Microplastics are getting into mosquitoes and contaminating new food chains



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khlungcenter/Shutterstock

Amanda Callaghan, University of Reading and Rana Al-jaibachi, University of Reading

There is no doubt that plastic pollution in oceans is a growing worldwide problem. The internet is full of images of seabirds and other marine animals entangled in plastic waste, and animals starve because their guts are blocked with plastic bags.

But the problem goes much deeper than this. Much plastic pollution is in the form of microplastics, tiny fragments less than five micrometres in size and invisible to the naked eye. Our new research shows that these microplastics are even getting into tiny flying insects such as mosquitoes. And this means the plastic can eventually contaminate animals in a more unlikely environment: the air.

Microplastics can come from larger plastic items as they break down, but are also released directly into waste water in their millions in the form of tiny beads found in many cosmetic products including face wash and toothpaste (though these are now banned in many countries). Many tiny animals can’t tell the difference between their food and microplastics so end up eating them. Once inside an animal, the plastic can transfer via the food chain into fish and other creatures and eventually become a potential health problem for humans.

Mosquitoes leave the water and take microplastics with them.
Shaun Wilkinson/Shutterstock

By studying mosquitoes, we have found a previously unknown way for plastic to pollute the environment and contaminate the food chain. Our new paper, published in Biology Letters, shows for the first time that microplastics can be kept inside a water-dwelling animal as they grow from one life stage to another.

Although most microplastic research has focused on the sea, plastic pollution is also a serious problem in freshwater, including rivers and lakes. Much of the freshwater research has concentrated on animals that live in the water throughout their life. But freshwater insects such as mosquitoes start their lives (as eggs) in water and, after several stages, eventually fly away when they grow up.

Testing the mosquitoes

It occurred to us that aquatic insects might carry plastics out of the water if they were able to keep the plastics in their body through their development. We tested this possibility by feeding microplastics to mosquito larvae in a laboratory setting. We fed the aquatic young in their third larvae stage food with or without microplastic beads.

We then took samples of the animals when the larvae shed their skin to become larger fourth-stage larvae, when they transformed into a non-feeding stage called a pupa, and when they emerged from the water as a flying adult. We found the beads in all the life stages, although the numbers went down as the animals developed.

Plastics were retained as the mosquitoes went through different life stages.
Blue Ring Media/Shutterstock

We were able to locate and count the microplastic beads because they were fluorescent. We found beads in the gut and in the mosquito version of the kidney, an organ that we know survives the development process intact. This shows that not only do aquatic insects such as mosquitoes eat both sizes of microplastics, they can keep them in their gut and kidney as they develop from a feeding juvenile larva up to a flying adult.

In this way, any flying insect that spends part of its life in water can become a carrier of plastic pollution. And flying insects are eaten in their thousands by predatory insects in the air such as dragonflies as well as by birds and bats.

Our results have important implications since any aquatic insect that can eat microplastics in the water could potentially carry them in their body to their flying stage where they can move the plastics into new food chains. As a result, freshwater plastic pollution is a problem that has implications far beyond those of water quality and eventual marine pollution.

Clearly these results raise a number of questions, including what effect microplastics have on the survival and development of mosquitoes through their life stages. And we still need to examine the effect of different types and sizes of plastics on more species to see how widespread an issue this could become.The Conversation

Amanda Callaghan, Associate Professor of Zoology, University of Reading and Rana Al-jaibachi, PhD researcher, University of Reading

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

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Wasps, aphids and ants: the other honey makers



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Myrmecocystus honeypot ants, showing the repletes, their abdomens swollen to store honey, above ordinary workers.
Greg Hume via Wikimedia Commons, CC BY-SA

Manu Saunders, University of New England

There are seven species of Apis honey bee in the world, all of them native to Asia, Europe and Africa. Apis mellifera, the western honey bee, is the species recognised globally as “the honey bee”. But it’s not the only insect that makes honey.

Many other bee, ant and wasp species make and store honey. Many of these insects have been used as a natural sugar source for centuries by indigenous cultures around the world.




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By definition, honey is a sweet, sticky substance that insects make by collecting and processing flower nectar. The commercial association between honey and honey bees has mostly developed alongside the long-term relationship between humans and domesticated honey bees.

