The globe skimmer (Pantala flavescens), sometimes also called the wandering glider, is a widespread species of dragonfly, and can be spotted across all continents save Antarctica. It is also one of the only two members of the genus Pantala; it shares the genus with its relative, Pantala hymenaea, also known as the spot-winged glider.
Back in 2009, marine biologist and self-professed “old-fashioned naturalist” Charles Anderson noticed that these globe skimmers from the Maldives flew in from the direction towards India; these same insects, on the other hand, also flew out in what appears to be the direction towards eastern Africa. To him, this was a sign that these insects were migrating between these areas—and for distances that are unheard of in the insect world.
Now, a team of researchers led by Lund University is on the case to figure out if these insects can truly travel such long distances. Their study on the matter was published in the journal Frontiers in Ecology and Evolution.
However, initial thoughts from the researchers presented a pretty distinct problem: while naturalists can easily slap transmitters and trackers onto flying vertebrates like birds and bats to study where they go, you can’t really do the same with insects at the moment. At that point, the researchers got creative and resorted to computer modeling.
To address these shortcomings, the researchers computed how much energy a dragonfly’s body can possibly store, then compared that to its physiological properties to determine how long it can stay airborne. Paired with meteorological modeling, the team also tried to look for winds atop the sky that can shuttle these insects to and from their seemingly distant destinations.
Said Lund biology researcher Johanna Hedlund: “Our study shows that this migration from India to East Africa is actually possible. However, the globe skimmer dragonfly can’t manage it using only the fat it can store in its body. It also requires favourable winds and these are present during certain periods of the year.”
They also found that around 15% of dragonflies that leave India manage to reach eastern Africa; meanwhile, about 40% of those that leave Africa manage to return to India. These dragonflies leave India by spring, according to Hedlund and the team.
Hedlund and team were surprised at what they had just found out. “We have got a lot closer to solving the mystery of how a tiny dragonfly, which only weighs 300 mg, can cross 2,000 km (1243 mi) of open sea”, said Hedlund.
To them, it is remarkable that an insect of such a small size can cross such a huge distance; they also hope that better understanding of these migrational behaviors and patterns can help scientists better model and analyze the spread of diseases in the animal kingdom facilitated by these migrations, as well as aid ecosystem services worldwide.
(For more insect news, check out how bees get fooled by orchid “pseudopollen”; if you’re more of a “computer modeling” kind of reader, check out how paleontologists used computational power to model how some dinosaurs walked.)
References
- GrrlScientist. (2011, April 6). Discovering dragonflies that cross oceans. The Guardian. http://www.theguardian.com/science/punctuated-equilibrium/2011/apr/06/1
- Hedlund, J. S. U., Lv, H., Lehmann, P., Hu, G., Anderson, R. C., & Chapman, J. W. (2021). Unraveling the world’s longest non-stop migration: The indian ocean crossing of the globe skimmer dragonfly. Frontiers in Ecology and Evolution, 9, 525. https://doi.org/10.3389/fevo.2021.698128
- Lund University. (2021a, October 4). Dragonflies likely migrate across the Indian Ocean. ScienceDaily. https://www.sciencedaily.com/releases/2021/10/211004104132.htm
- Lund University. (2021b, October 4). Study supports theory that dragonflies migrate across the Indian Ocean. Lund University. https://www.lunduniversity.lu.se/article/study-supports-theory-dragonflies-migrate-across-indian-ocean
- Smith, J. (2013, September 16). Dragonfly migration: A mystery citizen scientists can help solve. Cool Green Science. https://blog.nature.org/science/2013/09/16/dragonfly-migration-a-mystery-citizen-scientists-can-help-solve/
