A Life Without Bugs is no Life at all
| June 17, 2019
A name which should be widely recognised when it comes to any talk of creepy crawlies (although given her clear respect for insects, she might begrudge the disparaging nickname) is Maria Sibylla Merian. Merian, who was both a botanical artist and entomologist in 17th century Germany, developed a passion for insects as a child, when she began collecting and raised caterpillars in order to accurately paint them. Her observations of their lives intrigued her and led to the discovery of the origination of butterflies, a key aspect of modern ecology and entomology. As a single mother against the odds, she became one of the pioneers of a reformed, scientific understanding of the variance, abilities, aptitudes, complexities and roles of insects. Revisiting Maria’s story reminds us that insects have captured the human imagination – both creatively and intellectually – for centuries. We once didn’t know anything about them, and cast them aside with a naive indifference, but thanks to her research, they were revealed to humanity as a crucial (and rather remarkable) part of nature’s puzzle.
I think of Maria as I read and absorb the recent spate of sobering and very alarming reports about the rapid decline of insects around the world. These very little things are still often overlooked largely as irritating pests at worst, and often given no consideration at all at best. If she were alive, how worried Maria would no doubt be to learn that most of the creatures she was so dedicated to understanding are now under threat of extinction globally despite their crucial role in the larger ecological scheme. No doubt she would be mobilising her efforts to educate humanity on their importance and what we can each do to secure their habitats and existence, if not for their sake, then our own. And so, drawing upon Maria’s enthusiasm for the littlest of creatures, I speak to modern-day entomologist, Michelle Gleeson, Australia’s resident ‘Bug Lady’, children’s educator at Bugs Ed, Adjunct Industry Fellow at the University of Queensland and author of ‘Miniature Lives: Identifying Insects In Your Home and Garden’.
Michelle talks about the threat to insect populations in Australia and what we can do as home gardeners (of both the grand and humble scale) to help out our much in-need insect population.
How did your own passion for insects begin? My parents ran a small wildlife refuge for sick, injured and orphaned animals out of our home on the North side of Brisbane. I was constantly surrounded by animals such as snakes, birds, possums and wallabies. One of my jobs from when I was a toddler was to go into the garden and dig up worms to feed birds, or catch grasshoppers for the possums. I was always out looking for bugs and would often come across things that were new to me, so I would then try and look them up in books. My passion for all things creepy crawly grew from there. As soon as I found out that entomology was actually a job (I was around eight years old at the time), I declared that that was what I was going to be when I grew up and I never wavered from that decision.
Do you think insects have a stigma or are considered un-likeable compared with cute, furry animals? How can we be brought round to rethinking our relationship with bugs? Insects (and other invertebrates) are definitely seen as something to be scared of, repulsed by, or treated with complete indifference. Most of us are oblivious to the profound impact they have on our survival and wellbeing and rarely give them a second thought unless they are invading our homes or munching their way through our vegetable gardens. Their small size and often bizarre appearances makes them much less appealing than the cute furry animals. I believe the younger generation holds the key to getting us grownups to learn to appreciate insects more. The fear or yuck factor is often something drummed into children by their parents. Don’t touch that bee, it will sting you. Don’t pick up that caterpillar, it might have germs. Nurturing the natural curiosity children have about the wonderful world of minibeasts, teaching them about the vital role they play in our ecosystems and then getting them to take that message home to the rest of their family would go a long way towards changing people’s attitudes towards insects. That’s why I am involved in the education side of things and not plugging away on (often tedious) research at a university.
Can you tell me about Australia’s role in the current global insect population decline? What bugs are threatened here? Most of the current media attention is from overseas studies, particularly the study that recently came out from Germany where dozens of amateur entomologists across the country began using strictly standardised ways of collecting insects in 1989. Special tents called malaise traps were used to capture more than 1,500 samples of all flying insects at 63 different nature reserves. This study found the annual average fell by 76% over the 27-year period, but the fall was even higher – 82% – in summer, when insect numbers reach their peak.
In Australia, many of our threatened or vulnerable species are butterflies, mainly because their larvae are often tied to a single species of host plant”
If the survival of that plant is threatened by land clearing or the introduction of invasive species, then the survival of the caterpillars which feed upon it is invariably under threat. And while they are not technically listed as threatened (as far as I know), one of the most persistent questions I get when I talk to the public is “where have all of the Christmas beetles gone?” As children, most of us remember the sound of Christmas beetles banging against our screen doors at night as they bumble around our outdoor lights and service stations, street lights and shopping centres were literally crawling with these beetles after dark. I haven’t seen a Christmas beetle at my house for many summers, and I’m not the only one.
Why are insect populations in such rapid decline? There are several factors that can be used to explain the global decline in insect populations. It could be attributed to one of these factors, a combination of several, or all of them. In certain areas one factor may cause more of an impact than others – more research is needed. But the main culprits are habitat destruction, clearing of vegetation for development and agriculture, climatic changes (natural and man-made) and the use of chemical pesticides and fertilisers.
