A lone tree makes it easier for birds and bees to navigate farmland, like a stepping stone between habitats


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Carla Archibald, Deakin University; Eduardo van den Berg, Federal University of Lavras, and Jonathan Rhodes, The University of QueenslandVast, treeless paddocks and fields can be dangerous for wildlife, who encounter them as “roadblocks” between natural areas nearby. But our new research found even one lone tree in an otherwise empty paddock can make a huge difference to an animal’s movement.

We focused on the Atlantic Forest in Brazil, a biodiversity hotspot with 1,361 different known species of wildlife, such as jaguars, sloths, tamarins and toucans. Habitat loss from expanding and intensifying farmland, however, increasingly threatens the forest’s rich diversity of species and ecosystems.

We researched the value of paddock trees and hedges for birds and bees, and found small habitat features like these can double how easily they find their way through farmland.

This is important because enabling wildlife to journey across farmlands not only benefits the conservation of species, but also people. It means bees can improve crop pollination, and seed-dispersing birds can help restore ecosystems.

Connecting habitats

Lone trees in paddocks, hedges and tree-lined fences are common features of farmlands across the world, from Brazil to Australia.

They may be few and far between, but this scattered vegetation makes important areas of refuge for birds and bees, acting like roads or stepping stones to larger natural habitats nearby.

Scattered paddock trees, for instance, offer shelter, food, and places to land. They’ve also been found to create cooler areas within their canopy and right beneath it, providing some relief on scorching summer days.

Hedges and tree-lined fences are also important, as they provide a safe pathway by providing hiding places from predators.

White-browed meadowlark perched on a bush in a farm paddock within the Atlantic Forest
White-browed meadowlark perched on a bush in a farm paddock within the Atlantic Forest.
Milton Andrade Jr, CC BY

For our research, we used satellite images of the Atlantic Forest and randomly selected 20 landscapes containing different amounts of forest cover.

We then used mathematical models to calculate the habitat connectivity of these landscapes for three groups of species — bees, small birds such as the rufous-bellied thrush, and large birds such as toucans — based on how far they can travel.




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And we found in areas with low forest cover, wildlife is twice as likely to move from one natural habitat to another if paddock trees and hedges can be used as stepping stones.

We also found vegetation around creeks and waterways are the most prevalent and important type of on-farm habitat for wildlife movement. In Brazil, there are legal protections for these areas preventing them from being cleared, which means vegetation along waterways has become relatively common compared to lone trees and hedges, in places with lower forest cover.

Insights for Australia

While the contribution of lone trees, hedges and tree-lined fences towards conservation targets is relatively low, our research shows they’re still important. And we can apply this knowledge more widely.

Two koalas sitting on a branch
Koalas use roadside vegetation for feeding and resting.
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For example, in Australia, many koala populations depend on scattered trees for movement and habitat. In 2018, CSIRO researchers in Queensland tracked koalas using GPS, and found koalas used roadside vegetation and scattered trees for feeding and resting significantly more than they expected.

Likewise, lone trees, hedges and tree-lined fences can also facilitate the movement of Australian fruit-eating birds such as the olive-backed oriole and the rose-crowned fruit dove. Improving habitat connectivity can help these birds travel across landscapes, feeding and dispersing seeds as they go.

In fragmented landscapes, where larger patches of vegetation are hard to find, dispersing the seeds of native plants encourages natural regeneration of ecosystems. This is a key strategy to help achieve environmental restoration and conservation targets.

Policies overlook lone trees

In Brazil, there’s a strong initiative to restore natural areas, known as the Brazilian Pact for Restoration. This pact is a commitment from non-government organisations, government, companies and research centres to restore 15 million hectares of native vegetation by 2050.

However, the pact doesn’t recognise the value of lone trees, hedges and tree-lined fences.




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Likewise, the Brazilian Forest Code has historically provided strong legal protection for forests since it was introduced. While this policy does value vegetation along waterways, it overlooks the value of lone trees, hedges or tree-lined fences.

These oversights could result in poor connectivity between natural areas, seriously hampering conservation efforts.

Australia doesn’t fare much better. For example, in Queensland, the native vegetation management laws protect only intact native vegetation or vegetation of a certain age. This means scattered, but vital, vegetation isn’t protected from land clearing.

Small habitat features scattered across a farm paddock in the Atlantic Forest.
Flávia Freire Siqueira, CC BY., Author provided

Helping your local wildlife

But farmers and other landowners in Australia can make a big difference through land stewardship grant schemes (such as from Landcare) and private land conservation programs (such as Land for Wildlife or conservation covenants).

These schemes and programs can help landowners finance revegetation and protect native vegetation. Grants and programs vary by state and territory, and local council.




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Restoring natural areas is a key goal on the global conservation agenda for the next decade, and it’s clear that lone trees, hedges and tree-lined fences on farms may play a larger role than once thought.

So think twice before you remove a tree or a hedge. It might be a crucial stepping stone for your local birds and bees.


The authors gratefully acknowledge the contributions of Dr Flávia Freire Siqueira who led this research collaboration, and co-authours Dr Dulcineia de Carvalho and Dr Vanessa Leite Rezende from the Federal University of Lavras.The Conversation

Carla Archibald, Research Fellow, Conservation Science, Deakin University; Eduardo van den Berg, , Federal University of Lavras, and Jonathan Rhodes, Associate Professor, The University of Queensland

This article is republished from The Conversation under a Creative Commons license. Read the original article.

About 500,000 Australian species are undiscovered – and scientists are on a 25-year mission to finish the job


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Kevin Thiele, The University of Western Australia and Jane Melville, Museums VictoriaHere are two quiz questions for you. How many species of animals, plants, fungi, fish, insects and other organisms live in Australia? And how many of these have been discovered and named?

To the first, the answer is we don’t really know. But the best guess of taxonomists – the scientists who discover, name, classify and document species – is that Australia’s lands, rivers, coasts and oceans probably house more than 700,000 distinct species.

