A comprehensive review and call for studies on firefly larvae

Buscando Luciérnagas: findings on Mexican fireflies from an 8-year virtual citizen science project

Fireflies are charismatic and conspicuous animals that often evoke childhood memories, which make firefly watching an emotional and even transformative experience. Citizen science projects have the potential to enhance transformative interactions with nature. Like many insects, firefly populations are declining due to land-use change, urbanization and watershed pollution, but ecological data for this group is scarce, particularly in Mexico. Virtual Citizen Science (VCS) initiatives can serve as a scientific instrument, yield reliable and relevant scientific data, and may also offer a platform to promote broader educational outcomes. We established a VCS project to document fireflies through a Facebook page named Buscando Luciernagas with the following hashtag in every post #veobrillar in 2015. After seven years we complied the gathered data and analyzed the results. We had 647 reports in total, with strong fluctuations from year to year that were correlated with the number of posts and publicity we made each year. The largest number of sightings (319) occurred in 2021, coinciding with a change in our reporting format. Most of the reports came from central Mexico (91.5%), but we had reports from eight states and also received some international reports from nine different countries. Fireflies were most frequently seen in habitats characterized as grasslands (35%) or forests (27%), followed by gardens (17%), vacant lots (9%) and parks (5%) but also paved areas and agricultural lands were reported (3% each). Most citizen scientists reported few fireflies, 1-5 individuals (31%) while only 11% reported more than 50 fireflies per sighting. Our study can serve as a preliminary approach to explore more focused research areas in the future. For example, in areas with no sightings, we could reach out to specific local people to corroborate that there are no fireflies in the region, or in areas with high sightings we could promote conservation measures. Notably, we found it intriguing to discover numerous sightings of fireflies in urban areas, which could offer a potential avenue for further research in urban ecology.

Exploring Aquaporin Diversity in Elateroidea: Insights From RNA-Seq Data Sets

Osmoregulation, the physiological regulation of water and ion balance, is vital for the survival of both aquatic and terrestrial insects. In freshwater aquatic insects, such as those within the Lampyridae family, this function is important due to the natural variation of aquatic habitats. Aquaporins play a key role in this process by facilitating the rapid transport of water molecules across cell membranes, maintaining cellular water balance, and adapting to changes in external salinity. In this study, I investigate the genetic diversity and expression levels of aquaporins in Elateroidea, particularly focusing on the Lampyridae family, using transcriptomic data and in silico analyses. The results reveal the diversity of aquaporins and compare gene expression patterns between freshwater aquatic Lampyridae and terrestrial Elateroidea species, such as Lycidae, Phengodidae, and Elateridae. Phylogenetic analyses identify seven distinct clades of aquaporins and uncovered gene duplication events related to the diversification of Elateridae and Lampyridae. A comparative abundance analysis indicated higher aquaporin expression in aquatic fireflies, aligning with the need for efficient osmoregulation in aquatic environments. Additionally, stage-specific expression patterns in Aspisoma lineatum (Neotropical firefly) and Aquatica lateralis (Paleartic firefly) suggest species-specific strategies for coping with osmotic challenges during development. This study provides insights into the evolutionary adaptations of aquaporins in Elateroidea, highlighting their importance in both aquatic and terrestrial insect physiology.

Glowing wonders: exploring the diversity and ecological significance of bioluminescent organisms in Brazil

Bioluminescence, the emission of light by living organisms, is a captivating and widespread phenomenon with diverse ecological functions. This comprehensive review explores the biodiversity, mechanisms, ecological roles, and conservation challenges of bioluminescent organisms in Brazil, a country known for its vast and diverse ecosystems. From the enchanting glow of fireflies and glow-in-the-dark mushrooms to the mesmerizing displays of marine dinoflagellates and cnidarians, Brazil showcases a remarkable array of bioluminescent species. Understanding the biochemical mechanisms and enzymes involved in bioluminescence enhances our knowledge of their evolutionary adaptations and ecological functions. However, habitat loss, climate change, and photopollution pose significant threats to these bioluminescent organisms. Conservation measures, interdisciplinary collaborations, and responsible lighting practices are crucial for their survival. Future research should focus on identifying endemic species, studying environmental factors influencing bioluminescence, and developing effective conservation strategies. Through interdisciplinary collaborations, advanced technologies, and increased funding, Brazil can unravel the mysteries of its bioluminescent biodiversity, drive scientific advancements, and ensure the long-term preservation of these captivating organisms.

