New Research Suggests Spiders Are Extremely Strategic, Manipulating The Light Of Male Fireflies To Lure More Prey Into Their Webs

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.

mamorshedalam – stock.adobe.com – illustrative purposes only, not the actual spider
Almost as soon as the beetles were caught, the spiders began to feed on them. However, they left the fireflies on the web to increase their food supply.
The findings have opened a window into how predators can use mimicry to target a specific type of prey.
Overall, the strategy of the orb-weaver spider highlights the complexity of feeding techniques in nature.
It is possible that more examples could exist. Further research is needed to determine what exactly makes the male fireflies flash like females.
“Spiders didn’t bite the lantern directly,” said Daiqin Li, a co-author of the study and an animal behavior expert at Hubei University in China.
“Perhaps the spider’s venom disrupts normal flashing behavior by interfering with the delivery of oxygen supply.”
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