Important information about how ant populations are evolving in the face of global warming, forest farming and urbanisation has come from a citizen science project involving hundreds of Danish children.
The project involved youngsters and their families collectively trapping 19,000 ants near their homes or holiday sites across Denmark. Comparing the new catches with specimens dating back to 1900, an international research team has detected major population shifts in these 鈥渉ugely important, but vastly underappreciated鈥� insects, says team member at the University of Copenhagen.
Most population studies have focused on 鈥渃harismatic鈥� insects like butterflies, dragonflies, grasshoppers and bees, she says. 鈥淏ut ants pollinate plants, spread seeds and aerate the soil, so they鈥檙e also extremely important.鈥�
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Sheard and her colleagues provided 1500 families and schools with the Ant Hunt project ant-baiting kits. The kits explained to the children 鈥� aged from 3 to 18 years old 鈥� how to set the traps and leave them for 2 hours, and to then send them back to the research centre. In the laboratory, the scientists analysed the specimens and gave the children details about the species they found and sent them a diploma.
Last year, DNA analyses revealed that the children had 鈥� the immigrant pavement ant (Tetramorium immigrans) 鈥� for the first time in Denmark.
In their latest study, the team compared ant-baiting kit catches with historical specimens housed in Danish museums. Taking into consideration the year in which historical specimens were captured and the locality of capture, the researchers used modelling to estimate how the geographical range and population size of 29 ant species has changed across the years.
They found that while half of the species have had stable populations since 1900, the other half have either declined, increased or fluctuated, Sheard says. Among those that have fluctuated, three are currently in decline 鈥� including two species that build mounds in sunny patches of forests. This is probably because tree-farming has made forests denser and less hospitable to insects, she says.
Five species have grown in number. These include Hercules ants (Camponotus herculeanus) and red wood ants (Formica rufa), both of which possibly benefit from a growth in their preferred habitat of pine tree forests, says Sheard.
But jet ants (Lasius fuliginosus), European fire ants (Myrmica rubra) and two other Myrmica species have seen their populations decline, mainly since the 1950s. This could be linked to the significant decrease in dry, open lands in Denmark 鈥� from 25 per cent in 1888 to less than 10 per cent in 2004 鈥� and the recent increase in rainfall, as these species primarily thrive in arid environments.
Changes in ant populations can reflect critical environmental changes and can also set off a chain of events involving other species that rely on ants, either directly or indirectly, says Sheard.
Citizen science projects like the Ant Hunt have a two-fold benefit, providing access to otherwise inaccessible sites like people鈥檚 private gardens and raising awareness about the importance of protecting nature, she says.
All the ants provided by the children are now part of the permanent collection of the Danish Natural History Museum.
Biology Letters
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