Illuminating Firefly Diversity: Trends, Threats and Conservation Strategies

Abstract

Fireflies are a diverse group of bioluminescent beetles belonging to the family Lampyridae. Recent research on their diversity, evolution, behavior and conservation has greatly advanced our scientific understanding of these charismatic insects. In this review, we first summarize new discoveries about their taxonomic and ecological diversity, then focus on recent endeavors to identify and protect threatened fireflies around the world. We outline the main threats linked to recent population declines (habitat loss and degradation, light pollution, pesticide overuse, climate change and tourism) and describe relevant risk factors that predict which species will be particularly vulnerable to these threats. Although global coordination of firefly conservation efforts has begun only recently, considerable progress has already been made. We describe work by the IUCN SSC Firefly Specialist Group to identify species currently facing elevated extinction risks and to devise conservation strategies to protect them. To date, IUCN Red List assessments have been completed for 150 firefly taxa, about 20% of which face heightened extinction risks. The conservation status for many species has yet to be determined due to insufficient information, although targeted surveys and community science projects have contributed valuable new data. Finally, we highlight some examples of successful firefly habitat protection and restoration efforts, and we use the framework of the IUCN SSC Species Conservation Cycle to point out high-priority actions for future firefly conservation efforts.

Keywords: Coleoptera; IUCN Red List; Lampyridae; beetles; biodiversity; citizen science; insects; light pollution; pesticides; tourism.

Figure 2

Among the top threats facing fireflies are loss of suitable habitat for firefly juvenile stages and adult reproduction and excessive artificial light at night; both occur on a local scale yet are pervasive globally: (A) Residential development, roads and construction have replaced the interdunal wetland habitat of Photuris bethaniensis along parts of the mid-Atlantic coast, USA (photo by US Army Corps of Engineers). (B) Clearing of riverine mangrove forest in peninsular Malaysia degrades habitat used by Pteroptyx tener life stages (photo by Lawrence Kirton). (C) Illustration depicting diverse sources of artificial light that can disrupt the nocturnal courtship signaling of fireflies and glow-worms; sources include streetlights, car headlights, commercial and greenhouse lighting, skyglow from cities and residential security, decorative and interior lighting (illustration modified from [48], CC BY).

Figure 1

(a) Number of taxonomic articles and newly described species of Lampyridae published by decade from 2001 to 2023 (projection to 2030). (b) Number of lampyrid species newly described between 2001 and 2023 by geographic region (see Supplementary Table S1 for additional information).

Figure 3

A selection of globally imperiled fireflies in their habitats: (A) Female of the threatened Florida intertidal firefly Micronaspis floridana (photo by Richard Joyce). (B) Mangrove habitat of Micronaspis floridana, Florida, USA (photo by Richard Joyce). (C) Courtship flashing of Pteroptyx malaccae in mangrove forest, Thailand (photo by Banthoon P). (D) Courtship glow from a threatened Oculogryphus chenghoiyanae flightless female, Hong Kong (photo by Vor Yiu). (E) Light pollution impacting the type locality of Oculogryphus chenghoiyanae on Lantau Island, Hong Kong (photo by Vor Yiu). (F) Male of Luciola singapura, listed as Critically Endangered on the 2023 Singapore Red Lists (photo by Shivaram Rasu). (G) Male of the threatened Southwest spring firefly Bicellonycha wickershamorum, Arizona, USA (photo by Scott Cylwik). (H) Perennial stream habitat of Bicellonycha wickershamorum, New Mexico, USA (photo by Anna Walker).

Figure 4

Worldwide use of insecticides in agriculture by country, shown as tonnes of active ingredient applied during 2020. Map published online at OurWorldinData.org (CC BY). Inset photos: Tractor by Aqua Mechanical (Flickr CC BY), farmer photo by Sundaram (Flickr CC BY). For maps showing trends from 1990–2020, see online resource https://ourworldindata.org/grapher/insecticide-use, accessed on 2 January 2024.

Figure 5

Conservation status of Lampyridae by region, showing the proportion of known species that have been initially evaluated as Critically Endangered (CR), Endangered (EN), Vulnerable (VU), Near Threatened (NT), Least Concern (LC) or Data Deficient (DD) according to IUCN Red List criteria or that have not yet been evaluated (NE). Proportions based on an estimated global total of 2200 species, with estimates of known species numbers for regions as follows: North America (172), Europe (63), South and Southeast Asia (150). (Species numbers not yet estimated for regions lacking any completed assessments).