Glow-worm larvae bioluminescence (Coleoptera: Lampyridae) operates as an aposematic signal upon toads (Bufo bufo)

It is an established fact that the spectacular bioluminescent displays of adult fireflies and glow-worms are used as courtship signals; however, the survival value of the glowing behavior of their larvae remained the subject of speculation for many years. Our study is the first that demonstrates that lampyrid larvae use luminescence to signal unpalatability to nocturnal, visually guided predators. Wild-caught toads (Bufo bufo) were more reluctant to attack luminescent artificial prey, and we show that avoidance learning increased this reluctance. After being exposed to glow-worm larvae (Lampyris noctiluca), which the toads experienced as disagreeable, attack latencies to luminescent prey increased, but not those to nonglowing prey. Not all toads showed avoidance learning to the same extent, because of either differences in previous experience with glow-worms or differences in memory. Copyright 2003.