Harlequin ladybirds

[STYRBJORN]

As a newbie to the site, I may well have missed prior discussion on this topic, in which case I apologise for raking over old coals.

I have noticed that on the mammal and bird forums/fora, there is reluctant but realistic acceptance that it may be necessary to "control", ie kill, invasive species in order to maintain indigenous species. In East Sussex where I now live (I am at Sussex University) we have a high population of harlequin ladybirds. I found one, not previously recorded in the UK, on campus. When harlequins were first recorded in the UK there were fears expressed that they would out-compete our native 'bugs, or even eat them. Yet the 'quins and the native 'bugs seem to be achieving a balance, at least on campus, such that each is living in its own ecological niche, with competition only on the margins. In evolutionary terms this is a fascinating occurrence, and I would love to get some feedback from folk on this site. Should we stomp on any 'quin we see or, in this case at least, let nature take her course - even though our introduction of 'quins was thoroughly UNnatural?

STYRBJORN

PS I am not a Quins fan. I'm from Leicester! Tigers man me!

[Susie]

I can't see how you could eradicate harlequins even if you wanted to.

[aeshna5]

Absolutely pointless squashing them as they are so well established at least in the southern half of the country.

I'm not sure how much of a problem they really are? They don't seem to be having any affect on 7-spots which seem to have done very well last year + so far this year.

2-spot is a species which has been suggested as a species most likely to suffer negative results. In the last week or so I'm seeing a few more 2-spots than for a while.

Certainly the genie is out of the bottle now, so all we can do is watch + record this man induced ecological experiment.

[Jason Green]

Evening STY,

Originally Posted by STYRBJORN

I found one, not previously recorded in the UK, on campus.

Really? Tell us more! Anyway, as Aesh says they are too-well established for any culling to work. So far this year I've had the Harlequin, Seven-spot Ladybird, Orange Ladybird, Fourteen-spot Ladybird, Twenty-two spot Ladybird, Rhyzobius litura and a Scymnus sp. - with Harlequin one of the most common, in fact I've seen three there today consisting of two forms.

Still, the others seem to be hanging on alongside...

Take care,

Jason

[STYRBJORN]

It was a variety of the black-with -two-red-spots. The range of varieties suggests to me that they are undergoing a period of rapid evolution.

STYRBJORN

[Paul mabbott]

Originally Posted by STYRBJORN

It was a variety of the black-with -two-red-spots. The range of varieties suggests to me that they are undergoing a period of rapid evolution.

STYRBJORN

Would need to know more than that! I don't think it tells us anything about evolution: our native species Adalia bipunctata and A. decempunctata are equally, if not more, varied in body patterns.

I agree with most other posters. I doubt that you will be able to control Harmonia axyridis other than locally and temporarily. Anything you could attack them with, as yet, would also kill all the other ladybirds (and many other insects beside). Furthermore, I don't think you can jump to any conclusions about their impact on other species over such a short time - studies over ten or twenty years might allow us to draw conclusions.

[STYRBJORN]

I too agree. My comment about stomping on them was made in jest. As I said, they appear to be co-existing with endemic 'bugs quite happily so far, at least locally.

My feeling about rapid evolution, and it is only a feeling, is based on the variability exhibited throughout the 'quins' range. Such variability provldes maximal chance for selection to occur. I can't defend the idea rigourously, it's more intuitive than intellectual.

Thanks for your comments all.

STYRBJORN

[Paul mabbott]

The variation of elytral and other body patterns is hardly likely to act as a stimulus for speciation. There's little evidence amongst those species (especially Adalia bipunctata that such patterns have very much adaptive value even at local, population levels. We shouldn't really confuse such trivial polymorphism with the major changes that are necessary for evolution into new species.

As far as we know, the species has been so variable for a very long time: pattern dominance in its native area varies considerably from e.g. Siberia to the China Sea but is linked mostly with climate. Similarly, the proportions of the various patterns in colonised areas will probably be determined by climate or weather ... but will have no evolutionary effect, probably.

Originally Posted by STYRBJORN

...........My feeling about rapid evolution, and it is only a feeling, is based on the variability exhibited throughout the 'quins' range. Such variability provldes maximal chance for selection to occur. I can't defend the idea rigourously, it's more intuitive than intellectual.
.........
STYRBJORN

[STYRBJORN]

Paul,
You are clearly more knowledgable than I about this than I, but I still wonder. My interest in insects and in evolution was triggered in the early 1950s. There was a lot of hoo-hah recently about Biston bistonaria, the peppered moth, and the way in which the melanic variety had spread as a result of industrial pollution, and is now on retreat. Well BIG DEAL. Not.

Back in the early 50's, I was finding more and more of what I called back to front ladybirds; to you and me today, melanic variants, mostly 7-spots. I started to try to find out what was going on. Solemn little 7-yr old lads were not taken very seriously, but I eventually found that ladybirds absorb solar energy through their spots. Atmospheric pollution - pre Clean Air Act! - was reducing the amount of solar radiation available for the 'bugs. The melanic variety was an uncommon sport which would in the ordinary way die from excess energy absorption, but was at an advantage in the lower energy environment.

It seems to me that the black bodied red spotted 'quins may prove to have greater reproductive fitness in the North, while the yellow/red bodied variants with black spots will have the advantage in the South. If that should be the case, then it is a perfect scenario for a speciation event.

Not that our pontification will make a scrap of difference!

STYRBJORN