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.

Vespula germanica (Fabricius, 1793)

You may well note that today is the day of wasps. 

There is a reasonable reason for this.

Today, at my oh-so-glamorous retail job, my colleagues were overreacting to this post's featured species. Earlier in the week, they called the exterminators in, who came and sprayed some poison and completely overlooked the fact that it is late summer in England.

Let me expand.

Towards the end of summer, the wasp queens gradually stop laying eggs. The workers, who have up to this point been using their developing siblings to convert mashed up insect remains into sweet sugary nectar, are left out of a job and out of food.

So, more than a bit peckish and possibly having mid-life crises as they realise that they have spent their entire adult life raising something which no longer needs them, they go a-wandering. And in their wanderings, they find that sweet things, previously only really encountered in flowers and at the business ends of their little brothers and sisters, are everywhere.

In retail, sweet things often go out of date, or are dropped on the floor and rendered somehow unsaleable. They are then thrown into a large bin, in a half-heartedly tied bag, and put outside.

Starving wasps smell this sweet waste from some distance and come flocking. Having temporarily eaten their fill at the waste, they explore the surrounding area, and, should they wander inside, become disoriented by artificial light-sources, and become trapped inside, where they will eventually either find their way out, or die.

Killing the wasps inside the shop, or even on the bin, or - should you locate it - at the nest will have little effect. None of these is the source of the wasps, which are now vagrants with sweet... mandibles, and indeed the only extermination that could wholly prevent their arrival is of every social wasp in the country. Even if this was viable, the reduced predation on insect larvae the following year could easily turn large swathes of the country into desert.

So - as I have now told you, and as I told my co-workers before they called for the exterminators, extermination is useless. As preventing access to the shop is also not viable (customers and staff fit through holes a little too large to exclude wasps), the only reliable way to discourage these wasps is to remove the local food source - to whit, to clean the years of sugary filth of the outside of the bins, to ensure that the bins are closed and thus not attracting wasps, and to be certain to contain and clean up any spillages.

An easier option is to simply avoid sitting on or swatting at the wasps. As they are no longer protecting nests, they tend to sting much less readily, although they can still become aggressive if directly offended - to whit, being swatted at or partially crushed.

One argument against this laissez-faire attitude is that they are annoying.

This, and note sarcasm, is absolutely a reason to take something's life. 

I'll reward you for trawling through that lengthy pre-amble with a photograph. Spheksophobes should either accept that a picture is not going to sting them or skip ahead. 

A female V. germanica eating sugar. Bosham, West Sussex, UK.

 
After that picture break, here's the taxonomy: 

 - Eukaryota
   - Animalia
     - Eumetazoa
       - Bilateralia
         - Nephrozoa - see also Thelotornis capensis, Lygodactylus capensis, Chalcophaps indica, Sterna hirundo, Ardea goliath, Trachylepis varia and Hipposideros vittatus.
           - Protostomia
             - Ecdysozoa
               - Arthropoda - see also Ligia oceanica, Dicranopalpus ramosus, Enoplognatha ovata and Hyllus argyrotoxus
                 - Hexapoda
                   - Insecta
                     - Dicondylia
                       - Pterygota
                         - Manopterygota - see also Enallagma cyathigerum and Pseudagrion hageni
                           - Neoptera - see also Sybilla, Stictogryllacris punctata and Cyathosternum prehensile.
                             - Eumetabola - see also Pephricus and Anoplocnemis curvipes
                               - Endopterygota - see also Hagenomyia tristis, Zebronia phenice, Laelia robusta, Anthocharis cardamines, Acada biseriata, Panorpa germanica, Megistocera filipes, Diasemopsis meigenii, Episyrphus balteatus, Helophus pendulus  Demetrias atricapillus, Anthia fornasinii, Melolontha melolontha, Otiorhynchus atroapterus, Malachius bipustulatus and Senaspis haemorrhoa

                                         - Hymenopterida
                                           - Hymenoptera
                                             - Apocrita
                                               - Aculeata - see also Astata tropicalis
                                                 - Vespoidea
                                                   - Vespidae - see also Synagris proserpina

                                                     -Vespinae

Vespula germanica

(Fabricius 1793)

Otherwise known as the German wasp - rather misleadingly, as it is not confined to Germany but native to much of Europe and introduced to just about every large city within the temperate zones of the world, where - in the absence of various similar Eurasian species - it is often known simply as the yellowjacket.

