Commidendrum robustum (Roxb.) DC. (St Helena gumwood) and C. rugosum (Dryand.) DC. (St Helena scrubwood) are ecologically important, endemic woody Asteraceae from the isolated South Atlantic island of St Helena. Once very abundant, they now exist in sparse fragmented populations due to 500 years of environmental destruction. They are sister taxa that evolved on the island and are reported to hybridise. Commidendrum rugosum has a saucer-like erect capitulum, whereas C. robustum has a somewhat globular hanging capitulum. Using daytime timelapse photography to follow capitula through their life cycle, we found that C. rugosum appears to be myophilous, visited largely by flies (including the endemic syrphid, Sphaerophoria beattiei Doesburg & Doesburg) and occasionally by Lepidoptera. Commidendrum robustum, on the other hand, although visited by flies, strongly attracts moths (especially noted at the Millennium Forest site). Our data suggest that moth visits may reduce visits from flies due to the sensitivity of flies to interference by other insects. We conclude that C. robustum may have a mixed syndrome of myophily/phalaenophily and that there is apparently some divergence of the pollination niche between the two species. Its potential in attracting moths, coupled with its former abundance, suggests that it may have been a major food source for adults of the numerous endemic moths. Pollinator activity was measured by insect visitation rates (mean visits per capitulum per day, V) and insect residence time (mean pollinator kiloseconds per capitulum per day, R). Both are higher for C. robustum (C. rugosum, V = 16.4, R = 3.101; C. robustum, V = 34.0, R = 8.274), reflecting the abundance of moths on the capitula at the Millennium Forest site. The conservation implications of the pollination mode are that: (1) there is considerable pollinator activity on the capitula and pollination is not currently a limiting factor for plant reproduction; (2) gene exchange between geographically-isolated populations of C. rugosum is likely to be minimal due to the apparent reliance of the species for pollination on small flies (especially Sphaerophoria beattiei), which are believed to be not effective as pollinators over long distances (> 1 km). A possible exception is the strong-flying drone-fly, Eristalis tenax Linn. which, although not as abundant as Sphaerophoria, does visit the flowers; (3) there is considerable overlap between the two species in flower visitors and interspecific pollen transfer is possible where the two species grow intermixed (which has potential positive and negative implications for species survival).

中文翻译：

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飞蛾与苍蝇：两种来自圣赫勒拿的特有菊科植物（Commidendrumrobustum和C.rugosum）的授粉模式及其保护意义的初步研究。

鲁棒肉（Roxb。）DC。（St Helena胶木）和C. rugosum（Dryand。）DC。（圣赫勒拿（St Helena）灌木丛）是生态上重要的，来自偏僻的南大西洋圣赫勒拿岛的特有木本菊科。它们曾经非常丰富，但由于500年的环境破坏，现在存在于零散的人口中。它们是在岛上进化的姊妹类群，据报道会杂交。普通有碟形直立的花序，而罗布斯梭状芽孢有稍球形的垂花。使用日间缩时摄影来追踪头虱在其整个生命周期中的活动，我们发现皱纹炭疽菌似乎是亲脂的，主要由苍蝇（包括地方性的蓝鳍鲷，Sphaerophoria beattiei杜斯堡和杜斯堡）访问，偶尔由鳞翅目访问。另一方面，罗布麻 尽管被苍蝇拜访，但强烈吸引飞蛾（尤其是在千年森林遗址中注意到）。我们的数据表明，由于蝇对其他昆虫干扰的敏感性，蛾类访视可能会减少苍蝇的访视。我们得出的结论是，强壮梭菌可能具有嗜肌/嗜性的混合综合征，并且在这两个物种之间的授粉位明显存在差异。它具有吸引飞蛾的潜力，加上它以前的丰富性，表明它可能已经成为众多地方性飞蛾成虫的主要食物来源。通过昆虫的访视率（每头每天的平均访视次数，V）和昆虫的停留时间（每头每天的平均授粉者千分之几，R）来测量授粉媒介的活性。C.robustum（C.rugosum，V = 16.4，R = 3.101; C.robustum，V = 34.0，R = 8.274），两者均较高 反映了千年森林遗址的小鳞片上飞蛾的数量。授粉方式的保护意义是：（1）头cap上有相当大的传粉媒介活动，而授粉目前还不是植物繁殖的限制因素；（2）在地理上分离的皱纹念珠菌种群之间的基因交换可能极少，这是由于该物种明显依赖于授粉的小苍蝇（尤其是Sphaerophoria beattiei），据信长距离授粉无效。 （> 1公里）。一个可能的例外是强力飞行的无人驾驶飞机Eristalis tenax Linn。尽管不如球菌丰富，但确实能开花。