How to Overcome a Snail? Identification of Putative Neurotoxins of Snail-Feeding Firefly Larvae (Coleoptera: Lampyridae, Lampyris noctiluca)

The larvae of some lampyrid beetles are highly specialized predators of snails. They have been observed to climb on the shells of their prey and use this exposed position to bite and inject secretions potentially originating from the midgut. Besides serving the purpose of extra-oral digestion (EOD), injected compounds also seem to have a paralyzing effect. Up to now, the toxins causing this paralyzing activity have not been identified. In the current study, we provide a first compositional analysis of the midgut secretion from lampyrid larvae, with a focus on identifying putative neurotoxins causing the observed paralyzing effect. For this purpose, we utilized a combined proteo-transcriptomic approach to characterize the compounds present in the midgut secretion of larval stages of Lampyris noctiluca. In terms of the absolute numbers of identified compounds, the midgut secretion is dominated by hydrolyzing enzymes comprising peptidases, carboxylesterases, and glycosidases. However, when considering expression levels, a few rather short cysteine-rich peptides exceed all other compounds. Some of these compounds show moderate similarity to putative neurotoxins identified in the venom of other arthropods and could be responsible for paralyzing effects. In addition to these potential toxins, we provide a list of peptides typical of the midgut secretion of L. noctiluca, supplemented by the corresponding precursor sequences.

Zampaulo R, Rivera SC, Pellegrini TG, da Silveira LFL. Larval and adult morphology of Photuriselliptica Olivier (Coleoptera, Lampyridae) and a Halloweeny case of cave-dwelling firefly larva feeding on bat guano

The predatory firefly Photuriselliptica is common throughout the Atlantic Forest and has been proposed as a biomonitor due to the species' narrow niche and elevational range. However, the species is only known from adults, and a more effective monitoring of its populations hinges on the lack of knowledge on their immature stages. Recent sampling in ferruginous caves and inserted in other lithologies, on sites in the Atlantic Forest and Cerrado, have led to the capture of firefly larvae later reared to adults in the lab. Firefly larvae have been reported in South American caves before; however, they have only been identified to family due to the adult-biased taxonomy of Lampyridae. Here, we provide an updated diagnosis of Photuriselliptica, describe its immature stages for the first time, and update the distribution of the species. The larvae of Photuriselliptica were observed to interact with guano of several bat species, including that of vampire bats. These observations are consistent with the less specialized feeding preferences of photurine larvae, unlike most other firefly taxa, which specialize in gastropods and earthworms. It is yet unclear whether P.elliptica are cave specialists. However, since its occurrence outside caves remains unknown, protecting cave environments must be considered in conservation strategies for this important biomonitor species.

Function of snail shell hairs in anti-predator defense

The function and evolutionary background of the hairs on the shells of terrestrial gastropods is largely unknown. Many hypotheses proposed by malacologists have never been proven, and the long-held hypothesis of mechanical stability in wet environments has been rejected by recent studies. It would therefore be worthwhile to reexamine other hypotheses regarding the adaptive significance of shell hairs. We investigated the defense function of shell hairs against a specialist predator, the snail-eating firefly, in the long-haired snail Moellendorffia diminuta. The firefly larvae, which hunt snails using abdominal suckers, were unable to attach to the shell because of the shell hairs but were able to attach to the shells that had lost their hairs. About half of the hairy snails successfully defended themselves by swinging their shells and dropping firefly larvae, but most of the snails without hair failed to defend. The hairs reduce the ability of the larva to attach to the shell and increase the effectiveness of the shell-swinging defense behavior in removing the larva from the shell. As shell hairs grow longer with shell development, they may confer an advantage based on the predator's growth stage. Our findings highlight the anti-predator defense role of shell hairs in land snails, introducing a hypothesis previously overlooked in the evolutionary context of hairy snails.

Illuminating Firefly Diversity: Trends, Threats and Conservation Strategies

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.

