Plants use advertising-like strategies to attract bees with colour and scent


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A honeybee (left), a scarab beetle (middle), and a fly (right) feeding on flowers of the white rock rose in a Mediterranean scrubland.
Aphrodite Kantsa., Author provided

Aphrodite Kantsa, University of the Aegean and Adrian Dyer, RMIT University

Watching plants and pollinators such as bees can teach us a lot about how complex networks work in nature.

There are thousands of species of bees around the world, and they all share a common visual system: their eyes are sensitive to ultraviolet, blue and green wavelengths of the light spectrum.

This ancient colour visual system predates the evolution of flowers, and so flowers from around the world have typically evolved colourful blooms that are easily seen by bees.

For example, flowers as perceived by ultraviolet-sensitive visual systems look completely different than what humans can see.

However, we know that flowers also produce a variety of complex, captivating scents. So in complex natural environments, what signal should best enable a bee to find flowers: colour or scent?

Our latest research uncovered a surprising outcome. It seems that rather that trying to out-compete each other in colour and scent for bee attention, flowers may work together to attract pollinators en masse. It’s the sort of approach that also works in the world of advertising.




Read more:
Want a better camera? Just copy bees and their extra light-sensing eyes


Daunting amount of field work

Classic thinking would suggest that flowers of a particular species should have reasonably unique flower signatures. It makes sense that this should promote the capacity of a bee to constantly find the same rewarding species of flower, promoting efficient transfer of pollen.

So a competition view of flower evolution for different flower species with the same colour – for example purple – would suggest that each flowering plant species should benefit from having different scents to enable pollinator constancy and flower fidelity. By the same logic, flowers with the same scents should have different colours so they’re easily distinguished.

To know for sure what happens requires a daunting amount of field work. The challenges include measuring flower colours using a spectrophotometer (a very sensitive instrument that detects subtle colour differences) and also capturing live flower scent emissions with special pumps and chemical traps.

A wild bee of the genus Anthophora upon making the decision to visit the flowers of purple viper’s bugloss, in a Mediterranean scrubland in Greece.
Aphrodite Kantsa.

At the same time, in order to record the actual pollinator “clientele” of the flowers, detailed recordings of visits are required. These data are then built into models for bee perception. Statistical analyses allow us to understand the complex interactions that are present in a real world evolved system.

Not what we thought

And what we found was unexpected. In two new papers, published in Nature Ecology & Evolution and in Nature Communications, we found the opposite to competition happens: flowers have evolved signals that work together to facilitate visits by bees.

So flowers of different, completely unrelated species might “smell like purple”, whilst red coloured species share another scent. This is not what is expected at all by competition, so why in a highly evolved classical signal receiver has this happened?

The data suggests that flowers do better by attracting more pollinators to a set of reliable signals, rather than trying to use unique signals to maximise individual species.

By having reliable multimodal signals that act in concert to allow for easy finding of rewarding flowers, even of different species, more pollinators must be facilitated to transfer pollen between flowers of the same species.




Read more:
Which square is bigger? Honeybees see visual illusions like humans do


Lessons for advertising

A lot of research on advertising and marketing is concerned with consumer behaviour: how we make choices. What drives our decision-making when foraging in a complex environment?

While a lot of modern marketing emphasises product differentiation and competition to promote sales, our new research suggests that nature can favour facilitation. It appears that by sharing desirable characteristics, a system can be more efficient.

This facilitation mechanism is sometimes favoured by industry bodies, for example Australian avocados and Australian honey. En masse promotion of the desirable characteristics of similar products can grow supporter base and build sales. Our research suggests evolution has favoured this solution, which may hold important lessons for other complex market based systems.

A successful colour–scent combination targeted at attracting bees can be adopted by several different plant species in the same community, implying that natural ecosystems can function as a “buyers markets”.




Read more:
Curious Kids: Do bees ever accidentally sting other bees?


We also know from research that flowers can evolve and change colours to suit the local pollinators. Colours can thus be changed by flowers if instead of bees pollinating flowers, flies, with different colour perception and preferences, dominate the community.

These findings can also prove useful for identifying those colour-scent combinations that are the most influential for the community. This way, the restoration of damaged or disrupted plant-pollinator communities can become better managed to be more efficient in the future.

The ConversationWhen next enjoying a walk in a blooming meadow, remember plants’ strategies. The colourful flowers and the mesmerising scents you experience may have evolved to cleverly allure the efficient pollinators of the region.

Aphrodite Kantsa, Postdoctoral Researcher, University of the Aegean and Adrian Dyer, Associate Professor, RMIT University

This article was originally published on The Conversation. Read the original article.