On the second, taxonomists estimate almost 200,000 species have been scientifically named since Europeans first began exploring, collecting and classifying Australia’s remarkable fauna and flora.

Together, these estimates are disturbing. After more than 300 years of effort, scientists have documented fewer than one-third of Australia’s species. The remaining 70% are unknown, and essentially invisible, to science.

Taxonomists in Australia name an average 1,000 new species each year. At that rate, it will take at least 400 years to complete even a first-pass stocktake of Australia’s biodiversity.

This poor knowledge is a serious threat to Australia’s environment. And a first-of-its kind report released today shows it’s also a huge missed economic opportunity. That’s why today, Australia’s taxonomists are calling on governments, industry and the community to support an important mission: discovering and documenting all Australian species within 25 years.

Australia: a biodiversity hotspot

Biologically, Australia is one of the richest and most diverse nations on Earth – between 7% and 10% of all species on Earth occur here. It also has among the world’s highest rates of species discovery. But our understanding of biodiversity is still very, very incomplete.

Of course, First Nations peoples discovered, named and classified many species within their knowledge systems long before Europeans arrived. But we have no ready way yet to compare their knowledge with Western taxonomy.

Finding new species in Australia is not hard – there are almost certainly unnamed species of insects, spiders, mites and fungi in your backyard. Any time you take a bush holiday you’ll drive past hundreds of undiscovered species. The problem is recognising the species as new and finding the time and resources to deal with them all.

Taxonomists describe and name new species only after very careful due diligence. Every specimen must be compared with all known named species and with close relatives to ensure it is truly a new species. This often involves detailed microscopic studies and gene sequencing.

More fieldwork is often needed to collect specimens and study other species. Specimens in museums and herbaria all over the world sometimes need to be checked. After a great deal of work, new species are described in scientific papers for others to assess and review.

So why do so many species remain undiscovered? One reason is a shortage of taxonomists trained to the level needed. Another is that technologies to substantially speed up the task have only been developed in the past decade or so. And both these, of course, need appropriate levels of funding.

Of course, some groups of organisms are better known than others. In general, noticeable species – mammals, birds, plants, butterflies and the like – are fairly well documented. Most less noticeable groups – many insects, fungi, mites, spiders and marine invertebrates – remain poorly known. But even inconspicuous species are important.

Fungi, for example, are essential for maintaining our natural ecosystems and agriculture. They fertilise soils, control pests, break down litter and recycle nutrients. Without fungi, the world would literally grind to a halt. Yet, more than 90% of Australian fungi are believed to be unknown.




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fungi on log
Fungi plays an essential ecosystem role.
Shutterstock

Mind the knowledge gap

So why does all this matter?

First, Australia’s biodiversity is under severe and increasing threat. To manage and conserve our living organisms, we must first discover and name them.

At present, it’s likely many undocumented species are becoming extinct, invisibly, before we know they exist. Or, perhaps worse, they will be discovered and named from dead specimens in our museums long after they have gone extinct in nature.

Second, many undiscovered species are crucial in maintaining a sustainable environment for us all. Others may emerge as pests and threats in future; most species are rarely noticed until something goes wrong. Knowing so little about them is a huge risk.

Third, enormous benefits are to be gained from these invisible species, once they are known and documented. A report released today
by Deloitte Access Economics, commissioned by Taxonomy Australia, estimates a benefit to the national economy of between A$3.7 billion and A$28.9 billion if all remaining Australian species are documented.

Benefits will be greatest in biosecurity, medicine, conservation and agriculture. The report found every $1 invested in discovering all remaining Australian species will bring up to $35 of economic benefits. Such a cost-benefit analysis has never before been conducted in Australia.

The investment would cover, among other things, research infrastructure, an expanded grants program, a national effort to collect specimens of all species and new facilities for gene sequencing.




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A few months ago, science gave this rare lizard a name – and it may already be headed for extinction


Two scientists walk through wetlands holding boxes
Discovering new species often involves lots of field work.
Shutterstock

Mission possible

Australian taxonomists – in museums, herbaria, universities, at the CSIRO and in
government departments – have spent the last few years planning an ambitious mission to discover and document all remaining Australian species within a generation.

So, is this ambitious goal achievable, or even imaginable? Fortunately, yes.

It will involve deploying new and emerging technologies, including high-throughput robotic DNA sequencing, artificial intelligence and supercomputing. This will vastly speed up the process from collecting specimens to naming new species, while ensuring rigour and care in the science.

A national meeting of Australian taxonomists, including the young early career researchers needed to carry the mission through, was held last year. The meeting confirmed that with the right technologies and more keen and bright minds trained for the task, the rate of species discovery in Australia could be sped up by the necessary 16-fold – reducing 400 years of effort to 25 years.

With the right people, technologies and investment, we could discover all Australian species. By 2050 Australia could be the world’s first biologically mega-rich nation to have documented all our species, for the direct benefit of this and future generations.




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The Conversation


Kevin Thiele, Adjunct Assoc. Professor, The University of Western Australia and Jane Melville, Senior Curator, Terrestrial Vertebrates, Museums Victoria

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Fly infertility shows we’re underestimating how badly climate change harms animals


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Belinda van Heerwaarden, The University of Melbourne and Ary Hoffmann, The University of MelbourneEvidence of declining fertility in humans and wildlife is growing. While chemicals in our environment have been identified as a major cause, our new research shows there’s another looming threat to animal fertility: climate change.

We know animals can die when temperatures rise to extremes they cannot endure. However, our research suggests males of some species can become infertile even at less extreme temperatures.

This means the distribution of species may be limited by the temperatures at which they can reproduce, rather than the temperatures at which they can survive.

