Malaria remains one of the leading causes of death worldwide, particularly in Africa, where various control interventions such as case management, insecticide-treated nets (ITNs), intermittent preventive treatment in pregnant women and infants, and indoor residual spraying (IRS) have been implemented. Insecticide resistance in malaria vectors poses a major challenge to vector control efforts. This study assessed the insecticide resistance status of Anopheles gambiae s.l. populations in rice agroecosystems of Anambra State, Nigeria. Mosquito larvae were sampled from four rice-farming clusters in Anambra state, reared to adulthood at the National Arbovirus and Vector Research Center (NAVRC) and tested using the WHO susceptibility bioassay against four insecticides namely dichloro-diphenyl-trichloroethane (DDT), pirimiphos-methyl, bendiocarb, and deltamethrin. Knockdown resistance (kdr) mutations were also analyzed. Results revealed confirmed resistance to DDT and deltamethrin, likely due to past agricultural use of DDT and cross-resistance with pyrethroids, which are widely used in ITNs and IRS. However, An. gambiae s.l. populations remained susceptible to bendiocarb and pirimiphos-methyl, except in Umunze, where resistance to pirimiphos-methyl was detected. The L1014F kdr mutation was detected at varying frequencies across locations, a key genetic marker for resistance to pyrethroids and DDT, in both An. gambiae s.s. and An. coluzzii. These findings highlight the importance of continuous insecticide resistance monitoring in rice agroecosystems, improved pesticide regulations and the implementation of integrated vector control management to slow down the spread of resistance in malaria vectors in Anambra

Aedes aegypti and Aedes albopictus mosquitoes are the primary vectors of tropical diseases, including dengue fever (DHF), chikungunya, and Zika, particularly in tropical regions such as Malaysia. Vector control efforts are now increasingly focused on biological and environmentally friendly approaches, one of which is using insect growth regulator (IGR)-based insecticides such as pyriproxyfen. Pyriproxyfen works by disrupting the metamorphosis process of mosquito larvae into adults without causing direct death, but it is effective in inhibiting the emergence of adult mosquitoes by more than 90%, depending on the dose and environmental conditions. This study evaluated the concentration-dependent effects of pyriproxyfen on laboratory and field populations of Aedes spp. Laboratory strains exhibited 100% adult mortality at 1.04 ppm (Ae. aegypti) and 1.08 ppm (Ae. albopictus), whereas field populations required 1.15 – 1.71 ppm depending on locality. LC50 values were lowest in laboratory strains (0.267 ppm for Ae. aegypti and 0.236 ppm for Ae. albopictus), while field strains ranged from 0.326 to 0.571 ppm. LC95 values followed a similar trend, with 1.026 ppm (Ae. aegypti) and 1.107 ppm (Ae. albopictus) in laboratory strains. Inhibition of emergence (IE%) was high in laboratory strains, reaching 97.89% at 0.50 ppm in Ae. aegypti and 63.54% at 0.50 ppm in Ae. albopictus. Field populations required higher concentrations for similar suppression, with IE% ranging from 17.68 – 98.23% in Ae. aegypti and 13.14- 98.24% in Ae. albopictus, peaking at 1.50 ppm. From this finding, it is suggested that pyriproxyfen effectively inhibits adult emergence in both laboratory and field populations, with laboratory strains more sensitive at lower concentrations and field strains responding at higher doses. These results provide strong evidence for pyriproxyfen as an effective, adaptive, and sustainable component of integrated vector management in Malaysia.