Two species of giant Asian mantises are spreading across Europe, helped by climate change and urbanization, and scientists warn they are threatening pollinators, frogs and lizards
Two species of giant Asian mantises are spreading rapidly across Europe, with scientists officially classifying them as an invasive threat to native wildlife.Aided by rising global temperatures and warm conditions created by cities, these fast-breeding predators are moving steadily northward. Researchers warn that these insects are actively hunting important native pollinators such as bees, protected critters such as lizards and tree frogs, and even Europe’s native mantis species through lethal mating.The official classification of these two species (Hierodula tenuidentata and Hierodula patellifera) as invasive alien species comes from a new study published in the open-access Journal of Orthoptera Research. The study, led by Roberto Battiston of the “G. Zannato” Museum of Archeology and Natural Sciences, reveals a highly successful ecological invasion that has so far received little attention from the scientific community.
Climate change drives northward spread
Although these insects have been present in Europe for about a decade, their numbers have increased dramatically across the continent and the Mediterranean in recent years. Warmer urban environments and overall climate changes allow them to spread into areas that were once too cold to survive.“They are pushing further and further north due to climate change,” Battiston said, adding that established populations are now often found in parks and gardens. Because these mantises are large, colorful, and eye-catching, many people view them as an interesting garden insect rather than a possible environmental threat.“This study was born to give people those answers and develop strategies to contain them,” Battiston added.
Rapid reproduction gives them an advantage
The success of these Asian mantises comes from their adaptability and extremely high reproductive rate. Both species spend most of their lives hidden in trees and bushes, where they are efficient hunters.A single egg box laid by an invasive female can produce about 200 pups. This is almost double the number of mantises (Mantis religiosa) native to Europe. Young invasive mantises are also much less likely to kill each other than native species, allowing more to survive into adulthood.Rapid human population growth is posing a serious threat to local wildlife. Large invasive females release pheromones to attract native male European mantises. When native males try to mate with them, they are often caught and eaten, reducing the native species’ breeding population.Invasive mantises also prey on many other animals. They feed on important pollinators such as bees and pose a serious risk to protected small animals such as tree frogs and lizards. Researchers say this is particularly concerning for Mediterranean islands, which are home to many unique plant and animal species found nowhere else in the world.
Two Asian mantises are spreading across Europe, and scientists warn they may now threaten native wildlife
How cities and domestic cats can get involved
Man-made cities inadvertently create ideal conditions for these invasive insects. The extra warmth created in urban areas, called the urban heat island effect, allows mantises to stay active and hunt later than usual into fall and winter.Additionally, insect hotels built to support native insects are now used by Hierodula mantises as excellent hunting sites.The study also found an unexpected link to domestic cats. Data shows that free-roaming cats are the primary vertebrate predators of these invasive mantises, accounting for 45% of all recorded successful attacks on mantises.However, cats don’t solve the problem. They couldn’t tell the difference between the invasive Asian mantis and the native European mantis. As a result, they also kill native mantises, which are already under pressure from increasing suburban competition.
Looking for egg cartons in winter
To monitor and slow the spread of these insects, researchers are asking the public to help through a large-scale citizen science project.“My colleagues William di Pietro and Antonio Fasano (GRIO) successfully built a massive citizen science project and collected more than 2,300 reports from enthusiasts and citizens,” said Battiston. “Citizen science is an essential tool not only for monitoring, but also for raising awareness and making people aware of these issues in an active and participatory way.”Environmental groups say people can help during the winter when trees and shrubs lose their leaves. Without leaves, mantis egg cases (called ootheca) are easier to spot on bare branches. These brown, spongy eggshells usually measure about 2 to 3 centimeters.While these egg cases can be safely removed to prevent new mantises from hatching in the spring, Battiston warns that people should first ask an expert to identify the species. This helps ensure they don’t accidentally destroy the eggs of Europe’s already troubled native mantis species.
