Many insects eat plants, but some plants can turn the tables on their would-be diners. The pitcher plants are among several groups that can capture insects and digest their flesh. And one species – the fanged pitcher plant – goes even further. It digests insects with insects.
There are around 120 species of pitcher plants and all of them have large leaves that fold to produce fluid-filled traps. The rims of the pitchers are usually extremely slippery, and insects that wander by lose their foothold and fall into the pool of fluid within. There, they drown and are digested by the plant.
The fanged pitcher is unusual. Its rim lacks the usual waxy layer and is less slippery than those of its cousins. And it’s the only species that recruits ants. The base of each pitcher contains a swollen tendril that houses ants of the species Camponotus shcmitzi. These insects are permanent residents; they’ve never been seen in any other plant.
Imagine a world of two dimensions, a world with no up or down… just across. No climbing, falling, jumping, or ducking… just shimmying and sidling. Welcome to the world of the sea skater.
Sea skaters, or ocean striders, are small bugs. They’re relatives of the pond skaters or water striders that zip spread-eagled across the surface of ponds and lakes. Except they skate over the open ocean, eating plankton at the surface. “They skate through storms and wind and waves,” says Miriam Goldstein from the University of California San Diego and the Deep Sea News blog. “They even have a little ‘life jacket’ – the hairs on their body trap air so if they get sunk by a wave, they pop back up. They’re amazing!”
There are only five species of sea skaters, all belonging to the Halobates group. Of all the millions of insect species, these five are the only ones to live out at sea. Now, Goldstein has discovered that one sea skater Halobates sericeus actually benefits from what most people would regard as an ecological disaster – the circling mass of plastic and debris known as the Great Pacific Garbage Patch.
The worst sex you have ever had pales in comparison to what female water striders have to put up with. Put it this way: you have never been held down by your eyes.
As the female skates over the surface of ponds and lakes, males will try to force themselves upon her. She resists by struggling vigorously. But in some species, males can avoid being thrown off with antennae that have evolved into antler-shaped restraints. They bend in on themselves and are loaded with an array of prongs and spikes that perfectly fit to the shape of a female’s head.
Locke Rowe from the University of Toronto has been studying water striders for almost 20 years. In many species, males have evolved structures that give them an edge in their indelicate liaisons with females. “But the traits I studied before were rather simple – a spine here or there,” says Rowe. The subject of his latest study, a species called Rheumatobates rileyi – is… well, the opposite of simple.
The Amazonian tree known Hirtella physophora looks rather unassuming, but it is the site of several grisly spectacles. Amid its leaves and branches, an animal, a plant and a fungus conspire to create a nightmarish trap where trespassers become meals, robbers get the death penalty, and assassins are assassinated.
The tree is home to ants called Allomerus decemarticulatus, which defend it from hungry insects. In return, the tree provides the ants with leaf pouches and swollen thorns as shelter, and feeds them with nectar and sugary nodules. These food sources are rich in carbohydrates but low in proteins. To supplement their diets, the ants need flesh, and they get it by shaping the tree into traps.
The ants cut hairs from the plant and weave them together into a hollow gallery, which extends down the side of the tree’s branches. Within the gallery, the ants hide inside small holes, jaws agape. From the outside, nothing can see them. If an insect lands on the trap, hundreds of lurking jaws seize its legs and pull it spread-eagled, as if on a medieval ‘torture rack’. The victim is overpowered and dismembered.
Many insects eventually evolve to resist insecticides. This process typically takes many generations and involves tweaks to the insect’s genes. But there is a quicker route. Japanese scientists have found that a bean bug can become instantly resistant to a common insecticide by swallowing the right bacteria.
The bug forms an alliance with Burkholderia bacteria, and can harbour up to 100 million of these microbes in a special organ in its gut (see arrow above). Some strains of Burkholderia can break down the insecticide fenitrothion, detoxifying it into forms that are harmless to insects. In fields where the chemical is sprayed, these pesticide-breaking bacteria rise in number. And if bugs swallow them, they become immune to the otherwise deadly chemical.
In a French meadow, a creature that specialises in corrupting the bodies of other animals is getting a taste of its own medicine.