This association is also supported by the Codex Alimentarius, the international food standards established by the United Nations and the World Health Organisation. The Honey Codex mentions only “honey bees” and states that honey sold as such should not have any food additives or other ingredients added.

Oh honey, honey

Biologically, there are other insect sources of honey. Stingless bees (Meliponini) are a group of about 500 bee species that are excellent honey producers and are also managed as efficient crop pollinators in some regions. Stingless bees are mostly found in tropical and subtropical regions of Australia, Africa, Southeast Asia and the Americas.




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Their honey is different in taste and consistency to honey bee honey. It has a higher water content, so it’s a lot runnier and tastes quite tangy. Stingless bee honey is an important food and income source for many traditional communities around the world.

Harvesting “sugarbag”, as it’s known in Australia, is an important cultural tradition for indigenous communities in northern and eastern regions.

A sugarbag bee.
James Niland/Flickr, CC BY

Stingless bee honey production hasn’t reached the commercial success of honey bee honey, mostly because stingless bee colonies produce a lot less honey than an Apis honey bee hive and are more complicated to harvest. But keeping stingless bees in their native range for honey, pollination services and human well-being is an increasing trend.

Bumblebees also make honey, albeit on a very small scale. The nectar they store in wax honey pots is mostly for the queen’s consumption, to maintain her energy during reproduction. Because very few bumblebee colonies establish permanently, they don’t need to store large quantities of honey. This makes it almost impossible to manage these bees for honey production.

Bees aren’t the only hymenopterans that make honey. Some species of paper wasps, particularly the Mexican honey wasps (Brachygastra spp.), also store excess nectar in their cardboard nests. Local indigenous communities value these wasps as a source of food, income and traditional medicine.

Mexican honey wasp.
Wikimedia Commons

Ants have similar lifestyles to their bee and wasp cousins and are common nectar foragers. Some species also make honey.

“Honeypot ant” is a common name for the many species of ant with workers that store honey in their abdomen. These individuals, called repletes, can swell their abdomens many times the normal size with the nectar they gorge. They act as food reservoirs for their colony, but are also harvested by humans, particularly by indigenous communities in arid regions.

Close-up of three large replete honeypot ants (Myrmecocystus mimicus) at Oakland Zoo.
via Wikimedia Commons

These ants don’t just collect nectar from flowers, but also sap leaks on plant stems (called extrafloral nectaries) and honeydew produced by hemipteran sap-suckers like aphids and scale insects.

Aphids and scale insects aren’t all bad – they produce a delicious sugary syrup called honeydew. We mostly know these insects as garden and crop pests: warty lumps huddled on plant stems, often coated in sticky honeydew and the black sooty mould that thrives on the sugar.

Males of these insect species are usually short-lived, but females can live for months, sucking plant sap and releasing sweet sticky honeydew as waste from their rears. The sugar composition varies greatly depending on both the plant and the sap-sucking species.

Honeydew has long been a valuable sugar source for indigenous cultures in many parts of the world where native honey-producing bees are scarce. Many other animals that seek out floral nectar, like bees, flies, butterflies, moths and ants, also feed on honeydew. It’s an especially valuable resource over winter or when floral resources are scarce, and not just for other insects; geckoes, honeyeaters, other small birds, possums and gliders are all known to feed on honeydew.

Honeydew on a leaf.
Dmitri Don/Wikipedia, CC BY-SA

It’s also an indirect source of honey bee honey: plant sap that has been recycled through two different insect species! Honey bees are well-known honeydew collectors. In some parts of Europe, honeydew is an important forage resource for bee colonies.

Honeydew honeys have a unique flavour, depending on the host tree the scale insects were feeding on. Famous examples of this specialty honey are the German Black Forest honey and New Zealand’s Honeydew honey.




Read more:
Unique pollen signatures in Australian honey could help tackle a counterfeit industry


So why not find out a bit more about what insects are producing honey in your local region?The Conversation

Manu Saunders, Research fellow, University of New England

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

Insects that look like sticks, behave like fruit, and move like seeds



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Male spiny leaf insect, Extatosoma tiaratum.
James O’Hanlon, Author provided

James O’Hanlon, University of New England

The key to a stick insect’s survival may be allowing their eggs to be eaten and excreted by birds, according to new Japanese research.

