The Silent Selection Pressure: Exploring the potential role of Horticultural and Peri-Domestic Insecticide use in Mosquito Insecticide Resistance

Insecticide resistance in mosquito vectors continues to undermine the effectiveness of vector-borne disease control programmes, including those targeting dengue. Resistance is most often attributed to insecticide use within public-health operations; however, increasing evidence suggests that additional selection pressures may operate outside formal control systems. Among these, horticultural and peri-domestic insecticide use in urban and peri-urban settings remains comparatively under-examined. Urban gardens, nurseries and small-scale horticultural environments frequently involve the application of insecticides belonging to chemical classes also used in public-health vector control. Mosquito larvae and adults occupying these environments may therefore encounter heterogeneous insecticide residues at low or sub-lethal concentrations and irregular intervals. Such exposure scenarios, documented in laboratory and field studies, are recognised conditions under which metabolic, target-site and behavioural resistance mechanisms can potentially be selected and maintained. In parallel, routine domestic use of mosquito coils, vapourisers and aerosols may further contribute to background chemical exposure in resting and feeding habitats. Emerging evidence indicates that these decentralised environments may function as permissive ecological settings for resistance development and cross-resistance to insecticides of public-health relevance. Mosquito populations exposed to such chemical backgrounds may subsequently disperse into neighbouring communities, with possible implications for the operational longevity of space spraying, larviciding and emerging chemical control tools. This perspective synthesises ecological, mechanistic and operational evidence to highlight horticultural and domestic insecticide use as potential, but insufficiently monitored, contributors to the resistance landscape. It underscores surveillance and regulatory gaps and calls for targeted investigation of horticultural microhabitats, improved stewardship of domestic insecticides, and strengthened cross-sector coordination between public health, urban planning and agriculture.