Saturday 28 June 2014

Enicospilus - Stephens, 1835

National insect week continues!

The japantarra [Central Bearded Dragon - Walpiri] honours this by consuming as many as he possibly can in as short a time as possible. Of course, he does that every week, so it's unlikely that he's actually aware of the event.

Here's one that won't be going down his throat:

Chongwe, Lusaka, Zambia, February 2013. Photographed using Olympus E-420 DSLR, Zuiko 40-150mm lens and 3 KOOD magnifiers.

In Chewa dialects, this - and numerous species both similar and dissimilar - are referred to as Abemberezi (singular form bemberezi), a group of insects of particular benefit to both farmers and scientists; in English - and related languages - these are the Ichneumon wasps.

Their use to farmers is twofold: first, like almost all wasps, the adults are valuable pollinators; second, ichneumon wasps are one of the most diverse groups of parasitoids on land; animals which spend a significant period of their life as a parasite on or within another animal.

This second point is where the ichneumons stand out from other wasps; unlike potter wasps such as Synagris proserpina [link], most ichneumons are rather specific in their choice of baby-food, with any species usually sticking to a particular family, genus or species as a host for their developing larvae.

The upshot of all this is that a farmer having a particular problem with any given insect pest can encourage or introduce a selection of species that are known to preferentially parasitize that species, and, so long as chemical control doesn't wipe out the pest or the parasitoid, their problem will be kept at a manageable level thereafter.

While abemberezi are interesting to scientists in a great many ways, they - along with a diversity of other parasitoids - are of particular value as biological indicators.

You may or may not be aware that the top of the food chain is, in evolutionary terms, a very dangerous place to be. It is. Being fussy at the top of the food chain, although a great way to avoid competitive exclusion, is an even better way to go extinct.

Imagine, if you will, that any healthy population required only eight individuals in that species (which would be very low). If a species is a producer (a plant, algae or various bacteria), it only needs enough resources to be available to support eight individuals. Provided that no competitive exclusion, mass predation or cataclysmic event wipes them out, they'll generally survive.

Now say that a herbivore of about the same size as the plant exists, and it needs a population of, conveniently, eight plants, in order for enough food to support it to be consistently available.

Now we need sixty-four plants, in order to support those eight herbivores.

And those herbivores have a predator, again of similar size and, by a curious coincidence (I like the number eight today), requiring a population of around eight herbivores to eat so that it doesn't eat them faster than they can breed (and yes, this is a laughably low figure). That means we need at least sixty-four herbivores to support our predator, and its seven colleagues, and 512 plants.

We are, of course, assuming that these plants, herbivores and carnivores are the only species around and lack disease and exist in a perfectly stable environment.

In this environment, we could perhaps expect a tertiary consumer, or top predator. Think about eagles preying on falcons, or wolves eating pet dogs. That sort of thing. Anyway, the same rules apply about how many need to be around for him to not eat them too fast.

Anyway, this now gets to 4096 plants that need to be alive and well at any given time.

So now, we introduce the real world.

Populations fluctuate. A surprise abundance of plants due to good rain one year means that the rabbits are healthy enough to have an extra litter and double their numbers. Before fox populations can respond, the rabbits have eaten the plants down to their roots and after the winter, only 130 rabbits have survived.

Bad news for the foxes, only sixteen of whom can survive this famine, although, on a happy note - given how dispersed the foxes are within the environment at this stage - not even the two wolves who might theoretically have managed to survive on this population can forage efficiently, so these surviving foxes do quite well for themselves, and only one wolf makes it through the winter.

Oops. No more wolves. Ever.

This is not a real world example. But it serves its purpose well; no matter how fragile the situation gets in the lower levels, the most dangerous place to be is always the top. This used to apply to business, too, until the British Government started bailing out failing giants at the taxpayers expense...

But I digress.

As a parasitoid is essentially a specialist predator, it is in an extremely fragile position and, although some species may thrive in disturbed environments, a diverse assemblage of parasitoid wasps is usually a good indicator of an intact invertebrate fauna - which itself is an indicator of high-value habitats worthy of protection and/or study.

That has to be the most words it has ever taken anyone to get to the point.

Anyhow, this wasp is a member of the vast genus,

Enicospillus
Stephens, 1835

And as such, probably parasitises a selection of Noctuoid moths (such as, but probably not its actual host, the Erebid Laelia robusta [link]). 

Also, it's somewhat bizarre and alienesque. Here's another picture, to give you more of an idea of its form:


And that, folks, is all.

Thursday 26 June 2014

Catopsilia florella (Fabricius 1775)

Four days into national insect week, it seems as though it would be atrocious if I allowed the long-standing funk I seem to be in to stop me from posting something appropriate.

I had planned a lengthy discourse with tons of pictures of invertebrates, but focusing on anything lately has not been very doable (you may have noticed, in the unlikely event that you read through it, that the lengthy taxonomic notes have disappeared from recent posts. Which makes navigation harder, but saves about half an hour of distractedly re-doing the same thing.

