Orchid and Fruit Fly – Scientists have discovered a unique new relationship between plant and animal

interrelationship between fetal stomach and pollinators, both of which feed primarily on mushrooms. The flowers give off a mushroom-like scent that attracts flies. While the flies feed on the flowers, pollen sticks to their backs (1). When the fly leaves one flower and visits another to lay its eggs, the adherent pollen grains come into contact with the stigma, and pollination is completed (2). After successful pollination, the flower begins to wither and the larvae that hatch internally begin to consume the petals (3). The larvae grow larger by consuming the petals that have fallen to the ground (4). After about a week, they become adults. Credit: Ansai Shun

For the first time, it has been observed that fungus-consuming orchids offer their flowers to fungus-eating fruit flies in exchange for their pollination services. This finding represents the first evidence of nursery pollination in orchids. This unique new plant-animal relationship signals an evolutionary shift toward mutual symbiosis.

Orchids have been known to trick their pollinators into visiting flowers by mimicking food sources, breeding grounds, or even mates without offering anything in return. Orchids are fungi-eating, non-photosynthetic stomach No different: to attract fruit flies (Drosophila spp.) The plants usually give off an odor that resembles their common diet of fermented fruits or decomposing mushrooms.

The larva of the fruit fly feeds on the decaying tissues of flowers on the ground. Credit: Sutsugo Kenji

Fruit flies are attracted to the inside of flowers, stay there for a short time, get pollen on their backs, and then transfer it to other plants of the same species classify. Thus this deceptive relationship offers benefits to only one partner.

Kobe University plant biologist Sutsugo Kenji, who specializes in these orchids, notes that a certain species of this genus, fetal stomachIt has particularly fleshy petals that loosen and fall off a few days after pollination. He decided to investigate these plants for the first example of orchids practicing “nursery pollination,” a plant that provides a breeding ground for its pollinator.

The fruit fly lays its eggs inside a flower fetal stomach. Credit: Sutsugo Kenji

And indeed in the study now published in the journal EcologyHe stated that fruit flies often lay their eggs in the flowers of plants and that their larvae can fully develop into adult flies in this environment.

“The most interesting aspect is that, contrary to its common name, fruit fly, Drosophila bezonataa species that specializes in feeding mushrooms, mostly using decomposition fetal stomach Flowers as brood sites. The possible explanation is the fact that it is fetal stomach It is an orchid that does not perform photosynthesis and feeds on fungi. Orchids that don’t photosynthesize often show a chemical similarity to the fungi that ingest them, confirming the old adage “you are what you eat”. like a plant that feeds on mushrooms, G. Wojtyda It likely tastes similar to mushrooms, making it a prime target for mushroom-specific fruit flies. This discovery is significant because it reveals a new type of incubation pollination system, beyond the deceptive strategies commonly found in the genus.

flower fetal stomach. Credit: Sutsugo Kenji

The researcher at Kobe University further explains that the relationship is neither obligatory nor specific, meaning that fruit flies also lay fully-developed eggs on fungi. Thus, this result may represent an example of a transition from a chimeric relationship towards mutualism, which is suggested by two factors: the low cost of the plant, in which the petals are no longer needed after pollination; which are closely related stomach Mostly using deceptive strategy without providing custody.

flower from fetal stomach on the brink of decomposition. Credit: Sutsugo Kenji

Sutsugu concludes: “This study represents the first evidence of nursery pollination in orchids, which, with nearly 30,000 species, are the most diverse plant group in the world. In addition, it contributes to a vital understanding of the complex and mutually beneficial relationships that can evolve in Nature Understanding how plants can provide real benefits rather than simply deceiving pollinators could influence the broader study of plant-animal interactions and their evolutionary dynamics.

Reference: “A New Incubation Pollination System Between Fungal Orchids and Mushroom-Eating Flies” by Kenji Sutsugo, August 23, 2023, Available here. Ecology.
doi: 10.1002/ecy.4152

The study was funded by the Japan Science and Technology Agency.