Citizen science data on the presence of invasive mosquitoes in Hungary

Climate change, intensified tourism and trade activity result in several
exotic mosquito species invading the temperate zone, which has
considerable ecological and economic consequences and threatens human
health due to the pathogen-transmitting role of these organisms.
Accordingly, three invasive mosquito species (Aedes albopictus, Ae.
japonicus, and Ae. koreicus) have been described in the last decade in
Hungary, a Central European country. It is crucial to understand how
invasive species are introduced and their distribution is expanded at the
country-level, for which intense surveillance programs are needed. We have
established a citizen science program, in which we asked the public to
submit reports on their observations of invasive mosquitoes. During a
three-year campaign, we have collected and taxonomically validated about
3,000 reports that can be arranged along both the temporal and spatial
scales. We aggregated these observations into 35 km2 quadrats and examined
if these can be reliably used for scientific inferences. We first found
that the number of validated reports in a quadrat depends on the
underlying sampling effort (i.e., number of total reports), but this
relationship varies among species and study years. Second, after
controlling for study effort, we showed that the prevalence and
presence/absence of invasive mosquitoes within quadrats are significantly
repeatable among years, but this consistency varies in a species-specific
way. Third, we demonstrated that conclusions about the local
presence/absence of focal species based on citizen reports corroborate
well the results of direct field sampling with conventional trapping
protocols.  Synthesis and applications. We suggest that if the
reporting intensity is appropriate (i.e., the number of reports reaches a
species-specific threshold), citizen science results can be used to derive
biologically meaningful conclusions about the distribution of invasive
mosquitoes in a country. Distribution maps of the three invasive species
in Hungary can be used to identify ecological predictors that determine
such spatial patterns and also to develop a mosquito control program and
assess epidemiological risk.