There has been a national recording scheme for ladybirds in the United Kingdom since 1971. This evolved into the United Kingdom Ladybird Survey¹ in 2005, one of the first online wildlife recording schemes (Brown et al., 2008). Together these have engaged tens of thousands of people with recording the distribution and ecology of ladybirds in the United Kingdom, contributing over 229,000 verified records. The United Kingdom Ladybird Survey launched the smartphone app iRecord Ladybirds in 2013. The current European Ladybird App builds on that model. The substantial recording effort in the United Kingdom has greatly increased our understanding of the distribution and ecology of native and introduced ladybird species. In particular, verified records of H. axyridis have allowed the unusual opportunity of highly detailed mapping of the spread of a new invasive species (Brown et al., 2008, 2018).

Monitoring of ladybirds in the Czech Republic has been partially covered by the work of the Nature Conservation Agency of the Czech Republic (AOPK CR), which monitors all living organisms using the BioLog and iNaturalist applications. There is also monitoring of H. axyridis on the popular BioLib server. In 2019, the NAJDI.JE² platform was launched for monitoring invasive invertebrates in the Czech Republic using citizen science, including H. axyridis overwintering sites. Additionally the databases of taxonomists Ivo Kovář and Oldřich Nedvěd contain a large amount of data, obtained by determining records for a very large base of amateur entomologists within the Czech Entomological Society.

No targeted ladybird monitoring project has yet been created in the Czech Republic, so the European Ladybird App will enable widespread recording of ladybirds in the country.

In Belgium, a large-scale citizen science ladybird mapping project was launched in 1999. Skilled volunteer recorders collected standardized data on ladybird occurrence and ecology using a standard recording form (Adriaens et al., 2008). The aim was to use these data to publish distribution atlases (Branquart et al., 1999; Adriaens and Maes, 2004) and a Red List (Adriaens et al., 2015a). The project was supported by the Research Centre for Nature, Forests and Wood in the Walloon Region and the Institute for Nature Conservation (INBO) in Flanders. Observations were underpinned with pictures or other means of verification (e.g., based on recorder experience). Updated distribution maps were published regularly and people were actively stimulated to fill gaps through dedicated searches in insufficiently sampled grid squares. The project engaged about 800 volunteers actively submitting records. The data gathered were openly published on the Global Biodiversity Information Facility in 2012 (Adriaens et al., 2021). Since 2008, after the launch of the online reporting portal³ and its mobile phone applications by the conservation NGO Natuurpunt (cf. Swinnen et al., 2018), paper recording was replaced by online recording which greatly increased the number of ladybird observations, the speed of record submission, the number of volunteers as well as the spatial resolution and quality of ladybird records. As this platform is well established for recording, the European Ladybird App is anticipated to be used less used in Belgium by the established naturalist community, though it might still appeal to people wanting to increase their ladybird identification skills, wanting to contribute to European ladybird mapping specifically, as well as to a crowd outside the classical recording community. As several recording tools generate useful ladybird data, the focus should be on openly publishing data and sharing them through the application of data standards and interoperability (Adriaens et al., 2015b; Groom et al., 2016).

Haviar (2007) contributed much to the knowledge of occurrence, distribution and ecology of ladybirds in Slovakia. Related short-term monitoring and research activities in this country targeted communities of arboricolous ladybirds in forest and urban habitats (Panigaj et al., 2014; Viglášová et al., 2017; Holecová et al., 2018) and the year-round dynamics of H. axyridis in Scots pine forest habitats (Zach et al., 2020). The citizen science project Ladybirds of Slovakia (2015–2017)⁴ focused on ladybird data collection from volunteers via Facebook.

In the Azores (Portugal), since 2019, a project that allows citizens to assist in the monitoring of ladybirds is available.⁵ Under this project, face-to-face activities are organized for schools of all levels of education and institutions with children in need. Scientists and students undertake field work and training to collect and record ladybirds. Under this project, two important outputs were already produced; an updated checklist of the ladybird species of Portugal, including the Azores and Madeira archipelagos (Soares et al., 2021) and a biodiversity database of ladybirds (Coleoptera: Coccinellidae) of the Azores archipelago (in prep.). There is no equivalent project for mainland Portugal, so the European Ladybird App will enable widespread recording of ladybirds in the country.

Many short-term monitoring and research activities informed the knowledge of habitats and distribution of ladybirds in Italy. Many local papers updated the distribution of Harmonia axyridis at regional level and data from citizen science, i.e., iNaturalist or local bioblitzes (see Menchetti et al., 2016), have been used in scientific literature. There is no global recording scheme for ladybirds in Italy, so the European Ladybird App will enable widespread recording of ladybirds in the country (Figure 1).

This open-source mobile application (link)⁶ was developed using standard web-based technologies (HTML, CSS, JavaScript). This way we were able to reuse many supporting open-source libraries and tools which helped to streamline the development process. The app is essentially a responsive website that is designed to work well on small mobile devices. As a website it couldn’t be directly installed onto users’ smartphone devices therefore it was wrapped with a Cordova container. Traditionally, mobile applications are re-written for each mobile platform but packaging the code in such a way allows reuse of the same codebase for multiple platforms. Such an app is called a Hybrid and it can be deployed to both iOS and Android app stores.

