Evidence of increasing L1014F kdr mutation frequency in Anopheles gambiae s.l.pyrethroid resistant following a nationwide distribution of LLINs by the Beninese National Malaria Control Programme

Objective:To determine the susceptibility status to pyrethroid in Anopheles gambiae s.l.(An.gambiae),the distribution of kdr"Leu-Phe"mutation in malaria vectors in Benin and to compare the current frequency of kdr"Leu-Phe"mutation to the previous frequency after long-lasting insecticide treated nets implementation.Methods:Larvae and pupae of An.gambiae s.l.mosquitoes were collected from the breeding sites in Littoral,Zou.Borgou and Alibori provinces.CDC susceptibility tests were conducted on unfed females mosquitoes aged 2-5 d old.An.gambiae mosquitoes were identified to species using PCR techniques.Molecular assays were also carried out to identify kdr mutations in individual mosquitoes.Results:The results showed that An.gambiae Malanville and Suru-lere populations were resistant to deltamethrin.Regarding An.gambiae Parakou and Bohicon populations,they were resistant to permethrin.PCR revealed 100%of mosquitoes tested were An.gambiae s.s.The L1014F kdr mutation was found in An.gambiae s.s.Malanville and Parakou at various allelic frequencies.The increase of kdr allelic frequency was positively correlated with CDC bioassays data.Conclusions:Pyrethroid resistance is widespread in malaria vector in Benin and kdr mutation is the main resistance mechanism involved.More attention may be paid for the future success of malaria control programmes based on LLINs with pyrethroids in the country.

Study of the efficacy of a Wheaton coated bottle with permethrin and deltamethrin in laboratory conditions and a WHO impregnated paper with bendiocarb in field conditions

Objective:To determine the efficacy of WHO impregnated paper and CDC coated bottle based on number of storage days and number of limes of consecutive use,in the assessment of insecticide vector susceptibility tests in laboratory and field conditions.Methods:Larvae and pupae of Anopheles gambiae s.l.mosquitoes were collected from the breeding sites in Seme-Kpodji and Cotonou districts in Southern Benin in April 2013 during the first rainy season.Anopheles gambiae s.l.mosquitoes were also collected from the breeding sites in Parakou district in Northern Benin in May 2013 at the beginning of the rainy season.Susceptibility tests were done using impregnated paper with bendiocarb(0.1%)following WHO protocol and stock solutions of permethrin(21.5 ug per bottle)and deltamethrin(12.5 ug per bottle)following CDC protocol on unfed female mosquitoes aged 2-5 days old.These bioassays were repeated a certain number of times.The temperature and relative humidity were monitored and recorded during the susceptibility tests.Results:This study showed that a WHO impregnated paper with bendiocarb could be used four times during four consecutive days in field conditions.Regarding a Wheaton coated bottle with permethrin or deltamethrin,they could be used at least three limes during four consecutive days in laboratory conditions.Conclusions:The day storage and the number of times that a WHO impregnated paper and a CDC coated bottle maintained their efficacy are useful in the assessment of insecticide vectors susceptibility tests.