The challenge, which runs until 30 September, was launched by a team of researchers from the Faculty of Sciences of the University of Lisbon and is called "Cigarras de Portugal - insect singers" and is part of a broader initiative, the creation of the first "Red List of Invertebrates" in the country.
According to the most recent census of cicadas, carried out by scientists in 2004, there are 13 species in Portugal that group together in small nuclei in the northern, central, Alentejo and Algarve regions.
But, according to researcher Paula Simões, of the Centre for Ecology, Evolution and Environmental Change (cE3c) of the Faculty of Sciences of the University of Lisbon, it is necessary to have a "finer and more detailed record of their location".
The specialist in the study of cicadas explained to Lusa that the challenge to people is to obtain data that will allow us to "know better the area of distribution" of the species and "monitor their population and assess the vulnerability to the risk of extinction" and "promote citizen-science".
The data collected by people – the sound emitted by cicadas, the date and geographical location of the sound recordings, preferably with GPS coordinates - can be sent to the project page "Cigarras de Portugal - insect singers" on Facebook or to the digital platform Biodiversity4All.
The information gathered will enable scientists to know more accurately what the status of the species of cicadas in Portugal is.
Paula Simões estimates that half of the species identified in 2004 on the mainland face "various threats".
The loss of 'habitat' due to deforestation, urbanization and intensive agriculture and the use of pesticides, and pollution are identified by the researcher as the factors that have contributed most to the decline in cicada population.
One of the species that worries scientists more is the black-and-white ("Lyristes plebejus"), the largest cicada in Portugal, once abundant in the centre region: it is about five centimeters long and its song is reminiscent of the noise of a pressure cooker.
Experts estimate that there are 3,500 species of cicadas around the world, mainly in the subtropical regions.
Only the males sing to attract the females to mating during the few weeks of life they have as adults. The singing is species-specific, allowing to identify the cicadas that live in a certain region.
Before reaching the adult stage, when they emerge from the trees, the cicadas develop for three years in the soil, feeding on the sap of the plants, said researcher Paula Simões.