New Developments in Vector Control Insecticide Resistance and Natural Product Development Janet McAllister Centers for Disease Control and Prevention Fort.

New Developments in Vector ControlInsecticide Resistance and Natural Product Development

Janet McAllisterCenters for Disease Control and Prevention

Fort Collins, CO

"The findings and conclusions in this presentation are those of the author and do not necessarily represent the views of the Centers for Disease Control and Prevention."

Public Education and Community Outreach

Resistance MonitoringPhysical Control Biological

ControlChemical Control

DiseaseSurveillance Mapping

Mosquito Sampling and Surveillance

Legal Actions

Resistance Issues

What is it? When will it arrive? Once it’s here that’s it for that chemical/class. How do I know I have it? What do I do? What roles do outside forces play in selection

for resistance? Where do I go for help?

Areawide Mosquito Adulticides

Chemical Class Year usesMalathion OP 1950 Crops, livestock, home,

ornamental, forest, public health

Naled OP 1960 Crops, livestock, ornamental, greenhouses, forest, public health

Chlorpyriphos OP 1966 Crops, home, stored products, public health

Resmethrin PY 1968 House, ornamental, livestock premisis, public health

Sumethrin PY 1971 House, greenhouses, livestock premisis, ornamentals, public health

Permethrin PY 1974 Crops, livestock, public health, ornamentals, greenhouses

Pyrethrins PY* ca1828 Crops, livestock, home, public health, ornamentals, pets, food handling establishments

What’s it all mean to a mosquito control district: The problem

Current application rate of resmethrin was not killing mosquitoes in some parts of Harris county

No knowledge of what rate to use for alternative pyrethroids

Field testing is cost and labor intensive and traditional resistance tests have never been correlated to field results

Harris County Mosquito Control District Adulticide Usage Timeline 1965-2004

SLE and WNV Mosquitoes

Initial field-trial results from Area 51

0

5

10

15

20

25

30

35

40

45

Per

cen

t M

ort

alit

y

Scourge.003 lb/acre

Scourge.007 lb/acre

Anvil 10:10.003 lb/acre

Perm-X .003lb/acre

Materials for Bottle Bioassay.

Insecticides vary in the rate in which they intoxicate mosquitoes

0102030405060708090

100

0 15 30 45 60 75 90

time (min.)

Per

cent

Mor

talit

y MalathionFenthionResmethrinPermethrinNaledTemephos

An. freeborni

Wiebull Distribution with frailty model and interval sensing components

2005

2006

Change in area 205 from 2005 to 2006

Steps to field test mosquitoes

Field Study Site in Harris County

Mortality of Culex quinquefasciatus in field and bottle tests from Area 51

0

20

40

60

80

Sumethrin Permethrin Resmethrin

Field Tests Bottle Tests

Mortality of Culex quinquefasciatus in caged field trials

020406080

100

Area 51 Area 55 Area 67

Malathion SumethrinPermethrin Resmethrin

Objectives

Is there a correlation between results from field tests for resistance and bottle bioassays?

Help characterize the resistance mechanism(s) involved in resistance to pyrethroids in Harris County.

Enzyme results – area 109

Oxidase levels not significantly different

Esterase levels are significantly higher

Oxidases in Cx. quinquefasciatus

0

10

20

30

1 4 7 10 13 16 19 22 25 28 31 34 37 40

absorbance (x 0.1)

freq

uen

cy

colony area 109

a esterases in Cx. quinquefasciatus

0

5

10

15

20

1 4 7 10 13 16 19 22 25 28 31 34 37 40

absorbance (x 0.1)

freq

uen

cy

colony area 109

b esterases in Cx. quinquefasciatus

0

5

10

15

1 4 7 10 13 16 19 22 25 28 31 34 37 40

absorbance (x 0.1)

freq

uen

cy

colony area 109

Malathion mechanism expression from area 109

0102030405060708090

100

0 15 30 45 60

Time (min.)

Per

cen

t M

ort

alit

y

Malathion

Mal + PBO

Mal + DEF

Esterase +

Esterase +

Oxidase

EsteraseOxidase +

Esterase

Esterase +

Oxidase

The plan for now- 2005-2008

Alternate highest rate of Resmethrin with Malathion

If Resmethrin totally fails, switch to permethrin

Incorporate yearly resistance testing to determine when changes in treatment scheme need to happen

Re-evaluate how to test for resistance

Malathion susceptibility from field tests – data with both years

0102030405060708090

100

51 53 55 67 520 721 936

2005 2006 Average

Still to go

Correlation between types of test? Data “manipulation” still underway

Mapping of mechanisms Multiple mechanisms detected from different foci,

mapping still underway

More intense collecting from selected areas to see how resistance genes are distributed with more precise resolution

How is rotation of chemicals affecting control?

Area 51 collection sites as of Aug 2006 and treatment history

2004 – 5 treatments with Scourage®

2005 – 13 treatments with Scourage® and 13 with Fyfanon®

2006 – 7 treatments with Scourage® and 8 with Fyfanon®

New Chemicals for Control? Incense Cedar

Thymoquinone Pure Incense Cedar Nootkatone Carvacrol

Others Vanillin D-limonene

Alaskan yellow cedar Nootkatone Nootkatol Carvacrol 13-hydroxy-valencene Valencene-13-aldehyde Pure Alaskan yellow

cedar Nootkatene Nootkatone-1,10-11,12-

diepoxide Valencene5 Cadinene fraction Vanillin D-limonene

Monoterpene and Eromophilane Sesquiterpenes Isolated from Alaska Yellow Cedar

NOOTKATOL

Previous Work

Tick repellent and toxicity tests1st small scale field trials in NJ in

2006 against larval and adult TicksFormulated with all 25b inerts

Initial screening for mosquito repellency and toxicity

Intrinsic Toxicity of AYC and IC components

050

100150200250300350400450500

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LC

50 (

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/ml)

Ae. aegypti Cx. quinq.

Intrinsic Toxicity of AYC and IC components

0

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Ae. aegypti Cx. quinq.

64

.09 .06

Natural products – Intrinsic Toxicity compared to common insecticides

Species Insecticide LD50 (ng/mg)

LD95

(ng/mg)

Py ratio

Ae.aegypti Malathion 1.5 3.51 0.15

Permethrin 18.2 156 1.8

pyrethrum 10.1 39.8 --------

Thymoquinone 631 1765 62

Carvacrol 1206 2273 119

Incense cedar 1251 2148 124

Cx. quinq. Malathion 3.53 7 0.66

Permethrin 3.18 15 0.60

pyrethrum 5.32 13.5 ----------

thymoquinone 355 635 67

carvacrol 857 1450 161

Incense cedar 748 1366 141

MOA Study Design

NaturalProductTopical

Application toMosquitoes

An. gambiaeMRA-698

Na+ channelmutation

An. gambiaeMRA-116

GABAmutation

Culex?ACHE

mutation

???Octopamine

mutation

An. gambiaeG3

susceptiblebase-line

See if you can find your way through this perplexing maze!

Start

Finish

Immediate Next Steps

Fill in a few gaps with An. gambiaeMode of Action study with An.

gambiaeField “feasibility” study – minimal

formulationShop for a partner with industryOther ideas???

Thanks to:

Joe Piesman and Marc Dolan, CDC

Joe Karchesy, Oregon State University

Harris Co. Mosquito Control