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. 2010 Jan 19:9:21.
doi: 10.1186/1475-2875-9-21.

Evaluation of PermaNet 3.0 a deltamethrin-PBO combination net against Anopheles gambiae and pyrethroid resistant Culex quinquefasciatus mosquitoes: an experimental hut trial in Tanzania

Patrick Tungu  1 , Stephen Magesa, Caroline Maxwell, Robert Malima, Dennis Masue, Wema Sudi, Joseph Myamba, Olivier Pigeon, Mark Rowland
Affiliations

Evaluation of PermaNet 3.0 a deltamethrin-PBO combination net against Anopheles gambiae and pyrethroid resistant Culex quinquefasciatus mosquitoes: an experimental hut trial in Tanzania

Patrick Tungu et al. Malar J. .

Abstract

Background: Combination mosquito nets incorporating two unrelated insecticides or insecticide plus synergist are designed to control insecticide resistant mosquitoes. PermaNet 3.0 is a long-lasting combination net incorporating deltamethrin on the side panels and a mixture of deltamethrin and synergist piperonyl butoxide (PBO) on the top panel. PBO is an inhibitor of mixed function oxidases implicated in pyrethroid resistance.

Method: An experimental hut trial comparing PermaNet 3.0, PermaNet 2.0 and a conventional deltamethrin-treated net was conducted in NE Tanzania using standard WHOPES procedures. The PermaNet arms included unwashed nets and nets washed 20 times. PermaNet 2.0 is a long-lasting insecticidal net incorporating deltamethrin as a single active.

Results: Against pyrethroid susceptible Anopheles gambiae the unwashed PermaNet 3.0 showed no difference to unwashed PermaNet 2.0 in terms of mortality (95% killed), but showed differences in blood-feeding rate (3% blood-fed with PermaNet 3.0 versus 10% with PermaNet 2.0). After 20 washes the two products showed no difference in feeding rate (10% with 3.0 and 9% with 2.0) but showed small differences in mortality (95% with 3.0 and 87% with 2.0). Against pyrethroid resistant Culex quinquefasciatus, mediated by elevated oxidase and kdr mechanisms, the unwashed PermaNet 3.0 killed 48% and PermaNet 2.0 killed 32% but after 20 washes there was no significant difference in mortality between the two products (32% killed by 3.0 and 30% by 2.0). For protecting against Culex PermaNet 3.0 showed no difference to PermaNet 2.0 when either unwashed or after 20 washes; both products were highly protective against biting. Laboratory tunnel bioassays confirmed the loss of biological activity of the PBO/deltamethrin-treated panel after washing.

Conclusion: Both PermaNet products were highly effective against susceptible Anopheles gambiae. As a long-lasting net to control or protect against pyrethroid resistant mosquitoes PermaNet 3.0 showed limited improvement over PermaNet 2.0 against Culex quinquefasciatus.

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Figures

Figure 1
Figure 1
Efficacy of treated netting after washing as determined by WHO cone bioassay tests with Anopheles gambiae Kisumu.
Figure 2
Figure 2
Efficacy of PermaNet 3.0 top and side panels against pyrethroid resistant Culex quinquefasciatus Masimbani as determined by WHO cone bioassay tests.
Figure 3
Figure 3
Tunnel tests using PermaNet 3.0 top and side netting before and after washing (10 or 20 times) against pyrethroid susceptible (Anopheles gambiae and Culex TPRI) and resistant (Culex Masimbani) mosquitoes - Percentage passage through the holed netting.
Figure 4
Figure 4
Tunnel tests using PermaNet 3.0 top and side netting before and after washing (10 or 20 times) against pyrethroid susceptible (Anopheles gambiae and Culex TPRI) and resistant (Culex Masimbani) mosquitoes - Percentage blood-feeding.
Figure 5
Figure 5
Tunnel tests using PermaNet 3.0 top and side netting before and after washing (10 or 20 times) against pyrethroid susceptible (Anopheles gambiae and Culex TPRI) and resistant (Culex Masimbani) mosquitoes - Percentage blood-feeding among those mosquitoes that penetrated the netting.
Figure 6
Figure 6
Tunnel tests using PermaNet 3.0 top and side netting before and after washing (10 or 20 times) against pyrethroid susceptible (Anopheles gambiae and Culex TPRI) and resistant (Culex Masimbani) mosquitoes - Percentage mortality.
Figure 7
Figure 7
Chemical analysis of deltamethrin and PBO content of PermaNets used in the hut trial. Content of samples were analyzed pre and post washing and post trial. Number of washes are recorded in parenthesis on X axis. PBO content was 10 times the values recorded on the Y axis. Confidence intervals reported for deltamethrin on side netting.
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