Leptopilina boulardi is a wasp that lays its eggs in fly maggots. When the wasp grub hatches, it devours its host form the inside out, eventually bursting out of its dead husk. A maggot can only support a single grub, and if two eggs end up in the same host, the grubs will compete with one another until only one survives. As such, the wasps ensure that they implant each target with just one egg. And if they find a maggot that has already been parasitized by another L.boulardi, they usually stay away.
Usually, but not always.
L.boulardi is sometimes infected by a virus called LbFV, which stands for L.boulardi filamentous virus. And just as the wasp takes over the body of its maggot target, so the virus commandeers the body of the wasp. It changes her behaviour so that she no longer cares if a maggot is already occupied. She will implant her eggs, even if her target has an existing tenant. After infected wasps are finished, a poor maggot might have up to eleven eggs inside it.
Even the topmost layer of the ocean, just millimetres below the air above, is full of life. This zone, where two worlds meet, is home to small creatures like animal larvae, algae, bacteria, and other plankton. Among the most abundant residents of this zone are copepods – tiny relatives of crabs and shrimp. And some of them have the ability to leave this world altogether, and take to the air.
When threatened by fish, some copepods can jump straight out of the water and shoot over many times their own body lengths. From the fish’s point of view, its prey suddenly disappears. Flying fish use the same tactic to escape from predators. Now, we know that one of the most common groups of ocean animals shares their strategy.
“A male fruitfly will try to court a female by nuzzling her genitals, tapping her abdomen and singing with his wings. If all that fails, he drowns his sorrows in booze.”
That’s how my latest piece for Nature News starts. It’s obviously a cute result, but there’s some serious and intriguing science underlying it. These twin rewarding activities – sex and drinking – are linked by a chemical called neuropeptide F (NPF), which acts as a sort of currency of reward in the brain.
The study suggests that NPF is part of a system that acts like a ‘reward-thermostat’. If flies aren’t getting rewarding feelings from sex, their levels of NPF fall, and this compels them to get their kicks elsewhere, such as in a boozy meal.
Mammals also have a counterpart of NPF, known as NPY, which may play a similar role. It’s depleted in the brains of people who attempt suicide or suffer from PTSD, and some clinical trials are testing it as a way of dealing with addictions or mood disorders.
This movie has been filmed under conditions so harsh that they would kill virtually any animal. And yet, the star of the film is clearly alive – you can see it moving its legs, and after the shot was completed, it crawls away unharmed. It’s a tick, and it’s the first animal to be filmed with a scanning electron microscope.
These microscopes (known as SEM) can capture the most beautiful images of the tinier side of life, from pollen grains to insect feet to crawling cells. But they’re not very good for looking at living things while they’re still alive.
SEM microscopes work by firing a beam of electrons (the negative particles that form part of atoms), which rakes across the sample. Depending on the object’s shape and what it’s made of, the electrons scatter, reflect and absorb in different ways. The microscope collects this information to construct a picture of the object. The whole process happens in a vacuum, because air would distort the shape of the beam. And the specimen you’re trying to see also needs to be treated, which often involves drying, staining, and mounting. They’re often coated in a metal, such as gold, which helps to sharpen the resulting image.
You can see why a living animal might not fare so well after being dried and slathered in metal, starved of air, and bombarded with a high-energy electron beam. But look at the video. The tick’s doing fine.
A black bean aphid is about to have a rough day. It has been targeted by a parasitic wasp, which lays several eggs inside its body. When the eggs hatch, the wasp grubs will try to eat the aphid from the inside out. If they succeed, the aphid will die, and the young wasps will burst from its corpse to find aphids of their own.
But the aphid isn’t necessarily doomed. There’s a chance that it will resist the attempt to usurp its body. If it does, the wasps will have done it a favour. When the mother wasp implanted its eggs, it also infected the aphid with bacteria that protect against parasitic wasps. It inadvertently vaccinated the aphid against its own kind.
Ed Yong is an award-winning British science writer. His work has appeared in New Scientist, the Times, WIRED, the Guardian, Nature and more. Not Exactly Rocket Science is his attempt to talk about the awe-inspiring, beautiful and quirky world of science to as many people as possible.
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Many insects eat plants, but some plants can turn the tables on their would-be diners. The pitcher plants are among several groups that can capture insects and digest their flesh. And one species – the fanged pitcher plant – goes even further. It digests insects with insects.