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Pesticide bans might give us a buzz, but they won’t necessarily save the bees


Caroline Hauxwell, Queensland University of Technology

Public pressure is growing in Australia to ban the sale of pesticides called neonicotinoids because of their harmful effects on bees.

The retail chain Bunnings will stop selling the Confidor pesticide brand for homes and gardens by the end of 2018.




Read more:
Ten years after the crisis, what is happening to the world’s bees?


Neonicotinoids along with fipronil, another systemic insecticide that has also been blamed for bee deaths, are widely used in Australia on major crops such as maize, canola and cotton.

Between them they account for up to 30% of global insecticide sales. Will banning these insecticides stop the decline of bees worldwide?

Mites and disease

Insects are in trouble. A recent study found an 80% decline in flying insects, including butterflies, moths and wild bees, in German nature reserves. This has prompted questions about the impact of large-scale intensive agriculture.

Colony collapse disorder, in which worker bees dramatically disappear from honey bee hives, increased hugely in the decade up to 2013, particularly in the United States and Europe. This caused international concern and led to a ban on neonicotinoids and fipronil by the European Union in 2013.




Read more:
Sometimes science can’t see the wood for the bees


However, there are no reports of colony collapse disorder in Australia, according to the Australian Pesticides and Veterinary Medicines Authority, which regulates the use of pesticides and monitors the effect of insecticides on bees. Why not?

We don’t fully understand the causes of colony collapse in honey bees, but it appears that a likely culprit is the Varroa mite and the lethal viruses it transmits. This parasite feeds on both larvae and adult bees, and has been blamed for infecting vast numbers of bees with several viruses including deformed wing virus.




Read more:
Explainer: Varroa mite, the tiny killer threatening Australia’s bees


Australia’s honey bees, in contrast to the rest of the world, are still free of Varroa mites. A CSIRO survey of 1,240 hives across Australia found that deformed wing virus is also not present. The absence of both the mite and the viruses it carries may help to explain why colony collapse has not (yet) been observed in Australia.

Pesticide and fungicides, oh my!

While there is clear evidence of harm to bees from the use of neonicotinoids and fipronil, particularly from drift during application, their role as the direct cause of colony collapse is not proven.

And while they can be harmful, neonicotinoids are not necessarily the biggest chemical threat to bees. Perhaps surprisingly, fungicides appear to be at least as significant.

One study found that bees that eat pollen with high levels of fungicide are more likely to be infected with a pathogen called Nosema. Other research showed that presence of the fungicide chlorothalonil was the best predictor of incidence of Nosema in four declining species of bumblebees. What’s more, the toxicity of neonicotinoids to honey bees doubles in the presence of common fungicides.

This is not to say that Australian bees are safe, or that neonicotinoids are not harmful. Australia has more than 5,000 native bee species, and studies suggest that the main impacts of neonicotinoids are on wild bees rather than honey bees in hives. The combination of widescale use of multiple agrochemicals, loss of plant and habitat diversity, and climate change is a significant threat to both wild and domesticated bees.

And if the Varroa mite and the viruses it carries were to arrive on our shores, the impact on Australia’s honey bees could be catastrophic.

Banning pesticides affects farmers

The EU insecticide ban left Europe’s farmers with few alternatives. Surveys of 800 farms across the EU suggest that farmers have adapted by increasing the use of other insecticides, particularly synthetic pyrethroids, as well altering planting schedules to avoid pests, and increasing planting rates to compensate for losses. Most farmers reported an overall increase in crop losses, in costs of crop protection and in time needed to manage pests.

A ban on fipronil and neonicotinoids would create similarly significant problems for Australian farmers, increasing costs and reducing the efficacy of crop protection. As in Europe, they would potentially increase use of synthetic pyrethroids, organophosphates and carbamates, many of which are even more harmful to bees and other insects.




Read more:
Give bees a chance: the ancient art of beekeeping could save our honey (and us too)


Reliance on a more limited range of insecticides could also worsen the incidence of insecticide resistance and destabilise Australia’s efforts to balance resistance management and pest control with preserving beneficial insects.

Further development of these sophisticated pest management strategies, with emphasis on the use of less harmful alternatives such as microbial and biological controls, offers a route to a more effective, long-term solution to the decline in insects and bee health.

The ConversationA ban on neonicotinoids might give campaigners a buzz, but it might not save the bees.

Caroline Hauxwell, Associate Professor, Queensland University of Technology

This article was originally published on The Conversation. Read the original article.

