Five reasons not to spray the bugs in your garden this summer

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play4smee/Flickr, CC BY-NC

Lizzy Lowe, Macquarie University; Cameron Webb, University of Sydney, and Kate Umbers, Western Sydney University

The weather is getting warmer, and gardens are coming alive with bees, flies, butterflies, dragonflies, praying mantises, beetles, millipedes, centipedes, and spiders.

For some of us it is exciting to see these strange and wonderful creatures return. For others, it’s a sign to contact the local pest control company or go to the supermarket to stock up on sprays.

But while some bugs do us very few favours – like mozzies, snails and cockroaches – killing all insects and bugs isn’t always necessary or effective. It can also damage ecosystems and our own health.

Read more: The hidden secrets of insect poop

There are times when insecticides are needed (especially when pest populations are surging or the risk of disease is high) but you don’t have to reach for the spray every time. Here are five good reasons to avoid pesticides wherever possible, and live and let live.

1. Encourage the bees and butterflies, enjoy more fruits and flowers

Hover fly.

Flowers and fruits are the focal points of even the smallest gardens, and many of our favourites rely on visits from insect pollinators. We all know about the benefits of European honey bees (Apis mellifera), but how about our “home grown” pollinators – our native bees, hover flies, beetles, moths and butterflies. All these species contribute to the pollination of our native plants and fruits and veggies.

Read more: The common herb that could bring bees buzzing to your garden

You can encourage these helpful pollinators by growing plants that flower at different times of the year (especially natives) and looking into sugar-water feeders or insect hotels.

2. Delight your decomposers, they’re like mini bulldozers

Slaters improve your soil quality.
Alan Kwok

To break down leaf litter and other organic waste you need decomposers. Worms, beetles and slaters will munch through decaying vegetation, releasing nutrients into the soil that can be used by plants.

The problem is that urban soils are frequently disturbed and can contain high levels of heavy metals that affects decomposer communities. If there are fewer “bugs” in the soil, decomposition is slower – so we need to conserve our underground allies.

You can help them out with compost heaps and worm farms that can be dug into the ground. It’s also good to keep some areas of your lawn un-mowed, and to create areas of leaf litter. Keeping your garden well-watered will also help your underground ecosystems, but be mindful of water restrictions and encouraging mosquitoes.

3. An army of beneficial bugs can eat your pests

Mantises and dragonflies are just some of the hundreds of fascinating and beautiful bugs we are lucky to see around our homes. Many of these wonderful creatures are predators of mozzies, house flies and cockroaches, yet people are using broad-spectrum insecticides which kill these beneficial bugs alongside the pests.

It may sound counterproductive to stop using pesticides in order to control pests around the home, but that’s exactly what organic farmers do. By reducing pesticides you allow populations of natural enemies to thrive.

Read more: Even ‘environmentally protective’ levels of pesticide devastate insect biodiversity

Many farmers grow specific plants to encourage beneficial insects, which has been shown to reduce the damage to their crops.

This form of pest control in growing in popularity because spraying can result in insecticide resistance. Fortunately, it’s easy to encourage these bugs: they go where their prey is. If you have a good range of insects in your yard, these helpful predators are probably also present.

Jumping spiders are great at eating flies and other pests.
Craig Franke

4. Your garden will support more wildlife, both big and small

Spraying with broad-spectrum pesticides will kill off more than just insects and spiders – you’re also going after the animals that eat them. The more insects are around, the more birds, mammals, reptiles and frogs will thrive in your backyard.

Read more: Four unusual Australian animals to spot in your garden before summer is out

Baiting for snails, for example, will deter the blue-tongue lizards that eat them, so cage your vegetables to protect them instead. Keeping your garden well-watered, and including waterbaths, will also encourage a balanced ecosystem (but change the waterbaths regularly).

5. You and your family be happier and healthier

Engaging with nature increases well-being and stimulates learning in children. Insects are a fantastic way to engage with nature, and where better to do this than in your own back yard! Observing and experimenting on insects is a wonderful teaching tool for everything from life cycles to the scientific method. It will also teach your kids to value nature and live sustainably.

It’s also a hard truth that domestic pesticides present a significant risk of poisoning, especially for small children.

In reality, the risk of exposing your children to the pesticides far outweighs the nuisance of having a few bugs around. Instead, integrated pest management, which combines non-chemical techniques like cleaning of food residues, removal of potential nutrients, and sealing cracks and crevices, is safer for your family and your garden ecosystems.

Think globally, act locally

Your backyard has a surprising impact on the broader health of your neighbourhood, and gardens can make significant contributions to local biodiversity. Insects are an important part of ecosystem conservation, and encouraging them will improve the health of your local environment (and probably your health and well-being too).

