Fireflies and Bioluminescence - An Interview with Will Kuhn

One of the most exciting and fabulously popular events each year in late May and early-to-mid June is the flashy mating ritual of the synchronous fireflies in the Great Smoky Mountains. This year’s peak dates for firefly viewing are June 7-14 and thousands of visitors will be gathering, just as they have for years, near the Elkmont Campground to observe this naturally occurring phenomenon. 

Why does Photinus carolinus attract not only its mate but also a large human fan club through its rhythmic flashing? We asked Dr. William R. Kuhn, a National Science Foundation Postdoctoral Fellow at the University of Tennessee, to illuminate this topic.

FF: First of all, how are you involved with Great Smoky Mountains National Park and what makes it exciting for you? 

WK: I am a member of Discover Life in America's board and have recently become chair of the Science Committee. In addition, I've helped with the All Taxa Biodiversity Inventory's sampling effort, including collecting assassin bugs (predatory insects related to stink bugs and cicadas) in the park, as they were considered under-studied here. So far, this work has resulted in a new species record for the park. Every time I work in the Smokies, I think to myself what a privilege it is to be in such a beautiful and diverse place! 

FF: You are going to be giving a talk about bioluminescence June 15 at the Sugarlands Visitor Center. What is bioluminescence and why are you interested in it? 

WK: Bioluminescence is the process that fireflies and other bioluminescent creatures use to create light. These biological processes are the result of millions of years of evolution and are extremely efficient (much more so than light bulbs). The light itself tells a story about communication. Sometimes that communication is for love, and sometimes it has a more sinister purpose. That's the story I want to tell.

FF: How many species of fireflies are in the park and have any been discovered in the ATBI work? 

WK: There are 19 species of fireflies known to GSMNP and ten have been discovered since the ATBI began in 1998, so we have doubled the number previously known to be in the park. (There are an additional few species that are known in the area and suspected to be here, but they just haven't been documented in the park yet.) Of the 19 species known to be here, six are diurnal (active during the day) and don't produce light; the remaining 13 are nocturnal and do light up. Species differ in the time of year they display, in the time of day (dusk or dawn), in the area (canopy, open fields, wooded hollows, etc.), and in the rhythm and even colour of their flash.

FF: The synchronous firefly events in the Smokies are some of the most well-known and popular. Can you speak to the importance of fireflies and why these events need to be managed sustainably? 

WK: It's wonderful to see so many people excited about an insect-like the synchronous firefly of the Smokies, and this presents an excellent opportunity to learn about the importance of biodiversity. Ironically, the yearly influx of human appreciators can harm this species as visitors inadvertently trample their woodland habitat. Hence, GSMNP has made efforts to allow viewers to marvel at the synchronous fireflies from a safe distance so that they can continue to thrive. 

FF: What do fireflies eat and does anything prey on them? 

WK: Just like other creatures in the Smokies, fireflies have their special place in the ecosystem. Their larvae feed on small invertebrates like insects, slugs and snails, and their adults, which are distasteful to predators, are at the centre of an interesting mimicry complex. Several beetle species are known to mimic the firefly's characteristic yellow-orange and black motif, protecting them from would-be predators who know that fireflies are—for lack of a better term—yuck.

FF: What are some of the other bioluminescent species here besides the firefly?

WK: Fireflies are definitely the most well-known bioluminescent creatures in GSMNP, but there are a few other insects and fungi in the area that also create light. Across the world, there are myriad creatures that use light for different purposes, from attracting food or mates to warning colours and camouflage. Many of these are marine creatures, but there are also other arthropods, invertebrates, and a variety of fungi that create light in terrestrial habitats.

You are invited to join us when Will sheds further light on this topic June 15, speaking about bioluminescence in the park as part of DLIA’s Science at Sugarlands series. The talk begins at 1 p.m. and is family-friendly, free and open to the public at Sugarlands Visitor Center, 1420 Fighting Creek Gap Road, Gatlinburg. 

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