Which square is bigger? Honeybees see visual illusions like humans do


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Flowers may take advantage of visual illusions to attract bees.
from www.shutterstock.com

Scarlett Howard, RMIT University and Adrian Dyer, RMIT University

When a human looks at a distant skyscraper, it appears small to the eye. It’s a visual illusion, and we use other contextual information to know the building is actually tall.

Our new study shows, for the first time, that honeybees see size-based visual illusions too. Whether a size illusion is seen, or not, depends on how a target object is viewed.

These new results help us understand how visual illusions evolved in different species over time.


Read more: Three visual illusions that reveal the hidden workings of the brain


How humans experience illusions

Humans see lots of different illusions such as mirages, illusions of shape, length, size, and even colour (remember that dress?).

The lines or shapes around an object can change the way your brain sees it.
Provided by Scarlett Howard

Visual illusions are errors in your own perception which can allow you to process the very complex visual information you see more easily.

One of the strongest geometric illusions we humans see is an illusion of size, called the Ebbinghaus Illusion.

Ebbinghaus Illusion: The central circles are of identical size, but are perceived as very different by humans because we use context to inform our vision.
Provided by Scarlett Howard

Interestingly, species such as bottlenose dolphins, bower birds, domestic chicks, and redtail splitfins see this illusion in the same way as humans. However, animals such pigeons, domestic dogs, and bantams see the opposite illusion to what we see, and baboons do not see an illusion at all.

To understand why different species see size illusions in such different ways, and how an insect with a miniature brain might view a size illusion, we developed an experimental design using honeybees.


Read more: Want a better camera? Copy bees and their extra light-sensing eyes


Bees can help us design better camera technology.

Why do animals perceive illusions differently?

It’s intriguing that some species view size illusions the same way as us, and some animals do not. Why is it that a baboon does not see any illusion when looking at the Ebbinghaus Illusion? Why do pigeons and dogs see the opposite illusion to us? Our team decided to look into the methodology of the past studies that had shown these differences.

When baboons, pigeons, dogs, and bantams were tested, they were looking at the illusion from either a set distance or from a forced close-range distance. For example, dogs had to touch the correct option with their noses, and birds had to peck the correct option meaning these species were viewing the illusion at a very close distance. Baboons, on the other hand, were viewing the illusion at a set distance, unable to move closer than a certain distance from a screen that presented the illusionary pictures.

With this knowledge, we decided to test honeybees using two study conditions:

  1. a free-flying set-up where bees could fly at any distance from the size illusion before making decisions, and
  2. a constrained viewing set-up where bees could only view and make decisions about the illusion from one set distance.

How does a bee view size illusions?

To determine if bees could perceive size illusions, we first had to find a way to ask them.

We trained one group of bees to always choose the larger black square on a square white background and another group of bees to always choose the smaller black square on a square white background.

When bees had learnt to either choose larger or smaller sized black square targets, we manipulated the size of the background, thus trying to induce the perception of a visual illusion (similar to the Delboeuf Illusion).

Stimuli used in experiments.
Provided by Scarlett Howard

We ran this experiment using our free-flying, unrestricted viewing condition and also using a restricted viewing condition where independent bees were unable to choose their own distance to make decisions.

Eureka! Training conditions explain why different animals see illusions differently. Bees in the unrestricted viewing condition perceived illusions, while bees in the restricted viewing condition did not see size illusions.

Now, we are interested in whether some past study results were due to experimental set-up: maybe more or even all animals could perceive illusions like humans, depending on the context in which they are viewing these illusions.

What does this mean for the evolution of vision?

Visual illusions are useful because they allow us to process complex scenes, with multiple pieces of information, as a whole by using context as a cue. Since different animals see size illusions, understanding how this works could help us learn more about how vision itself evolved.

One explanation of why such different animal species, from humans to bees, see size illusions is because an ancient ancestor had this ability, and it has been conserved throughout evolution. However, a more likely scenario is that the evolution of visual illusion perception is due to convergent evolution. This occurs when different species evolved the ability to perceive illusions separately.

The ability of bees to perceive a size illusion in a free-flying environment also has implications for flower evolution. Flowers could have evolved to exploit the ability of bees seeing illusions to make nectar areas look more appealing. One genus of flower, Wurmbea, appears to have illusionary properties such as differently sized flowers with patterns reminiscent of size illusions such as the Ebbinghaus and Delboeuf Illusions.

Wurmbea flower as seen through a special camera simulating bee vision.
http://ro.uow.edu.au/asj/vol5/iss1/7

The ConversationA very important lesson from this study is that viewing context can make scenes appear very different to reality. This is very important to remember when working on vision in humans or any other animal.

Scarlett Howard, PhD candidate, RMIT University and Adrian Dyer, Associate Professor , RMIT University

This article was originally published on The Conversation. Read the original article.