These findings are important, because they mean we may be underestimating the impacts of climate change on animals – and failing to identify the species most likely to become extinct.

two flies mating on a leaf
The distribution of some species may be limited by the temperatures at which they can reproduce.
Shutterstock

Feeling the heat

Researchers have known for some time that animal fertility is sensitive to heat stress.

For example, research shows a 2℃ temperature rise dramatically reduces the production of sperm bundles and egg size in corals. And in many beetle and bee species, fertilisation success drops sharply at high temperatures.

High temperatures have also been shown to affect fertilisation or sperm count in cows, pigs, fish and birds.

However, temperatures that cause infertility have not been incorporated into predictions about how climate change will affect biodiversity. Our research aims to address this.




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eggs on straw
High temperatures can affect bird reproduction.
Shutterstock

A focus on flies

The paper published today involved researchers from the United Kingdom, Sweden and Australia, including one author of this article. The study examined 43 species of fly to test whether male fertility temperatures were a better predictor of global fly distributions than the temperatures at which the adult fly dies – also known as their “survival limit”.

The researchers exposed flies to four hours of heat stress at temperatures ranging from benign to lethal. From this data they estimated both the temperature that is lethal to 80% of individuals and the temperature at which 80% of surviving males become infertile.

They found 11 of 43 species experienced an 80% loss in fertility at cooler-than-lethal temperatures immediately following heat stress. Rather than fertility recovering over time, the impact of high temperatures was more pronounced seven days after exposure to heat stress. Using this delayed measure, 44% of species (19 out of 43) showed fertility loss at cooler-than-lethal temperatures.




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The researchers then matched these findings to real-world data on the flies’ distribution, and estimated the average maximum air temperatures the species are likely to encounter in the wild. They found the distribution of fly species is linked more closely to the effects of high temperature on male fertility than on temperatures that kill flies.

These fertility responses are crucial to species survival. A separate study led by one author of this article, using simulated climate change in the laboratory, showed experimental populations of the same flies become extinct not because they can’t survive the heat, but because the males become infertile. Species from tropical rainforests were the first to succumb to extinction.

The prediction that tropical and sub-tropical species may be more vulnerable to climate change is not new. But the fertility findings suggest the negative impact of climate change may be even worse than anticipated.

Flies on a stick
The research found fly fertility is affected at lower-than-lethal temperatures.
Shutterstock

What does all this mean?

Some animals have adapted to minimise the effect of high temperature on fertility. For instance, it’s thought testes in male primates and humans are externally located to protect the developing sperm from excessive heat.

As the planet warms, animals may further evolve to withstand the effects of heat on fertility. But the speed at which a species can adapt may be too slow to ensure their survival. Our research has shown both tropical and widespread species of flies could not increase their fertility when exposed to simulated global warming, even after 25 generations.

A study involving beetles also indicates fertility damage from successive heatwaves can accumulate over time. And more work is needed to determine how other stressors such as salinity, chemicals and poor nutrition may compound the fertility-temperature problem.

Whether our findings extrapolate to other species, including mammals such as humans, is not yet clear. It’s certainly possible, given evidence across the animal kingdom that fertility is sensitive to heat stress.

Either way, unless global warming is radically curbed, animal fertility will likely decline. This means Earth may be heading for far more species extinctions than previously anticipated.




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The Conversation


Belinda van Heerwaarden, Future Fellow, The University of Melbourne and Ary Hoffmann, Professor, School of BioSciences and Bio21 Institute, The University of Melbourne

This article is republished from The Conversation under a Creative Commons license. Read the original article.

After the floods, stand by for spiders, slugs and millipedes – but think twice before reaching for the bug spray


Lukas Koch / AAP

Caitlyn Forster, University of Sydney; Dieter Hochuli, University of Sydney, and Eliza Middleton, University of SydneyRecord-breaking rain has destroyed properties across New South Wales, forcing thousands of people to evacuate and leaving hundreds homeless.

Humans aren’t the only ones in trouble. Many of the animals that live with and around us are also heading for higher ground as the floodwaters rise.

Often small creatures — especially invertebrates like spiders, cockroaches and millipedes — will seek refuge in the relatively dry and safe environments of people’s houses. While this can be a problem for the human inhabitants of the house, it’s important to make sure we don’t add to the ecological impact of the flood with an overzealous response to these uninvited guests.

Warragamba Dam in southwestern Sydney has been spilling a Sydney Harbour’s worth of water each day during the rains.
Eliza Middleton, Author provided

What floods do to ecosystems

Floods can have a huge impact on ecosystems, triggering landslides, increasing erosion, and introducing pollutants and soil into waterways. One immediate effect is to force burrowing animals out of their homes, as they retreat to safer and drier locations. Insects and other invertebrates living in grass or leaf litter around our homes are also displaced.

Burrowing invertebrates come to the surface during floods, providing food for opportunistic birds.
Dieter Hochuli, Author provided

Snakes have reportedly been “invading” homes in the wake of the current floods. Spiders too have fled the rising waters. Heavy rain can flood the burrows of the Australian funnelweb, one of the world’s most venomous spiders.

Some invertebrates will boom; others may plummet

Rain increases greenery, which can support breeding booms of animals such as mosquitoes, locusts, and snails.

Even species that don’t thrive after floods are likely to become more visible as they flock to our houses for refuge. But an apparent short-term increase in numbers may conceal a longer story of decline.




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After periods of flooding, the abundance of invertebrates can fall by more than 90% and the number of different species in an area significantly drops. This has important implications for the recovery of an ecosystem, as many of the ground dwelling invertebrates displaced by floods are needed for soil cycling and decomposition.

So before you reach for the bug spray, consider the important role these animals play in our ecosystem.

What to do with the extra house guests?

If your house has been flooded, uninvited creatures taking shelter in your house are probably one of the smaller issues you are facing.

Once the rain subsides, cleaning in and around your property will help reduce unwanted visitors. Inside your house, you may see an increase in cockroaches, which flourish in humid environments. Ventilating the house to dry out any wet surfaces can help get rid of cockroach infestations, and filling crevices can also deter unwanted visitors.




