Elucidating food plants of the aggregative, synchronously flashing Southeast Asian firefly, Pteroptyx tener Olivier (Coleoptera, Lampyridae)

A peer-reviewed open-access journal BioRisk 12: 25–39 (2017) BioRisk25 Elucidating food plants of the aggregative, synchronously flashing Southeast Asian firefly... doi: 10.3897/biorisk.12.14061 RESEARCH ARTICLE www.pensoftonline.net/biorisk Elucidating food plants of the aggregative, synchronously flashing Southeast Asian firefly, Pteroptyx tener Olivier (Coleoptera, Lampyridae) Shawn Cheng1, Kar-Men Chan1, Shah-Fadir Ishak1, V. Khoo2, M.Y. Chew3 1 Genetics Laboratory, Forest Research Institute Malaysia (FRIM), 52109 Kepong, Selangor, Malaysia 2 Entomology Branch, FRIM, 52109 Kepong, Selangor, Malaysia 3 Herbarium, FRIM, 52109 Kepong, Selangor, Malaysia Corresponding author: Shawn Cheng (), Kar-Men Chan () Academic editor: Josef Settele | Received 8 June 2017 | Accepted 23 July 2017 | Published 17 August 2017 Citation: Cheng S, Chan K-M, Ishak S-F, Khoo V, Chew MY (2017) Elucidating food plants of the aggregative, synchronously flashing Southeast Asian firefly, Pteroptyx tener Olivier (Coleoptera, Lampyridae). BioRisk 12: 25–39. https://doi.org/10.3897/biorisk.12.14061 Abstract The aggregative, synchronously flashing firefly, Pteroptyx tener congregates on a nightly basis on Berembang trees (Sonneratia caseolaris) growing along the lower reaches of the Selangor River (West Malaysia). Every night, the males and females of this species engage one another in a pre-mating ritual of flash communication. Little is known of the dietary requirements of the adults of P. tener apart from suggestions that these beetles feed on the nectar and sap of mangrove trees. The drastic reduction in their numbers in recent years has sparked an urgency to understand their dietary needs. Here, we report on a series of probing experiments where we sequenced and analysed DNA fragments obtained from the gut contents of adult P. tener specimens. We detected coding and non-coding chloroplast DNA (cpDNA) gene sequences in the gut DNA extracts of P. tener. One DNA sequence was in reasonably good condition to allow us to match it to the cpDNA sequence of a Malvacean, that is, Heritiera littoralis, a common inhabitant of estuarine habitats. We also detected the DNA sequences of plants (cultivated and natural) that may have come from hamlets or isolated freshwater swamps located further inland. The findings reported here provide early indication that P. tener may be able to travel further inland to search for their hosts. Future research should focus on visually confirming if P. tener feeds on H. littoralis and obtaining a more complete reference DNA database of plants in the firefly habitat. Keywords Pteroptyx tener, host, firefly, plants, chloroplast DNA Copyright Shawn Cheng et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. 26 Shawn Cheng et al. / BioRisk 12: 25–36 (2017) Introduction The synchronous firefly, Pteroptyx tener Olivier (Coleoptera: Lampyridae), congregates in the thousands in estuaries in several locales throughout Peninsular Malaysia. Here, they perform their synchronous flashing behaviour throughout the year (Figure 1). During their nightly aggregation in estuarine habitats, the males and females of this species engage one other in a pre-mating ritual of flash communication before deciding upon their partners. Females which have mated then fly inland to lay their eggs on the ground (Nada and Kirton 2004). Lampyrid larvae require land snails for food with the type of hosts utilised highly dependent upon the snail species found locally (Madruga and Hernandez 2010). In comparison, little is known of the dietary requirements of P. tener with some speculating that the beetle feeds on the nectar of Sonneratia caseolaris Lythraceae (in Buck 1988; Nallakumar 2003) or that it required no food at all in the adult stage. In North America, a similar hypothesis was suggested for Photunis carolinus Green (Lampyridae), which was rejected after laboratory studies showed that firefly individuals reared on fruit had an increased lifespan (Faust 2008). In temperate regions, fireflies have been reported to feed on a diverse range of host plants such as ginger lilies, honey-dew, pomegranate and floral segments of the milkweed, Asclepias syriaca (L.) (Lloyd 1998; Wedincamp Jr. et al. 1996; Ballantyne et al. 2013; Faust and Faust 2014). The males of Photinus and Luciola fireflies also provide nutrition to conspecific females during copulation (Rooney and Lewis 1999; Cratsley et al. 2003; South et al. 2008a; South et al. 2008b; South and Lewis 2012). These nuptial gifts contain nutrients essential for egg production in Photinus females (Rooney and Lewis 2002; Cratsley et al. 2003; Lewis et al. 2004). Photuris fireflies however have a slightly different way of obtaining nutrition. Considered the femme fatales of the insect world, the Photuris mimic the flash display of Photinus females in order to ensnare and devour male Photinus. This is done to obtain nutrients and defensive steroids missing in the Photuris, which would otherwise leave them defenceless against their natural enemies (Eisner et al. 1997). Unfortunately, fireflies are not afforded the same attention, funding or structured research programmes given to insects of economic importance such as agricultural, livestock or stored product pests. The situation is also dire for P. tener in Malaysia, as the country’s best-known insect species is threatened by waste pollution and destruction of its breeding habitat for the purpose of commercial planting of oil palms (Chiew 2009). The limited nature of funding for firefly conservation work in Malaysia has led us to conduct some probing experiments to solve the mystery of the nutritional requirements of P. tener. We set out first and foremost to determine if adult fireflies require plants or insects for food by extracting the whole gut content of adult P. tener beetles and screening them with plant chloroplast and invertebrate mitochondrial DNA (mtDNA) markers. We then compared these sequences with the DNA barcodes of plants from the firefly habitat. When a match to these reference plant DNA sequences was not available, Elucidating food plants of the aggregative, synchronously flashing Southeast Asian firefly... 27 Figure 1. Aggregative, synchronously flashing firefly, Pteroptyx tener (Coleoptera: Lampyridae) performing their nightly mating ritual along the Selangor River. we compared our DNA sequences with sequences on the GenBank database. We also compared mtDNA gene sequences obtained from the gut DNA extracts of P. tener with mtDNA gene sequences obtained from the tissue material of P. tener. Materials and methods Insect and plant DNA extraction Adult P. tener fireflies were collected from the wild from Selangor, Sepetang (Perak) and Rembau Rivers (Negeri Sembilan) along the west (...truncated)