Bee aware, but not alarmed: here’s what you need to know about honey bee stings



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Bees don’t attack unless they feel threatened.
Shutterstock

Ronelle Welton, University of Melbourne and Kymble Spriggs, University of Melbourne

A Victorian man died yesterday after being stung by several bees. While bee sting deaths are rare (bees claim around two Australian lives each year), bees cause more hospitalisations than any venomous creature.

Bee stings cause nearly the same number of deaths each year as snake bites.
The University of Melbourne’s Pursuit/Internal Medicine Journal

Around 60% of Australians have been stung by a honey bee; and with a population of more than 20 million, that’s a lot of us who have just experienced pain and some swelling.

So what happens when we’re stung by a bee, and what determines whether we’ll have a severe reaction?


Further reading: Ants, bees and wasps: the venomous Australians with a sting in their tails


How do bees sting?

Honey bees work as collective group that live as a hive. The group protects the queen, who produces new bees, with worker bees flying out to collect nectar or pollen to bring back to the hive.

Bees have a venom sac and a barbed stinger at the end of their abdomen. This apparatus is a defensive mechanism that is used if they feel under attack; to defend the hive from destruction. The barb from a bee sting pierces the skin to inject the venom, with the bee releasing pheromones that can incite other nearby bees to join the defensive attack.

Honey bees work as a collective.
Shutterstock

The venom is a complex mixture of proteins and organic molecules, that when injected into our body can cause pain, local swelling, itching and irritation that may last for hours. The specific activity of some bee venom components have also been used to treat cancer.


Further reading: Curious Kids: Do bees ever accidentally sting other bees?


A single bee sting is almost always limited to these local effects. Some people, however, develop an allergy to some of these venom proteins. Anaphylaxis, a severe allergic reaction that is potentially life-threatening, is the most serious reaction our body’s immune system can launch to defend against the venom.

It is our body’s allergy to the bee venom, rather than the venom itself, that usually causes life-threatening issues and hospitalisation.

How do I know if I am allergic?

If you have not been stung by a bee before you are unlikely to be allergic to the venom. However, if you have been stung by a bee, there is the potential to develop an allergy. We do not know why some people become allergic and others don’t, but how often you are stung seems to play a role.

If you have experienced very large local reactions from a bee sting, or symptoms separate from the sting site (such as swelling, rashes and itchy skin elsewhere, dizziness or difficulty breathing) you may have an allergic sensitivity. Your doctor can assess you by taking a full history of reactions. Skin testing or blood allergy testing can help confirm or exclude potential allergy triggers.

An allergy specialist is key to assess people’s risk of severe allergic reactions (anaphylaxis).

There is an effective treatment for severe honey bee allergies, called immunotherapy. This involves the regular administration of venom extracts with doses gradually increased over a period of three to five years. This aims to desensitise the body’s immune system, essentially to “switch off” the allergic reaction to the venom.

Venom immunotherapy is very effective at preventing severe reactions and is available on the Pharmaceutical Benefit Scheme, whereas other immunotherapy treatments in Australia cost an average of A$1,200 per year.

First aid for a bee sting

Bees usually leave their barbed sting in the skin and then die. Remove the sting as soon as possible (within 30 seconds) to limit the amount of venom injected. Use a hard surface such as the edge of a credit card, car key or fingernail to flick/scratch out the barb.

For a minor reaction such as pain and local swelling, a cold pack may help relieve these symptoms.

If a bee stings you around your neck, or you find it difficult to breathe, or experience any wheezing, dizziness or light-headedness, seek medical advice urgently.

Prevention

Despite being a species introduced by European settlers, the honey bee (Apis mellifera) plays an essential role within Australian agriculture. We need to appreciate their essential functions, and try to prevent stings.


Read more: Losing bees will sting more than just our taste for honey


If you see a bee let it be (sorry); don’t swat it or step on them. Our bees don’t attack unless they feel they need to defend their hive.

Do not attempt to locate a hive, call an expert.

The ConversationFor more information on allergies go to the ASCIA website. Local bee keeping groups are a good source of knowledge about local bee populations.

Ronelle Welton, , University of Melbourne and Kymble Spriggs, Clinical Associate Professor, University of Melbourne

This article was originally published on The Conversation. Read the original article.

Ten years after the crisis, what is happening to the world’s bees?



