Invasive ants: federal budget takes aim but will it be a lethal shot?

Argentine ants are a fact of life in many parts of Australia, but can still potentially be banished from Norfolk Island.
Davefoc/Wikimedia Commons, CC BY-SA

Lori Lach, James Cook University

Amid all the usual items we expect to see in the federal budget was one that raised eyebrows: A$28.8 million for three ant eradication programs.

Yet amid the inevitable media puns about the government “upping the ant-e”, we should note that these funds are for the continuation of existing programs that have already attracted significant funding and made substantial progress. Stopping now would have meant previous funding was wasted.

The funds will go a long way towards protecting Australia’s economy and environment from the damage wrought by invasive ants. But despite the apparent cash splurge, it nevertheless falls short of what is really needed.

Of the $28.8 million, $18.3 million was for the National Red Imported Fire Ant Eradication Program. These funds are part of a $411 million, ten-year program begun in 2017 to eradicate red imported fire ants from southeast Queensland, the only place they are found in Australia.

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Cannibalism helps fire ants invade new territory

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Removing these pests will avoid an estimated $1.65 billion in total costs to 19 different parts of the economy. With previous funding, the program eradicated these ants from 8,300 hectares near the Port of Brisbane, making it the world’s largest ant eradication to date.

The Yellow Crazy Ant Eradication Program was allocated $9.2 million over three years. Yellow crazy ants have caused a cascade of ecological effects on Christmas Island, and at their peak abundance temporarily blinded a Queensland cane farmer with their acid spray.

The Wet Tropics Management Authority, which runs the program, had requested $6 million per year for six years to continue removing the ant from in and around the Wet Tropics World Heritage Area. The federal funding is $3 million short of this, and the authority is still waiting to hear whether the Queensland government will provide the remainder.

Since 2013, the program has received $9.5 million from the federal government (and $3 million from the Queensland government). No yellow crazy ants have been observed in about half of the target area in more than a year. A yet-to-be published analysis estimates the benefit-cost ratio for the program as 178:1.

“It’s a mop-up operation… we’ve got our foot on the throat of this thing.”

A further $1.3 million was allocated to the Argentine Ant Eradication Strategy on Norfolk Island in the South Pacific. Argentine ants have invaded places with Mediterranean-type climates all over the world, including southwestern Western Australia and parts of southern Australia, and become firmly established. But unlike those areas, the population on Norfolk Island is still considered small enough to be eradicable, and federally funded efforts to remove them began in 2010.

Yellow crazy ants in Queensland and Argentine ants on Norfolk Island directly threaten World Heritage Areas. The ants can have significant impacts on native birds, mammals, insects, reptiles, amphibians, and plants. Getting rid of them is important for meeting Australia’s international obligations to protect World Heritage sites.

What is ant eradication?

Ant eradication means removing all individuals of a particular ant species from a given area.

The first step is to define the extent of that area. Depending on the species, this may involve visual searches and/or placing lures such as sausages, cat food, or jam to attract the ants. The public can help by notifying relevant authorities of unusual ants in their gardens, and by not transporting materials that have ants on them.

The second step is treatment. Currently, the only way to eradicate ants is with insecticidal baits. Ants’ social structure makes this particularly challenging: killing the queens is vital for eradication, but queens typically stay sheltered in the nest – the only ants we see out foraging are workers.

Some of the most problematic ant species can have hundreds of queens and tens of thousands of workers per nest. They can reach extraordinarily high densities, partly because invasive ant species, unlike most of our native ant species, do not fight one another for territories.

Yellow crazy ants, proving it is possible to feel sorry for a cockroach.
Bradley Rentz/Wikimedia Commons, CC BY-SA

Beating ants means turning their biology against them. Bait needs to be attractive enough for workers to bring back to the colony and share, but not so deadly that they die before they get there. (And yes, this means if you’re spraying foraging ants in your kitchen you won’t get rid them for good, because the queens are somewhere hidden, laying more eggs and making more ants.)

Most ant eradication programs take three to four years to fine-tune their baiting regime because of a multitude of factors that need to be considered, such as seasonal changes in ant foraging behaviour and food preference, and the desire to avoid harming non-target species. Typically, two to six treatments are required, depending on the ant species, the size of the area, and the habitat type.

Beating the 1%

The hardest part of ant eradication is the end-game. Getting rid of the final 1% requires first finding them. This may mean painstaking searches through hundreds of hectares of bushland and residential areas, and the placement of hundreds of thousands of lures. Detector dogs can be very helpful, but they cannot be used in all environments and also need substantial resources for training, handling, and maintenance.

Ironically, it is at this stage that public and political support for eradication programs is most likely to wane, because ant numbers are too low to be seen as a threat to the public, economy or environment. Yet it is vital not to stop now, or else the remaining 1% will simply build up their numbers again. Experienced staff are also lost when programs suffer cuts or delays in their funding.

