When Ant Love Turns Sour

Myrmecophile. That’s a word. It’s a big word, too. It’s a word that means “ant lover”, so it is also a word that could apply to you, dear reader. Usually, “myrmecophile” describes any of an impressively large number of species that have close-knit relationships with ants.

We have myrmecophiles on the mind today, because we recently encountered some myrmecophiles in the mind of an ant, courtesy of illustrator and entomologist @czbugsart:

First, it looks like this beauty is not (yet?) up for sale on the artist’s associated Etsy page. But fear not, formicid friends – this similarly heady option is available for the bargain price of $14.50! [Editor’s note: We have not been paid to promote this artist’s work. We just love ants from head to tarsus.]

Now, astute observers will have noticed a claim that myrmecophiles are “often in a toxic relationship” with ants. How could this be?

It turns out that while many myrmecophiles are commensal, such as the inquiline woodlouse Platyarthrus hoffmannseggii that lives in ant nests and noshes on ant poop and mildew, some are more pernicious.

Take the Mountain Alcon Blue butterfly (Phengaris rebeli). Larvae (caterpillars) of this species live inside Myrmica schencki nests as a parasite, receiving food, shelter, and care from their hapless ant hosts. The caterpillars execute this deception through the use of chemicals that mimic their hosts’ cuticular hydrocarbons – chemicals that cover insect exoskeletons that ants use to distinguish friend from foe. But the covert operation doesn’t end there! The sneaky nest parasite can even mimic the sounds that M. schencki queens and workers make, a behavior known as “stridulation”. For more information about stridulation, see this description from the shamelessly plugged Ants: A Visual Guide, coming out tomorrow and already available for pre-order today:

It should be beautiful that ants not only communicate via chemical signals but also through sounds. Yet, instead of appreciating this beauty for what is, Mountain Alcon Blue caterpillars evolved instead to manipulate stridulation for their own benefit, tricking ants into loving them as their own larvae. A toxic relationship indeed!