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Bees have been living with the mysterious Colony Collapse Disorder for a decade.
Simon Klein, Author provided

Simon Klein, Université de Toulouse 3 Paul Sabatier and Andrew Barron, Macquarie University

Ten years ago, beekeepers in the United States raised the alarm that thousands of their hives were mysteriously empty of bees. What followed was global concern over a new phenomenon: Colony Collapse Disorder. The Conversation

Since then we have realised that it was not just the US that was losing its honey bees; similar problems have manifested all over the world. To make things worse, we are also losing many of our populations of wild bees too.

Losing bees can have tragic consequences, for us as well as them. Bees are pollinators for about one-third of the plants we eat, a service that has been valued at €153 billion (US$168 billion) per year worldwide.

Ten years after the initial alarm, what is the current status of the world’s bee populations, and how far have we come towards understanding what has happened?

The current status of bees worldwide

Since the alarm was first raised, many countries have created new monitoring methods to judge the status of their bee stocks. As a result we have much more data on bee populations, although coverage is still patchy and differences in survey methods make it hard to compare between continents.

It is clear that bees in the United States are still struggling. Beekeepers can tolerate up to 15% losses of colonies over winter, but the US is massively above this threshold, having lost 28.1% of colonies over the 2015-16 winter.

Canada, by contrast, reported 16.8% losses. This is better, but still above the level of losses at which beekeepers can easily restock.

Only recently have we had data from central Europe. There, honey bees seem to be doing better: 11.9% losses in 2015-16. Meanwhile, in New Zealand surveys only began in the last year and have reported winter loss of 10.7%. Australia does not yet have a countrywide survey of the state of bee colonies.

Fortunes are mixed for bees around the world.
Simon Klein, Author provided

Honey bees are not the only bees that we should care about: wild bees are vital pollinators too. Some plants are pollinated by only one wild bee species, such as the macropis bees that forage on the loosetrife plant.

Unsurprisingly, we have much less data on wild bees than honey bees, and those data we do have point to bigger concerns. For our wild bees we only really have good data for populations that are endangered or that have completely disappeared. Between 2008 and 2013, wild bee diversity in the US dropped by 23%, and a previously common bumblebee species was recently listed as endangered.

Do we understand why?

The good news is that the past decade has seen plenty of progress in understanding the mystery of Colony Collapse Disorder. The bad news is that we now recognise it as a complex problem with many causes, although that doesn’t mean it is unsolvable.

For all bees, foraging on flowers is a hard life. It is energetically and cognitively demanding; bees have to travel large distances to collect pollen and nectar from sometimes hard-to-find flowers, and return it all to the nest. To do this they need finely tuned senses, spatial awareness, learning and memory.

Anything that damages such skills can make bees struggle to find food, or even get lost while trying to forage. A bee that cannot find food and make it home again is as good as dead.

Because of this, bee populations are very vulnerable to what we call “sublethal stressors” – factors that don’t kill the bees directly but can hamper their behaviour.

For solitary species such as the blue-banded bee, difficulty foraging can be a very serious problem.
Simon Klein, Author provided

In a recently published review, we argue that modern agriculture and industry have created a host of sublethal stressors that damage bees’ cognition. For example, diesel fumes and neonicotinoid pesticides both reduce bees’ foraging efficiency by disturbing chemical communications in their brains. Modern intensive agriculture disturbs bee nutrition, which impairs their brain. Climate change interferes with the relationship between bees and the plants on which they feed.

In addition, managed honey bees are afflicted by a range of pests, viruses and predators that have been spread around the world as a side-effect of international trade. The worst is the ominously named Varroa destructor mite, which causes brain development disorders.

What can we do?

At the global level, to preserve our bees we have to improve the environments in which they collect food. Every small action can make a difference. Planting flower borders with bee-friendly flowers in your garden can provide food for both wild and domestic bees. You can reduce or eliminate the use of herbicides or pesticides when gardening. Even mowing the lawn less often can help bees out.

You could install a native bee hive or insect hotel. Another tempting option is to buy local honey, which often has a more distinctive flavour than mass-produced versions.

In Australia, we are fortunate in that our bees seem to be doing better than many other parts of the world. The Varroa mite has not yet invaded our shores, and in many areas bees can access pesticide-free bushland (although unlike Europe, Australia has not yet banned use of neonicotinoids in agriculture).

Australia also has an incredibly rich diversity of wild native bees: up to 1,600 different species, including our emblematic stingless bees. Even so, to protect this diversity we need better surveys of how these species are doing.

Ten years on from the alarm over disappearing bees, it is fair to say we now know the nature of the problem and what can be done to fix it. It’s up to us to take the steps needed to sustain these precious pollinators of our food for the future.

Simon Klein, Doctorant, Université de Toulouse 3 Paul Sabatier and Andrew Barron, Associate Professor, Macquarie University

This article was originally published on The Conversation. Read the original article.