Species: Temnothorax rugatulus ants

Habitat: High-elevation forests of the western US and Canada

A group of ants labelled as lazy in 2015 may play a more important role in their societies than we thought, possibly helping to feed their hard-working peers.

The ants belong to a species (Temnothorax rugatulus) that builds nests under rocks in the forests of western North America. Most individual ants are busy with daily duties, but and at the University of Arizona noticed in 2015 that some were consistently doing, well… nothing.

Now, Charbonneau and Dornhaus, and their colleagues, have studied the lazy ants to find out more. Their analysis of the ants’ anatomy and behaviour suggests they aren’t the freeloaders we might assume them to be.

First, these ants don’t simply do nothing all day, despite their lazy label. They simply behave differently from their peers, says Charbonneau. “These ants walk more slowly, are isolated in colony interaction networks and have the smallest behavioural repertoires,” he says.

They look different too: Charbonneau��says they tend to be plumper and more likely to contain egg cells inside their bodies than their more energetic peers.

Living larders?

These observations mean we can rule some things out, he says: lazy ants are not simply old, infirm worker ants, for instance. Instead, lazy ants seem to be immature workers. Their plumper bodies might be evidence that they are storing food in their crops to share with their nest mates later, says Charbonneau. What’s more, the eggs they carry might serve as food for other ants – particularly since other ant species are known to sometimes .

“Inactive workers [may be] storing food for the colony,” says Charbonneau.

An alternative function of these idle workers is that they may serve as a reserve, says at the University of Würzburg in Germany. “There should be situations in which a larger workforce comes in handy – like defending the nest,” he says. “It also leaves a buffer to replace dead foragers.”

Charbonneau is unconvinced by this idea, though. He says it has been , but these found no clear evidence that colonies have a “reserve worker” community.

Frank adds that there is probably no single explanation for the existence of lazy ants. “As the authors state, there very likely is not just one reason for these inactive ants,” he says. “They probably have various benefits for the colony and reasons for their inactivity.”

Now Charbonneau aims to explore the unusual ants even more thoroughly. He also plans to look beyond this species to see if lazy ants are a more common feature of ant colonies in general. “The next thing is really starting to look at the function and explanation for inactivity across species to see if there’s some main mechanism which facilitates inactivity,” he says.

Read more: Soldier ants carry comrades wounded in raids back to base

Disguise tactics

Evolutionary trade-off

You might call it a web of deceit: the webs made by one spider exploit a visual effect to entice nocturnal insects, which then become stuck in the silky threads. Such “lure and trap” dual-function spider webs have never been seen working at night before.

The lace sheet weaver (Psechrus clavis) is commonly found in low to mid-elevation subtropical Asian forests. It builds its large horizontal webs just above ground level in shady spots.

at Tunghai University in Taiwan and his colleagues noticed that the silk is highly reflective, giving the web a whitish appearance that may be visible to insects at night.

To test whether this had any effect – either advantageous or disadvantageous – on the number of nocturnal insects caught, Tso and his team removed the spiders from 51 webs and used charcoal powder to blacken 22 of them, reducing their reflectance.

The team found that the untreated spider webs attracted significantly more prey than the blackened ones.

“Spider webs are not usually considered as potential prey lures,” says Tso.

False open spaces

Tso’s team speculates that the spiders’ chief prey – moths – have relatively poor eyesight and might mistake the whitish web as an area of open space in the otherwise dark and dense forest. Moths are attracted to such bright, open spaces.

The study isn’t the first to suggest that spiders resort to optical trickery to attract prey. , which may attract insects given that many flowering plants produce yellow pollen. Other spiders use their bodies to reflect light and attract prey. But these visual tricks have so far all been seen working during the day. The new study is the first evidence of spiders using their webs for visual attraction at night.

“[It offers] a new perspective in understanding the foraging strategies of nocturnal animals,” says Tso.

at Macquarie University in Sydney, Australia, says the study adds to evidence that spiders can lure prey into their traps. “We know many nocturnal insects like moths and bees have perfectly good vision at night – even colour vision, unlike humans.”

That said, he thinks it’s probably the general “brightness” of the web rather than its colour that attracts the moths.

“It would also be neat to see if they are attracting the attention of [spider] predators like nocturnal birds, but recording predation events in the wild takes a lot of patience,” he says.

Tso thinks the nocturnal lure strategy may also be used by other animals. “We will perform field experiments to test the hypothesis in the near future”, he says.

Journal reference: Animal Behaviour, DOI:

Read more: Watch how spiders use sticky silk to win deadly wrestling match

Growth model

Long-lived species of the deep

��è����Ƶs are rising the dead. Well, almost. Plants discovered in “ghost ponds” are being revived after lurking underground as dormant seeds for up to 150 years.

These so-called ghost ponds are formed when agricultural land expansion means that existing ponds are filled in, and literally buried alive, says Emily Alderton, at University College London (UCL), who led the study.

To expand a field, farmers commonly remove hedgerows then use the uprooted plants and soil to fill up any ponds. This happened at the site Alderton’s team studied in Norfolk, UK.