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In the garden, you may see an increase in flies in the coming weeks and months as they lay eggs in rotting plants. Consider removing any fruit and vegetables in the garden that may rot.

Mosquitoes are also one to watch as they lay eggs in standing water. Some species pose a risk of diseases such as Ross River virus. To prevent unwanted mozzies, make sure to empty things that have filled with rainwater, such as buckets and birdbaths.

If you do encounter one of our more dangerous animals in your home, such as venomous snakes and spiders, do not handle them yourself. If you find an injured or distressed snake, or are concerned about snakes in your house, call your local wildlife group who will be able to relocate them for you.

Just like the floods, which will subside as the water moves on, the uninvited gathering of animals is a temporary event. Most visitors will quickly disperse back to more appropriate habitat when the weather dries, and their usual homes are available again.

You may see an increase in slugs in your local area after rainy conditions.
Eliza Middleton @smiley_lize

Don’t sweat the small stuff

While many of the impacts of floods are our own making, through poor planning and development in flood-prone areas, effective design of cities and backyards can mitigate the risks of floods. Vegetation acts as a “sponge” for stormwater, and appropriate drainage allows water to flow through more effectively. Increasing backyard vegetation also provides extra habitat for important invertebrate species, including pollinators and decomposers.




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With severe weather events on the rise, it is important to understand how ecosystems respond to, and recover from natural disasters. If invertebrates are unable to perform vital ecosystem functions, such as soil cycling, decomposition, and pollination, ecosystems may struggle to return to their pre-flood state. If the ecosystems don’t recover, we may see prolonged booms of nuisance pests such as mosquitoes.

A few temporary visitors are are a minor inconvenience in comparison to the impacts floods have on the environment, infrastructure and the health and well-being of people impacted. So while it may seem like a bit of a creepy inconvenience, maybe we should let our house guests stay until the flood waters go down.The Conversation

Caitlyn Forster, PhD Candidate, School of Life and Environmental Sciences, University of Sydney; Dieter Hochuli, Professor, School of Life and Environmental Sciences, University of Sydney, and Eliza Middleton, Laboratory Manager, School of Life and Environmental Sciences, University of Sydney

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Phantom of the forest: after 100 years in hiding, I rediscovered the rare cloaked bee in Australia


James B. Dorey, Flinders University

It’s not often you get to cast your eyes on a creature feared to be long-gone.

Perhaps that’s why my recent rediscovery of the native bee species Pharohylaeus lactiferus is so exciting — especially after it spent a century eluding researchers.

But how did it stay out of sight for so long?

A creature overshadowed

Australia is home to 1654 named species of native bee. Unfortunately, these are often overshadowed in the eyes of public by the widespread and invasive European honeybee.

Scientific research on Australian native bees is lagging, compared to many other nations.

With this in mind, it may not be surprising to learn some native species can go unnoticed for many years. Although, when it’s the only representative of a whole genus, one might start to worry about losing something special.

In this case the genus is Pharohylaeus, where “pharo” means “cloaked”, as these bees’ first three abdominal segments overlay the others to resemble a cloak.

I found the cloaked bee P. lactiferus during a major east coast sampling effort of more than 225 unique sites. The discovery, and what I learnt from it, helped me find more specimens at two additional sites.

It also made me wonder why P. lactiferus had been missing for so long. Is it naturally rare, hard to find, or perhaps threatened?




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Taxonomic trouble

Many Australian bees are very difficult to identify to a species level. In fact, some might be nearly impossible.

However, P. lactiferus is a relatively distinct black and white masked bee. Masked bees are those from the subfamily Hylaeinae, named so because they often have striking, bright facial patterns on an otherwise dark face.

With this distinctive appearance, identification issues weren’t a contributor to the mystery of P. lactiferus.

Seeing red

Still, despite having sampled extensively across sites and flowering plant species, I only found P. lactiferus on two types of plant: the firewheel tree and the Illawarra flame tree — both of which boast exuberant red flowers.

_Brachychiton acerifolius_ flowers.
The Illawarra flame tree (Brachychiton acerifolius).
James Dorey, Author provided

Bees generally don’t see shades of red, so such plants are usually pollinated by birds. It could be that bee researchers tend to avoid sampling these red flowering plant species for this reason.

Then again, bee vision and bee perception are not always the same. And bees are also guided by their keen sense of smell.

Habitat specialisation

So far, I’ve only found P. lactiferus within about 200 metres of one major vegetation subgroup, which is tropical or sub-tropical rainforest.

The first specimens I collected were in Atherton, Queensland. I later found more in Kuranda and Eungella. Some of these specimens are now stored in the South Australian Museum.

The habitat specialisation of P. lactiferus may suggest it has an above-average level of vulnerability to disturbances, particularly if it needs a strict set of requirements to make it through its entire life-cycle.

It is one of myriad bee species that nest in narrow, wooden hollows. Some bees such as Amphylaeus morosus dig these themselves and may require specific plant species to make their nest in.

Others such as Exoneurella tridentata need to use holes made by weevil larvae in two particular tree species: western myall and bullock bush.

Rainforests are also notoriously hard to sample. If a bee species spends much of its time in the high canopy, finding it would be difficult.

That said, two early collectors managed to find six specimens of P. lactiferus between 1900 and 1923. So its rarity doesn’t necessarily come down to it being a canopy-dweller.




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Potential threats

We know in the bioregions where P. lactiferus has been found that rainforests have undergone both habitat destruction and fragmentation since European colonisation. This threat hasn’t abated and Queensland is still a land-clearing hotspot.

We also know these rainforests burnt across Queensland every year between 1988 and 2016. The 2019-20 black summer megafires burnt nearly double the area of any previous year.

For some bee species this may not be a problem. But for a species that potentially requires specific foods, habitats and even other species, it could mean local extinction.