Read more: Conservation efforts must include small animals. After all, they run the world

The ConversationIn the end, insects and spiders are not out to get you. For the sake of our kids and our environment, you should give them a chance.

Lizzy Lowe, Postdoctoral researcher, Macquarie University; Cameron Webb, Clinical Lecturer and Principal Hospital Scientist, University of Sydney, and Kate Umbers, Lecturer in Zoology, Western Sydney University

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


Mozzies are evolving to beat insecticides – except in Australia

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Mosquitoes are the main vectors for dengue and zika. Insecticides are our best weapon against them.
Anja Jonsson/Flickr

Ary Hoffmann, University of Melbourne; Nancy Margaret Endersby-Harshman, University of Melbourne, and Scott Ritchie, James Cook University

Chemical pesticides have been used for many years to control insect populations and remain the most important method of managing diseases carried by pests, including mosquitoes. However, insects have fought back by evolving resistance to many pesticides. There are now thousands of instances of evolved resistance, which make some chemical classes completely ineffective.

The Aedes mosquito, largely responsible for the spread of viruses like dengue and zika, has globally developed resistance to commonly used chemicals, including pyrethroids. Pyrethroids are the most used insecticides in the world, which includes the control of dengue outbreaks and quarantine breaches at air and sea ports.

In Asia and the Americas, pyrethroid resistance in Aedes mosquitoes is now widespread. In Australia, our mosquitoes have not developed these defences and pyrethroids are still very effective.

The difference lies in our stringent and careful protocols for chemical use. As the global community fights zika and other mosquito-borne diseases, there are lessons to be learned from Australia’s success.

Developing resistance

Mosquitoes usually become resistant to pyrethroids through the mutation of a sodium channel gene that controls the movement of ions across cell membranes. Mutations in a single gene are enough to make mosquitoes almost completely resistant to the level of pyrethroids used in insecticides.

The mutations first arises in a population by chance, and are rare. However, they rapidly spread as resistant females breed. The more times a mosquito population is exposed to the same chemical, the more the natural selection process favours their impervious offspring.

Eventually, when many individuals in a population carry the resistance mutation, the chemical becomes ineffective. This can happen where insecticide “fogging” is common practice. Overseas, fogging is sometimes undertaken across entire neighbourhoods, several times a month, despite concerns about its effectiveness as well as its environmental and health impacts.

A pest exterminator carries out insecticide fogging in an apartment block in Singapore.
EPA, Wallace Woon/AAP

Once resistance develops, it can spread to non-resistant mosquito populations in other areas. Pest species, including mosquitoes, are often highly mobile because they fly or are carried passively (in vehicles, ships and planes) at any stage of their life cycle. Their mobility means mutations spread quickly, crossing borders and possibly seas.

We can still control Australian mosquitoes

Despite this, Australian populations of Aedes mosquitoes remain susceptible to pyrethroids. Aedes aegypti (the yellow fever mosquito) is the main disease-carrying mosquito in Australia. Its population is restricted to urban areas of northern Queensland, where dengue can occur.

Recent research found that all Australian populations of this species are still vulnerable to pyrethroids. None of the hundreds of mosquitoes tested had any mutations in the sodium channel gene, despite the high incidence of such mutations in mosquito populations of South-East Asia.

A female Aedes aegypti mosquito during a feed.
James Gathany, CDC Prof Frank Hadley Collins/Wikimedia

We believe these mosquitoes remain vulnerable to pyrethroids because in Australia pressure to select for resistance has been low.

Australia does not carry out routine fogging. If dengue is detected in an area, pyrethoids are used in highly regimented and limited fashion. Spraying is restricted to the insides of premises within selected house blocks, and then only for a short period.

Importantly, water-filled artificial containers, which can serve as a habitat for larvae, are treated with insect growth regulators, which do not select for the pyrethroid resistance mutations.

Exporting resistance

With chemical resistance growing around the world, it is more urgent than ever that we co-ordinate action to control and reduce risk of resistance. Unfortunately, no global guidelines exist to minimise the evolution of resistance in mosquitoes.

Adopting pesticide resistance management strategies has proven to be effective against other pests – for example, the corn earworm (Helicoverpa armigera). Guidelines include rotating different class of pesticides to deny pests the chance to develop resistance, and investing in non-chemical options such as natural predators of target pests.

Resistance management strategies are particularly critical for new pesticides that have different modes of attack, such as preventing juvenile insects from moulting, or attacking various chemical receptors.

The ConversationTo prolong the effectiveness of pesticides, we must develop these strategies before resistance begins to develop. North Queensland may be an example to the rest of the world on the best path forward.