An Overview of Aquatica Fu et al., a Phylogeny of Aquatic Fireflies Using Mitochondrial Genomes, a Description of Two New Species, and a New Record of Aquatic Fireflies in China (Coleoptera: Lampyridae: Luciolinae)

There are now seven species in the genus Aquatica Fu & Ballantyne, with all but one known from the characteristics of males, females, and larvae. Molecular information is combined with morphological taxonomy for the delimitation of both genus and species. The monophyly of the genus Aquatica is strongly supported in six trees, and its position as sister to the genus Nipponoluciola Ballantyne Kawashima Jusoh et Suzuki is stable across maximum likelihood and Bayesian inference results. Two new species of Aquatica Fu & Ballantyne, A. qingshen sp. nov. and A. xianning sp. nov., described from the features of males, females, and larvae, are closely related within a single clade within the genus Aquatica. Females have distinctively shaped median oviduct plates. A Chinese population identified as A. lateralis was found to be morphologically similar to the Japanese population, but genetic distances suggest that it is a distinctive species. No larvae are associated with this species. Definitions of the aquatic status of Luciolinae fireflies are expanded.

Living on the edge: urban fireflies (Coleoptera, Lampyridae) in Morelia, Michoacán, Mexico

Fireflies (Coleoptera, Lampyridae) are a globally threatened group of insects due to habitat loss and fragmentation, light pollution, climate change and pesticides. However, against all odds, some firefly populations persist in urbanized environments where all four of these factors are present simultaneously. In this work, we compiled several data sources to document the diversity of fireflies in the urbanized area of Morelia, characterize their current habitats, and determine the main stressors affecting these bioluminescent insects. We found seven genera and 26 species of fireflies (19 nocturnal, seven diurnal) associated with 32 urban, peri-urban and extra-urban areas; at least, 14 are new records for Michoacán, and the list for the state now includes nine genera and 41 species. Five additional sites were documented as extinction sites. We compared the characteristics of these five sites with those of the sites with extant populations. We found that in Morelia, fireflies are mainly associated with areas that have high to moderate proportions of vegetation cover, are near water bodies, have very gentle to moderate slopes, and are exposed to low levels of light pollution. In contrast, the extinction sites showed high proportions of artificial surfaces and high levels of light pollution. Because some fireflies are considered bioindicators of ecosystem integrity as they are associated to specific habitats, are highly diverse and due to their sensitivity to environmental changes, we consider that sites from Morelia's urban core and extinction sites show the highest levels of environmental degradation, threatening most fireflies and other insects living in the urban core with local extinction. At the same time, our results also suggest that implementing conservation strategies and sustainable planning for the urban development of Morelia in the short term could allow fireflies and other vital elements of the city's insect communities to persist for future generations. Restoration and conservation of green areas and nighttime environments are essential for biodiversity and human health, especially in intra-urban zones.

Luminescent characteristics and mitochondrial COI barcodes of nine cohabitated Taiwanese fireflies

Background

Over 50 Taiwanese firefly species have been discovered, but scientists lack information regarding most of their genetics, bioluminescent features, and cohabitating phenomena. In this study, we focus on morphological species identification and phylogeny reconstructed by COI barcoding, as well as luminescent characteristics of cohabited Taiwanese firefly species to determine the key factors that influenced how distinct bioluminescent species evolved to coexist and proliferate within the same habitat.

Methods

In this study, 366 specimens from nine species were collected in northern Taiwan from April to August, 2016-2019. First, the species and sex of the specimens were morphologically and genetically identified. Then, their luminescent spectra and intensities were recorded using a spectrometer and a power meter, respectively. The habitat temperature, relative humidity, and environmental light intensity were also measured. The cytochrome oxidase I (COI) gene sequence was used as a DNA barcode to reveal the phylogenetic relationships of cohabitated species.