Only so many populations of a single species can disappear, before there are none left.

Where does this leave us?

P. lactiferus persists, which is wonderful. Unfortunately, we can’t yet say whether or not it is threatened.

To determine this confidently would require a robust, extensive and targeted survey regime.

We may not be able to undertake such a regime for all 1654 of the named bee species in Australia. But perhaps we could make that effort for the country’s only cloaked bee.The Conversation

James B. Dorey, PhD Candidate, Flinders University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

The mystery of the blue flower: nature’s rare colour owes its existence to bee vision



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Adrian Dyer, RMIT University

At a dinner party, or in the schoolyard, the question of favourite colour frequently results in an answer of “blue”. Why is it that humans are so fond of blue? And why does it seem to be so rare in the world of plants and animals?

We studied these questions and concluded blue pigment is rare at least in part because it’s often difficult for plants to produce. They may only have evolved to do so when it brings them a real benefit: specifically, attracting bees or other pollinating insects.

We also discovered that the scarcity of blue flowers is partly due to the limits of our own eyes. From a bee’s perspective, attractive bluish flowers are much more common.

A history of fascination

The gold and blue funerary mask of the ancient Egyptian pharaoh Tutankhamun.
The ancient mask of the pharaoh Tutankhamun is decorated with lapis lazuli and turquoise.
Roland Unger / Wikimedia, CC BY-SA

The ancient Egyptians were fascinated with blue flowers such as the blue lotus, and went to great trouble to decorate objects in blue. They used an entrancing synthetic pigment (now known as Egyptian blue) to colour vases and jewellery, and semi-precious blue gemstones such as lapis lazuli and turquoise to decorate important artefacts including the Mask of Tutankhamun.




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Blue dye for fabric is now common, but its roots lie in ancient Peru, where an indigoid dye was used to colour cotton fabric about 6000 years ago. Indigo blue dyes reached Europe from India in the 16th century, and the dyes and the plants that produced them became important commodities. Their influence on human fashion and culture are still felt today, perhaps most obviously in blue jeans and shirts.

Renaissance painters in Europe used ground lapis lazuli to produce dazzling works that captivated audiences.

A painting of a woman in a vivid blue robe and white hood, with bowed head and clasped hands.
The Virgin in Prayer by the Italian painter Sassoferrato, circa 1650, highlights the vivid blue colour made with ground lapis lazuli.

Today many blues are created with modern synthetic pigments or optical effects. The famous blue/gold dress photograph that went viral in 2015 not only shows that blue can still fascinate — it also highlights that colour is just as much a product of our perception as it is of certain wavelengths of light.

Why do humans like blue so much?

Colour preferences in humans are often influenced by important environmental factors in our lives. An ecological explanation for humans’ common preference for blue is that it is the colour of clear sky and bodies of clean water, which are signs of good conditions. Besides the sky and water, blue is relatively rare in nature.

What about blue flowers?

We used a new online plant database to survey the the relative frequencies of blue flowers compared to other colours.

Among flowers which are pollinated without the intervention of bees or other insects (known as abiotic pollination), none were blue.

But when we looked at flowers that need to attract bees and other insects to move their pollen around, we started to see some blue.

This shows blue flowers evolved for enabling efficient pollination. Even then, blue flowers remain relatively rare, which suggests it is difficult for plants to produce such colours and may be a valuable marker of plant-pollinator fitness in an environment.

Global flower colour frequency for human visual perception (A) shows when considering animal pollinated species less than 10% are blue (B), and for wind pollinated flowers almost none are observed to be blue (C).
Dyer et al., Author provided

We perceive colour due to how our eyes and brain work. Our visual system typically has three types of cone photoreceptors that each capture light of different wavelengths (red, green and blue) from the visible spectrum. Our brains then compare information from these receptors to create a perception of colour.

For the flowers pollinated by insects, especially bees, it is interesting to consider that they have different colour vision to humans.




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Bees have photoreceptors that are sensitive to ultraviolet, blue and green wavelengths, and they also show a preference for “bluish” colours. The reason why bees have a preference for bluish flowers remains an open field of research.

Various blue flowers from our study.

Why understanding blue flowers is important

About one-third of our food depends on insect pollination. However, world populations of bees and other insects are in decline, potentially due to climate change, habitat fragmentation, agricultural practices and other human-caused factors.

The capacity of flowering plants to produce blue colours is linked to land use intensity including human-induced factors like artificial fertilisation, grazing, and mowing that reduce the frequency of blue flowers. In contrast, more stressful environments appear to have relatively more blue floral colours to provide resilience.

For example, despite the apparent rarity of blue flower colours in nature, we observed that in harsh conditions such as in the mountains of the Himalaya, blue flowers were more common than expected. This shows that in tough environments plants may have to invest a lot to attract the few available and essential bee pollinators. Blue flowers thus appear to exist to best advertise to bee pollinators when competition for pollination services is high.

Knowing more about blue flowers helps protect bees

Urban environments are also important habitats for pollinating insects including bees. Having bee friendly gardens with flowers, including blue flowers that both we and bees really appreciate, is a convenient, pleasurable and potentially important contribution to enabling a sustainable future. Basically, plant and maintain a good variety of flowers, and the pollinating insects will come.




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The Conversation


Adrian Dyer, Associate Professor, RMIT University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

The cicada’s deafening shriek is the sound of summer, and humans have been drawn to it for thousands of years



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Eliza Middleton, University of Sydney and Linda Evans, Macquarie University

Around Australia, the buzz-saw siren of cicadas heralds the beginning of summer. With 237 recorded species of cicada in Australia, almost no area of the country is untouched by their song. Up to 800 species in Australia are still to be scientifically recognised.

Cicadas, however, aren’t unique to Australia: the insects are found all over the world, though they’re most common in tropical regions.

