impact of sub-lethal exposure to insecticides on vector control

Impact of Sub-Lethal Exposure to Insecticides on Vector Control

Lee Cohnstaedt and Sandra AllanUSDA-ARS-CMAVETriservices Meeting

Feburary 2010

Insecticide contact

Pyrethroids

If not dead, then what?

Mosquito species

Behavioral assays

Entrance

Air+CO2

*Capillary release attractant*CO2 release 50ml/min

Attractant

*Infrared light was used illuminate nocturnally active mosquitoes.

*Treatment level lethal dose25

Flight path analysis

Untreated Cx. quinquefasciatus

Deltamethrin treated Cx. quinquefasciatus

Flight path analysis

Untreated An. albimanus

Permethrin treated An. albimanus

Flight path analysis

Treated Ae. aegypti

Untreated Ae. aegypti

Average flight velocity

**Velocity

020406080

100120

Cx quinquefasciatus An albimanus Ae aegpyti

Mea

n ve

loci

ty (c

m/s

)

Contol Deltamethrin Permethrin

0

1

2

3

4

5

6

7

8

Cx quinquefasciatus An albimanus Ae aegypti

Seco

nds

Control Deltamethrin Permethrin

Time in flight

012345678

Cx quinquefasciatus An albimanus Ae aegypti

Seco

nds

Control Deltamethrin Permethrin

* *

Heading

-20-15-10

-505

101520

Deg

rees

Control Detamethrin Permethrin0

1

2

3

4

5

6

7

8

Cx quinquefasciatus An albimanus Ae aegypti

Seco

nds

Control Deltamethrin Permethrin

*

*

0.0%10.0%20.0%30.0%40.0%50.0%60.0%70.0%80.0%90.0%

100.0%

Cx quinquefaciatus An albimanus Ae aegypti

% B

lood

Fed

Control Permethrin Deltamethrin

Blood feeding

*

0

1

2

3

4

5

6

7

8

Cx quinquefasciatus An albimanus Ae aegypti

Seco

nds

Control Deltamethrin Permethrin

Implications

The sublethal affects of pyrethroids on a mosquito’s ability to detect and locate hosts may increase the efficacy of aerial and residual spraying treatments beyond their immediate killing impact.

Personal protective measures

Band

Sleeve

Phlebotomuspapatasi

Treatment Hand Band Sleeve Bite protection

Untreated 20 (29%) 11 (16%) 37 (54%) ---

Sleeve (permethrin) 43 (26%) 40 (24%) 84 (50%) -28.5%

Sleeve (permethrin) + Band (TL-I-73) 129 (27%) 86 (18%) 269 (56%) 16.9%

Band (TL-I-73) 39 (49%) 12 (15%) 28 (35%) 21.8%

Sleeve (permethrin) + Band (UB-21) 27 (40%) 12 (18%) 28 (41%) 94.1%

Number of landings per 20 minutesLanding site

Band

Sleeve

Implications

Sand flies predominantly land on the sleeve before moving towards the exposed skin; therefore a lethal insecticidal barrier at the uniform-skin interface will reduce disease transmission.

Acknowledgments• Uli Bernier• Matt Aubuchon

• Adrian Duehl• Erin Vrzal • Nathan Newlon