Why do some mushrooms glow in the dark? A study involving real bioluminescent mushrooms and fake ones with LED lights has added to the evidence that the glow attracts insects such as flies.
鈥淭he light serves to attract potential spore dispersers,鈥� says at the University of California, Berkeley. These animals probably eat some of the spores, she says, but as mushrooms produce billions of spores, they can sacrifice some to help spread others more widely.
Very few studies have tried to test why some fungi glow. In 1981, John Sivinski at the University of Florida found that more arthropods 鈥� including springtails and woodlice 鈥� than in controls that produced no light, when the tubes were put on forest floors in Florida.
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In 2015, Anderson Oliveira at the University of S茫o Paulo, Brazil, and his colleagues did a study with plastic mushrooms containing a green LED and coated with a glue called Tanglefoot to ensnare any small arthropods. They found at night when the LED was lit.
Inspired by this study, Adams and her colleagues created plastic mushrooms with green, red, blue and yellow LEDs. They placed them overnight near patches of real bioluminescent mushrooms that glow green in a mountain oak forest in Costa Rica, coating the plastic mushrooms and one of the real mushrooms with Tanglefoot glue.
The team thought it might be difficult to find bioluminescent mushrooms, but after walking along a trail for a while, they found some as soon as they turned off their lights. 鈥淚 was not expecting to find them quite so easily,鈥� says Adams.
What鈥檚 more, the team thinks the mushrooms it found are a previously unknown species, though this has yet to be confirmed.
The team found the mock mushrooms with lit LEDs attracted many arthropods, while none at all were caught by controls with the LED turned off. The green LEDs attracted several times more animals than the real mushrooms, probably because they were brighter.
The red, yellow or blue LEDs caught slightly fewer animals than the real mushrooms. Flies of various kinds were the most common type trapped.
But with so few studies to date, more evidence is needed, says Adams. 鈥淭his is not really enough to draw any firm conclusions.鈥�
For instance, it is possible that the role of bioluminescence varies in different species or in different places. A that the glow of the ghost fungus Omphalotus nidiformis attracted more insects, for instance.
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