The Matryoshka dolls of the insect world and their herders

Truth is weirder than fiction atleast that the way insect do it.

by Aditi Mishra — I picked up a bad habit this year. I steal from the ants.

It’s not like I have fun stealing, but unfortunately I have to.

You see, I need aphids, a.k.a. ‘ant-cows’, to rear hoverflies. Hoverfly larvae are aphid-guzzling machines. And who can give us better aphids than aphid-herding ants?

In case you are wondering what aphids are — they are many species of sap-sucking arthropods with amazing reproductive capabilities. A single aphid can give rise to 600 billion descendants in one season.

That is 6 followed by 11 zeros or -

600000000000

Going forth and multiply

So how do they do it? Aphids owe their astonishing ability to breed to three things.

First, asexual reproduction — aphids need no man, literally. Aphid moms are strong, independent mothers indulging in parthenogenesis, i.e they make babies without mates.

Second, viviparity — aphids give birth to their young ones live. This reduces a lot of risk since aphids don’t have to lay eggs just to see them become some other insect’s lunch. Plus there is no waiting. Aphid kids pop out ready to reproduce.

Third, paedogenesis — since aphids can reproduce asexually, the young start reproducing super early — sometimes as early as in her mother’s womb! So an aphid female can be pregnant with her daughter and granddaughters at the same time.

So aphids are the Matryoshka dolls of the insect world. Arthropods that are born pregnant and reproduce asexually.

Ant is my shepherd

Aphids often suck up too much plant sap and swell up like balloons, oozing sugary secretions from their pores. This is exactly what makes them attractive to ants. Ants have domesticated aphids to harvest these sugary secretions and their aphid husbandry skills would put any human to shame.

Ants release semiochemicals (chemical that convey messages) that impede aphids’ ability to develop wings and make them sluggish.

Ants are the Jedis of this world

And once the Jedi mind control is complete the domesticated aphids, become docile, devoid of anti-predatory instincts. If an aphid develops wings even after all that, then the ants bite their wings off.

But it not all suppression. Like any good farmer, ants tend to aphids, starting new aphid colonies in spring, protecting the aphid eggs from harsh winters and predators.

Ants actively manage the resource allocation for their herds. Like shepherds herding sheep to greener pastures, these ants herd aphids to a new juicier plants if the old site becomes overcrowded.

What do ants get out of all this? Honeydew. Honeydew is the extra sugar ingested by aphids that they secrete out. Ants milk aphids by stroking them with their antennae which forces the liquid out. In some cases, the aphids have lost all ability to excrete so they completely depend on their ant masters to be milked.

Syrphids’ choice*

Sugary, sluggish aphids are one of the easiest prey. But ants are not the only ones eyeing this honey pot.

A plethora of insects from flies, bugs and beetles like to lay eggs in aphid colonies and munch on them. After all, who doesn’t like to munch on insects that taste like jelly beans?

The benefit is two fold, the sugar in aphid helps the larvae (including syrphid larvae) to grow and the body bags of aphids can be accumulated in the hindgut.

Why do that? Well once you have muched on 3000–5000 aphids and accumulated them in your hindgut. It gives a nice colour to your behind.

This cryptic color pattern can be used to scare predators or to blend in with the environment and avoid getting eaten. Neat isn’t it?

The Aphid wars

Aphids are one of the best bounty a hoverfly mother could guarantee for her unborn larvae. However, it comes at a great risk to her.

Laying eggs next to an aphid colony patrolled by ants is dangerous business.

Ants frequently attack predators. They even locate and destroy the larvae and eggs.

However, the good news is that there are aphid colonies without ants as well. The bad news is that these colonies have their own issues.

Without ants, the dispersal abilities of aphids gets pretty limited and overcrowding and colony collapse becomes a huge concern. While aphids can develop wings, these wings are not of much use anyway. At best all the aphids can hope for is to catch a breeze and drift away.

This opens new complications for hoverfly mothers everywhere. As aphid colony collapses become more common in the absence of ants, gravid females must know how to predict the aphid apocalypse.

Matching up to the challenge, syrphid mothers plan well.

Researchers have found that a hoverfly looking for a site to lay eggs would visually inspect the vegetation housing the the aphid colony first. She favors healthy green foliage in her survey.

Subsequently, she looks and smells the aphids’ colony to determine if they are worthy of her eggs. Finally, she tastes the honeydew, savoring its amino acids and sugar to decide whether to stop or move on.

The hoverfly’s judgment is more nuanced than one would expect. Females prefer younger sparser aphid colonies over denser heavily infested ones.

Perhaps these mothers understand compound interest and know that the aphid bounty would be ready just in time for her little ones to munch.

Scientists corroborate her judgement - aphid colonies with the lowest number of founding members grow the fastest.

A marmalade hover fly surveying an aphid colony guarded by ants.

With aphid freedom comes aphid responsibility

Lack of ants often brings out harsh reality for the aphids themselves.

Domesticity has to become a thing of the past, now that defense and dispersal can no longer be outsourced to the ants. Some aphids adapt to this by producing soldier aphids — aphids whose sole job is to defend.

Individuals become more aggressive as well.

Aphids are kickboxers by nature — they dig their hind legs into their aggressors. Now that the ants are gone, aphids must take up this old hobby once again.

On a less aggressive note, the aphids grow spines making them unpalatable, and they exude waxy fluids that literally seal their predators’ mouths shut.

Cool defense.

So Aphids do fight back, Ants practice Jedi mind control and aphid slavery.

I don’t feel so bad about stealing from the ants after all.

Thank you for enjoying this article this far. Hate it? Love it? Please let me know, any feedback helps me grow.

I would greatly appreciate if you could share this or comment here :)

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