CP's use UV light to catch prey

[Flytyer]

News item from the BBC....

http://www.bbc.co.uk/nature/21459520

[Sarracenia1983]

I read the article, I think it is very fascinating. I always thought that carnivorous plants attracted its prey with a scent, not a fluorescent light.

[Flytyer]

It's been know for a while that plants use UV light to draw insects onto their flowers for pollination purposes, trust our favourite plants to use UV for other purposes. There's more to CP's than we realised

[olive84]

Very interesting thanks.

Oliv

[Sarracenia1983]

I didn't realise that other plants use uv light to attract insects to their flowers for pollination purposes. From reading the article I thought it was just the carnivorous plants just used uv lights to attract prey. I suppose the carnivorous plants using uv light to attract their prey, is only the same as when humans hunt animals and use bait to attract them to be hunted.

[mantrid]

An interesting article but a bit misleading. The use of the word 'emitting' suggests that the plant has light producing organs, but my understanding is that they are just reflecting UV in the same way as a green leaf reflects green light.

[Sarracenia1983]

Whether the plant emits the UV light to attract and catch its prey, or it just reflects UV light in the same way as a green leaf reflects green light. Carnivorous plants, will have probably evolved to be able to have the ability to be able to attract its prey using UV light. Just like humans will have evolved to be as smart and as clever as they are. So plants have a clever feature to attract its prey, whereas humans are smart enough to bait animals, so they can be hunted.

Edited February 21, 2013 by Sarracenia1983

[Vince81]

Hello,

Some days ago, I played around with some blacklight with some of my CPs.

Most of the "blacklight" is in the UV spectrum, but, unfortunately, there is a little part above 400 nm (from Wikipedia : http://en.wikipedia....ks_labelled.gif)

On my Heliamphora, I think what we can see is the visible light, which is reflected by the reflective white hairs, like a mirror. In my opinion, it isn't fluorescence.

It was the same on my N. jamban. I should try with other species, as what I see is clearly distinct from the published paper (http://onlinelibrary...0709.x/abstract).

As well as on a C. follicularis :

But, the most interesting fact was on my D. scorpioides :

Here, it is fluorescence . Welcome to the Avatar's world !

I don't know if it has any adaptative value, attracting insects. I think that further studies are required to understand this phenomenon.

Are the insects lured by the plant because of the UV reflection/contrasts (as it has already studied by several researchers) and/or fluorescence ? The later appears strange, but time (and studies) will tell . I wish I could investigate such an issue !

[olive84]

Superbe ces photos Vince ! Effectivement on dirait AVATAR.

[mantrid]

Interesting find Vince. Coincidence or evolutionary function, worthy of some research.

Maybe by being attracted to the centre they blunder into the surrounding tentacles at a fairly high speed causng them to stick more securely, whereas if the tentacles were reflecting UV the insect would have slowed down as they are about to land on them and so not impacting so hard enabling them to fly free easier.

It would be worth looking at other spp of Drosera to see if they have similar properties.

Edited February 26, 2013 by mantrid

[Sarracenia1983]

Some really interesting photographs, they have some fantastic effects and are really pretty.

[Manekineko]

Although this article is very interesting, many questions remain ... And, in my opinion, it is really too early to conclude that carnivorous plants use UV light to attract preys ... The authors have shown that UV light (366 nm) can induce fluorescence in the blue (visible) on some parts on carnivorous plants, and that's all. It is not the UV light that is supposed to attract preys, but the induced fluoresence in the blue region of the visible spectrum. In the day light, this phenomenon is hidden to our eyes, and it has to be proved that it is not the same for the insects ... Furthermore, the authors have just studied fluorescence induced at 366 nm. What's about for the other wavelengths in the UV ??? So many questions remain ...

