Insect fauna visiting flowers of the entomophilous broadleaf evergreen trees Castanopsis sieboldii, Castanopsis cuspidata, and their hybrid in fragmented urban woods in Aichi Prefecture, Japan

The genus Castanopsis consists of entomophilous broadleaf evergreen tree species that dominate forests in warm temperate regions of Japan, where they are often selected as national "specific plant communities" that are representative or typical of the flora of Japan in terms of size, structure, distribution, etc., that have no alternatives, or that are extremely fragile and are in danger of extinction if left unchecked. These forests include small areas of shrine and temple forests that remain in isolation in urban regions. Therefore, identification of potential Castanopsis pollinators between trees separated by medium to long distances is important for the breeding, renewal, and conservation of genetic diversity of these species. In this study, we collected insects visiting the flowers of Castanopsis sieboldii, Castanopsis cuspidata, and their hybrid among isolated trees and urban fragmented woods in Nagoya, Aichi Prefecture, Japan. Flower-visiting insects were identified from six orders, > 33 families, 45 genera, and 65 species including insects not identified to species level. We also collected insects after nightfall, and found that various moths visited Castanopsis flowers. Based on the ecological traits of the recorded insects, we speculate that Castanopsides hasegawai, Odontopera arida arida, Vespa sp., Polistes sp., Bombus ardens ardens, and Oxycetonia jucunda may be efficient mid- to long-distance pollinators of Castanopsis spp. in this urban setting.