Phasmatodea – more commonly known as stick insects – were so named because they genuinely look just like sticks.

While some stick insects do look like the classic stick – mottled brown with elongated limbs – others look remarkably like green leaves. They even have intricate leaf-like veins in their broad green wings.

Stick insects use camouflage to hide from predators.
Shutterstock

But these new findings show that not only do these insects look like plants, they also behave like them – by using birds to disperse their offspring.

Surprisingly, researchers led by Kenji Suetsugu of Kobe University found that stick insect eggs can actually survive being digested by birds, and in some cases still successfully hatch.

Young stick insects.
Shutterstock



Read more:
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They fed three eggs from three stick insect species to their main bird predator, the brown-eared bulbul. Within three hours, 5-20% of these eggs had been defecated and were completely intact.

Even more impressively, a few of these eggs subsequently hatched. This leads us to ask what would happen if an adult female was eaten by a bird. Would the eggs inside of unlucky stick insect survive the bird’s digestive system and stand a chance of making it out at the other end?

Creative transportation

Plants have evolved ingenious ways of moving their seeds across large distances. Some seeds are carried by the wind or ocean currents, or by animals. Bushwalkers will be very familiar with prickly seeds designed to attach to animal hair, as they are also annoyingly good at sticking to trousers.

Prickly stick insect.
Shutterstock

Many plants pack their seeds in delicious fruit which attracts animals with bright colours and alluring fragrances. When animals eat the fruit, some of the seeds make it through their digestive tract and are deposited far away.

This gives these seeds a better chance at survival, because they are not in competition with the parent plant.

This is a challenge that stick insects also face, as they’re not the most mobile twigs on the bush. Stick insects are slow and only move at night to avoid being seen by predators. Dispersal by birds helps avoid localised competition between generations.

Greenheaded ant carrying an Acacia seed.
James O’Hanlon, Author provided

But this isn’t where the similarities end. Some species of stick insect have eggs that are covered in long prickly spines that may have evolved to stick to animal fur, just like plant seeds.

There is even some evidence that stick insects arrived in Madagascar from somewhere on the other side of the Indian Ocean. This prompts the question of whether their eggs float across the vast seas like miniature coconuts.




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Everyone wins

Stick insects and plants have also developed a mutually beneficial relationship with ants to disperse their eggs and seeds.

In Australia, we have a huge diversity of “myrmecochorous” plants (trees and shrubs whose seeds are picked up and carried by ants). These plants attract ants with “elaiosomes”, which are small structures on their outer surface packed full of nutritious ant food.

Some species stick insects’ eggs also have strange-looking structures on their outer surface. It turns out that these structures, called “capitula”, are also full of nutritious ant food. And sure enough, after the eggs are laid, ants will pick them up and carry them to their nests.

An ant’s nest is a surprisingly safe place for an egg or seed. In there, they are protected from fire, predators, parasites, and drying out.

A green-headed ant inspecting a goliath stick insect egg.
James O’Hanlon, Author provided

(Exactly how the newly hatched stick insects escape from the ant nest is a mystery – for now.)

It appears stick insects may have taken more than just one leaf out plants’ book – they may be more “plant-like” than we had ever imagined.


The Conversation


Read more:
Australia’s rarest insect goes global: Lord Howe Island stick insect breeding colonies now in US, UK and Canada


James O’Hanlon, Postdoctoral research fellow, University of New England

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

Nature’s traffic engineers have come up with many simple but effective solutions



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Ant colonies direct traffic flows of millions of individuals along the best routes – army ants even manage inbound and outbound lanes – but how?
Geoff Gallice/Wikimedia, CC BY

Tanya Latty, University of Sydney

This is the third article in our series, Moving the Masses, about managing the flow of crowds of individuals, be they drivers or pedestrians, shoppers or commuters, birds or ants.


As more and more people move to cities, the experience of being stuck in impenetrable gridlock becomes an increasingly common part of the human experience. But managing traffic isn’t just a human problem. From the tunnels built by termites to the enormous underground networks built by fungi, life forms have evolved incredible ways of solving the challenge of moving large numbers of individuals and resources from one place to another.

But how do natural systems – which lack engineers or in some cases even brains – build and manage their transportation networks?