The app has species names and other related content translated and managed by multiple collaborators from different countries (Figure 1G). The species datasheet is extensive and currently holds over 160 columns with species-related information. We are hosting the datasheet online on OneDrive cloud which essentially is our simple but flexible real-time content management system. We have agreed on a custom column header formatting schema which allowed us to write a command-line script to transform the columns into a JSON-formatted file which is then pulled into the app programmatically. In such a way, collaborators from multiple countries can update the content in parallel and the updates can then be imported into the app with little effort and few errors.

Using a Microsoft Excel spreadsheet for translations for multiple countries wasn’t very practical, so we use the Transifex web platform for managing species and app interface translations. At the time of writing, it is free for open-source projects such as this and allows us to pull the translations into the app.

The app is linked to an open-source Indicia database (warehouse)⁷ where the records are stored. It has a lot of tooling to streamline the verification process and to export and exchange data with other systems. Indicia has extensive online documentation⁸ of all aspects of installing and maintaining a data warehouse to support data capture projects, including mobile application approaches such as European Ladybird App (Figure 1). The system architecture, data model and coding conventions allow any developers to contribute to the open source development of the software through the project Github repository.⁹

The use of Indicia for data storage gives a flexible solution for data sharing agreements and allowing species records to be linked to the same user accounts from multiple connected mobile applications and websites. One of the sites our mobile app is linked to is iRecord¹⁰ which is used in the United Kingdom for sharing wildlife observations, supports multiple recording apps such as this and has a big community of recorders and verifiers.

iRecord incorporates verification rules developed by national recording schemes for a desktop application (the National Biodiversity Network Record Cleaner). Validation is assisted by automated record checks which highlight records outside the known spatial or temporal range of the species, and records of species which are difficult to identify. If records are highlighted by Record Cleaner the observer receives a message, with the option of editing the record. The expert verification of records on iRecord applies a two tier approach. Verifiers choose from a set of validation categories that they can apply to a record. A record is accepted as meeting the standard required for inclusion by the recording scheme or project in question when a verifier accepts it as correct on the basis of the submitted photo or is considered correct when the verifier has not seen photo/s or specimen/s (or cannot be absolutely sure of the identification from submitted photo/s) but has a high degree of confidence that the record is likely to be correct, based on difficulty of ID, date, location and recorder skills/experience etc. Other categories include unable to verify, incorrect, unconfirmed or plausible.

The application requires participants to create a record of the ladybird they observe and so, it is necessary for them to identify the species, which will later be verified by an expert. Additionally, the following information is requested: the coordinates of the location (usually derived from mobile phone GPS), date, number of individuals, habitat where the individual was found, and a photo (to enable identification). To increase the ease of use we selected the three most specific morphological features (main color, size, and pronotum pattern) and coupled these with country-based ranking of the relative occurrence (based on the total number of grid cells with observations of the species) for each species. Such filters (Figure 1D) enable the users to select from a reduced number of likely species when recording, thus helping to reduce misidentifications.

Information collated through the European Ladybird App will be openly available to address many potential questions but we focus on three main areas: (1) Understanding the ecology and distribution of ladybird species; (2) Informing ladybird conservation; (3) Education and engagement in biological recording and entomology. In a preliminary release of the European Ladybird App, we received over 1,600 records of 26 species between January 2019 and May 2021, mostly from GB and Ireland but also from other places in Europe. About 75% of these records have been accepted as accurate, indicating the high potential of this app for citizen science.

This initiative is the first step of a collaborative approach involving the recording of ladybirds through citizen science across Europe¹¹ (Supplementary Figure 1). Currently, the application builds on existing collaborations between six countries that have ladybird recording, but in the long-term we aim to include additional countries and use the data generated to produce a European ladybird distribution atlas. This will also require integrating the data from the ladybird app with other available data on ladybird distribution. This can be achieved through an open approach to publishing and sharing data from the app and the promotion of the app with other active mapping projects in Europe. Long-term conservation trends for ladybirds are so far only available for very limited regions (e.g., United Kingdom; Roy and Brown, 2018) or databases (e.g., GBIF—the Global Biodiversity Information Facility) and we aim to use the European data to inform Red List assessments (Maes et al., 2015)¹² Additionally the app has the potential to generate timely data on the arrival of new ladybird species in a country: for example in the United Kingdom, the first records of Oenopia conglobata L. were received via similar citizen science tools (Brown et al., 2015b).

Furthermore, ladybirds offer an appealing way of encouraging people to have an interest in entomology; in many ways ladybirds represent an “easy way in” to entomology, which can appear a daunting field. We consider the successful engagement of people to be as important as the ecology and conservation knowledge gained from the records themselves. The engagement benefits come from encouraging an interest in wildlife and the environment, as well as encouraging the next generation of entomologists and biological recorders. Additionally, connecting with nature is known to enhance the well-being of participants (Pritchard et al., 2020).