AIMSurv: First pan-European harmonized surveillance of Aedes invasive mosquito species of relevance for human vector-borne diseases

Human and animal vector-borne diseases, particularly mosquito-borne diseases, are emerging or re-emerging worldwide. Six Aedes invasive mosquito (AIM) species were introduced to Europe since the 1970s: Aedes aegypti, Ae. albopictus, Ae. japonicus, Ae. koreicus, Ae. atropalpus and Ae. triseriatus. Here, we report the results of AIMSurv2020, the first pan-European surveillance effort for AIMs. Implemented by 42 volunteer teams from 24 countries. And presented in the form of a dataset named “AIMSurv Aedes Invasive Mosquito species harmonized surveillance in Europe. AIM-COST Action. Project ID: CA17108”. AIMSurv2020 harmonizes field surveillance methodologies for sampling different AIMs life stages, frequency and minimum length of sampling period, and data reporting. Data include minimum requirements for sample types and recommended requirements for those teams with more resources. Data are published as a Darwin Core archive in the Global Biodiversity Information Facility- Spain, comprising a core file with 19,130 records (EventID) and an occurrences file with 19,743 records (OccurrenceID). AIM species recorded in AIMSurv2020 were Ae. albopictus, Ae. japonicus and Ae. koreicus, as well as native mosquito species.

effort for AIMs. Implemented by 42 volunteer teams from 24 countries. And presented in the form of a dataset named "AIMSurv Aedes Invasive Mosquito species harmonized surveillance in Europe. AIM-COST Action. Project ID: CA17108". AIMSurv2020 harmonizes field surveillance methodologies for sampling different AIMs life stages, frequency and minimum length of sampling period, and data reporting. Data include minimum requirements for sample types and recommended requirements for those teams with more resources. Data are published as a Darwin Core archive in the Global Biodiversity Information Facility-Spain, comprising a core file with 19,130 records (EventID) and an occurrences file with 19,743 records (OccurrenceID). AIM species recorded in AIMSurv2020 were Ae. albopictus, Ae. japonicus and Ae. koreicus, as well as native mosquito species.

DATA DESCRIPTION Background
Vector-borne diseases (VBDs) are caused by a pathogen transmitted by vectors (often an arthropod) between hosts. Emerging or re-emerging VBDs in humans and animals are of increasing concern for public health worldwide [1], particularly mosquito-borne viral diseases such as chikungunya, dengue, West Nile fever and Zika [2,3].  Early detection and surveillance of invasive mosquito species are challenging in terms of coordination and resources. Detection of AIM species may include different means and roles, from national surveillance programs to detect invasive species at points of entry, and to establish early warning rapid response systems to monitor AIM populations.
Surveillance is commonly organized at the local and regional levels by public agencies, universities and research institutions [50], leading to different methodologies and strategies for sampling life stages of AIM (eggs, larvae/pupae and adults). Valuable guidelines for conventional surveillance have been produced by the ECDC and the World Health Organization Europe regional Office (EU-WHO) [51]. However, to date, they have never been harmonized and used simultaneously by different entomologist teams across Europe.
To increase harmonization between European entomologists, the Aedes Invasive Mosquito species (AIM) COST Action [52] was initiated in 2018. It had three major objectives: (i) to develop pan-European networking and collaboration in monitoring and surveillance of AIM species; (ii) to increase preparedness and capacity to fight against AIMs by triggering optimization and innovation in AIM control strategies; and (iii) to disseminate, customize and communicate the AIM-COST Action outcomes.
The AIM-COST Action aims to promote data sharing and harmonization. A particularly important objective is to ensure that vector sampling is consistent and compatible throughout Europe to enable an accurate continental picture of vector distributions. For this, AIM-COST organized a training course in Cyprus in January 2020 on harmonizing AIM surveillance across Europe. As a result of this course, trainers and trainees developed a protocol for surveying AIM species that can be applied across Europe. Forty-two teams from 24 countries (23 from Europe and one from North Africa) agreed to participating in the first ever pan-European surveillance of AIMs using a harmonized protocol [53]. The AIMSurv protocol was first implemented in 2020, then extended to 2021 and 2022. The main aim was to provide longitudinal data enabling comparison of seasonality and abundance across Europe and, in a subsequent phase, to compare field data with reports obtained by citizen science (for example, the Mosquito Alert App [54], the data of which has also been published in GBIF [55]). Accordingly, both the presence and absence results of AIMs species were considered equally important to improve the information at the continental level. The use of a common platform for data collection was also suggested: the VECMAP ® App system [56] (Avia-GIS, Zoersel, Belgium), which was made freely available by Avia-GIS to all participants during AIMSurv activities.

