Spiders may lure male fireflies to their death with a call of love

A new study suggests orb-weaving spiders may manipulate the flashes of male fireflies caught in their web to mimic the mating call of a female.



A male firefly is caught in the web of an orb-weaving spider, Araneus ventricosus. Researchers believe that these spiders may manipulate the bioluminescent signals that fireflies use to find mates.
Photograph by Xinhua Fu

By Gennaro Tomma
August 19, 2024

Spiders have evolved an impressive array of hunting techniques—from trapping their prey with spit to building webs strong enough to capture snakes. Now, researchers have discovered a particularly malicious tactic that some orb-weaver spiders might use to trick fireflies into their webs.

A new study published in Current Biology found that some spiders seem to manipulate the flashing signals of male fireflies they’ve ensnared in their webs to mimic the signals of a female. This glittering call of love attracts other male fireflies to the spider’s web, just like a siren song attracts sailors to death.

The idea that spiders would put off a meal to use their prey as bait is in itself intriguing, says Dinesh Rao, a researcher at the Universidad Veracruzana who reviewed the paper but wasn’t involved in the study. “Spiders are always hungry, right? So to say, ‘Okay, I'm not going to eat this firefly now and I'll wait for the next one’, it’s […] very interesting.”

But while Rao and other experts agree that something is changing the flashing patterns of the captive males, they say that more research is needed to determine whether the spiders are actually behind it—and how they’re pulling it off.

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Volume 34, ISSUE 16, PR768-R769, August 19, 2024

Spiders manipulate and exploit bioluminescent signals of fireflies

Xinhua Fu
Long Yu
Wei Zhou
Qiuying Huang
Shichang Zhang
Daiqin Li 8

DOI:https://doi.org/10.1016/j.cub.2024.07.011

Summary
Predators often search for prey while moving through the environment, but there are important exceptions, including the way sedentary predators sometimes rely on signals for drawing prey to within striking distance1,2. Some spiders, for instance, leave the remnants of previously-captured prey in their webs where they function as static lures that effectively attract a diverse array of additional prey3456. However, important questions remain concerning how specific the targeted prey may be and how dynamic, instead of static, signalling might be. With these questions as our rationale, we initiated research on Araneus ventricosus (L. Koch, 1878), an orb-weaving spider, as the predator and the firefly Abscondita terminalis males as the prey (Figure 1A–C). Using two lanterns situated on their abdomen (Figure 1D,F), A. terminalis males make female-attracting multi-pulse flash trains (Figure 1J), whereas sedentary females attract males by making single-pulse signals (Figure 1C,K) with a single lantern (Figure 1E,G). Drawing from extensive field observations, we propose that A. 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. The outcome is that the entrapped male fireflies broadcast false signals that lure more male fireflies into the web.

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