Building a transport network

Perhaps the most familiar animal transport systems are the trail networks of ants. As ants walk through their environment they leave behind tiny droplets of an attractive chemical called a pheromone. Other ants are attracted to the chemical bouquet and as they follow it they add to the trail by leaving their own droplets of pheromone. Like Hansel and Gretel leaving a trail of breadcrumbs, ants use their trails to find their way back home.

The Argentine ant (Linepithema humile) builds chemical trail networks that connect their nests using the shortest possible path. Connecting points via the shortest path saves on construction costs by using less material and requiring less effort.

Argentine ant trails connect nests using an approximation of the shortest path. The grey lines are ant trails visualised by overlaying several photos of the trail system. The inset shows the actual shortest path solution.
Tanya Latty- supplied

Yet calculating the shortest path between a set of points is a very difficult task. So how do ants, which have brains smaller than a pinhead, figure out the solution?

The answer is elegant in its simplicity. Short, direct paths are faster to traverse, and so more pheromone gets deposited by the higher density of ants. As ants are more likely to follow stronger pheromone trails, shorter, more direct trails attract more ants than do long meandering trails.

Meanwhile, fewer and fewer ants travel along the long paths, as they are attracted away by the stronger, shorter path. Eventually the longer paths disappear altogether due to evaporation, leaving only the direct routes. This simple mechanism allows small-brained Argentine ants to solve a difficult problem.

Australian meat ants (Iridomyrmex purpureus) take trail-building to the next level. Meat ants diligently cut away all vegetation from their trails, creating a smooth path. Unlike Argentine ants, meat ants do not connect their nests using the shortest possible route. Instead they build a network that includes extra “redundant” links.

Meat ants clear the grass from their trails and nest.
Nathan Brown, Author provided

Connecting points with the shortest path takes less time and uses less energy, but it would also result in a fragile network; any damage to any trail would isolate one of the nests.

This is less of an issue for Argentine ants, which can rapidly repair any damage to their trail system by depositing more pheromone droplets. For meat ants, however, damage to the system takes more time to fix. So rather than building a cheap but fragile network, meat ants build networks whose structure neatly balances the competing demands of cost and robustness.

Walking in lanes

In most human road networks, traffic flows are organised by dividing traffic into lanes where all the cars travel in the same direction. The army ant (Eciton burchellii) also uses lanes – two outer ones for outbound traffic, and one inner lane for nest-bound traffic.

But how do the army ants organise this? Lanes form because ants heading to the nest often carry heavy loads and so tend not to turn away during head-on collisions. Ants leaving the nest tend to veer away from their heavily laden sisters and so end up in the outer lanes.

Again, a simple set of behavioural rules allows ants to ensure they have a fast, efficient transport system.

Pothole pluggers

Potholes are an annoying and jarring part of driving that can slow traffic to a crawl. So when workers of the army ant (Eciton burchellii) encounter uneven surfaces, they take one for the team and plug it with their living bodies. Workers even match their size to the hole that needs filling.

Teams of ants cooperate to fill larger holes. Ants will even form bridges to span larger gaps. They adjust the width, length and position of the bridge to accommodate changes in traffic.

The result of these hardworking ants is a smooth, fast-flowing transport system that works even over the bumpiest terrain.

Humongous fungus

It’s not just insects that build transport networks. Brainless organisms such as fungi and slime moulds are also master transportation designers.

Fungi build some of the biggest biological transportation systems on Earth. One giant network of honey fungus (Armillaria solidipes) spanned 9.6km. The network is made up of tiny tubules called mycelia, which distribute nutrients around the fungi’s body.

The honey fungus is connected by vast underground transportation networks, spanning many kilometres.
Armand Robichaud/Flickr, CC BY-NC

Slime moulds – which are not fungi but giant single-celled amoebas – use a network of veins to connect food sources to one another.

In a highly creative experiment, researchers used tiny bits of food to make a map of the Tokyo metro system, with the food representing stations. Amazingly, the slime mould quickly connected all the points in a pattern that closely matched the actual Tokyo metro system. It seems slime moulds and engineers use the same rules when constructing transport networks – yet the slime mould does it without the aid of computers, maps or even a brain!

Slime mould form a map of the Tokyo railway system.

Nature has found many different solutions to the universal problem of building and managing a transport system. By studying biological systems, perhaps we can pick up a few tips for improving our own systems.


