Abstract / Summary
Insecticide resistance in mosquito vectors threatens control of vector-borne diseases across the Caribbean. In Jamaica, resistance in Aedes aegypti has been documented in both urban and rural settings, while susceptibility of other potential vector species and transcriptional responses to insecticide exposure in Ae. aegypti remain poorly characterised. Aedes aegypti were collected from urban (Metropolitan Kingston and the parish of St. Andrew, KSA) and rural (Lances Bay, Hanover) parishes in Jamaica and assessed for susceptibility to pyrethroids and malathion using CDC bottle bioassays. Aedes albopictus was collected from urban KSA only and evaluated for deltamethrin susceptibility. Transcriptomic analyses following exposures to malathion and pyriproxyfen were conducted on Ae. aegypti collected from KSA. Urban and rural Ae. aegypti populations exhibited multi-class resistance to permethrin, deltamethrin, and malathion. At the 30-min diagnostic time point, urban KSA populations showed 0% mortality to permethrin, 22.0% ± 2.7% to deltamethrin, and 70.5% ± 9.8% to malathion. Aedes aegypti populations from rural Hanover showed 0% mortality to permethrin and malathion and only 8.1% ± 2.6% to deltamethrin. Both Ae. aegypti and Ae. albopictus from KSA demonstrated resistance to deltamethrin, with mortality values below the CDC threshold for susceptibility. Transcriptomic analyses showed strong malathion-associated overexpression of detoxification- and cuticle-associated genes, while pyriproxyfen elicited a moderate but broad response involving metabolic and endocrine pathways, consistent with transcriptional responses occurring across multiple gene families following insecticide exposure. Insecticide resistance in Jamaican Aedes populations is widespread, heterogeneous, and dynamic. These findings support the need for locally informed resistance surveillance and integrated vector management strategies beyond reliance on pyrethroids.