Flowering biology of Aspidistra (Asparagaceae): new data on pollination by dipteran insects

Abstract

The genus Aspidistra comprises about 160 species of herbaceous plants. In previous investigations, different authors suggested that Aspidistra is pollinated by flies, fungus gnats, slugs, amphipods and even collembolans. The vast majority of data was based on only one species, A. elatior, and was not confirmed by direct observations. Recent field observations of anthetic plants confirm the idea of pollination by flies for two other species of the genus. The present study summarizes direct observations of flowering phenology and pollination of five previously unstudied species of Aspidistra. Flowering biology was studied using visual observations as well as video and photo monitoring. Flowers and captured pollinators were investigated using scanning electron microscopy. As a result, knowledge of the flowering biology of Aspidistra has been increased. The absence of heat production and an ultraviolet pattern were verified. The present data show that flowers of Aspidistra can serve as a food resource for animals. The investigated species of Aspidistra are pollinated by dipteran insects: A. formosa, A. marasmioides and A. subrotata are pollinated by fungus gnats; A. multiflora and A. oviflora are pollinated by flies. The occurrence of fungus-gnat pollination was directly demonstrated for the first time in the genus Aspidistra. The present study confirmed the idea of myiophily in the genus Aspidistra. Apparently, myiophily is common and diverse in Aspidistra. More likely, pollinators are attracted by scent, which is undetectable by humans, but the attraction mechanism is still not completely clear.

To cheat or to treat? Fungus gnat pollination in Aspidistra

“…To the best of our knowledge, our observations provide the first evidence indicating the occurrence of brood‐site pollination in fungus‐gnat pollinated Aspidistra . Although fungus gnat pollination was also reported in other Aspidistra species, no larva or egg was found in their flowers (Suetsugu & Sueyoshi, 2018a, 2018b Vislobokov, 2017).…”

“…Some recent, though limited, evidence from comprehensive and direct field observations shows that Aspidistra plants are effectively pollinated by Diptera insects, mainly flies, fungus gnats (members of Sciaridae and Mycetophilidae), and gall midges. In Aspidistra phanluongii , A. multiflorawas , A. oviflora , and A. dolichanthela , pollinators are either flies or hoverflies (Vislobokov, 2017; Vislobokov et al, 2013; Wu, 2018). A. xuansonensis , A. retusa , and A. saxicola are pollinated by female gall midges (Ma et al, 2017; Vislobokov et al, 2014; Wu, 2018).…”

“…A. xuansonensis , A. retusa , and A. saxicola are pollinated by female gall midges (Ma et al, 2017; Vislobokov et al, 2014; Wu, 2018). Fungus gnats are the main pollinators of A. formosa , A. marasmioides , A. subrotata , A. longipetala , and A. elatior (Suetsugu & Sueyoshi, 2018a; Vislobokov, 2017; Wu, 2018).…”

“…Researchers conjecture that fungus gnat‐pollinated Aspidistra species cheat their pollinators by mimicking mushrooms (Suetsugu & Sueyoshi, 2018a, 2018b Vislobokov, 2017) using their enlarged mushroom‐shaped stigma. Larvae of fungus gnats primarily feed on fungi and often use basidiomycetes as brood sites.…”

“…Larvae of fungus gnats primarily feed on fungi and often use basidiomycetes as brood sites. However, in Vislobokov's studies, although three species of Aspidistra flowers were all visited by female fungus gnats, neither larvae nor eggs were found in any of them (Vislobokov, 2017). In A. elatior , visiting fungus gnats were strongly male biased, and neither larvae nor eggs were found in the flowers (Suetsugu & Sueyoshi, 2018a, 2018b).…”