Ary Hoffmann, Professor, School of BioSciences and Bio21 Institute, University of Melbourne; Nancy Margaret Endersby-Harshman, Research fellow, University of Melbourne, and Scott Ritchie, Professorial Research Fellow, James Cook University

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.

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

Daniel Spring, University of Melbourne; Jonathan Keith, Monash University, and Tom Kompas, University of Melbourne

Australia needs to spend millions of dollars more to eradicate one of the nation’s worst invasive species, the fire ant, according to recent reports.

Fire ants, first detected in Brisbane in 2001, pose a major health and agricultural risk. A recent independent review of the eradication program recommended that A$380 million be spent over 10 years to eradicate the ants, on top of the A$330 million already spent since 2001.

Improvements in knowledge and control methods mean that eradicating the Australian invasion is challenging, but still potentially feasible. We now face a stark choice.

Lessons from previous attempts

The fire ant eradication program began in September 2001 after the species was detected at two locations in Brisbane. By that time, it may have been present for at least five years or perhaps even longer, and large areas were already infested. Fire ants had never been eradicated from areas this large.

However, improved eradication methods mean we have increased the chances of eradicating larger invasions.

Most of the original funds were spent on pesticides and monitoring areas with likely infestations. Monitoring information was used to estimate how far the invasion had spread (“delimitation”) and management efforts were focused on the delimited area.

The early years of the program showed that large infestations, such as those at the Port of Brisbane and Yarwun, can be eradicated when the geographic range of the infestations is known.

However, when this is not the case, undetected nests beyond the known infested area can spread unchecked. In a published reconstruction of the invasion we estimated that undetected nests existed a relatively short distance beyond the delimited area.

Had those nests been detected by monitoring a larger area over the first few years of the program, the ants may already have been eradicated. However, the initial focus on intensively treating known infestations rather than expanding the monitored area reflected the best available scientific advice at the time.

It also reflected an urgent need to protect people from the potentially serious health consequences of coming into contact with fire ants in areas known to be infested.

Pustules caused by fire ant stings.
Daniel Spring, Author provided

Is eradication still possible?

Although the invasion now occupies a larger area than it did when the program began, fire ant numbers have effectively been suppressed and some individual infestations have been eradicated. These facts, and the availability of a cheaper monitoring method involving remote sensing with airborne cameras, have kept alive eradication hopes.

A recent meeting of agricultural ministers agreed with the finding of the independent review that eradication remains technically feasible.

The review’s recommendation that eradication program funding be increased is a logical response to the invasion’s expansion. The expansion not only increased the area that requires management, thus increasing costs, but also showed that the areas previously searched and treated each year were too small to achieve eradication, implying there was insufficient annual funding.

Geographic expansion of the invasion cannot continue much longer without the invasion becoming too large to eradicate. The review panel’s finding that increased funding should be made available soon is therefore timely.

A lack of monitoring during the early years of the program led to the erroneous conclusion in 2004 that eradication was imminent, when in fact the invasion was expanding in area. To avoid this mistake being repeated, substantial monitoring will be required beyond known infestations and monitoring data will need to be assessed with reliable statistical methods.

In a recent report we wrote to help the eradication program, we showed that the invasion boundary can be estimated with a high degree of confidence if adequate monitoring data are available.

Pesticide treatment and monitoring will underpin eradication efforts. We need highly sensitive monitoring methods, including sniffer dogs and trained spotters, to confirm absence of fire ants in and near treated locations.

A large enough area should be monitored to ensure all fire ant colonies are found and removed. We need continued support for community members to report fire ants, particularly in urban areas. Remote sensing will be needed in less developed areas where contact between people and fire ants is less likely.

A stark choice

The choice is to continue eradication efforts or live with fire ants forever. Living with fire ants will incur large costs for agricultural producers and households.

The most recent cost-benefit analysis of the program estimated that if these costs were added up over each of the next 70 years they would exceed A$25 billion in today’s dollars.

Over half these estimated costs arise from damage to agricultural activities, with household losses being of a similar magnitude.

Large numbers of people are likely to come into contact with fire ants if the species is left unchecked. Environmental damages could also be substantial. These losses far exceed estimated eradication costs.

The review panel’s report makes it clear that we face an urgent choice between increased eradication funding or living with fire ants. There is not much time left to make this choice.

The Conversation

Daniel Spring, Research Fellow, School of Biosciences, University of Melbourne; Jonathan Keith, Associate Professor, School of Mathematical Sciences, Monash University, and Tom Kompas, , University of Melbourne

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

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.

The Conversation

Ravindra Palavalli Nettimi, PhD student in Ecological Neuroscience

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