For a similarly misleading regional name, see Panorpa germanica.


That's all, folks.

Synagris proserpina, Gribodo 1891

Possibly my favourite wasp of all (and it's worth noting that I'm generally quite keen on wasps).

If we're being complete about it, there's a subgenus and a subspecies as well (because after nearly a year of failure, I wrote to an entomologist with a published interest in the genus. That doesn't usually work. That's just how awesome Synagris wasps are. People write back), so I'll expand it to:

Synagris (Synagris) proserpina nyassae

(although I don't know who gave it the subspecific name, which is why Gribodo 1981 remains in pride of place in the title)

The subspecific epithet - nyassae - is a reference to a pre-independence name for Malawi, in central Africa.

The specific epithet is the name of the roman goddess of spring (wiki tells you more, here), although the origins of the word is from the latin "to emerge", proserpere. 

The generic (and subgeneric) seems to be from the latin agrum, meaning field, and the greek συν ("syn"), or with/together (As far as I'm aware, the same root prefix for "Sympathy" and so forth).

If we were to take this on face value to make up a "common" name for the subspecies, we'd go with Malawi Proserpina's (or emergent) True Field Associated Wasp. We'd probably tone that down to Malawi Proserpina's Field Wasp.

Alternatively, I could just reveal that the genus Synagris is often referred to as "Tusk(ed) wasps". for a reason which I can reveal quite simply with an image of a male specimen:

(I apologise for interrupting your day with an image of a deceased insect, but it may help to know that it was found dead rather than killed, in an area thronging with females, and so probably died happy. Very happy)

In case you're having trouble working it out, it has long, curved tusks springing from the base of its (also quite long) mandibles. 

So, today's special guest might be best described as a Malawi Proserpina's (or emergent) Tusked Wasp. 

We're going to talk about behaviour, now. 

Some of you may have been told that insects are simple creatures which basically lay their eggs and leave them (I was first told this by a secondary school biology teacher. However, she was a young earth creationist, so her misgivings about insects aren't her major disqualification there).

The wasps (which includes the bees and ants, by the way), are the most stunning illustration of this not being true. While some - notably the parasitoid Ichneumons, and many of the herbivorous sawflies - have no contact with their young after meticulously selecting a suitable host/foodplant, several lineages have evolved complex social organisations and even the most complex invertebrate communication system known entirely for the purpose of raising the next generation. 

Potter wasps in the subfamily Eumeninae are not truly social, unlike the paper wasps of the Vespinae and Polistinae, but do, as individuals, go to impressive lengths to provide for their undeveloped offspring. In most cases, this simply involves finding a suitable site, building an elaborate structure to keep the elements off the soon-to-be larva, preparing a suitable meal and sealing the egg in with it. 

As if doing this for each and every egg they lay is not enough work for an animal less than an inch long and with only a year or two to live, Synagris (and several other groups) go further. They don't seal the pot, which has usually been built on a sturdy blade of grass, high enough to be overlooked by roving ants and similar ground predators, but not so high as to attract the attention of birds, but instead keep it open and, every day until the larva pupates, they find food, mash it up, and give it to their larva. When they're not doing this, they sit on top of the nest, ready to chase away any parasitoid wasps or flies that would otherwise harm their young. They also try - with some success - to chase away birds and mammals (including humans) that get too close. And I've heard of them unsuccessfully trying to chase away a tractor.

So now, before I lament that this group isn't better studied, conserved and loved (people shouldn't drive tractors at them), on with the show:

Eukaryota
  Animalia
    Eumetazoa
      Nephrozoa
        Bilateralia
          Protostomia
            Arthropoda
              Hexapoda
                Insecta
                  Dicondylia
                    Pterygota
                      Metapterygota
                        Neoptera
                          Eumetabola
                            Endopterygota
                              Hymenopterida
                                Hymenoptera
                                  Apocrita
                                    Aculeata
                                      Vespoidea
                                        Vespidae
                                          Eumeninae
                                            Synagris
                                              Synagris (Synagris)
                                                Synagris (Synagris) proserpina
   

 Synagris (Synagris) proserpina nyassae. 

That's all, folks.



Acknowledgements. Identified as probably belonging to Synagris by me, confirmation of genus and species through Dr. Rob Longair, of the University of Calgary.