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
Thy
moq
uino
ne
Car
vacr
ol
Ince
nse
Ced
ar
Noo
tkat
one
pow
der
Noo
tkat
one
crys
talli
ne
Noo
tkat
one
8
13-
hydr
oxyv
alen
cene
Noo
tkat
one
1-10
epox
ide
Noo
tkat
ol
Val
ence
ne-1
3-al
dehy
de
pure
AY
C
Noo
tkat
ene
Noo
tkat
one-
1,10
-11
,12-
diep
osid
e
Val
ence
ne 5
Cad
inen
e F
ract
ion
Van
illin
d-Li
mon
ene
LC
50 (
mg
/ml)
Ae. aegypti Cx. quinq.
Intrinsic Toxicity of AYC and IC components
0
10
20
30
40
50P
yret
hrum
Thy
moq
uino
ne
Car
vacr
ol
Ince
nse
Ced
ar
Noo
tkat
one
pow
der
Noo
tkat
one
crys
talli
ne
Noo
tkat
one
8
Noo
tkat
ol
Val
ence
ne-1
3-al
dehy
de
pure
AY
C
LC
50 (
mg
/ml)
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