“Small ponds were not drained, but were filled in while they were still wet. We think this is likely to have contributed to the survival of the seeds buried within the historic pond sediments,” she says.

These buried ponds can often be seen as a ghostly mark on the landscape – a damp depression, change in soil colour, or patch of poor crop cover, where the ground never quite dries out, says Alderton.

“We also suspected that ghost was the right word as it hints at some form of life still hanging on and this is exactly what we have,” says co-author Carl Sayer, director of the UCL Pond Restoration Research Group. “The species that lived in the past pond are still alive, dormant and waiting!”

Buried treasures

The team estimates that there are around 8000 of these ghost ponds in Norfolk County alone, and as many as 600,000 more may be buried across England’s agricultural landscape.

To locate these buried treasures, researchers often use Ordnance Survey maps and other historical records, which reveal the location of former ponds that have since been converted into agricultural land.

Once researchers locate a ghost pond, and obtain permission from the farmers, they can use an excavator to dig out the metre or two of soil that usually covers it.

So far, the team has dug out three ghost ponds, all from farmland in Norfolk, and “resurrected” a total of eight aquatic plant species. These particular plants are commonly found in the landscape, but Alderton thinks that further ghost pond hunting in other areas could reveal surprises.

“Given the range of different seed types that we found capable of germination after 150-plus years, it could be reasonable to expect that ghost ponds could provide suitable reservoirs of rare or even extinct species,” says Alderton.

What’s more, ghost ponds could reveal dormant animal species. The team found resting eggs from two crustacean species, although they have not yet assessed their viability.

“This study is fascinating because it demonstrates not only a new way to repair the damage that we have done to the environment, but also the resilience of some species,” says Christopher Hassall at the University of Leeds.

“For plants to grow back after being buried for over 150 years is remarkable. Ponds are often neglected compared to lakes and rivers because of their small size, but they punch above their weight in terms of the number of species that they contain,” he says. “It is great to see a successful conservation effort that is bringing back some of these lost habitats.”

Sayer is excited about the prospect of resurrecting species that are locally or nationally extinct in the future. “It is a very positive conservation message – a rare positive,” he says.

Pheromone lure

Species: birch caterpillar (Drepana arcuate)

Habitat: Deciduous woodland with birch or alder in North America

Bees buzz, cicadas sing, but caterpillars are the real musical maestros of the insect world. It turns out they use different parts of their body to get the attention of other caterpillars.

The tiny birch caterpillar makes special vibrations, inaudible to human ears, using their mouths, body and anal parts. These appear to send out information about food and shelter to other caterpillars nearby.

Within a couple of hours, a small group of some 2-6 individuals forms around the drummer – a behaviour that may provide safety from predators or bad weather.

“These tiny caterpillars produce a complex diversity of signals – they shake their bodies, drum and scrape their mouthparts, and drag specialised anal ‘oars’ against the leaf surface to create bizarre signals,” says evolutionary biologist Jayne Yack at Carleton University in Ottawa, Canada, who led the new study.

“I’ve been studying insect sounds for more than 30 years, and I’ve never seen one insect species produce such a diversity of signal types.”

The study is the first to provide evidence for the use of vibratory signals for complex acoustic communication in caterpillars, Yack says.

But why does this tiny caterpillar need such a complex repertoire of signals? This is still not clear, says Yack. “But probably they are using different signals to gauge distance or different food quality, or to help others localise the source,” she adds.

In fact, the vibrations continue even after the group has formed. “They keep communicating with each other,” says Yack. “Maybe they are saying things like ‘hey, we need to fix this big hole in the shelter’ or ‘Hey guys, I’m over here! I found a really good feeding spot!’ or perhaps ‘Move over! this is MY spot!’

Conflict resolution

Until recently caterpillars were thought to rely primarily on chemical signals such as pheromones to communicate��– unlike insects such as wasps, bees and ants, which use both vibratory and chemical signals to communicate information about food or safety.

In an earlier study, Yack’s team discovered the vibratory signals in the late stages of these caterpillars. They found that the signals were used to solve territorial disputes – the anal scraping, for example, was thought to have evolved as a way to avoid one-to one confrontations.

The latest study reveals a whole new facet of this behaviour. Yack’s team recorded the vibrations made by the early stages of these caterpillars, as they formed their groups.

Analysis of the sounds showed that they produce four different types of vibratory signals associated with feeding and silk-making, which is used to build shelters. They used their mandibles and anal parts to scrape the surface of the leaf, shook their body to make a buzzing sound, and drummed with their mandibles.

The big difference between the vibrational signals sent by these young caterpillars compared with their older counterparts lies in the intentions, says Yack. These younger caterpillars only use their vibrations to tell other caterpillars about food and shelter, rather than to fight over a piece of leaf.

The finding could have implications for pest control, as many pests spent a significant part of their lives as caterpillars, and they likely have similar types of communication.

So, cracking the communication code could help researchers develop novel alternatives to pesticides. “Perhaps by jamming their signals or by monitoring the abundance of pest species on plants,” Yack says.

However, not everyone agrees that the caterpillars are using the vibrations to communicate. Tomer Czaczkes, from the University of Regensburg in Germany, says there might be another explanation.

