Long thought that insects migrants go where wind blows. However, more and more evidence indicates that they are indeed excellent navigators and can choose favorable conditions for their travels – this applies to a certain type of moth.
In an article published in the science, the researchers demonstrate that the skull butterfly can maintain a perfectly straight flight path. According to research, these butterflies are able to adjust their trajectory to compensate for harsh wind conditions.
Some research methods have already tried to understand this process using observations made with radar, analyzes of population processes and genetics, or measurements of isotopes in tissues (which can reveal food and water sources of insects and provide information about their location). origin).
How individual insects behave during migration (and the paths they follow) has been relatively difficult to study, mainly due to their size and large populations. But recent advances in tracking technology have helped create transmitters small enough to fit into larger insects.
These transmitters weigh less than a gram and can be linked to individual insects, allowing scientists to directly track their migration and learn what that process involves.
“Our research focused on Acherontia atropos, a mysterious butterfly native to Europe and Africa. Africa. This species is well known for the unusual skull mark on its chest. When disturbed, he also has a habit of squealing and flashing his bright yellow belly. Talk.
According to the statement, this type of moth feeds on the honey it steals. beespenetrating into the hives and piercing the honeycombs with its strong proboscis (an elongated appendage, which in some animal species is located on the head and serves as a feeding tube).
Butterflies leave the European continent in autumn towards North Africa.
In spring in Europe (May and June), adult butterflies tend to appear on the continent, from where they fly away in autumn (August to October), probably heading for the Mediterranean or North Africa, and possibly as far south as the Sahara.
“It is believed that this species cannot winter north of the Alps, so its migration is likely driven by low temperatures and resource availability,” says the study, which tracked 14 individuals for four hours each – a period of time long enough to be considered a migratory flight.
“We provided each person with a small radio transmitter weighing less than 0.3g before releasing them. A Cessna aircraft with receiving antennas followed them as they migrated, pinpointing their exact location every 5 to 15 minutes,” said Miles Mentz, professor of zoology and ecology at James Cook University in Australia. “This method allowed us to study their flight behavior in detail.”
According to co-author Martin Wikelski, director of the migration department at the Max Planck Institute for Animal Behavior and professor emeritus at the University of Konstanz in Germany, radio tracking has been successfully used to study the migration of some flying insects. , such as the monarch butterfly (Danaus plexippus) and the dark green dragonfly (Anax junius). “However, it has never been applied to nocturnal insects either in the wild or in this dimension. In fact, our study marks the furthest distance any insect has ever been continuously tracked in the field.”
Read more:
So what do moths do during migration? “To our surprise, we found that they were flying on very direct trajectories, effectively taking the ‘fastest route’ to their destination. Some of the longest tracks reached almost 90 km within four hours,” the researchers said.
Moths have also shown different strategies to deal with different wind conditions. “When there was a favorable headwind — in the same direction as the insects — they flew downstream and moved towards their destination or shifted their direction slightly to maintain control of their trajectory.”
Already in adverse conditions, such as headwinds (coming from the front) and crosswinds (lateral), the butterflies flew to the ground and directly into the headwind, adjusting their trajectory to stay on course, the scientists said. “They also increased their speed to keep control.”
This ability to stay on course even in adverse conditions indicates that the skull butterfly has improved compass mechanisms. “We have shown that insects can be skilled navigators compared to birds, and not depend on the whim of the wind, as we thought. This is an important discovery in the science of migration,” they said.
We still have a lot to learn about how and where insects migrate. The next step, according to Menz, Wikelski and other authors of the study, is understanding exactly what mechanisms these moths use to stay on their way. “Do they follow the Earth’s magnetic field? Or perhaps rely heavily on visual cues? The more we understand, the closer we are to predicting the phenomenon of insect migration.”
