<p>Overall pooled proportional mortality (REML).</p>

Background

Arboviruses including dengue, Zika, and chikungunya pose a growing health threat in Nigeria, where Aedes aegypti is the main vector. Insecticide-based control is increasingly undermined by resistance. Although individual studies have reported resistance, no systematic review has synthesized these findings. This study assessed the prevalence, distribution, and mechanisms of insecticide resistance in Nigerian Aedes populations.

Methodology

We conducted a systematic review and meta-analysis following PRISMA 2020 guidelines, with protocol registered on the Open Science Framework (https://doi.org/10.17605/OS…). Searches across PubMed, Scopus, Web of Science, Google Scholar, AJOL, and VectorBase identified studies from Nigeria. Eligible studies examined field-collected Aedes aegypti populations for insecticide susceptibility via WHO bioassays or resistance mechanisms such as kdr mutations and metabolic enzyme activity. Data were pooled using random-effects models, with heterogeneity assessed by I² and Cochran’s Q. Nine studies published between 2015 and 2025 met inclusion criteria.

Results

Pooled estimates showed entrenched resistance to pyrethroids (75.6%, 95% CI: 40.5–93.4) and DDT (28.0%, 95% CI: 6.6–68.3), consistently below WHO thresholds. Carbamates displayed variable susceptibility (91.1%, 95% CI: 22.6–99.7), ranging from full susceptibility in Abia to resistance in Kogi. Organophosphates had the highest pooled mortality (98.3%, 95% CI: 96.8–99.1), though emerging resistance was reported in several states. Mechanistic evidence implicated frequent F1534C kdr mutations and elevated detoxification enzyme activity.

Conclusion

This review confirms widespread insecticide resistance in Ae. aegypti across Nigeria, especially to pyrethroids and DDT, with regional variation in carbamate susceptibility and emerging organophosphate resistance. The findings emphasize the urgent need for adaptive vector control strategies, expanded surveillance in northern regions, and integration of genomic tools to better characterize resistance mechanisms. Nigeria’s resistance profile mirrors challenges faced in many low- and middle-income countries, reinforcing the global imperative to strengthen monitoring systems and sustain effective arbovirus vector control.