Insecticide Susceptibility Profile of Anopheles gambiae s.l. from Ikot-Ekpene, Akwa Ibom State, Nigeria
K. N. Opara *
Department of Animal and Environmental Biology, University of Uyo, Uyo, Nigeria.
M. S. Ekanem
Department of Animal and Environmental Biology, University of Uyo, Uyo, Nigeria.
N. I. Udoidung
Department of Animal and Environmental Biology, University of Uyo, Uyo, Nigeria.
F. M. Chikezie
Department of Animal and Environmental Biology, University of Uyo, Uyo, Nigeria.
G. Akro
Ministry of Health, Akwa Ibom State, Nigeria.
L. P. Usip
Department of Animal and Environmental Biology, University of Uyo, Uyo, Nigeria.
D. E. Oboho
Department of Animal and Environmental Biology, University of Uyo, Uyo, Nigeria.
M. A. Igbe
Federal Ministry of Health, National Onchocerciasis Elimination Programme, Abuja, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Background: Mosquito resistance to routinely used insecticides is threatening malaria vector control strategies in sub-Saharan Africa. This study reports the susceptibility of wild populations of Anopheles gambiae s.l. from Ikot-Ekpene, Akwa Ibom State, Southern Nigeria to insecticides.
Methods: WHO standard methods were used to detect knock-down and mortality in wild female Anopheles mosquitoes collected from 4 rural communities in Ikot-Ekpene. The WHO diagnostic doses of 0.05% deltamethrin, 0.05% lambdacyhalothrin, 0.75% permethrin and 5% malathion were used. Bioassays were performed on non-blood-fed mosquitoes of ages 2 to 3 days old. Post exposure mortality after 24 hours and knock-down values for KDT50 and KDT95 were calculated.
Results: According to WHO criteria, insecticide resistance was not recorded at any of the studied sites and for any of the tested insecticide. Knock-down within 1 hour post insecticide exposure ranged from 98.7% to 100%. Mortality after 24 hours post exposure was 100% for all insecticides except lambdacyhalothrin which averaged 99.1%. There was high variability in KDT50 and KDT95 values across the sites.
Conclusion: Since the local Anopheles gambiae populations were susceptible to all the insecticides tested, vector control campaigns employing the use of any of the insecticide would not be compromised; however, there is need for continued monitoring to ensure early detection of resistance.
Keywords: Malaria, vectors, organophosphate, pyrethroid, assay, Ikot Ekpene, Nigeria