Results

Nine species-eight adult species (Abscondita chinensis, Abscondita cerata, Aquatica ficta, Luciola curtithorax, Luciola kagiana, Luciola filiformis, Curtos sauteri, and Curtos costipennis) and one larval Pyrocoelia praetexta-were morphologically identified. The nine species could be found in April-August. Six of the eight adult species shared an overlap occurrence period in May. Luminescent spectra analysis revealed that the λ _max of studied species ranged from 552-572 nm (yellow-green to orange-yellow). The average luminescent intensity range of these species was about 1.2-14 lux (182.1-2,048 nW/cm²) for males and 0.8-5.8 lux (122.8-850 nW/cm²) for females, and the maximum luminescent intensity of males was 1.01-7.26-fold higher than that of females. Compared with previous studies, this study demonstrates that different λ _max, species-specific flash patterns, microhabitat choices, nocturnal activity time, and/or an isolated mating season are key factors that may lead to the species-specific courtship of cohabitated fireflies. Moreover, we estimated that the fireflies start flashing or flying when the environmental light intensity decreased to 6.49-28.1 lux. Thus, based on a rough theoretical calculation, the sensing distance between male and female fireflies might be 1.8-2.7 m apart in the dark. In addition, the mitochondrial COI barcode identified species with high resolution and suggested that most of the studied species have been placed correctly with congeners in previous phylogenies. Several cryptic species were revealed by the COI barcode with 3.27%-12.3% variation. This study renews the idea that fireflies' luminescence color originated from the green color of a Lampyridae ancestor, then red-shifted to yellow-green in Luciolinae, and further changed to orange-yellow color in some derived species.

Fireflies in Art: Emphasis on Japanese Woodblock Prints from the Edo, Meiji, and Taishō Periods

Examining how insects are represented in artwork can provide insight into people's perceptions and attitudes towards arthropods, as well as document human-insect interactions and how they change through time. Fireflies are well-known bioluminescent beetles (Coleoptera: Lampyridae) of great cultural significance, especially in Japan. A selection of online museum collections, art databases, and dealer websites were used to find artwork featuring fireflies, with an emphasis on Japanese ukiyo-e wood block prints from the Edo, Meiji, and Taishō time periods (1600-1926). Quotes from early twentieth century texts were used to provide additional historical context. Over 90 different artists created artwork featuring fireflies, including several renowned masters. Artists depicted adult fireflies in a variety of ways (e.g., relatively accurately, more generalized, symbolic or abstract, yellowish dots) in the absence and presence of people. Most images were set outdoors during the evening near water, and primarily featured women and children, groups of women, and large parties catching fireflies or observing caged fireflies. 'Beauties', geisha, courtesans, kabuki actors, and insect vendors were also common subjects. Various types of collecting tools and a diversity of cages were featured, as well as insect vendors. The artwork highlights the complex connections between fireflies and humans. Insect-related art can contribute to education and conservation efforts, particularly for dynamic insects such as fireflies that are facing global population declines.

Life cycle and description of the immature stages of a terrestrial firefly endemic to Mexico: Photinusextensus Gorham (Coleoptera, Lampyridae)

The life cycle, morphology, and bionomy of Photinusextensus Gorham, 1881, an endemic species of Mexico, are described. Redescriptions of adults (male and female) are also presented. Larvae were reared to the adult stage from eggs laid by females collected at the El Pedregal de San Ángel Ecological Reserve, south of Mexico City. The activity period of adults of P.extensus begins at the end of July and finishes by the end of August. Females lay between 3 and 198 eggs. Larvae hatch from the eggs after a period of 11 to 71 days, undergo 6 larval instars and a pupal stage in an annual cycle. Morphological characters of the sixth larval instar of P.extensus are compared with those of several other genera assigned to the tribe Photinini. Knowledge of the natural history of firefly larvae is relevant since most species do not feed as adults and therefore depend on resources acquired during the larval stage.

Species-Specific Flash Patterns Track the Nocturnal Behavior of Sympatric Taiwanese Fireflies

It is highly challenging to evaluate the species' content and behavior changes in wild fireflies, especially for a sympatric population. Here, the flash interval (FI) and flash duration (FD) of flying males from three sympatric species (Abscondita cerata, Luciola kagiana, and Luciola curtithorax) were investigated for their potentials in assessing species composition and nocturnal behaviors during the A. cerata mating season. Both FI and FD were quantified from the continuous flashes of adult fireflies (lasting 5-30 s) via spatiotemporal analyses of video recorded along the Genliao hiking trail in Taipei, Taiwan. Compared to FD patterns and flash colors, FI patterns exhibited the highest species specificity, making them a suitable reference for differentiating firefly species. Through the case study of a massive occurrence of A. cerata (21 April 2018), the species contents (~85% of the flying population) and active periods of a sympatric population comprising A. cerata and L. kagiana were successfully evaluated by FI pattern matching, as well as field specimen collections. Our study suggests that FI patterns may be a reliable species-specific luminous marker for monitoring the behavioral changes in a sympatric firefly population in the field, and has implication values for firefly conservation.