As the world’s loudest insects, the ear-splitting call from the males is a love song to draw their mates near. But humans, too, have been drawn to singing cicadas, with the insects featuring in ancient poetry and literature of different cultures for thousands of years.

So, as we settle into summer, let’s explore the curious life-cycle of cicadas, and how people in ancient Greece and China, in particular, revered them.

The sound of summer

The life of a cicada begins as one of up to 400 eggs laid by a female in the bark of a tree. A nymph (juvenile) cicada hatches, falls to the ground and tunnels into the dirt to begin the majority of its life.

Cicada nymphs will live in the soil for between one and five years, though different species may remain underground in the nymph stage for longer. In the US, for example, one species can live underground for up to 17 years before emerging.

When ready to become adults, nymphs must leave the soil to moult. A split opens along the back of the nymph’s exoskeleton and the adult cicada pushes its way out.

These cicada shells — the ghost of its youth — are often the only evidence we can find of the insect. As an adult, a cicada will eat, sing, mate and die, all in a few weeks.

A dry cicada shell clinging precariously to a post. The shell is fragile with a large split from the head down the back to the abdomen.
The shell left behind as a cicada changes from a nymph to an adult. You can see a large split from the head down the back to the abdomen the adult emerged from.
Eliza Middleton

Each species has its own unique call, and the noise can be truly deafening. For perspective, normal conversation between humans is recorded at about 60 decibels. But some cicada species, such as the Greengrocer cicada (Cyclochila australasiae) found along the coast of southeast Australia, can reach 120 decibels.

This is like standing beside emergency sirens. It’s also on the edge of causing pain or injury to human ears, which generally occurs at 130 decibels.

The noise is created by a structure called the tymbal, which works a bit like a drum. The tymbal is a thin membrane stretched across a number of “ribs” creating large chambers. These membranes vibrate rapidly through muscle action, which makes a clicking sound that’s amplified by their hollow abdomen.

After 17 years underground, cicada nymphs emerge in the billions | Planet Earth.

There are more than 3,200 cicada species scientifically described, and many more waiting to be discovered. They belong to the superfamily called the Cicadoidea, which is part of a larger animal group — the order Hemiptera, or the “true bugs”.

Insects in the Hemiptera order, such as aphids, leafhoppers and bed bugs, alongside cicadas, are known for having sucking and piercing mouthparts. This allows them to feed on sap by piercing the tree and drinking from the xylem (plant tissue that transports water and nutrients from roots to stems). This is how both the nymphs and adult cicadas feed — the former feeds off the roots while the latter feeds from the trunk.




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Symbolism and stories

For the people of ancient Greece and China, cicadas were the focus of many beliefs that, despite the separation of East from West, were surprisingly similar. Both cultures admired them.

For the Greeks, the “tettix” was carefree and harmless. For the Chinese, the “tchen” was noble, yet also humble.

A nymph cicada that just emerged from its shell, which lies beside it.
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Both societies loved the insects’ incessant call. Greek literature describes their call as “sweet”, such that a friendly cicada, legend says, once replaced the missing note when a string broke on a musician’s lyre. Like they do for us today, the cicadas’ hum also heralded the summer, especially the midday heat.

The Chinese of the Tang dynasty (618 to 906 AD) were so enamoured with the insects’ song, cicadas were caught and sold in small cages as pets. The Greeks may also have kept cicadas, as revealed by epitaphs written after their death, although the captive insects would have quickly died from starvation.

The esteem with which the cicada was held is also reflected in their association with the arts in both cultures.

They were the popular subject of Chinese poetry and paintings. And another Greek story tells us that when the Muses, goddesses of the arts, were born, an ancient race of men sang non-stop until they died, after which they transformed into cicadas.

Jade cicada
Jade cicada from the Han Dynasty, at the Xuzhou Museum.
Mary Harrsch/Wikimedia, CC BY-SA

Cicada biology was also noted in these ancient times. In the 4th century BC, Aristotle determined correctly that only the male cicada sings and the cicada’s call was produced by the movement of abdominal membranes. Chinese observers also noted the female’s lack of sound in the 6th century AD.

The insects’ life cycle was of enormous significance to both peoples. The nymphs’ emergence from the earth provided a powerful symbol of Greek “autochthony”, the belief a community had always lived in a particular place as the original inhabitants. And the moulted skin of adult cicadas was a sign of immortality.




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What’s more, cicadas held similar ornamental values in both ancient China and Greece.

During China’s Han Dynasty (206 BC to 220 AD), jade cicadas were placed in the mouths of the dead. The stone had supposed preservative qualities, while the insect offered the hope of resurrection.

The Greek elite are said to have worn gold cicadas in their hair to signal their ties to Athens. Such ornamentation was also associated with Chinese nobility, in which golden cicadas adorned the hats of Han Dynasty court officials. Intriguingly, this practice was said to have been introduced by outsiders.

We cannot yet say whether such similar beliefs stem from early East-West contact. But the prominent cultural role of the “tchen” and “tettix” is certainly testimony to humanity’s enduring summer love affair with the curious caterwauling cicada.




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The Conversation


Eliza Middleton, Invertebrate and behavioural ecology laboratory manager, University of Sydney and Linda Evans, Associate professor, Macquarie University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Photos from the field: zooming in on Australia’s hidden world of exquisite mites, snails and beetles



Dragon springtails (pictured) are widely distributed in forests of eastern Australia — yet they’re still largely unknown to science.
Nick Porch, Author provided

Nick Porch, Deakin University

Environmental scientists see flora, fauna and phenomena the rest of us rarely do. In this series, we’ve invited them to share their unique photos from the field.


Which animals are quintessentially Australian? Koalas and kangaroos, emus, tiger snakes and green tree frogs, echidnas and eastern rosellas, perhaps. And let’s not forget common wombats.

Inevitably, most lists will be biased to the more conspicuous mammals and birds, hold fewer reptiles and frogs, and likely lack invertebrates — animals without a backbone or bony skeleton — altogether.

