Masatoshi Takeuchi

Dependence of the endangered arboreal snail Satsuma (Luchuhadra) eucosmia eucosmia (Camaenidae) on Ficus (Moraceae) trees as its main habitat

ABSTRACT The specific vegetation required by the endangered arboreal snail Satsuma (Luchuhadra) is subtropical rainforest characterised by Ficus tree species (Moraceae), such as Ficus virgata and Ficus microcarpa. This study aimed to elucidate the tree habitat preference of Luchuhadra eucosmia eucosmia inhabiting the northern part of Okinawa Island, which is an area characterised by different tree communities containing various species of Ficus. First, the preference for Ficus trees by the snails was evaluated by comparing the number of empty shells in quadrats where Ficus trees were present and absent. Noticeably, more shells were found in Ficus-occupied quadrats. Second, a belt transect survey was conducted to analyse the relationship between the abundance of live snails and the horizontal crown width of six Ficus species. In total, 72 live snails were recorded, but their presence was not proportional to the relative dominance of Ficus species, with more snails occurring on established F. virgata and Ficus ampelas. Overall, our results support previous studies, demonstrating that Ficus trees represent a critical habitat resource for S. (L.) eucosmia eucosmia. However, further investigation of the aerial distribution of snails at night and during the reproductive season is necessary to determine the true resource usage pattern of this snail species.

Insect Fauna Visiting Wildflowers in Autumn.

東京都世田谷区の大学研究圃場に設けた小規模な実験区と神奈川県川崎市の多摩川河川敷の公園において, 秋季ワイルドフラワーに集まる昆虫類を調査した。その結果, ワイルドフラワーにはチョウ目, ハチ目, ハエ目, 甲虫目などの訪花が認められ, 特にコスモス, マリーゴールドでの観察数が多く, セイタカアワダチソウのようにワイルドフラワーと混生する野草の中にも昆虫の観察数が多い種があった。またバッタ目の昆虫は, 周辺の草地に比べ, ワイルドフラワーの栽培区内で多く観察された。これらの結果をふまえ, 昆虫の生息空間として視点から, ワイルドフラワーの管理について考察した。