What’s so special about insects?

What is an insect and should we really care about these creepy crawlies? In a word – yes. As American biologist Edward O Wilson puts it, they are “the little things that run the world”.

There are about a million species worldwide with New Zealand home to over 20,000 species, and insects make up more than half of all living animals. There are insects living in almost all habitat types (although not in the deep sea), and many species have amazing characteristics that allow them to thrive in harsh environments. Insects play many critical roles in the environment as pollinators, nutrient mixers in the soil and food sources. They have inspired stories and invention (biomimicry) and can even help us to solve crimes (forensic entomology).

The natural world and, in particular, insects are being used by science to inspire and solve a number of problems, especially in the development of drones. High-tech drones copying nature’s design is an example of biometrics inspiring drone research. Entomologists can also be key investigators in forensic investigations – in The food detectives article, it was entomologists who disproved two food contamination claims.

Biocontrol

Biocontrol is an important tool in controlling pest species. The Irish parasitoid wasp was introduced to help control another introduced pest species – the clover root weevil. The heather beetle was released to help with the control of heather, a pest plant. The demand for beneficial insects has led to the development of Bioforce, an innovative New Zealand company that breeds and supplies beneficial bugs for farmers and orchardists.

Importance to farming

In 2013, after years of research and consultation, two new species of dung beetles were released in New Zealand. Dung beetles bury the dung of large grazing animals such as sheep and cattle, and this helps increase soil health and pasture productivity and reduces farm pollution issues. Honey bees are very important pollinators of pasture and many cultivated food crops and other flowering plants.

Food

Insects play an extremely important role in food chains and food webs as the sole food source for many amphibians, reptiles, birds and mammals.

Insects are also starting to be seen as a potential future food source for humans. Whilst not yet common in New Zealand, entomophagy (the consumption of insects) is a common practice that’s been taking place for tens of thousands of years in many other countries. The Food and Agriculture Organization of the United Nations has around 1,900 species listed as edible. The most commonly eaten bugs are beetles, caterpillars, bees, wasps and ants.

New Zealand company Otago Locusts is one example of how this new food source is starting to take off here. In 2017, Otago Locusts won the novel food category at the New Zealand Food Awards, which came with $10,000 worth of product development assistance from science and technology facility FOODBOWL.

In 2019, a survey by AgResearch looked at New Zealanders’ appetite for adding insects to our diet. The survey showed that, given the choice, participants are more likely to eat black field cricket nymphs and locust nymphs, followed by mānuka beetle and then huhu beetle grubs.

Conservation

Often these tiny species are forgotten when fighting for the protection of threatened species. It can be hard to get people excited about bugs. They may not be as charming as other at-risk species such as the kākāpō, but there are many that are just as endangered. Little is known about our insect species, the species that have been lost forever and their impact on food webs as a food source for many other animals. Dr Mike Dickenson says, some insect species can remain undetected for decades and then pop up again, so it makes it difficult for the official extinction criteria to cope with insects. For a species to be deemed extinct, it needs to be 50 years without a sighting. Due to their size, insects can be difficult to detect, and some species remain underground for years before emerging.

The discovery of Houdinia flexilissima, nicknamed Fred the Thread, in 2006 is an example of science uncovering new species through other research – in this case, investigating the natural ecosystem of peat bogs in the Waikato. It was so tiny that scientists were unaware of the existence of both the moth and its caterpillar.

New species are still being found. In 2013, Manaaki Whenua – Landcare Research discovered six new native wasp species, which help control pest caterpillars.

Species decline

The decline in insect numbers has sometimes been referred to as the ’windscreen (or windshield) effect’. This is based on anecdotal observations that people believe that they are now finding fewer insects smashed on their car windscreens compared to a decade or several decades ago.

Some long-term overseas studies have demonstrated that insects, like other animals, are also vulnerable to habitat loss and invasive predators. More than 1,000 invertebrates (insects and spiders) are listed as threatened or at risk in New Zealand. However, for many of our native insects, we don’t know enough about them to know whether they’re at risk or not. There is a lot of coverage in the media about the worldwide "insect apocalypse", but caution needs to be taken with this claim and further research is required.

It is thought that the likely causes for declining insect numbers around the world is habitat destruction, including intensive agriculture, pesticides (particularly insecticides), urbanisation and industrialisation, introduced species and climate change. Scientific studies are ongoing to find out more.