SAVE THE INSECTS!
25% of Earth's insects have disappeared over the last three decades. If they all disappear, so will we, as these small creatures perform tasks which are crucial for the survival of humans. We can all help scientists save them.
Insects around the world are dying, and entire ecosystems could die with them, including humans. Why are they dying, and what can we do to save them before it’s too late?
The dawn is barely visible in the sky above the trees as biologist Bradford Lister and his team of assistants busy themselves in the rainforest of Puerto Rico. They are placing insect traps in the trees and on the forest floor. At sunset, Lister and his team will return to collect their catch.
Thirty-six years earlier, when Lister went through the exact same procedure in the exact same place, a trap on the ground caught an average dry weight of 473mg of insects a day, while a trap in the trees caught 37mg. This time around, it is just 13mg per trap on the ground, and 5mg per trap in the trees – a reduction of 97.3% and 86.5% respectively.
The disappearance of these Puerto Rican insects is just one indicator within a potentially disastrous global trend. Scientists everywhere are reporting alarming reductions in insect numbers. The most recent news comes from an international team of scientists who have analysed 166 long-running studies covering almost 1700 different locations around the world from a period right back to 1925 and up to 2018.
The conclusion is that the global insect population has reduced by 9% per decade. About 25% of the world’s insects have disappeared since 1990, and half have been lost over the past 75 years. And the road toward insect extinction is threatening to end life on Earth – not just theirs, but ours too, and countless other species. We underestimate creepy-crawly insects: they form the cornerstone of world ecosystems to the extent that some experts claim our own species would go extinct in a few months if insects disappeared. Scientists are now fighting against the clock to identify the causes of decline and find efficient solutions that can save the insects – and everything that depends on them – before it is too late.
Who rules the world?
We sometimes imagine that humans are the planet’s top species, but the success of insects is hard to over-estimate. Even with the huge losses of recent decades, insects are still extraordinarily numerous. The global population is estimated at 10 quintillion individuals – with combined biomass that is 17 times greater than that of humankind.
The six-legged creatures form the vast majority of the world’s species and have invaded all ecosystems except those in deep oceans. They make up around 90% of all animal species amd half of Earth’s some two
million known animal and plant species. And scientists estimate that perhaps 4.5 million more insect species have not even been discovered or described yet. Unknown species will exist under unique living conditions in regions yet to be thoroughly explored, in a particular type of soil, under withered leaves deep inside dense rainforests, or high up a mountain.
The high number of insects is down to formidable fertility. Queens of the African Dorylus wilverthi ant species can lay 3-4 million eggs in a month. An East African termite queen delivers an egg every three seconds, corresponding to almost 30,000 eggs a day, or more than 164 million eggs in her 15-year life-span.
Insects in free fall
The reductions in insect numbers have been dramatic, particularly in the US and in Europe. In a study from 2017, a team of scientists reported that more
than 75% of the biomass of flying insects had disappeared from natural reserves in Germany over a period of 27 years. And in 2019, other scientists revealed that more than 40% of world insect species are in decline, with one-third of all species endangered. The scientists have calculated that insects are becoming extinct eight times faster than mammals, reptiles and birds.
The only upswing has been for freshwater insects such as mosquitoes, which are thriving. Fresh-water insects are increasing in numbers by 11% per decade, probably helped by improved conditions as humans work to purify polluted lakes and rivers. However, fresh-water insects make up only around 10% of all insect species, and these are not as important to the eco-systems that we depend upon as are those in decline.
Humans need insects
Without insects, the world’s ecosystems would collapse, and according to some experts, humans would be unlikely to survive more than a few months before lack of food would send our species into extinction.
That’s because insects are particularly important in agriculture. True, some of farmers’ worst enemies may be insects that consume crops, but the vast majority of them benefit agriculture. Pollinators such as bees and wasps carry pollen between plants, ensuring the next generation of crops. And the insects that live below the ground are crucial in maintaining the health of soil used for agricultural purposes. Their tunnels improve soil quality by making sure that oxygen and water can pass down through soil more easily. The oxidation accelerates the breakdown rate of dead material from animals and plants, which subsequently fertilises the soil. And insects assist the breakdown even more by digesting large quantities of plant remains.
Moreover, the creepy crawlies’ activity improves the soil’s ability to hold water, as well as making it easier for plant roots to pass though the soil. They even help prevent surface erosion.
Finally, many predatory and parasitic insects contribute to reducing the number of serious pests that attack farmers’ fields. Without insects undertaking all these activities, our food production would collapse.
Prepare to eat beetles
Not only do insects make an essential contribution to agriculture, they are a food source in themselves – and an efficient one. Around two billion people already regularly eat insects such as locusts, beetles, ants, and butterfly larvae.
