Species Spotlight: The Harlequin Ladybird

Hi everyone,

This week's species spotlight focusses on what is, now, a very common species in the UK - the harlequin ladybird (Harmonia axyridis).

This familiar and fascinating species can teach us something important about both wildlife recording and about species in general.

First let's get one thing straight - contrary to popular childhood rumours, the number of spots on a ladybird's back is nothing to do with how old they are! Different ladybirds have different markings because they are different species (most of the time... read on to find out more). In fact, there are approximately SIX THOUSAND species of ladybirds! Ladybirds are a family of beetles, known as the Coccinellidae family. So, onto one of these species, the harlequin...

A native of Asia, the harlequin ladybird only arrived in the UK in 2004, but quickly established itself as our most common ladybird species, taking the title from our native 7-spot ladybird (Coccinella septempunctata). The harlequin has been able to do this as it is a voracious predator with an aggressive attitude - not only will it outcompete other ladybird species for aphid prey, it will also eat the eggs and larvae of other species too! The same thing happened in North America in the late 1970s - the harlequin was introduced to control aphid populations, but quickly began outcompeting native species, and is now the continent's most common species.

This brings us on to an important point about wildlife recording, and why the pictures you all upload are so important. Citizen science is a vital tool in understanding which species are common and which are rare, and how this changes over time. These patterns help biologists work out how things like climate change, urbanisation, agricultural practices, and habitat loss affect species, and how species respond to them. This tells us something about the state of health of populations, ecosystems, and the planet in general.

Therefore, if you're thinking it's pointless taking a picture of a species you see all the time, that is NOT the case! If a species is common, it is good to make a recording of it, as this shows scientists that the species is indeed common, and this helps scientists track species declines/rises over time, as with our 7-spot and harlequin ladybirds. So don't worry if you're not finding any rare species in your recording - your pictures of common species are just as helpful!

Let's look more at the species itself now. If you look at the Wild Watch observations page, you will see, currently, we have five harlequin observations, and each looks different from the other! This is not an identification mistake; it's because the harlequin ladybird is EXTREMELY variable in how it looks, with about TWENTY different forms existing, all of this one species! They can be red and have anywhere between zero and twenty-two black spots; they can be black with red spots, or black with no spots; they can be orange (again, with or without spots); or even a complex pattern of red, orange, and black!

This shows us that relying on looks alone is not enough to tell species apart, even though this is usually the simplest and most reliable way. However, if we relied solely on looks, we would split the harlequin into about twenty species instead of one, and I think, with over 6,000, we have quite enough ladybird species already!

So how do we tell species apart if not by looks alone? Taxonomists (biologists specialising in classifying things) have several methods up their sleeves, the most common of which, nowadays, is to use DNA. Taxonomists can also look at mating behaviour and phylogeny (the evolutionary relationships between organisms), but the answer still isn't always clear. This is because, as ridiculous as it sounds, biologists still aren't exactly sure what a species is! As I will write about in a future blog post, the idea of a "species" is actually very messy (as most things in biology are), but that really will require another post to explain. I will choose some species that gives us the opposite problem of the harlequin ladybird (i.e. looks near-identical, but are actually separate species) to explain this more in the future.

Anyway, I hope this has given you the confidence to know that WHATEVER you upload to this page is really useful for present-day and future scientists alike! Keep up the awesome work everyone and I'll be back with another blog post soon.

Diolch
Kieran

Posted on August 2, 2021 10:58 AM by kieran-182 kieran-182

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