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:
How the hard work of wild animals benefits us too


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.




Read more:
I have always wondered: why are some fruits poisonous?


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.

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The secret agents protecting our crops and gardens


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Lacewings are fantastic predators and are easy to rear and release.
Dan Papacek & Tony Meredith (Bugs for Bugs), Author provided

Lizzy Lowe, Macquarie University and Manu Saunders, University of New England

Insect pests cause a huge amount of damage to crops globally. In Australia alone, pests are responsible for around A$360 million of crop losses a year. Controlling pest outbreaks is crucial for food security and human health. Since the 1940s, our primary defence against crop pests has been synthetic pesticides. But using pesticides comes at a huge cost.

Not all bugs are bad!

Bees, flies and butterflies help to pollinate our plants. Decomposers like beetles and worms help break down wastes and return nutrients to the soil. Meanwhile, predators and parasites help control the species that are pests. One of the biggest environmental problems with pesticides is that they can affect these beneficial species as well as the pests they’re targeting.

Predatory insects and spiders control pests with none of the health and environmental risks of chemicals. So when we kill these species with insecticides, we are shooting ourselves in the foot.




Read more:
The real cost of pesticides in Australia’s food boom


Losing insects also has flow-on effects for larger animals that rely on them for food. Because invertebrates have such important roles to play in our environment, losing them to insecticides can completely change how ecosystems function.

An alternative to insecticides

Biological control (or biocontrol) relies on “secret agents” – the natural enemies (predators and parasitoids) of pests that live freely in the ecosystems around us.

There is a huge range of predatory invertebrates that eat pests. They include dragonflies, preying mantids, beetles (including ladybugs), lacewings, spiders, mites, wasps, and even some flies.

Parasitoids, meanwhile, are insects that lay their eggs in the bodies of other invertebrates. Their larvae extract nutrients from the host during their development, which ultimately kills the host. Wasps are best known for this strategy but there are also parasitoid flies and beetles.

Lady birds are voracious predators ready to eat pests in crops and gardens.
Manu Saunders

Predators and parasitoids are useful because they use pest insects, like caterpillars and aphids, as food to reproduce and grow their populations. We walk past many of these hard working agents every day without knowing it.

One biocontrol method that gardeners and land managers use is called augmentation. This simply means raising lots of live individuals of particular natural enemies, like ladybirds or wasps, and releasing them into an area to control pests.

Alternatively, gardeners might change the local environment to encourage these natural enemies to move in on their own. They might include natural insectariums or planting different types of vegetation to encourage diverse invertebrate communities. There is increasing evidence of the success of these strategies in organic farming so we should be thinking about using them more broadly.

Selecting your insects

If you want to release biocontrol agents, you need to choose them carefully, just like human special agents. Like any introduced plant or animal, there is a risk that good bugs could become pests (if they feed on the wrong insects, for example).

Selecting biological control agents requires close collaboration between managers, skilled entomologists and other scientists. For each new species, they identify the pest and some potential predators. They look at the predator’s life cycle and resource needs, and consider how it interacts not just with pests, but with other insects too. If agents are coming in from overseas, they also need to be cleared by government biosecurity.

Parasiotid wasps, lacewings, predatory mites, ladybird beetles, and nematodes are all common biocontrol agents. These species are relatively easy to raise in large numbers and work well when released into the field. Spiders are also a really important predator of many pest insects, but they’re often overlooked in the biocontrol game because they are harder to breed – and for some reason people don’t always like releasing large numbers of spiders.

Many biocontrol agents are enemies of pests in general, preying on aphids, caterpillars and fruit flies alike. It’s important to have generalists around for every day pest control, but sometimes a more targeted approach is needed. This is when specialised predators or parasitoids come in. These are species that only target specific pests like leaf miners, beetles, scale insects or spider mites. This way the target pest can be managed with no risk of the parasitoids accidentally attacking other beneficial invertebrates.

Raising good bugs

It’s very exciting to get live insects in the mail!
Lizzy Lowe

Once a biocontrol agent has been selected, greenhouses or lab facilities start raising a large population. This is an emerging market in Australia, but there are already a number of companies in Australia who specialise in rearing biological control agents.

This is a tricky job because demand for the product is variable and is not easy to predict. Warmer seasons are the peak time for most pests, but problems can arise at any time of the year. In most cases the biocontrol company will maintain breeding colonies throughout the year and will be ready to ramp up production at a moment’s notice when a farmer identifies a pest problem. Each company usually provides 10-20 different biocontrol agents and are always looking for new species that might be useful.




Read more:
Birds, bees and bugs: your garden is an ecosystem, and it needs looking after


When it comes to getting the agents to the farmers, the bugs can be shipped as eggs (ready to hatch on arrival), or as live adults ready to disperse and lay their own eggs. The packages are express posted in boxes designed to keep the insects cool and safe.

Once the farmer or natural resource manager receives the bugs, applying them is quite simple. The secret agents are released among the crops, usually by hand, but in some special cases they may be airlifted in via specialised drones!

Drones can be used to deploy biological control agents.
Nathan Roy (Aerobugs)

It’s important to monitor the pests and the biological control agents after release to check that the agents are working. Some farmers are happy to do this themselves but most biological control companies have experts to visit the farms and keep an eye on all parties.

Can I use good bugs in my garden?

The ConversationIf you have a problem with a pest like aphids it is possible to buy predators such as ladybirds or lacewings to quickly deal with the problem. But for long term pest control, there are probably already some natural enemies living in your garden! The easiest and cheapest way to help them is to put the insecticides away and ensure your garden is a friendly environment for secret agents.

Lizzy Lowe, Postdoctoral researcher, Macquarie University and Manu Saunders, Research fellow, University of New England

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.

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.
dakluza/flickr

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.