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The type of ovitrap was selected by each team according to their availability in the region, but usually consisted of 250 to 1000-ml capacity black containers filled with tap water. One scratched wooden tongue depressor (1.7 × 15 cm) per ovitrap was used as a substrate for oviposition. Some teams used similar sized pieces of Masonite board (when part of a pre-existing surveillance network was in place).
The selected sampling sites shared a similar ecology, when possible, in urban and/or suburban areas (e.g., a garden of single-family houses in residential urban/suburban areas, public parks near residential areas, recreational areas). The frequency of sample collection was biweekly over a minimum of 3 months, which included the population peak of the targeted AIM species (e.g., in Spain: from September to November for Ae. albopictus).
The following parameters were recorded: latitude and longitude of the position of each trap; the name of municipality/county/district (according to the country) and locality; start and end date of each trapping event (e.g., a period of 14 days for ovitraps); land use categories (urban, suburban and others); count of each life stage collected (egg and adult), including absences (0 values).

Recommended protocol
The more ambitious RP sampling included additional sampling sites sampled by five ovitraps per site, weekly sampling frequency and sampling length during the whole seasonality of the AIM species including start, peak and end of the mosquito season (e.g., May to November in Central Europe for Ae. albopictus). In addition, sampling adults using one BG-Sentinel™ (Biogents, Germany) trap baited with BG-Lure™ (Biogents, Germany) and/or CO 2 per site under a sampling frequency of one trap/night per week was also included. The use of VECMAP ® (AVIA-GIS, Belgium) to report the data was also suggested in the RP. Parameters to record were the same as for the MRP, plus the daily or weekly record of meteorological parameters (maximum, minimum, average temperature) per site, collected using data loggers or local weather stations (data not included in the current dataset).
The trap status per trapping event was recorded as follows: 'Valid' when the trap (either oviposition or BG-Sentinel) was fully functional during the sampling event; 'Trap altered' when oviposition trap was found dry or turned over, or objects or animals, such as snails and lizards, were found inside, but the sample could still be collected. 'Trap altered' also referred to BG-Sentinel traps when they were found unplugged or with the battery switched off, or if the funnel was blocked, but the sample could still be collected.
To process samples, eggs of AIM species collected were counted. When needed, for every location a subsample (two out of five ovitrap substrates per locality) of eggs was reared to confirm the species by larva/adult morphology, particularly in areas where several AIM species are present (i.e., Ae. albopictus and Ae. japonicus). Alternatively, when possible and depending on the team's resources, species were identified using: matrix-assisted laser desorption ionisation-time of flight mass spectrometry (MALDI-TOF MS) or molecular methods (e.g., DNA sequencing).
Adults of AIM species collected in BG-Sentinel™ traps were identified by morphology, and sexed and counted. Suggested identification keys were ECDC (2012) [51] and MosKeyTool V2.1 [57]. Samples of adults were preserved in 96% ethanol and/or cold preserved at −20∕−80 °C to confirm identification if needed (e.g., via molecular tools).

DATA VALIDATION AND QUALITY CONTROL
All participants in AIMSurv reported data using a harmonized template. All data reported has been curated and the terminology has been homogenized. Data has been validated using the validator available at the Global Biodiversity Information Facility (GBIF) [58].

REUSE POTENTIAL
Records presented here represent the first pan-European data on field surveillance of AIM species conducted with harmoniously methodologies and time scales across 24 countries. The records allow the accurate comparison of AIM surveillance, abundance, and seasonality between countries and/or regions. Data can also be compared with other sampling strategies of AIM species, such as citizen science.

DATA AVAILABILITY
The data supporting this article are published through the Universitat de les Illes Balears IPT and are available under a CC0 waiver from GBIF [58]. We kindly ask users to give appropriate credit and attribution if you use this data.

EDITOR'S NOTE
This paper is part of a series of Data Release articles working with GBIF and supported by the Special Programme for Research and Training in Tropical Diseases (TDR), hosted at the World Health Organization [59].

CONSENT FOR PUBLICATION
Not applicable.

COMPETING INTERESTS
The authors declare that they have no competing interests.