Why are insects of all varieties so important in the micro and macro ecological scheme? Over millions of years, certain species of insects have evolved close symbiotic relationships with plants, fungi, microorganisms and other animals. These relationships are often mutually beneficial and obligatory, meaning that each party in the relationship relies exclusively on the other for survival. Some species of plants can only be pollinated by a single species of insect. For example, fig wasps pollinating figs, yucca moths and yucca plants and native Australian cycads and tiny insects known as thrips. Here is an extract from my book about the cycad-thrips pollination mutualism – I spent several years studying this to see if the impacts of climate change could make this delicate system collapse:
Australian cycads in the genus Macrozamia rely exclusively on a certain kind of thrips for pollination. These ancient plants are made up of male and female individuals, each of which produces cones for reproduction. Male cones are laden with pollen, providing food for the thrips. Male and female cones release low levels of special air–borne chemicals that attract thrips. However, between the hours of 11am and 3pm, these emissions soar to toxic levels. At the same time, the cones begin to self heat, increasing their temperature up to 12°C hotter than their surrounding environment. These factors work together to drive thrips from cones, most importantly, pollen covered thrips from male cones. Later in the day the cones begin to cool and the chemical emissions drop, once again providing an inviting habitat for thrips. Female cones do not provide food; however, their chemical smell is very similar to that of male cones. Pollen covered thrips mistakenly enter female cones in search of food, facilitating pollination. This amazing relationship is known as ‘push–pull’ pollination – ‘pushing’ pollen covered thrips from male cones and later luring or ‘pulling’ them back into cones to drive pollination. It is this fragile relationship between plant and pollinator that makes cycads one of the most threatened groups of plants worldwide.
Changes to the survival of any insect species (or plant, fungi or animal species for that matter) can cause a knock-on effect for sometimes dozens of other organisms that depend on that species for their survival.
What are some benefits we may not have considered to having more insects in our own gardens? Most people are probably aware of the important role insects such as bees play in the pollination of our plants. But there is so much more to it than that. Insects (and other invertebrates) provide ‘ecoservices’ – services that us humans take for granted, but cannot live without. The digging behaviour of ants, burrowing wasps and native cockroaches is responsible for soil formation and aeration, bringing up nutrient rich soil from deeper down and mixing it with topsoil. They also break up hard soil making it more friable and therefore increase water penetration.
Insect predators and parasitoids keep populations of pest insects at a tolerably low level. For example, paper wasps do an amazing job at hunting down caterpillars in our vegetable gardens to feed to their young. Ants play an important role in seed dispersal, collecting fallen seeds and storing them in their underground nests for a later food source. This reduces competition by moving seeds away from the parent plant and by storing them underground, where seeds may be protected from fire.
Insects are also very important nutrient recyclers. Dung beetles clean up after larger animals, returning nutrients to the soil for our plants to utilise and reducing the food supply for annoying dung-breeding fly populations. Water striders and whirligig beetles scour our waterways for the bodies of dead animals, keeping them clean and healthy. Native cockroaches and certain kinds of moths feed on leaf litter, returning nutrients to the soil and also reducing the fuel load for fires. And many other animals (including us!) rely on insects either directly (e.g. birds feeding on grasshoppers and caterpillars) or indirectly (e.g. juvenile fish and crustaceans feeding on aquatic insects before ultimately ending up in our seafood baskets at the pub) as a food source.
What can home gardeners with small and large gardens (city and country folk) do to attract native (and other important) insects to their plants and gardens? From my point of view, the greater the diversity of plants in your yard and the more micro-habitats you make available, the higher diversity and abundance of insects. I always companion plant flowers throughout my vegetable crops (I have a huge veggie garden) to encourage pollinators. Also, many insects that make great biological control agents against pests drink nectar as adults. E.g. paper wasps kill caterpillars for their young (great bio-control) but the adults feed on nectar, so by planting lots of flowers you are encouraging these insects into your garden. The same goes for green lacewings which are predators of pests such as aphids as larvae, but feed on nectar and pollen as adults.
Micro-habitats are important to provide shelter for invertebrates. Bark, leaf litter, fallen logs and rocks offer places where they can nest, shelter and avoid predators and extreme environmental conditions. So leave small clippings around the base of your plants when you prune, pile dead leaves in garden beds and place large fallen branches off to the side to provide habitat for insects. You can also add in artificial habitats, such as bee boxes made of hollowed out sticks or attach corrugated cardboard around the trunks of trees to mimic loose bark. Providing a source of water for thirsty insects is also a good idea and I always make sure I have a patch of muddy soil to help the potter wasps and mud dauber wasps construct their nests.
Avoid pesticides wherever you can. They kill indiscriminately, meaning a lot of beneficial insects end up as collateral damage when you spray your pests.”
If people want to find out more about how to attract and protect Australia’s insects, what should they do/where should they look for information and inspiration? Your local museum or council-run environmental centre is always a great starting point – they often have fact sheets available for the specific insects you can find in your local area, people who can assist you with identification inquiries and further reading materials. Many nurseries now stock local plant species that are designed to attract beneficial insects (and other wildlife) to your garden. Community garden groups often run free workshops on how to build ‘insect hotels’ to provide additional habitat for insects in suburban backyards.
Still life with fruit, a grasshopper and a butterfly, by Maria Sibylla Merian. Sourced from Wikipedia Commons.