Insect consumption currently takes place mostly in relatively poor countries, but in the future, it will almost certainly become more common in the rest of the world, as insects are a far more climatefriendly source of protein than cattle, pigs, and poultry. Their by-products are also important, with insects providing honey, wax, silk, pigments, and shellac – a product that is used for surface treatment of food and as an ingredient of cosmetics. They also supply chemicals that could be used to save millions of human lives.
One of these comes from cockroaches. Because of their living conditions, roaches have developed an efficient defence against bacteria, and in an experiment, chemicals from cockroach hearts managed to kill 90% of the tested multiresistant bacteria, including MRSA staphylococci and E coli. The discovery is crucial, because doctors are running out of new types of antibiotics that can combat these dangerous bacteria.
Toxins from bees and wasps may also lead to drugs that can kill not only multiresistant bacteria, but even cancer cells. These toxins are also being found to ease pain and swelling in connection with arthritis, sclerosis and other inflammations.
Since 1990, the number of insectivorous birds in Euro pe has de clined by 1 3 %
Endangered in several ways
The majority of the world’s insects live in forests, and we are eliminating tropical forest at the rate of some 120,000km2 a year. So one of the major threats to insects is simply the removal of their natural habitat.
Former woodlands are often turned into farmland, and this is then sprayed with
96% of the world's flower-bearing plants depend on pollinators.
pesticides, which kill not only pests but also beneficial insects – particularly pollinators. Pesticides are one of the main reasons for the drastic reduction in the number of flying insects. The pesticides have affected bees badly, but another group of pollinators might be in even bigger trouble, with butterfly data from Denmark showing falls in 52 of 69 species, with some of the species not observed at all in 2020.
Here in Australia there have been far fewer long-term insect studies.
“While insect declines are no doubt occurring in Australia, the extent of the problem is unclear,” says Dr David Yeates of the CSIRO’s Australian National Insect Collection (ANIC). “We have good data on declines in some iconic species such as the Bogong moth, green carpenter bee and Key’s Matchstick Grasshopper; however very few of our estimated 250,000 insect species are being monitored. The worry is, if insect populations are in decline, so are the populations of larger animals such as birds and lizards who rely on them as food. We know in alpine NSW there’s been a collapse in Bogong moth populations – a staple food source for Mountain Pygmy Possums in Spring, and this decline is resulting in the possums starving. But for most species these detailed interconnections are unknown. We really need long-term data sets that would provide a better picture of what is happening.”
Parasites replace pesticides
Scientists are working hard to find a way to help insects survive. Protection and rehabilitation of habitats make up important steps.
However, we can also make useful efforts in our own homes. According to a new study, cities hold considerable potential when it comes to increasing the number of insects. Buildings and asphalt are a wilderness for insects, but if we plant flowers and flowering trees, they could thrive.
Pesticides bans are an obvious option – but not if they leave farmers’ fields entirely vulnerable to pests. So in some countries scientists have suggested using the pests’ natural enemies instead. English scientists accidentally discovered that the parasitic Microctonus brassicae wasp will feast on colonies of the cabbage-stem fleas that cause great damage to rapeseed fields. The wasps combat the cabbage-stem fleas by laying eggs in their bodies; the fleas become sterile and subsequently die when wasp larvae break through their digestive systems.
But introducing such a solution can get out of control; Australians need look no further than the cane toad, introduced here from Hawaii in 1935 to control the cane beetle in sugar cane fields in north Queensland. It didn’t end well. Not only did they have minimal effect on the beetles (which were too high in the cane for the toads to reach), Queensland proved such a fertile environemt that from the original 102 toads brought here, more than 200 million more have bred.
Create your own insect paradise
You can personally do a lot to save the insects. Plant flowers in your garden for nectar-craving pollinators. Leave the autumn leaves on your lawn to protect insects over winter. Allow your grass to get a little longer.
You can also build insect hotels in your garden or on your balcony for insects to live in, wooden structures with small holes that can be inhabited by butterflies, bees, wasps, ladybirds, and beetles. Look for a design online, and protect the hotel against rain.
There are also ‘citizen science’ apps with which we can all contribute to Australia’s meagre knowledge of insect populations. ‘iNaturalist’ began as a Masters project for students at UC Berkeley in the United States, but now operates globally, connecting scientists with observers who in 2020 logged 30 million identifications of 194,000 species. It links into local projects and provides feedback on your own observations.
Another is wildpollinatorcount. com, which twice a year encourages Australians to watch any flowering plant for just 10 minutes and submit observations. The next wild pollinator week runs from 11-18
April 2021.
With enough data, scientists may be able to find new ways to arrest the decline of the insects we all need to survive.