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Read more:
Eradicating fire ants is still possible, but we have to choose now

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Disappointingly not mentioned in the budget was funding for eradicating electric ants. Like red imported fire ants, electric ants have a painful sting, and when left to multiply will eventually turn gardens and swimming pools into no-go zones. They also pose a significant threat to native animals such as the southern cassowary, and can blind animals as large as elephants.

They are currently only found in the Cairns region. The National Electric Ant Eradication Program, funded by federal and state governments, ran from 2006 until 2017 and had likely reduced numbers down to that last 1%. The program has been running on state funding with reduced staff since then, but several new detections in the past three months demonstrate the cost of the gap in funding.

In those inevitable “federal budget winners and losers” lists, invasive ants have found themselves firmly in the losers column for 2019. But it’s worth remembering that most of the world’s roughly 15,000 known ant species provide vital services for the functioning of our ecosystems.

They aerate soil and redistribute its nutrients, protect plants from herbivores, disperse seeds, and repurpose dead organisms. They may even help slow down the spread of those pesky invasive ants that are much less friendly.

Lori Lach, Associate Professor, James Cook University

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

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.

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

Manu Saunders, Research fellow, University of New England

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

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

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.

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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.

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You 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.

Ants in Traffic

How ants walk backwards carrying a heavy load and still find home

Ravindra Palavalli Nettimi

Imagine carrying something heavy, like a couch, and walking backwards as you move it to a desired place. Now imagine doing it alone every day for tens of kilometres, but with the same ease as walking forwards and still reaching the place.

This is similar to what the Jack Jumper ant, Myrmecia croslandi, does almost everyday.

But the ability of these ants to navigate and reach home is not diminished by walking backwards while dragging heavy food, according to a study by researchers at the Insect Robotics Lab at the University of Edinburgh, Scotland, published in Frontiers of Behavioural Neuroscience in April this year.

How these ants do this is an interesting problem, and figuring that out could have a use in some of the latest technologies on driverless cars currently under development. More on that later.

The hunt for food

Myrmecia croslandi are commonly found in the eastern regions of Australia and nest in the ground. They get the name Jack Jumpers due to their ability to jump.

Each morning, individual ants go out searching for food (nectar or insects), and if they find an insect, they sting it and pick it up in their mandibles (insect jaw).

If the food is heavy, the ants drag it backwards while occasionally looking forward, and still manage to make their way home.

You may have seen ants in your garden carrying a dead insect or some other source of food. Some ants work together to carry the food.

Others pull it alone.

Whether they do it together or alone, they all need to reach home once they have found food. But how do they know their way back?

Finding their way home

You might know that some ants use chemical trails to navigate from one place to another.

But solitary foraging ants such as the Jack Jumpers do not use the chemical trails. So how do they not get lost?

A Jack jumper species pulls its prey backwards.

The solitary foraging ants use various visual cues to navigate: the sun’s position, panoramic view, landmarks and so on.

A widespread assumption is that an ant scans and memorises all the nest-ward views while it goes out foraging – similar to taking snapshots.

When it has to return home, it matches the memory of experienced views to current views and moves towards the direction with minimum difference between them (retinotopic alignment), while comparing the views continually.

Researchers at the Insect Robotics Lab tested this by displacing ants from their nest and seeing if they could return while pulling food backwards. That is, without facing the same way as when their memory was stored.

Surprisingly, the ants took similar paths home as they would moving forwards without food. This means that continuously aligning themselves towards minimum difference in the view comparison might not be necessary.

So how do they navigate?

Barbara Webb was the principal investigator of the study and, in an email conversation, she said the ants could be taking images and comparing them continuously, but are able to mentally rotate the views to adjust to backward walking.

Alternatively, they could be matching the views only when they occasionally look forward, and then make corrections to their path accordingly.

In this case, they could be maintaining their chosen direction by using a sky compass, such as the sun or other cues. This means they use information from visual memory and also the celestial cues from the sky to travel in the right direction.

Driverless cars

Self-driving cars or autonomous robots could have something to learn from the humble ants, and the race is on to find the best way for them to cope with a range of conditions, including severe weather.

What if self-driving cars were constantly taking images of their surroundings to monitor traffic lights, road signs, pedestrians etc. In addition to other ways of sensing the surroundings, they could use the same set of simple rules that ants use to visually navigate in their complex terrain.

Further studies are obviously needed to try to answer how these ants manage to navigate. Until then, you know what to do next time when you see ants in your kitchen or garden. Give them a cookie crumb and observe them lug the heavy booty. Perhaps displace them with the crumb to a far place, and see what they do.

