Specialized pollination by fungus gnats in the introduced population of Aspidistra elatior

Abstract

The monocot genus Aspidistra comprises rhizomatous perennials that are distributed in tropical to warm temperate regions of Asia. Little is known about the pollinators of almost all the species, probably due to the inconspicuous nature of Aspidistra flowers. Nevertheless, the unusual floral morphology suggests biotic pollination, since pollen grains are hidden under each flower's stigma. Aspidistra elatior has been suspected to have a very peculiar pollination ecology. So far, pollination by mollusks, crustaceans, or collembolans has been suspected. However, a recent study showed that A. elatior is mainly pollinated by species of fungus gnats in Kuroshima Island, southern Japan, which is its natural habitat. Here, we investigated the pollination ecology of A. elatior in Shiga Prefecture, central Japan, which is the introduced population, to reveal whether fungus gnats are also the main pollinator in the introduced population. Our study confirmed fungus gnats pollination in the investigated pollination. Furthermore, the main pollinators (i.e., Cordyla sixi and Bradysia sp.) are the same in both Kuroshima and Shiga Prefecture. Therefore, A. elatior mainly depends on a narrow taxonomic group of fungus gnats for pollination. In contrast, we failed to document any terrestrial amphipods visiting the A. elatior flowers, in spite of a relatively high fruit set in natural conditions. This fact will refute the amphipod pollination hypothesis proposed by previous studies. We consider that A. elatior is pollinated by fungus gnats through fungal mimicry, due to its superficial similarity to mushroom fruiting bodies and strong, musky floral scent.

To cheat or to treat? Fungus gnat pollination in Aspidistra

“…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.…”

“…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). Researchers concluded that fungus gnats received no benefits from their interaction with Aspidistra flowers.…”

Efficacy of Natural Extract from Ocimum Species against Fungus Gnats Infesting Plant Saplings

“…Every living being plays its role in maintaining ecological balance, a repelling approach unlike the insecticidal approach will not interfere with maintenance of ecological balance. [2][3][4][5] Hence we see this as a significant merit of using Ocimum extract over to other methods currently recommended for the management of fungus gnats infestation of plant saplings. Moreover the aroma of Ocimum extract is very pleasant to humans, wherein by stimulating the human olfactory system it is reported to improve immunity.…”

“…Fungus gnats are tiny flies commonly observed around household plants as the moist soil, organic contents and the tender roots of the plant provides an ideal environment to nourish their larvae. 1,2 While these flies are harmless to humans, they are often annoying when they navigate around your face. The larvae of the flies by feeding on the tender roots of the plant can impact the plant health, this is of specific concern for plant saplings as they may fail to cope and thrive from the minor root damage induced by the larvae.…”

Male mate‐seeking and mating behaviors of Eucera nipponensis (Hymenoptera: Apidae) at a nectarless orchid habitat: Are empty flower patches a profitable rendezvous site?

“…Here, we provide the following compelling evidence that empty flower patches of C. goeringii are not necessarily fruitless sites for mate-seeking E. nipponensis males: (i) flower visits by females were observed; (ii) two or more mate-seeking males were observed at the same time; and (iii) their activities resulted in at least nine successful matings. Recently, Suetsugu and Sueyoshi (2018) found that male fungus gnats of the genus Cordyla (Diptera: Mycetophilidae) are the primary pollinator of nectarless Aspidistra elatior Blume flowers. This finding might imply that male mate-seeking activities at non-rewarding plants are widespread among insect taxa other than aculeate Hymenoptera, including bees (Alcock et al 1978;Alcock 1980).…”