Emily Chan
Spiders are clever, cunning creatures, as evidenced by their hunting strategies. According to a new study, the arachnids are even craftier than we thought. Researchers in China discovered that orb-weaver spiders manipulate the signals of male fireflies to lure more of the insects into their webs.
In the study, the scientists noticed that male fireflies entangled in spiderwebs from the species Abscondita termanalis emitted flashes that mimicked the signals female fireflies use to attract mates.
When a spider was present, more male fireflies got trapped in its web, suggesting that orb-weaver spiders (Araneus ventricosus) influence the flashing pattern of fireflies to lure in more prey.
“Drawing from extensive field observations, we propose that Araneus ventricosus practices deceptive interspecific communication by first ensnaring firefly males in its web and then predisposing the entrapped male fireflies to broadcast bioluminescent signals that deviate from female-attracting signals typically made by A. terminalis males and instead mimic the male-attracting signals typically made by females,” wrote the researchers.
Male fireflies produce a series of pulses with the two lanterns on their abdomens to attract females. On the other hand, females generate single pulses from their one lantern.
The phenomenon was observed by Xinhua Fu, the lead author of the study from Huazhong Agricultural University in China. To figure out why orb-weaver spiders caught male fireflies in their webs but rarely captured female fireflies, Fu and colleagues investigated 161 webs.
The team used nets to catch male fireflies and placed them on the webs with tweezers. They used ink to black out the light of the fireflies in some of the webs while letting the others flash. They also tested webs when spiders were present and not present.
They found that webs with a spider and a firefly making visible signals trapped a lot more fireflies than other webs. Male fireflies used single-pulse flashes from one of their lanterns to resemble female signals only when a spider was around. Therefore, the spiders must be somehow manipulating the fireflies into producing such signals.
Furthermore, the spiders treated fireflies and non-flashing beetles differently. Fireflies were lightly wrapped so their light could still shine through, but the beetles were wrapped in a thicker layer of silk.
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