Control of pyrethroid-resistant Anopheles gambiae and Culex quinquefasciatus mosquitoes with chlorfenapyr in Benin.
OBJECTIVE
To compare the efficacy of chlorfenapyr applied on mosquito nets and as an indoor residual spray against populations of Anopheles gambiae and Culex quinquefasciatus in an area of Benin that shows problematic levels of pyrethroid resistance.


METHODS
Eight-week trial conducted in experimental huts.


RESULTS
Indoor residual spraying killed 82.9% of An. gambiae overall (mean mortality: 79.5%) compared to 53.5% overall (mean mortality: 61.7%) in the hut containing the lower dosed ITN. Analysis of data on a fortnightly basis showed high levels of mosquito mortality and blood-feeding inhibition during the first few weeks after treatment. Control of C. quinquefasciatus by the IRS and ITN interventions showed a similar trend to that of An. gambiae and though the average level of mortality was lower it was still much higher than with pyrethroid treatments against this population. Chlorfenapyr's reputation for being rather slow acting was evident particularly at lower dosages. The treatments showed no evidence of excito-repellent activity in this trial.


CONCLUSIONS
Chlorfenapyr has the potential to control pyrethroid resistant populations of A. gambiae. There is a need to develop long-lasting formulations of chlorfenapyr to prolong its residual life on nets and sprayed surfaces. On nets it could be combined with a contact irritant pyrethroid to give improved protection against mosquito biting while killing pyrethroid-resistant mosquitoes that come into contact with the net.
N'Guessan
Raphael
R
London School of Hygiene and Tropical Medicine, London, UK.
Boko
Pelagie
P
Odjo
Abiba
A
Knols
Bart
B
Akogbeto
Martin
M
Rowland
Mark
M
D000818:Animals; D000852:Anopheles; D001512:Bedding and Linens; D001541:Benin; D003465:Culex; D007305:Insecticide Resistance / Q000187:drug effects; D007306:Insecticides; D008288:Malaria / Q000517:prevention & control; D009032:Mosquito Control / Q000379:methods*; D011722:Pyrethrins
D007306:Insecticides; D011722:Pyrethrins; C436643:chlorfenapyr