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.
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.
Citation
Tungu, P.; Magesa, S.; Maxwell, C.; Malima, R.; Masue, D.; Sudi, W.; Myamba, J.; Pigeon, O.; Rowland, M. 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. Malaria Journal (2010) 9 (1) 21. [DOI: 10.1186/1475-2875-9-21]