Involving citizen scientists in monitoring arthropod vectors of human and zoonotic diseases: The case of Mosquito Alert in Italy.

Citizen science has been particularly effective in gathering reliable, timely, large-scale data on the presence and distributions of animal species, including mosquito vectors of human and zoonotic pathogens. This involves the participation of citizen scientists in research projects, with success strongly dependent on the capacity to disseminate project information and engage citizen scientists to contribute their time. Mosquito Alert is a citizen science that aids in the system surveillances of vector mosquitoes. It involves citizen scientists providing expert-validated photos of targeted mosquitoes, along with records of bites and breeding sites. Since 2020 the system has been disseminated throughout Europe. This article uses models to analyze the effect of promotion activities carried out by the Mosquito Alert ITALIA team from October 2020 to December 2022 on the number of citizen scientists recruited and engaged in the project, and their performance in mosquito identification. Results show a high level of citizen scientist recruitment (N > 18.000; 37 % of overall European participants). This was achieved mostly through articles generated by ad hoc press releases detailing the app's goals and functioning. Press releases were more effective when carried out at the beginning and end of the mosquito season and when mosquito's public health significance was emphasized. Despite the high number of records received (N > 20.000), only 30 % of registered participants sent records, and the probability of a participant sending a record dropped off quickly over time after first registering. Among participants who contributed, ∼50 % sent 1 record, ∼30 % ≥3 and 4 % >10 records. Participants showed good capacity to identify mosquitoes and improve identification skills with app usage. The results will be valuable for anyone interested in evaluating citizen science, as participation and engagement are seldom quantitatively assessed. Our results are also useful for designing dissemination and education strategies in citizen science projects associated with arthropod vector monitoring.