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German Cockroach Bait Aversion J. Silverman

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German cockroach bait aversion Jules Silverman North Carolina State University
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Page 1: German Cockroach Bait Aversion J. Silverman

German cockroach bait aversion

Jules Silverman North Carolina State University

Page 2: German Cockroach Bait Aversion J. Silverman

Blattella germanica – German cockroach

•  Exclusively synanthropic – No evidence of populations apart from

human-maintained structures •  Omnivores •  Coprophages

•  Semisocial – aggregations

Page 3: German Cockroach Bait Aversion J. Silverman

Blattella germanica - Importance

•  Potent source of allergens causing asthma

•  Mechanical vector of pathogens

•  Nuisance, necessitating control with insecticides –  Health and environmental impacts

Page 4: German Cockroach Bait Aversion J. Silverman

Transition to Baits

•  Extremely high selection pressure for the evolution of insecticide resistance

•  Some evidence of physiological/metabolic resistance to the AI

Since mid-1980s

Page 5: German Cockroach Bait Aversion J. Silverman

Product performance assessment

Page 6: German Cockroach Bait Aversion J. Silverman

Bait Performance Decline Observed in Scattered

Locations Across the Globe

•  e.g. Florida, California, Puerto Rico, South Korea

Page 7: German Cockroach Bait Aversion J. Silverman

Product performance decline

-40

-20

0

20

40

60

80

100

% p

opul

atio

n re

duct

ion

Pre-1989 1989

National averageT-164

MAXFORCE and COMBAT Baits

Page 8: German Cockroach Bait Aversion J. Silverman

What went wrong?

•  Determined that baits were effective against lab strain – i.e. no manufacturing errors

•  T-164 Blattella were not resistant to hydramethylnon

Page 9: German Cockroach Bait Aversion J. Silverman

What went wrong?

•  Determined that baits were not consumed by T-164 and some other strains

•  Subsequently deleted bait components one by one and evaluated against T-164

Page 10: German Cockroach Bait Aversion J. Silverman

Bait component deletion study findings

•  No rejection of hydramethylnon •  No rejection of bait binders •  No rejection of preservatives •  No rejection of oatmeal

•  What’s left?

Page 11: German Cockroach Bait Aversion J. Silverman

0

10

20

30

40

50

60

70

80

90

100

Orlando normal T-164Strain

% o

f tot

al c

onsu

mpt

ion

Effect of corn syrup on strain consumption

Stimulates feeding

Inhibits feeding

Page 12: German Cockroach Bait Aversion J. Silverman

0102030405060708090

100%

of t

otal

con

sum

ptio

n

T-164 Orlandonormal

Strain

1 M GlucoseCS55 1 M Fructose

Stimulates feeding

Inhibits feeding

Effect of sugar on consumption by cockroach strain

Page 13: German Cockroach Bait Aversion J. Silverman

Glucose aversion and food preference

Glucose-averse Wild-type

Fructose/agar

Glucose/agar

Page 14: German Cockroach Bait Aversion J. Silverman

Genetics of glucose aversion

•  Incompletely-dominant •  Autosomal •  Likely single major gene •  Chromosome 9

Page 15: German Cockroach Bait Aversion J. Silverman

Glucose aversion: A case of behavioral resistance

DO NOT

EAT Glucose 

•  Behavioral aversion to a bait ingredient, but not to the AI •  Glucose is not toxic •  Genetically-based •  Highly adaptive under toxic

bait pressure •  Multiple populations

How do cockroaches mis-process

glucose as a deterrent?

Page 16: German Cockroach Bait Aversion J. Silverman

Brain processing

Glucose-aversion: Peripheral vs. Central?

Tastants GRs GRNs Behavior expressed

Rejection

Acceptance

Peripheral ? CNS ?

Page 17: German Cockroach Bait Aversion J. Silverman

Glucose-averse Wild-type

Which sensory appendages are involved?

