton Unsprayed for any pest Insecticides for all pests as needed

Sampling by sweep nets, beat buckets, whole plants, pitfall traps

ANOVA, EstimatorS V. 5 (Colwell) for diversity analyses

Natural Enemy AbundanceNatural Enemy Abundance

Natural Enemy AbundanceNatural Enemy AbundanceNo InsecticidesNo Insecticides

Misum Collops Geocoris Orius Nabis Zelus Chrysop Drapetis Hymen

Cu

m. a

rth

rop

od

-day

s (5

0 sw

eep

s)

0

400

800

1200

1600

2000

2400

Misum Collops Geocoris Orius Nabis Zelus Chrysop Drapetis Hymen0

400

800

1200

1600

4530 5611

0.98 0.37

0.40

0.340.03

0.08 0.24

0.28

0.57

0.700.23

0.89

0.18 0.66

0.160.16

0.39

0.51

1999

2000 Bt cotton Non-Bt

Natural Enemy AbundanceNatural Enemy AbundanceNo InsecticidesNo Insecticides

1999

9 Jun29 Jun

19 Jul8 Aug

28 Aug17 Sep

Cu

m. a

rth

rop

od

-day

s (5

0 sw

eep

s)

0

4000

8000

12000

160002000

9 Jun29 Jun

19 Jul8 Aug

28 Aug17 Sep

0

2000

4000

6000

8000

P = 0.18 P = 0.29Bt cottonNon-Bt

Natural Enemy AbundanceNatural Enemy AbundanceInsecticides as Needed (e.g. 1999)Insecticides as Needed (e.g. 1999)

Bt cottonNon-Bt

UnsprayedSprayed

Arthropod Community StructureArthropod Community Structure

Diversity(Fisher's alpha)

1999 20000

5

10

15

20

Evenness(Shannon)

1999 20000.0

0.2

0.4

0.6

0.8

*

Non-Bt Bt cotton

Community Structure – Pitfall TrapsCommunity Structure – Pitfall Traps(Bt vs. Non-Bt)(Bt vs. Non-Bt)

70

68

57 57

Community Structure – Pitfall TrapsCommunity Structure – Pitfall Traps(Sprayed vs. Unsprayed)(Sprayed vs. Unsprayed)

69

74

68

40

Natural Enemy FunctionNatural Enemy Function

MethodsMethodsNatural Enemy FunctionNatural Enemy Function

Replicated experimental studies at MAC No insecticides Estimate rates of predation and parasitism

Sentinel pink bollworm egg masses (20 per plot)

Life tables for whitefly nymphs (50 per plot)

Natural Enemy FunctionNatural Enemy FunctionPredation on Pink Bollworm EggsPredation on Pink Bollworm Eggs

19 July 2001

Pro

po

rtio

n e

aten

0.0

0.2

0.4

0.6

0.8

1.0Bt cottonNon Bt

1 August 2001 30 August 2001

0.0

0.2

0.4

0.6

0.8

1.0

Natural Enemy FunctionNatural Enemy FunctionMortality of Whitefly NymphsMortality of Whitefly Nymphs

12 July 2001

Predation Parasitism

Mar

gin

al r

ate

of

mo

rtal

ity

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Bt cottonNon Bt

20 August 2001

Predation Parasitism0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Conservation Biological ControlConservation Biological ControlAn ExampleAn Example

Whitefly IPM in Cotton

Bt Cotton IGRs

Natural Enemies

Impact of ConservationImpact of Conservation

1997

Thanks toThanks to

Virginia Barkley

Kim Beimfohr

Becci Burke

Melanie Charney

Scott Davis

Ghislaine Majeau

Ruben Marchosky

Greg Owens

Jeffrey Rivas

Doug Sieglaff