I’m an invertophile, fascinated by our rich terrestrial invertebrate fauna, so my list will be different. I’m enchanted by stunning dragon springtails, by cryptic little Tasmanitachoides beetles, and by the poorly known allothyrid mites, among thousands of others.

Australia’s terrestrial invertebrate multitude contains several hundred thousand uniquely Australian organisms. Most remain poorly known.

To preserve our biodiversity, we first must ask: “which species live where?”. For our invertebrates, we are a long way from knowing even this.

The Black Summer toll

Last year, a team of scientists estimated that the Australian 2019-2020 bushfires killed, injured or displaced three billion animals. That was a lot. But it was also a woefully inadequate estimate, because it only accounted for mammals, reptiles, birds and frogs.

Hidden from view, many trillions more invertebrates burned or were displaced by the fires. And yes, invertebrates are animals too.

A mite from the family Bdellidae (on the right) has captured a springtail, and is using its piercing mouthparts to suck it dry. Mites and springtails are among the most abundant animals on the planet.
Nick Porch, Author provided

Admittedly, it’s hard to come to terms with invertebrates because they’re often hard to find and difficult to identify. Most species are inconspicuous, even if they belong to incredibly abundant groups, such as mites and springtails, which can occur in numbers exceeding 10,000 per square metre.

Most invertebrates are poorly known because there are so many species and so few people working on them. In fact, it’s likely only a quarter to one-third of Australia’s terrestrial invertebrate fauna is formally described (have a recognised scientific name).

A translucent land snail
Meredithina dandenongensis, a species from the wet forests of Victoria. It can be found during the day under rotting logs. The land snail family Charopidae contains hundreds of species across wetter parts of southern and eastern Australia.
Nick Porch, Author provided

One of the problems invertebrates have, in terms of attracting attention, is that many are not easily seen with the naked eye.

Macrophotography can magnify these wonders for a view into a world most of us are completely unfamiliar with. Even then, it often will be hard to know what we see. Everyone will recognise a kangaroo, but who can identify an allothyrid mite?

The photo below shows an undescribed species of mite from the family Allothyridae, from Mount Donna Buang in Victoria. The mite family Allothyridae has three described Australian species, and dozens more awaiting description.

An undescribed Allothyridae species. Just one of the many species in this group waiting to be studied.
Nick Porch, Author provided

This collage shows a selection of mites found in the forests of southeastern Australia. It’s likely many of the species shown here are unknown to science.

Mites are a very ancient and diverse group. They can be found abundantly in most terrestrial habitats but are rarely seen because most are several millimetres long or smaller.
Nick Porch, Author provided

A deeply ancient lineage

Animal ecologists, most of whom work on vertebrates, often joke that I “study the ‘food’, haha…”. They think they’re funny, but this reflects a deep seated bias — one extending from scientists to the wider public. This limits the development of a comprehensive understanding of biodiversity that has flow-on effects for conservation more broadly.

It’s true: invertebrates are food for larger animals. But their vital role in maintaining Australia’s ecosystems doesn’t end there.

Every species has an evolutionary history, a particular habitat, a set of behaviours reflecting that history, and a role to play in the ecosystem. And many terrestrial invertebrates belong to especially ancient lineages that record the deep history of Australia’s past.

The moss bug family Peloridiidae, for example, dates back more than 150 million years. For context, the kangaroo family (Macropodidae) is likely 15-25 million years old.

Their history is reflected in the breakup of the ancient supercontinent, Gondwana. In fact, Australian species of moss bugs are more closely related to South American species than to those from nearby New Zealand.

A bronze-coloured beetle with delicate, translucent wings
Chasoke belongs to the beetle family Staphylinidae, which is currently considered the largest family of organisms on Earth, with more than 60,000 scientifically described species. Mt. Donna Buang, Victoria.
Nick Porch, Author provided

This is a common pattern in terrestrial invertebrate groups. It reflects how the New Zealand plate separated from the remainder of Gondwana about 80 million years ago, while the Australian plate remained connected to South America via Antarctica.

Similar stories can be told from across the invertebrate spectrum. The photo below shows a few examples of these relics from Gondwana.

Peloridiid bugs — such as Hemiodoecus leai China, 1924 (top left) — are restricted to the wettest forests where they feed on moss. Top right: A new species of Acropsopilio (Acropsopilionidae) harvestman from the Dandenong Ranges. Bottom left: a new velvet worm from the Otway Ranges. Bottom right: Tasmanitachoides hobarti from Lake St Clair in central Tasmania.
Nick Porch, Author provided

Their fascinating evolution

Overprinting this deep history are the changes that occurred in Australia, especially the drying of the continent since the middle Miocene, about 12-16 million years ago.

This continent-wide drying fragmented wet forests that covered much of the continent, resulting in the restriction of many invertebrate groups to pockets of wetter habitat, especially along the Great Dividing Range and in southwestern Australia.




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A consequence of this was the evolution in isolation of many “short-range endemic” species.

A short-range endemic species means their geographic distribution is less than 10,000 square kilometres. A short-range endemic mammal you might be familiar with is Leadbeater’s possum, restricted to the wet forests of the Victorian Central Highlands.

A long, brown and orange thrips with six legs.
This is Idolothrips spectrum, the largest thrips in the world. It’s called the giant thrips, even though it’s less than 10mm long. Dandenong Ranges, Victoria.
Nick Porch, Author provided

But short-range endemism is much more common in invertebrates than other organisms. This is because many invertebrates are poor dispersers: they don’t move between habitat patches easily. They may also maintain viable populations in small areas of suitable habitat, and are frequently adapted to very specific habitats.

Take Tropidotrechus, pictured below, a genus of beetles mostly restricted to the same region as Leadbeater’s possum. They, however, divide the landscape at a much finer scale because they’re restricted to deep leaf litter in cool, wet, forest gullies.