Ablation assays

Page 18: German Cockroach Bait Aversion J. Silverman

Which gustatory appendages are involved in glucose aversion ? Paraglossae most important in glucose aversion

Ablation assays

Wada-Katsumata et al. 2011. Chemical Senses

Maxillary palps

Paraglossae

Labial palps

Paraglossae represent a minimal sensory

system for discriminating gustatory

stimuli

Page 19: German Cockroach Bait Aversion J. Silverman

Feed

ing

resp

onse

s (%

)

Concentration (mmol-1)

100

50

0 0.001 0.01 0.1 1 10 100 1000 0.001 0.01 0.1 1 10 100 1000

Glucose

Phagostimulants

Dose-response of the paraglossae to tastants

 Wild-type   Glucose-averse

Fructose Maltose Maltotriose

Glucose

Page 20: German Cockroach Bait Aversion J. Silverman

Glucose-averse %

coc

kroa

ches

resp

ondi

ng

Wild-type

100

50

0 100

50

0 % c

ockr

oach

es re

spon

ding

Concentration (mmol-1) 0.001 0.01 0.1 1 10 100 1000 0.001 0.01 0.1 1 10 100 1000

Glucose Fructose Maltose Maltotriose

Phagostimulants

Deterrents

Caffeine Quinine NaCl

Page 21: German Cockroach Bait Aversion J. Silverman

Do wild-type and glucose-averse strains differ in peripheral gustatory coding?

20 µm

●  ● 

Page 22: German Cockroach Bait Aversion J. Silverman

Different types of neurons excited by different types of chemical cues

Recording electrode

Glass capillary

Test solution

Gustatory neurons

Fructose Glucose Caffeine

Sensory differences: Tip recording

Indifferent electrode

Page 23: German Cockroach Bait Aversion J. Silverman

Sorting of impulses based on amplitude (mV) and duration (msec)

Cluster analysis

Recording

D-fructose stimulates 3 types of GRNs

● GRN1 ● GRN3 ● GRN4 

Fructose (8 mmol-1)

Duration

Am

plitu

de

Analysis of neuronal responses

Page 24: German Cockroach Bait Aversion J. Silverman

 Wild-type   Glucose-averse

Fructose stimulated a sugar receptor neuron

Fructose (8 mmol-1)

Caffeine (0.16 mmol-1)

Glucose (8 mmol-1)

● GRN1 ● GRN3 ● GRN4 

● GRN2 ● GRN3 ● GRN4 

● GRN1 ● GRN3 ● GRN4 

● GRN1 ● GRN2 ● GRN3 ● GRN4 

Amplitude

Dur

atio

n

Page 25: German Cockroach Bait Aversion J. Silverman

 Wild-type   Glucose-averse

Fructose stimulated a sugar receptor neuron

Fructose (8 mmol-1)

Caffeine (0.16 mmol-1)

Glucose (8 mmol-1)

● GRN2 ● GRN3 ● GRN4 

● GRN1 ● GRN3 ● GRN4 

● GRN1 ● GRN2 ● GRN3 ● GRN4 

● GRN1 ● GRN3 ● GRN4 

Amplitude

Dur

atio

n

Fructose stimulated a sugar receptor neuron = GRN1 Caffeine stimulated a bitter receptor neuron = GRN2

Page 26: German Cockroach Bait Aversion J. Silverman

Glucose (8 mmol-1)

Amplitude D

urat

ion

 Wild-type   Glucose-averse

Amplitude

Dur

atio

n

In glucose-averse cockroaches:

•  Glucose stimulates both sugar and bitter receptor neurons

Changes in gustatory sensillum function underlie glucose aversion (CNS may also be involved)

Wada-Katsumata et al. 2013. Science

Page 27: German Cockroach Bait Aversion J. Silverman

Generalization: Other strains

Page 28: German Cockroach Bait Aversion J. Silverman

Response to hydramethylnon – glucose bait

Page 29: German Cockroach Bait Aversion J. Silverman
Page 30: German Cockroach Bait Aversion J. Silverman

Resistance to Hydramethylnon

•  T-164 – 1.0

•  PR 712 - 30.4

•  PR 308 - 33.0

Resistance ratios – LD-50

Page 31: German Cockroach Bait Aversion J. Silverman

What’s next?

•  Assay other field-collected strains for resistance/aversion

•  Resistance to other bait AIs?

•  Aversions to other sugars (fructose)?

•  Determine linkage between resistance and aversion (in population and/or individual)

Page 32: German Cockroach Bait Aversion J. Silverman

Ayako Wada-Katsumata Blanton J. Whitmire Endowment

Coby Schal

Don Bieman

Southern IPM Center


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