Integrating citizen science and field sampling into next-generation early warning systems for vector surveillance: Twenty years of municipal detections of Aedes invasive mos-quito species in Spain
The spread of invasive mosquitoes Aedes albopictus, Aedes aegypti and Aedes japonicus in Spain represents an increasing public health risk due to their capacity to transmit arboviruses such as dengue, Zika and chikungunya among others. Traditional field entomological surveillance remains essential for tracking their spread, but it faces limitations in terms of cost, scalability and labor intensity. Since 2014, the Mosquito Alert citizen science project has enabled public participation in the surveillance through the submission of geolocated images via a mobile app, which are identified using AI in combination to expert validation. While field surveillance provides high accuracy, citizen science offers low-cost, large-scale real-time data collection aligned to open data managment principles. It is particularly useful for detecting long-distance dispersal events and has contributed up to one-third of the municipal detections of invasive mosquito species since 2014. This study assesses the value of integrating both surveillance systems to capitalize on their complementary strengths while compensating weaknesses in the areas of taxonomic accuracy, scalability, spatial detection patterns, data curation and validation systems, geographic precision, interoperability and real-time output. We present the listing of municipal detections of these species from 2004 to 2024, integrating data from both sources. Spains integrated approach demonstrates a pioneering model for cost-effective, scalable vector surveillance tailored to the dynamics of invasive species and emerging epidemiological threats. Simple SummarySpain, with its diverse ecological and climatic landscapes, represents a key area for the introduction and establishment of invasive mosquito species, posing threats to public health due to their capacity to transmit human diseases. Field entomological surveillance conducted by experts remains the primary tool for tracking their spread, though it is limited by geographical scales and cost factors. Advances in smartphone technology allows citizen science strategies of data collection such as submitting mosquito photos via the Mosquito Alert app. This type of information is of a different nature from the field sampling and still needs expert interpretation, but offers significantly broader and faster geographical coverage. Two decades have passed since the first detection of the Asian tiger mosquito in Spain in 2004, and following the Mosquito Alert creation in 2014, citizen science has contributed with one-third of the discoveries of this species at the municipal level in Spain. We discuss integration of both approaches in order to harness their respective strengths while compensating their drawbacks, to develop faster and more powerful early warning surveillance systems, and also returning value to the society by empowering citizenship.