2021年乗鞍岳の鱗翅目昆虫と個体数調査

抄録

Insects that live in an alpine area are considered to be survivors from the Ice Age. These insects will likely face in a critical situation as global warming increases. We conducted surveys in the alpine zone and the area near Mt. Norikura (alt.3026) , using the route census method (six surveys) around Meotomatu (alt.1960) , from Kikyougahara (alt.2703 m) to Hirayu Route (alt.2544 m), to Oonyu Pond (alt.2338) , to Gono Pond (alt.2721 m) and the light trap method (three surveys) was used at the identified location of Kikyougahara (alt. 2703 m) on April 13, July 16-17, August 5-7 and August 23 in 2021. Data from the light trap survey conducted on August 6, 2021, was used specifically to enumerate the proportion of alpine species. A total of 108 individuals belonging to 28 species were counted; the low number of species and individuals recorded was likely owing to poor weather conditions on that day.　Among them were included alpine species such as Entephria caesiata nebulosa，Heterothera taigana sounkeana，Xestia speciosa ussurica，Xestia wockei aldani，Papestra biren and Syngrapha ottolenguii nyiwonis. Considering species, the percentage of alpine was 21.43%, whereas alpine individuals accounted for 28.70% of total individuals. Although we conducted several surveys using the route census, only a few species could be counted. Colias palaeno sugitanii, Aglais urticae connexa, Sympistis heliophila and Parasemia plantaginis japonica were not recorded any survey. Overall, we recorded 102 species belonging to 18 families of Lepidoptera in all the surveys conducted in the alpine zone and the area near of Mt. Norikura. Among these, we obtained interesting records such as the records of Rhigognostis japonica, Lithophane consocia and Diarsia deparca emerged in an alpine area. On the other hand, Xestia albuncula has not been recorded in the last 10 years. In addition, the absence of several other alpine species was likely owing to a decreases in the number of individuals. It is unclear whether the cause of this decrease is the increase in global warming, and further investigations are required.