Anyway, whining over, meet today's guest:

Lusaka City, Lusaka Province, Zambia, in October 2011. Photographed with Olympus E-420 DSLR, Zuiko 40-150mm lens and 3 KOOD magnifiers.
This soft-touch of an entry to a blog supposedly focusing on under-loved groups (in my defence, it was suggested by a random number generator) is one of Zambia's many Agulugufe (Chewa - plural of gulugufe), but is far from endemic; it extends through most of Africa, including island nations such as Madagascar and the Canary islands - which, having remained a territory (=colony) of Spain, is often used by entomologists to say that the butterfly is found in Europe. A little bit like saying that penguins breed on British shores when they're actually in the Falklands, but I digress.

This gulugufe is also found as far east as India and Sri Lanka (பட்டாம், ~Pattaam in Tamil; तितली, ~Dtidt(a)li in Hindi), and just in case you hadn't worked it out from the picture, the English term is Butterfly. 






As an etymological aside, one Chewa term for these distinctly user-friendly insects is Peperu, which is, to my ears at least, surprisingly close to the French Papillon.

As with a lot of insects which are not particularly edible, a common name specific to the species is difficult to find in Chewa; the most direct translation from the English '[African] Migrant' I can find is Matchona, which means migrant workers, and, by its structure and the persistent use of Zimbabwe in the example usages, would seem to refer even more specifically to members of the Shona people of Zimbabwe, who make up a considerable proportion of migrant workers in Zambia and Malawi.

So I am forced to think more broadly for a Chewa name to reflect the nature of these insects; Mlendo, which translates most directly to Guest, but can also mean Stranger, Tourist, Foreigner or Traveller, seems the most appropriate.

Our Mlendo Gulugufe can be referred to, internationally, as

Catopsilia florella
(Fabricius, 1775)

Within the butterflies, it is in a generally not white subfamily (Coliadinae) of the 'White' Butterflies (gugulufe loyera), the Pieridae, of which only one other butterfly has thus far been featured, the also not-white (but in the largely white-ish subfamily, Pierinae) Eurasian Orange-Tip, Anthocharis cardamines


Same as opening image, but only 1 KOOD magnifier.
As with most butterflies, there is sexual dimorphism (males and females look different), but with the Mlendo Gugulufe it is imperfect; while the individual to the right(the same one pictured at the top of the post) shows a colour form found in both males and females, the more cryptic colouring  of the specimen below is only known from females. 

Photographed in Chongwe, Lusaka, Zambia, in February 2013, using Olympus E-420 DSLR and 40-150mm Zuiko lens with 1 KOOD magnifier.







And that, folks, is all.









For the identification of large and distinctive African butterflies, the most comprehensive guide I've found affordable is Steve Woodhall's Field Guide to Butterflies of South Africa, published through Struik and available through Amazon (here). As I remain the world's biggest fan of free information, I can't go without mentioning the late R. C. Dening's collection, which, although not as user friendly, is more appropriate to Zambia and, key point, freely accessible online (click here to visit it).

Saturday 21 June 2014

Podiceps cristatus (Linnaeus, 1758)

It's nearly National Insect Week.

This, by the way, is not an insect.


Attenborough Reserve, Nottingham, UK, in June 2014. Photographed using Olympus E-420 DSLR and Zuiko 70-300mm telephoto lens. Edited using GIMP to remove unwanted element from bottom right corner.


I know, it's a long unbroken string of vertebrates, which is somewhat biased, but that's life.


This lovely bird is, however, quite important for British insects.

It, like most British wildlife with any hint of the exotic in its appearance, was almost wiped out through overhunting. It was fortunate in its timing, however, as the peak of its destruction coincided with the existence of one Emily Williamson, who, in 1889, began a campaign to put life before fashionable hats.

This, to avoid unnecessary drama, was the foundation of the RSPB, one of several organisations now responsible for a large number of Britain's nature reserves and, despite some questionable management choices in some reserves, a major player in the conservation of the diversity of British insects.



The tenuous link to the upcoming insect week is not the only interesting thing about this lovely bird; it's also extraordinarily adapted to an aquatic lifestyle; their legs, perfectly positioned for swimming, are completely inappropriate for supporting the adult's weight on dry land, and cannot do so for more than a few steps.

This presents an obvious problems; watertight though they are, the amniotic membrane cannot usually absorb enough oxygen to sustain a growing bird if it's partially or wholly submerged. A nest on the immediate edge of the water, which would allow a bird limited to the water easy access and escape, is extremely vulnerable to changing water levels, which would limit the birds to extremely stable environments.

This bird, however, survives - and arguably even thrives - all over Europe, Asia, Australia and parts of Africa, and breed in a number of areas where water levels are rarely reliable.



So they build a nest that maintains a constant distance from the water, by building their nest on top of the water, and when their chicks hatch, the first order of business is teaching them to swim.



Nottingham, July 2013. Olympus E-420 DSLR and 70-300mm Zuiko lens.



This comes in an act of rather heartless parenting. First, they give the babies a tour of the neighbourhood while perched on Daddy's back. Once they're used
  

to this, Daddy swims away and leaves the babies to work out how to get back to him.

Still, it's not all bad - the chicks seen in the photograph to the right were several weeks past water-dumping age, but were still allowed to pass a lot of their time enjoying the scenery from the safety of their parents wings.






So what, drumroll please, is this mystery bird? Why, it's the great crested grebe (Puteketeke in New Zealand's Maori language; Kuifkopdobbertjie in Afrikaans; or Grèbe huppé  in French),

Podiceps cristatus  

(Linnaeus, 1758)

And that, folks, is all!