How do orchids affect their pollinators?

Everyone knows the orchid structure has a special feature, which is the petal below that turns into a lip, like a landing area for pollinators (pollinator). The lip wing changes (for example, a female insect) or releases pheromones that attract male insects to pollinate.

(Photo: Florian P. Schiestl) According to that logic, the relationship between orchids and pollinators can be considered symbiotic relationships because insects do not lose anything but the orchids are quite far away. cross-pollinated in a fairly accurate way. However, there are some things to consider before calling this relationship symbiotic.

This study was carried out and published in 2002, although it was not new, but because it brings a unique way of thinking of foreign scientists, it is a very good lesson.

The results of the study explain why the density of Chiloglottis trapeziformis , an insect-pollinated Australian Cymbidium, is negatively correlated with the species density of pollinators in the area. Meaning there are many Chiloglottis trapeziformis , there are few pollinators of it . Chiloglottis trapeziformis Pollinator is the male bee thynnine (Neozeleboria cryptoides) male, in this species, female bees do not have wings so it can only crawl in the ground and attract males with pheromones and bee-shaped backs. .

As for Chiloglottis, to be able to rely on male Thynnine bees carrying pollen, they not only have the same lips as the female bee but also have the ability to secrete pheromones with similar biological activity. When conducting experiments comparing the attractiveness of orchids and true bees, it was found that it was almost impossible to distinguish between bees and flowers. They fly into test tubes containing orchids, transparent female bees, sealed (try the ability to identify, not to smell) and black, open test tubes (try pheromone recognition ability, do not indicate shapes ) with the same frequency. In particular, the average number of male bees entering the female bees is 2.63 ± 0.86, orchids are 2.50 ± 1.20; n = 8, p> 0.05).

However, in reality, there is still a mechanism that helps some Thynnine bees to recognize the true bees and stay away from areas with orchids growing.

As a result, when surveying the field, people found that bees tend to fly less into areas with orchids that often fly into places where there is no spread. Based on the above statistics, we can also see the ' trust ' in bees cheated at first sight, 100% of these bees perform acts of mating with flowers without any Which manifest manifests.

The negative correlation of density between Chiloglottis trapeziformis and Neozeleboria cryptoides has been recognized for a long time but only after the study was published did people realize that the phenomenon of local insect density decline is due to themselves. Avoid going to another place.

This result rejects another idea that the mating between pollinating insects and orchids takes place many times reduces the reproductive power of male insects and thereby reduces pollination insect populations. In fact, the correlation of the number of bees - orchids is often only negative at a relative level, the spread always needs bees and bees, not all of them are smart enough to avoid being fooled.

Reference :
Bob BM Wong and Florian P. Schiestl. How an orchidharms its pollinator. Proc. R.Soc. Lond. B (2002) 269, 1529–1532
DOI 10.1098 / rspb.2002.2052

Nguyen Huu Hoang