橙螢生活史與在九份二山之季節性發生

Life history of Diaphanes citrinus Olivier and its seasonal occurrence in Jiu-Fen-Er-Shan, Nantou County, Taiwan

橙螢（Diaphanes citrinus Olivier）是臺灣低海拔山區常見的秋冬季螢火蟲，也是推動低海拔秋冬季賞螢活動的潛力物種。為瞭解橙螢生活史，本研究結合室內飼育及野外族群調查綜合探討。室內飼育部分，以南投縣九份二山雄成蟲及雌成蟲交尾所產蟲卵進行試驗，飼育條件為定溫23°C，相對濕度RH＝80±5%，光照L：D＝10：14。單隻飼育59隻橙螢幼蟲，成功羽化31隻，所有成功飼育個體，卵期平均172.4±4.9天，幼蟲期186.7±16.8天，前蛹期3.8±0.7天，蛹期11.0±4.7天，成蟲壽命18.7±6.7天，完成一世代約需392.6±18.2天。其次，經由九份二山野外族群調查顯示，橙螢成蟲發生期為10-11月，並以10月中旬至下旬為發生高峰。無論室內飼育及野外族群調查結果，均呈現橙螢生活史屬於一年一世代。本研究於九份二山樣區共記錄7屬10種2,339隻次的螢火蟲，建議春季的黑翅螢（Abscondita cerata（Olivier））以及秋季的橙螢，可作為九份二山主要的賞螢物種。

Diaphanes citrinus Olivier is an autumn firefly species commonly found in low altitude mountain areas of Taiwan, and it has become a potential species to promote firefly-watching activity in these areas. In order to understand the life history of the species, both laboratory and field investigations were conducted. Firstly, we collected male and female D. citrinus individuals from Jiu-Fen-Er-Shan, Nantou County, and reared them to mating and laying stages under laboratory conditions. The eggs were collected and incubated under the constant conditions of temperature (23°C), relative humidity (80% ± 5%), and the photoperiod of the light dark ratio (L: D = 10: 14). A total of 59 hatched larvae were reared separately, and 31 of them successfully emerged under the laboratory conditions. The durations of each life cycle stage (including egg, larva, prepupa, pupa, and adult longevity) were 172.4 ± 4.9 days, 186.7 ± 16.8 days, 3.8 ± 0.7 days, 11.0 ± 4.7 days, 18.7 ± 6.7 days, and completed mean generation time of 392.6 ± 18.2 days. Secondly, the results of the field investigations illustrated that the adult populations of D. citrinus occurred from October to November, and their peak appeared in mid to late October. Therefore, both laboratory and field investigations suggested that D. citrinus has only one generation per year. In this study, a total of seven genera, 10 species and 2,339 firefly individuals were recorded in the Jiu-Fen-Er-Shan sampling site. We recommend Abscondita cerata (Olivier) and D. citrinus as the two main firefly-watching species in spring and autumn, respectively.