Insects: Know Your Friends From Your Foes

Hannelene Badenhorst, a PhD candidate in entomology at the University of the Free State, explains the value of differentiating beneficial insects and other arthropods from harmful ones before resorting to blanket chemical control. Lloyd Phillips reports.

- Hannelene Badenhorst

The estimated 2,5 million to 10 million species of insects on the planet have a profound impact, directly and indirectly, on all other creatures and on the environment. This stands to reason; there are an estimated 10 quintillion (or 10 billion billion) individuals, and they represent 80% of all living organisms on earth.

DO YOUR BEST TO MAINTAIN THE DIVERSITY OF POLLINATORS

They are also the most diverse group of organisms.

“Slightly more than one million insect species have actually been named, and only a small proportion of them have been properly studied,” says Hannelene Badenhorst, a PhD candidate in entomology at the University of the Free State.

“They are responsible for pollinating about 85% of the world’s flowering plants.

“Non-insect arthropods, such as spiders, also have a significant environmental role. Some aid in predating on pests and by promoting the decomposition of organic matter, while others are pests themselves.”

(Insects comprise 90% of all arthropod species.)

Although insects are the main consumers of plants, including crops, fewer than 1% of the known insect species are considered pests by humans, explains Badenhorst. Of these, only a few hundred species have proved to be constantly problematic. All the other insects and arthropods are beneficial to humans and the environment, providing a diverse range of key ecosystem services between them.

One of these, she points out, is plant pollination. While bees make the largest contribution to pollination and rightfully deserve to be protected, it is also critical to maintain the diversity of other insect pollinators, as many plant species have co-evolved with them and can only be pollinated by specific groups of pollinators.