Olympians and spectators at the Sochi 2014 Winter Olympics could unknowingly promote cannibalism among certain insects.
The culprit is something common that goes far beyond the Olympics: international travel.
Whenever someone travels from one country to the next, there is a chance that the individual may take home more than he or she realizes.
It’s well established that viruses, insects and even larger species can wind up in suitcases, in clothing, in food, on planes, boats, trains and more. If the species arrives at its destination alive, along with others of its own kind, it can establish a new population under the right conditions.
Once settled, the new population might look the same as others, but there could be creepy differences.
For example, when a common ladybug (the harlequin ladybird) moves out of its natural habitat, it is far more likely to engage in cannibalism once it settles into its new digs, a paper in the latest issue of the journal BMC Evolutionary Biology determined.
The innocent-looking ladybug, when on its home turf in places such as Russia and Japan, is not always cannibalistic. It seems to prefer munching on other, smaller insects, such as aphids, making the ladybugs a welcome sight for gardeners hoping to rid their plants of aphids. Larvae of the ladybug eat aphids too.
When the insects wound up in Western Europe — either with unwitting help from humans or of their own free will — things changed.
“Cannibalism was significantly greater in larvae from invasive populations compared to native or biocontrol populations,” Ashraf Tayeh, a researcher at the French National Institute for Agricultural Research, and his colleagues determined. (Harlequin ladybirds were introduced into North America and Europe as a biological control for aphids.)
They studied incidences of cannibalism among native ladybug populations in Russia and Japan and compared them with invasive populations now in Western Europe. Larvae, which tend to be particularly voracious for this species, exhibited the greatest differences.
“This study is the first to provide evidence for a higher propensity for cannibalism in invasive populations compared to native ones,” the authors wrote.
Their findings could apply to other species prone to cannibalism. As the researchers note, the rather gruesome practice is “ubiquitous in the animal kingdom” and occurs in many species, and especially insects.
As for why the invasive insects are more likely to be cannibals, they suspect the behavior might help facilitate invasion of a new environment. Without sufficient food to eat at first, they perhaps resort to eating each other.
Image: AnemoneProjectors, Wikimedia Commons