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Dear all,

For ones not an identification question (I hope that is okay). But a question about the techniques diptera use for pollen transport.

I'm working on my Bsc literature thesis about the importance of non-bee pollinators, so I'm also looking at Diptera. But I can't find anywhere how diptera transport pollen. Is it just as for coleoptera that the pollen get stuck in the setea and pubescence? Or is it something else? Most preferebly with scientific literature :)

Thanks in advance,
Koen Verhoogt

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Species of Egle in family Anthomyiidae carry pollen on long hairs.

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In my former lectures on pollination biology I also dealt with Diptera. Their main reason to visit flowers is to feed on nectar, stigmatic secretion, and pollen. Some taxa take carrion-mimicking or fungus-mimicking flowers and inflorescences for breeding sites; these structures also serve as lekking arenas. Pseudocopulatory pollination by fungus gnats is known from Lepanthes (Orchidaceae). Many flies are hairy, even their eyes, so pollen sticks easily. Plant taxa that display rhinomyiophily are pollinated by flies with long proboscises, e.g. Nemestrinidae. Even if the flies visit different taxa, pollen transfer to a wrong species is avoided by the morphology of the flowers, depositing the pollen on different body parts that all are, of course, hairy. On the other hand, Orchid pollination (the transfer of stuck pollinaria) demands smooth surfaces. Pollinaria stick best on proboscises but also on smooth abdomen parts.
As flies do not collect pollen for their offspring, their legs or other body parts do not possess special adaptations. Their hairiness is an efficient tool in unintentional pollen transfer. As with other hairy pollinators, electrostatic forces play a certain role in pollen adhesion, but this is not Diptera-specific.
You can easily google texts about myiophily and its subcategories in which the kind of adhesion to the pollinator is mentioned. If you have more questions, send me a private message.
Regards, Sundew

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Thanks a lot for your help and time! :)

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As much as anything in evolution can be said to have a purpose, I think the purpose of the long hairs on Egle is to carry pollen. The flies are obligate associates of Salix, and benefit from pollinating their hosts.

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"Anything in evolution can be said to have a purpose" sounds a bit teleological to me, dear John. However, without drifting into philosophy (considering intelligent design etc.), a certain degree of mutualism between Salix and Egle cannot be denied. As the flies feed on the male as well as the female inflorescences and oviposit in the latter, cross-pollination of the dioecious plants is facilitated. There is a similar correlation between the hermaphroditic Trollius europaeus and Chiastochaeta. However, there is no total interdependency; the flowers may well set seed through other visitors or (Trollius) by selfing.
The hairs of Egle are not exceptionally long, but - and this is interesting! - their diameter seems to fit well into the colpi (furrows) of the pollen grains of Salix, so that the grains "grip" the hairs. Look at the nice pictures in https://www.bayce...H_2016.pdf p. 40. So colpate grains obviously are better adapted to this kind of transport than are porate grains. Floral biology is such a fascinating field; regarding this fact I pity that I am retired...