“For me the smoking gun is missing: without playing back the vibrations to caterpillars, and seeing them approach the vibrations, we don’t actually know it’s the vibrations that are important. Maybe the caterpillars are releasing chemicals while doing this scraping behaviour?” he says.

Journal reference: Behavioral Ecology and Sociobiology, DOI: 10.1007/s00265-017-2280-x

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Small surprise

Like small pitbulls

This lion king (pictured above) is a queen. And she’s not the only one.

Five lionesses in Botswana have grown a mane and are showing male-like behaviours. One is even roaring and mounting other females.

Male lions are distinguished by their mane, which they use to attract females, and they roar to protect their territory or call upon members of their pride. Females lack a mane and are not as vocal.

But sometimes lionesses grow a mane and even behave a bit like males. However, until now, reports of such maned lionesses have been extremely rare and largely anecdotal. We knew they existed, but little about how they behave.

Now, Geoffrey D. Gilfillan at the University of Sussex in Falmer, UK, and colleagues have reported five lionesses sporting a mane at the Moremi Game Reserve in Botswana’s Okavango delta.

Gilfillan started studying these lionesses back in March 2014, and for the next two years he focused on recording the behaviour of one of them, called SaF05. She had an underdeveloped mane and was larger than most females.

“While SaF05 is mostly female in her behaviour – staying with the pride, mating males – she also has some male behaviours, such as increased scent-marking and roaring, as well as mounting other females,” says Gilfillan.

“Although females do roar and scent-mark like males, they usually do so less frequently,” he says. “SaF05, however, was much more male-like in her behaviour, regularly scent-marking and roaring.”

A likely explanation is an increased level of testosterone as these lionesses mature, says , president and chief conservation officer at the global wild cat conservation organisation Panthera.

In lions, testosterone directly affects the development of manes. Castrated males, for example, lose their ability to produce testosterone and promptly lose their mane, too.

In 2011, a at the National Zoological Gardens of South Africa developed a mane. Tests revealed high levels of testosterone due to a problem in her ovaries, and once they were removed she reverted to a typical lioness.

The idea that testosterone is implicated in the Botswana lionesses is also backed by observations of their reproductive success, says at Virginia Tech in Blacksburg.

“While some of the maned lionesses were observed mating, none of them became pregnant, suggesting they are infertile, a known consequence of high levels of androgens such as testosterone in females,” she says. “The behavioural changes suggest this is likely the case.”

Hunter suspects this explanation applies to the animals studied by Gilfillan and his colleagues. “Given all five known maned females come from the Okavango region, there must be a genetic component in this population underlying the phenomenon,” he says.

“I don’t think this is anything to be concerned about,” says Hunter. “Although the females are apparently infertile, they otherwise appear to live long, healthy lives. And from a conservation perspective, there is nothing to suggest the pattern is increasing or will ever be anything more than a rare, local phenomenon.”

No one seems to be studying the exact genetic and hormonal causes of this phenomenon at the moment. “I guess there are just one or a few genes altered,” says at Imperial College London, who had a student briefly work on the possible causes. “I believe some masculinised genes have been documented in domesticated cats – it would be good to look into this, especially given that the cat genome is available as reference.”

Could the masculinised females in fact be a boon to the pride when it comes to competing with other prides? It’s possible, it seems.

Gilfillan says he once saw SaF05 bring down a zebra. “A neighbouring pride stole the zebra from SaF05, but in return SaF05 killed two of their cubs.”

Cub-killing behaviour is rare in females but common in males.

That’s one small step for an elephant, but a giant leap for the survival of tiny aquatic animals. In the swamp forests of Kibale National Park, Uganda, every step elephants take can give rise to a footprint-shaped mini-pond. They can hold substantial amounts of water – 200 litres, in the case of one formed of two merged footprints – and dozens of invertebrate species.

“I was surprised to find out that these footprints were water-filled all year round, and that they harboured such a high diversity,” says Wolfram Remmers at the University of Koblenz in Germany. Surveying 30 such prints over a three-day period in 2014, Remmers and his colleagues found over 60 species, including beetles, spiders and worms – plus tadpoles.

Many smaller species may live there, too – the team’s sampling method meant they only caught things bigger than 2 millimetres.

The footprints probably play an important role in allowing these small life forms to spread, as they form a network of connected ponds.

“We assume that [the animals] do ‘pond-hop’, especially since many of them can fly,” says Remmers. “The elephant footprints act as ‘stepping-stone-habitats’.”

This makes the presence of elephants unexpectedly important for tiny aquatic species.

“If the elephants disappear those habitats would vanish,” says Remmers. “It is likely that some species – such as some dragonflies – would have a very hard time finding suitable breeding habitats.” Some aquatic species might disappear locally, he adds.

The findings help us understand how large herbivores influence their habitat, says Gary Haynes at the University of Nevada, Reno. We already had an inkling of that, because of the way elephants remove trees and create gaps in forests – sometimes even encouraging the formation of grasslands. Their dung is also an important fertiliser.

But evidently they have an impact on the microscopic scale too. “Modern-day elephants and other mega-herbivores shape [their habitats] in ways we are just beginning to fully appreciate,” says Haynes.