黒い蜜は誰のため？ー黒い蜜を出すシタキソウの花は夜行性スズメガによって送粉されるー

2026-04-04 東京大学

東京大学の研究により、黒い蜜を分泌するシタキソウが、主に夜行性のスズメガによって送粉されることが明らかになった。従来、色のついた蜜を持つ植物は昼行性動物との関係が中心と考えられていたが、本研究は夜行性昆虫による送粉を示した初の例である。さらに、スズメガは長い口吻の先端に花粉塊を付着させて運ぶという特異な様式が確認された。これは花と送粉者の共進化の常識を覆す発見であり、色蜜の進化や夜間送粉システムの理解を深める重要な知見となる。

黒い蜜を出すシタキソウとその主要な送粉者である夜行性スズメガ

＜関連情報＞

暗闇の中の黒い汁：暗い蜜を持つジャスミンテス・ムクロナタ（キョウチクトウ科）の夜行性スズメガによる受粉

Black juice in the dark: Pollination of dark-nectared Jasminanthes mucronata (Apocynaceae) by nocturnal hawkmoths

Soma Chiyoda, Ko Mochizuki, Atsushi Kawakita

Ecology Published: 01 April 2026

DOI:https://doi.org/10.1002/ecy.70370

While nectar is generally a transparent and colorless liquid, approximately 70 flowering plant species, with at least 15 independent origins, secrete colored nectar (Hansen et al., 2007). Colored nectar is often associated with diurnal pollination by vertebrates such as birds and geckos, and most previous research has focused on such systems (Hansen et al., 2007; Johnson et al., 2006). A few insect-pollinated plants also secrete colored nectar (Cai et al., 2022; Funamoto, 2023), but these species are also plants with diurnal pollinators. For example, Stemona tuberosa, which produces red-colored nectar, nectar secretion starts in the evening before the flowers open, but pollination is ultimately done by diurnal saprophagous flies (Cai et al., 2022). Consequently, although colored nectar has been discussed as a putative display for diurnal flower visitors, the presence of nocturnal pollinators that visually search for nectar sources, such as moths, raises the possibility that colored nectar may also occur in nocturnal pollination systems.