Assessing the Insecticidal Resistance and kdr Status of Anopheles to Pyrethroid and Organophosphate Insecticides in Osun State, Nigeria.
1
Biological Sciences, Fountain University, Osogbo, Nigeria
2
Animal and Environmental Biology, Osun State University, Osogbo, Nigeria
3
Public Health and Epidemiology, Nigerian Institute of Medical Research, Yaba, Nigeria
Popul. Med. 2026;8(Supplement Supplement 1):
ABSTRACT
BACKGROUND:
The persistent problem of insecticide resistance in Anopheles mosquitoes continues to pose a global public health threat. This research assesses the resistance levels of adult female Anopheles gambiae s.l to pyrethroids (Permethrin) and organophosphate (pirimiphosmethyl) insecticides, and the presence of the knockdown resistant (kdr) gene in six locations across the three senatorial districts in Osun State, Nigeria.
METHODS:
Larvae were collected weekly from 0700 to 1100 hours between January and December 2022. These larvae were then reared to adulthood in the Department of Animal and Environmental Biology laboratory at Osun State University, Osogbo, Nigeria, and were identified morphologically using standard keys. Bioassays for insecticides, including Permethrin (0.75%), deltamethrin (0.05%), alpha-cypermethrin (0.05%), and pirimiphosmethyl (0.25%), were carried out according to WHO procedures. The mosquitoes were also analyzed for the kdr gene.
RESULTS:
Pirimiphosmethyl showed higher knockdown (KD60) and mortality rates compared to the pyrethroids tested (p<0.05). There was no resistance observed to Pirimiphosmethyl across the study sites, with susceptibility being highest in Ila (63%) and lowest in Inisa (40%) (p<0.05). Pyrethroid resistance was noted, with mortality rates between 90-97% across the study areas. Specifically, Ila exhibited confirmed resistance to Permethrin, while Ejigbo showed resistance to Alpha-cypermethrin and Deltamethrin, with mortality rates of 86%, 60%, and 40%, respectively (p<0.05). The kdr gene was detected throughout the study areas.
CONCLUSIONS:
The study highlights the effectiveness of pirimiphosmethyl against female Anopheles gambiae s.l and the limited efficacy of pyrethroids. This underscores the importance of enhancing surveillance of Anopheles insecticide resistance, using pirimiphosmethyl in indoor residual sprays (IRS), and frequently rotating the types of pyrethroids used in insecticide-treated nets (ITNs) to manage resistance.
The persistent problem of insecticide resistance in Anopheles mosquitoes continues to pose a global public health threat. This research assesses the resistance levels of adult female Anopheles gambiae s.l to pyrethroids (Permethrin) and organophosphate (pirimiphosmethyl) insecticides, and the presence of the knockdown resistant (kdr) gene in six locations across the three senatorial districts in Osun State, Nigeria.
METHODS:
Larvae were collected weekly from 0700 to 1100 hours between January and December 2022. These larvae were then reared to adulthood in the Department of Animal and Environmental Biology laboratory at Osun State University, Osogbo, Nigeria, and were identified morphologically using standard keys. Bioassays for insecticides, including Permethrin (0.75%), deltamethrin (0.05%), alpha-cypermethrin (0.05%), and pirimiphosmethyl (0.25%), were carried out according to WHO procedures. The mosquitoes were also analyzed for the kdr gene.
RESULTS:
Pirimiphosmethyl showed higher knockdown (KD60) and mortality rates compared to the pyrethroids tested (p<0.05). There was no resistance observed to Pirimiphosmethyl across the study sites, with susceptibility being highest in Ila (63%) and lowest in Inisa (40%) (p<0.05). Pyrethroid resistance was noted, with mortality rates between 90-97% across the study areas. Specifically, Ila exhibited confirmed resistance to Permethrin, while Ejigbo showed resistance to Alpha-cypermethrin and Deltamethrin, with mortality rates of 86%, 60%, and 40%, respectively (p<0.05). The kdr gene was detected throughout the study areas.
CONCLUSIONS:
The study highlights the effectiveness of pirimiphosmethyl against female Anopheles gambiae s.l and the limited efficacy of pyrethroids. This underscores the importance of enhancing surveillance of Anopheles insecticide resistance, using pirimiphosmethyl in indoor residual sprays (IRS), and frequently rotating the types of pyrethroids used in insecticide-treated nets (ITNs) to manage resistance.
| eISSN: | 2654-1459 |
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