Ravindra Palavalli Nettimi, PhD student in Ecological Neuroscience

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

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

David Yeates, CSIRO

The prize for the most painful and sometimes deadly (more on that later) stings in the insect kingdom goes to … wasps, bees and ants.

There are many insects that bite, such as beetles and dragonflies, or suck your blood with long hypodermic mouthparts (mosquitoes, for instance, and sandflies). But none of these are deadly in themselves.

Mosquitoes do transmit deadly diseases, such as malaria and dengue. But it’s not the mosquito bite as such that kills; it’s the tiny parasitic microorganism that the mosquito transmits.

It’s really bees, wasps and ants – a group known as Hymenoptera – that can claim the title of deadliest insects. How did they evolve to be so painful?

How insects stings evolved

Many wasps are parasitic and developed long pointy hypodermic needles (or ovipositors) to inject their eggs into their hosts. Over evolutionary time, some of these parasitic wasps changed their lifestyle and became predatory. Some even went on to feed on pollen and nectar (bees).

A worker bee can sting a person only once.
吉輝 温/Flickr, CC BY-NC-ND

What happened to the ovipositor when wasps no longer needed to inject eggs? It became a pointy sting, a device for subduing prey with venom, as well as laying eggs.

It’s important to remember that only female wasps, bees and ants can sting; males don’t have the right apparatus.

Many of these stinging wasps, bees and ants have also become highly social insects. This means they live in large colonies such as honeybee hives, or ant nests. In these colonies, generally only a pair (a queen and a male drone, in the case of honeybees) or a few individuals reproduce.

All the rest are genetically and anatomically sterile females, and they do all the work inside and outside the hive or nest. These workers no longer need an ovipositor to lay eggs and it has become their primary weapon of choice, solely devoted to defence of the nest.

Workers use the sting to defend the wasp or bee nest, or ant colony. Queen bees lay eggs with their ovipositor and can also sting, but are usually tucked away in the nest far from harm.

Worker bees can sting humans only once – their barbed sting lodges in our skin and doesn’t retract, so the entire sting and the poison gland breaks free from the bee when it stings. The worker bee dies soon after and releases alarm pheromone, which alerts other workers that the nest is under threat.

A very good way of provoking a large number of European (or any other) wasps is to disturb their nest.
Ziva & Amir/Flickr, CC BY-NC-ND

More bees sting and release more alarm pheromones, attracting more alarmed bees … you get the picture. If you’re stung, remove the sting as soon as possible – this minimises the amount of venom injected.

A very small number of people (about one or two in every 100) can become hypersensitive after a bee sting. They become allergic to the venom, and their reaction becomes stronger when stung in future.

A highly allergic person may suffer anaphylactic shock from the sting, which can be life-threatening and requires medical treatment. A self-injecting EpiPen containing adrenalin is used to treat anaphylactic shock.

The most painful

Another common introduced stinger in Australia is the European wasp, Vespula germanica. This wasp’s sting doesn’t get stuck in our skin, so they can inflict multiple stings when annoyed or provoked. A very good way of provoking a large number of European (or any other) wasps is to disturb their nest – never do this.

A very small percentage of people can also develop an allergic reaction to European wasp stings, just like honeybee stings. In severe cases, this can cause anaphylactic shock.

Arizona entomologist Justin O. Schmidt developed the Schmidt Pain Index 30 years ago to rank the painfulness of wasp, bee and ant stings on a four-point scale.

Zero on the Schmidt pain index is the feeling of an insect that can’t sting you, such as Australia’s native stingless bees. Two is the familiar pain of a honeybee. Four is reserved for just a few heavy hitters, such as a very large spider-killing wasp, or the infamous bullet ant (Paraponera clavata) of South America.

The notorious and excruciating pain of the bullet ant lasts for 24 hours. Schmidt has been stung by more than 100 insects to create his scale, and was awarded the 2015 Ig Nobel Biology Prize for his efforts.

Some of the most common painful stingers in the Australian bush are native bulldog ants of the genus Myrmecia. These are some of the largest ants in the world and combine a painful sting with an aggressive, take-no-prisoners attitude. On top of this, many species can jump. They rate up to three on the Schmidt Pain Index.

Bulldog or jack-jumper ants have impressive long, toothed and curved jaws, but it’s the sting at the end of their abdomen that does the damage.

My most painful memory as a boy was annoying a bulldog ant nest in the Sydney bushland with a stick. Eventually a huge worker bulldog ant crawled up out of sight underneath my stick and gave me a sting on the thumb I thoroughly deserved – and will never forget.

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This article is the last of our series Deadly Australia. You can see the whole series here.

David Yeates, Director of the Australian National Insect Collection, CSIRO

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

Ants Jaws

The Ant Colony

Ants

Ants