the wonderful world of insects -- 11/13/19
Today's selection -- from Buzz Sting Bite by Anne Sverdrup-Thygeson. The wonderful world of insects:
"The recipe for a successful insect life is simple: you just have to stay alive long enough to reproduce. And to stay alive, you need food. Much of an insect's life consists of eating and trying not to be eaten.
"Many insects eat one another. If there are fifty ways to leave your lover, I can assure you that there are an awful lot more ways of eating other creatures -- including your lover. You can eat them from the inside or the outside. You can eat them as eggs, larvae, or adults. You can eat them using mandibles, sponges, or drinking straws. On the other hand, you can simply stop eating: quite a few insects eat only as larvae but don't feed at all as adults.
"Since the objective is to keep on the right side of life's brutal but simple eat-or-be-eaten rule, insects go to extremes to avoid being gobbled up by other creatures. They may live in hiding, concealing themselves through camouflage or by pretending to be something else -- preferably something dangerous or inedible. They can opt to survive by disappearing in the crowd or by collaborating with others in ingenious ways. Insects' strategies for laying their hands on nutrition without themselves becoming food is an object lesson in jaw-dropping but often brutal adaptations, which would be criminal of me to keep from you.
"Take parasites, for example. Many insects are what we call parasitoids -- parasites that ultimately kill their host. The host is often devoured from the inside out: the parasitoid larvae hatch inside an animal, for example another insect, and slowly but surely eat their way through all its internal organs. The whole thing is elegantly done: the larvae leave the vital organs until last. Well, we all prefer fresh meat, after all! The host usually dies once the parasitoid larvae have eaten their fill and are ready for adult life.
|Freshly emerged Dinocampus coccinellae attacking its host|
"The natural historians and theologians of the 1800s tore their hair out when they found out about this. It just didn't fit in with their notion of a creation formed by a good and loving God. Darwin also struggled with it, writing to his American colleague Asa Grey in 1860, 'I cannot persuade myself that a beneficent and omnipotent God would have designedly created the lchneumonidae with the express intention of their feeding within the living bodies of caterpillars.'
"If only he had known! There are much worse things than that.
"The beautiful, green-eyed Dinocampus coccinellae is a parasite wasp. The female sticks her egg-laying tube, or ovipositor, into a ladybug and lays an egg. The egg hatches, and over the next twenty days the wasp larva chews its way through many of the ladybug's inner organs. Then the larva somehow squeezes its way out of the ladybug's abdomen while its unfortunate host is still alive. The wasp larva spins itself a little ball of silk between the ladybug's legs, where it transforms into a pupa.
"Something quite remarkable happens next: the ladybug's behavior abruptly alters. It stops moving and just stands there, stock still, like a living shield. But every time a hungry foe of wasps approaches, the ladybug gives a jerk, thereby scaring off anything that might consider eating the now helpless monster that has just eaten it up. This lasts for a week until the wasp hatches and flies off, leaving the ladybug to its own devices.
"The big question here is how the wasp mother can control the ladybug, transforming her into a zombie babysitter. After all, several weeks have passed since she laid her egg and vanished. The answer is that the wasp mother injects the ladybug not just with the egg but also with a virus. The virus accumulates in the brain and is controlled by a timing mechanism that paralyzes the ladybug at the precise moment when the larva is squeezing its way out. So the virus enables the wasp to take over the brain of the ladybug, making it serve not just as baby food but also as a babysitter. The only good thing we can say about all this is that, unbelievably enough, the ladybug sometimes survives the whole ordeal."