The combined insect hordes, trillions upon trillions of them, maintain the world as we know it. World Nature Conservation Day, 28 July, is observed to emphasise the importance of preserving and protecting our biodiversity and natural resources, including plants and animals, but we should also focus on the key role of insects in our lives.
Without them, soils would deteriorate, many plants would die and our food supply would be severely compromised.
They chew all types of plant material, shredding it and making the small pieces left over available for fungi and bacteria to break it down further. Combined with minerals, this is how the soil is made.
Because there are so many insects, it is not surprising that short-lived bodies soon litter the ground. But when insects die, it is mostly the ants that do the cleaning up by taking away and eating the carcasses. Many other types of insects pollinate flowering plants that grace our landscapes. Many of the flowering plants are our food. We would not have apples and pears if it were not for the insects that pollinate them.
But insect populations fluctuate and would spiral out of control if it were not for the checks and balances that take place in nature. This means all the insects that feed on living plant material must be stopped from destroying the plant through over abundance. In nature this is done mostly by other insects, like tiny parasitic wasps and predators such as ladybirds. These parasitic and predatory insects mostly live outside the crop itself and have very good powers of detection of their prey. They can hone into pests sitting on the crop plants, then move in to consume them.
This consumption is an important process in the case of crop plants. In agricultural systems, insects are classed as pests when they are too abundant and reduce the quality of the crop. The parasitic wasps and little predators stop ruining the crop. We aim therefore to encourage them as much as possible. A way to do this is to ensure that there is natural vegetation in the vicinity of the crop, either between the crop plants or around crop fields. The wasps and allies then move across from these natural reservoirs to control the pest. They can be so effective that use of harmful pesticides is reduced, and in some cases avoided completely. This organic approach is better for all of nature, and for our health.
The Cape Floristic Region is a special place, even by world standards, because it has so many plant species that live here and nowhere else. Most of these plants need pollinators, with pollinating insects doing most of the hard work. Interestingly, it is not just bees that do the pollinating, but also certain beetles and flies. Often these pollinators have adaptations that often lead to special relationships between certain plants and their specific pollinating insects.
There is also some competition among some widespread plants. This competition is often seen by the mass flowering displays that we see in the spring. The huge flower displays have a magnet effect, where a whole lot of flowers of the same species living close to each other have a major drawing effect on the pollinators, ensuring that at least some of the flowers get pollinated and produce seeds.
The Cape Floristic Region has another interesting characteristic. Many plant species have seeds with a tasty little morsel on their outside. This protrusion is highly attractive to certain ants, which carry the seed back to their nest and then eat the morsel, leaving the seeds behind underground. This hidden space is a haven for them to germinate, largely free from seed predators and fire.
The insect diversity is truly amazing, with many thousands of insect species in this one area. Some are of very ancient origin while others are more recent. This is against a background of very ancient mountains, the tops of which are 10 times more ancient than those of the Alps or Andes. Coupled with that, the Cape has had no glaciation events for more than 200 million years. During that time, there have been many swings in climate and sea level change, with the sea having been 120 metres lower and 10 metres higher at different times in the past.
All these changes over a long time have isolated insect populations, leading to much diversification in more modern times. This has led to there being both ancient insects and some modern ones through isolation and diversification events. We are still discovering many new insect species in the Cape Floristic Region, often exposed through molecular studies. What was thought to be one species often turns out to be many.
Not surprisingly, insect conservation is a major priority in the Cape, as in many other parts of the world. But because so many of the Cape species occur only here, it is imperative and a race against time to conserve them all. Our nature reserves are playing an enormous role. Also, the transition to eco-friendly farming is providing huge benefits. The wine farms that promote this practice often say so on the neck of the bottle, with the words “Integrity and Sustainability”.
Insects are now part of the integrated process of biodiversity conservation. This is something we all must support for the ensured future of our world, with all its complex beauty and wonder. Besides, we really do need these little creatures.
Michael Samways is emeritus distinguished professor in the Department of Conservation Ecology and Entomology at Stellenbosch University.He authored Conservation of Dragonflies: Sentinels for Freshwater Conservation (CABI/Royal Entomological Society, 2024) and co-edited theRoutledge Handbook of Insect Conservation (Routledge, 2024).