As Australia dried, populations of Tropidotrechus became isolated in small patches of upland habitat, evolving into at least seven species across the ranges to the east of Melbourne.

Tropidotrechus victoriae, Victoria’s unofficial beetle emblem (left). Related described and undescribed species are found in the nearby Central Highlands and South Gippsland ranges (right)
Nick Porch, Author provided

Discoveries waiting to happen

The trouble with knowing so little about Australia’s extraordinary number of tiny, often locally unique invertebrates, is that we then massively underestimate how many of them are under threat, or have been badly hit by events like the 2019-2020 fires.

If we wish to conserve biodiversity widely, rather than only the larger charismatic wildlife, then enhancing our knowledge of our short-range species should be a high priority.

One shiny green beetle on top of another
You don’t necessarily need specialist equipment to take pictures of our fascinating invertebrates. This is a phone picture of mating Repsimus scarab beetles (relatives to the Christmas beetles). It was taken at Bemboka in NSW, which burnt during the 2019-2020 fires.
Nick Porch, Author provided

We’ve only just scratched the surface of Australia’s wonderful invertebrate fauna, so there are enough discoveries for everyone.

You can join iNaturalist, a citizen science initiative that lets you upload images and identify your discoveries. Perhaps you’ll discover something new — and a scientist just might name it after you.




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The Conversation


Nick Porch, Senior Lecturer in Environmental Earth Science, Deakin University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Bzzz, slap! How to treat insect bites (home remedies included)



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Cameron Webb, University of Sydney

It’s the holidays and we’re spending more time outdoors. This means we’re exposed to the more annoying and painful aspects of summer — insect bites and stings.

There are plenty of products at the local pharmacy to treat these. Some treat the initial bite or sting, others the itchy aftermath.

What about natural remedies? Few studies have actually examined them. But if they work for you, and don’t irritate already inflamed skin, there’s likely no harm in continuing.




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Why do insects bite and sting?

When insects bite and sting, they are either defending themselves or need something from us (like blood).

Whatever the motivation, it can leave us with a painful or itchy reaction, sometimes a severe allergic reaction, or even a debilitating disease.

While insects sometimes get a bad rap, there are relatively few that actually pose a serious threat to our health.

Flies, mosquitoes

Many types of flies, especially mosquitoes, bite. In most instances, they need blood for nutrition or the development of eggs. The method of “biting” can vary between the different types of flies. While mosquitoes inject a needle-like tube to suck our blood, others chew or rasp away at our skin.

While researchers have studied what happens when mosquitoes bite, there is still much to learn about how to treat the bites.

So, avoiding mosquito bites is especially important given some can transmit pathogens that make us sick.




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We still have lots to learn about treating mosquito bites.
A/Prof Cameron Webb

Fleas, lice, mites and ticks

There are lots of other insects (such as bed bugs, fleas, lice) and other arthropods (such as mites, ticks) that bite.

But it is difficult to determine which insect has bitten us based on the bite reaction alone. This is generally because different people react in different ways to the saliva injected as they start to suck our blood.

Bees, wasps, ants

Then there are stinging insects, such as bees, wasps and ants. These are typically just defending themselves.

But as well as being painful, the venom they inject when they sting can cause potentially severe allergic reactions.

How do you best treat a sting or bite?

If you suffer potentially severe allergic reactions from bites or stings, immediately seek appropriate medical treatment. But for many other people, it is the initial painful reaction and itchy aftermath that require attention.

Despite how common insect bites can be, there is surprisingly little formal research into how best to treat them. Most of the research is focused on insect-borne diseases.

Even for recommended treatments, there is little evidence they actually work. Instead, recommendations are based on expert opinion and clinical experience.

For instance, heath authorities promote some general advice on treating insect bites and stings. This includes using pain relief medication (such as paracetamol or ibuprofen). They also advise applying a cold compress (such as a cold pack, ice, or damp cloth soaked in cold water) to the site of the sting or bite to help reduce the inflammation and to ease some of the discomfort.

Refreshing red drink in glass with ice cubes and lemon
Ice cubes aren’t just for summer cocktails. They can help reduce inflammation from insect bites and stings.
Shutterstock

There is also specific advice for dealing with stings and removing ticks.

However, if you do nothing, the discomfort of the bite or sting will eventually fade after a few days. The body quickly recovers, just as it would for a cut or bruise.

If you’re still in pain for more than a couple of days, or there are signs of an allergic reaction, seek medical assistance.

What about the itch?

Once the initial pain has started to fade, the itch starts. That’s because the body is reacting to the saliva injected when insects bite.

For many people, this is incredibly frustrating and it is all too easy to get trapped in a cycle of itching and scratching.

In some cases, medications, such as corticosteroid creams or antihistamines could help alleviate the itchiness. You can buy these from the pharmacy.

Then there’s calamine lotion, a mainstay in many Australian homes used to treat the itchiness caused by insect bites. But there are few studies that demonstrate it works.




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Do any home remedies work?

If you’re looking for a home remedy to treat insect bites and the itchiness that comes with it, a quick internet search will keep you busy for days.

Potential home remedies include: tea bags, banana, tea tree or other essential oils, a paste of baking soda, vinegar, aloe vera, oatmeal, honey and even onion.

There is little evidence any of these work. But not many have actually been scientifically evaluated.

Tea tree oil is one of the few. While it is said to help treat skin reactions, the oil itself can cause skin reactions if not used as directed.

However, if a home remedy works for you, and it’s not causing additional irritation, there’s no harm in using it if you’re getting some relief.

With so much uncertainty about how to treat insect bites and stings, perhaps it is best if we avoid exposure in the first place. There are plenty of insect repellents available at your local pharmacy or supermarket that do this safely and effectively.The Conversation

Cameron Webb, Clinical Associate Professor and Principal Hospital Scientist, University of Sydney

This article is republished from The Conversation under a Creative Commons license. Read the original article.