Characteristics of Pteroptyx Firefly Congregations in a Human Dominated Habitat

Abstract

© 2018, Springer Science+Business Media, LLC, part of Springer Nature. Riverbanks in Thailand are home to two fireflies, Pteroptyx malaccae and Pteroptyx valida, which form massive mixed-species mating congregations. In conservation, both represent flagship species that attract much public attention. However, their populations have become sparse. With the increasing spread of urbanization, more information is needed on whether and how the fireflies are able to adapt to such new environments. 24 population surveys were conducted across 13 months at a park surrounded by an urban area in Samut Prakan Province to record their pattern of occurrence. The results showed a year-round presence with high abundance around Jul-Oct, corresponding to local rainy season. On average, the park housed 7 ± 3 congregations with a total of 488 ± 274 displaying males (Mean ± SD, Max = 1281, Min = 111, N = 24). Congregation sizes ranged from 5 to 560 males with an average of 70 (N = 172) and the ratio of P. malaccae to P. valida around 3:1. The distribution pattern was dominated by a few very large and long-lasting congregations that contained most of the males in the area. Location-wise, these large congregations tended to occur at certain “hotspots”, which may aid in flash visibility. Theoretical comparison to hilltopping and other lekking insects was discussed. In terms of plant species, the fireflies most often utilized Sonneratia caseolaris as congregation platform which is consistent with many other areas. However, exotic ornamental plants such as Terminalia catappa were also frequently used here, especially during the rainy season. The behavioral adaptability may aid conservation efforts.