The ConversationYou can find other articles in the series here.

Tanya Latty, Senior lecturer, University of Sydney

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

Honeybees hog the limelight, yet wild insects are the most important and vulnerable pollinators



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Szefei / http://www.shutterstock.com

Philip Donkersley, Lancaster University

Pollinating insects like bees, butterflies and flies have had a rough time of late. A broad library of evidence suggests there has been a widespread decline in their abundance and diversity since the 1950s. This matters because such insects are critical both for the reproduction of wild plants and for agricultural food production.

The decline of these pollinators is linked with destruction of natural habitats like forests and meadows, the spread of pests such as Varroa mite and diseases like foulbrood, and the increasing use of agrochemicals by farmers. Although there have been well documented declines in managed honeybees, non-Apis (non-honeybee) pollinators such as bumblebees and solitary bees have also become endangered.

There are more than 800 wild (non-honey) bee species in Europe alone. Seven are classified by the IUCN Redlist as critically endangered, 46 are endangered, 24 are vulnerable and 101 are near threatened. Collectively, losing such species would have a significant impact on global pollination.

Though much of the media focus is on honeybees, they are responsible for only a third of the crop pollination in Britain and a very small proportion of wild plant pollination. A range of other insects including butterflies, bumblebees and small flies make up for this pollination deficit.

Butterfly pollinating during monsoon season.
Hitesh Chhetri / http://www.shutterstock.com

Not all pollinators are created equal

Pollinators also vary in their effectiveness due to their behaviour around flowers and their capacity to hold pollen. Bigger and hairier insects can carry more pollen, while those that groom themselves less tend to be able to transfer pollen more effectively. Bumblebees, for example, make excellent pollinators (far superior to honeybees) as they are big, hairy and do not groom themselves as often.

Where they are in decline, honeybees suffer primarily from pests and diseases, a consequence of poor nutrition and artificially high population density. This differs from other pollinators, where the decline is mainly down to habitat destruction. It seems pesticides affect all pollinators.

An ashy mining-bee (Andrena cineraria) settles in for a snack.
Philip Donkersley, Author provided

Save (all) the bees

Curiously, the issues facing non-Apis pollinators may be exacerbated by commercial beekeeping, and attempts to help honeybees may even harm efforts to conserve wild pollinators.

The problem is that there are only so many flowers and places to nest. And once the numbers of honeybees have been artificially inflated (commercial-scale beekeeping wouldn’t exist without humans) the increased competition for these resources can push native non-Apis pollinators out of their natural habitats. Honeybees also spread exotic plants and transmit pathogens, both of which have been shown to harm other pollinators.

The European honey bee (Apis mellifera) is the most common species of honey bee.
Philip Donkersley, Author provided

Over the coming decades, farmers and those who regulate them are faced with a tough challenge. Agricultural output must be increased to feed a growing human population, but simultaneously the environmental impact must be reduced.

The agriculture sector has tried to address the need to feed a growing population through conventional farming practices such as mechanisation, larger fields or the use of pesticides and fertiliser. Yet these have contributed to widespread destruction of natural landscapes and loss of natural capital.

Limited resources and land use pressure require conservation strategies to become more efficient, producing greater outcomes from increasingly limited input.

A mosaic of different flowers: these sorts of landscapes are paradise for bees.
Philip Donkersley, Author provided

Cooperative conservation

So-called agri-environment schemes represent the best way to help insect pollinators. That means diversifying crops, avoiding an ecologically-fragile monoculture and ensuring that the insects can jump between different food sources. It also means protecting natural habitats and establishing ecological focus areas such as wildflower strips, while limiting the use of pesticides and fertilisers.

As pollinating insects need a surprisingly large area of land to forage, linking up restored habitats on a larger scale provides far more evident and immediate benefits. However, so far, connections between protected areas have not been a priority, leading to inefficient conservation.

The ConversationWe need a substantial shift in how we think about pollinators. Encouraging land managers to work cooperatively will help create bigger, more impactful areas to support pollinators. In future, conservation efforts will need to address declines in all pollinators by developing landscapes to support pollinator communities and not just honeybees.

Philip Donkersley, Senior Research Associate in Entomology, Lancaster University

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

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.




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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.




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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”.




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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.

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.




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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.




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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.