[Siggi_Hartmeyer]

Together with our friend Richard Bayerl (hobby mineralogist) we could verify the article "Carnivorous plant species glow blue to lure prey" (Remark: by fluorescence when illuminated with UV-light). When using 254 & 366 nm wavelength the peristome and lower side of the lid as well as nectaries glow bluish. A diode-lamp with black light (390 nm) did not work well, as we checked even one year ago, therefore we were of course doubtfully (with 390 nm a lot of visible blue/violett light is simply reflected, but that is no fluorescence!). We will write a short article on our results on numerous different species, therefore we show only two photos at the moment. More will follow after publication, probably in May. We could actually confirm N. khasiana to fluorescence, but no Drosera did that, except the dense hairs of D. ordensis (and probably other members of section Lasiocephala will do that too). The photos below show a positive result for our (crossed at our greenhouse) N. talangensis x truncata and a negative result for N. jacqueliniae.

However, this phenomenon does not necessarily mean that the fluorescence is responsible for a better trapping success, but the sugar of the nectaries, which is obviously produced together with a flurorescent compound. Soon more ...

[Manekineko]

However, this phenomenon does not necessarily mean that the fluorescence is responsible for a better trapping success, but the sugar of the nectaries, which is obviously produced together with a flurorescent compound. Soon more ...

This is exactly what I think ! ;-)

[mantrid]

So the plant does actually emit a different wavelength of light to what it receives?

Any idea of how this happens?

[Manekineko]

So the plant does actually emit a different wavelength of light to what it receives?

Any idea of how this happens?

It's just the laws of physics. A fluorescent substance absorbs radiations at shorter wavelength than the ones it re-emits ... Some energy is absorbs by the substance during this process. Shorter the wavelength of the radiation is, greater is the energy that it transports ...

[Siggi_Hartmeyer]

Somebody asked me the question for what reason I think that the pitchers fluoresce. A very good question, worth a discussion. Here is my reply:

For what reason do you think that your fingernails do fluoresce like a peristome under UV-light, if not to attract insects?

Please consider that fluorescence is a very common and wide spread phenomenon in nature. Many compounds like poly cyclical aromatic hydrocarbons fluoresce, but most important are their pharmacological effects, their luminescence is just an outgrowth. And that is exactly the point where I criticize the article. The important questions should be: what kind of compound inside (not only!) the Nepenthes nectar is responsible for the fluorescence and does it have a pharmacological impact on insects that drink the nectar. Only this way will lead to a serious answer to the above question.

Is it (in my opinion very likely) a compound related to that in Sarracenia nectar? That Coniin called compound shows also a very nice bluish fluorescence (as clearly mentioned in chemical but not CP-related publications) but has also a real deafening effect to insects. For that reason I know that also Sarracenia is fluoresce without checking it personally (due to dormancy). Unfortunately I am retired and do not have the technical capabilities anymore to check that with appropriate analytical equipment.

However, maybe some persons who read this forum take the chance to search for that compound(s), the analytical methods to realize that are not very challenging for a modern laboratory.

Last but not least the answer to my question above: Blood is also a strong fluoresce compound. For that reason Bones (TV-series) is always looking for blood with a black light torch. Under UV-light the epidermis of your skin is blocking the luminescence, but your fingernails are more or less translucent. Therefore they show a slight bluish fluorescence under UV-lamps and (invisible due to outshining) with sunlight. However, I don't know any person who reported the attraction of insects by its fingernails.

[Dave Evans]

Somebody asked me the question for what reason I think that the pitchers fluoresce. A very good question, worth a discussion. Here is my reply:

For what reason do you think that your fingernails do fluoresce like a peristome under UV-light, if not to attract insects?

Good one Siggi. I wonder though, your test shows some species peristomes don't fluoresce so perhaps there is some good reason a plant which has glowing nectar has bothered to conceal it?

[Siggi_Hartmeyer]

No Coniin on the peristome = no glowing. Maybe the poison-free peristomes belonged to older pitchers, maybe nectar was removed by sprinkling with water, maybe several species do not produce Coniin. We simply need to learn more about this phenomenon.