Nakita White, of Balclutha Primary School, asks :-

Do we need insects?

Barbara Barratt, an entomologist at AgResearch, responded.

Most people would probably think that insects are mostly a nuisance to us, and that we don’t need them. They can bite, sting, suck blood, damage our crops, transmit diseases, and sometimes look very scary. However, our world would be very different without them, and if they all disappeared now, we would be hard pressed to survive.

Insects evolved a long time before us, and they have developed in harmony with other animals and plants. They have a role in many processes that are crucial to us since we appeared on earth. Insects are important members of the food chain providing food for many birds, mammals and fish. In some countries, insects are an important source of protein in the human diet.

Insects comprise a large component of the biodiversity of most ecosystems, and the different functions they perform help keep the biota in ‘balance’. However, we depend upon insects to perform a number of important and specific functions for us, known as ecosystem services. Insects such as bees pollinate flowers of many of the plants which we depend upon for food, and without them many fruits and vegetables would not be able to develop to the stage that we use for food. Some of the pollinators such as honey bees provide us with honey and other products which are used for medicinal purposes.

Because of the way we grow crops in large monocultures, some insects which feed on these plants become very abundant, and hence we call them pests. However, there are also many natural enemies of these plant-feeders amongst the insects which help restore a more natural balance and control pests. We have become quite skilful at manipulating this process and can use it to our advantage – this is known as biological control, and often means that we don’t have to use pesticides.

Insects are also responsible for the early stages of decomposition of dead animal and plant material, breaking organic material down so that microbes can take over and return nutrients to the soil. Insects such as beetles which bury dung are critical to the ecosystem of countries with large mammals. Without insects providing these ecosystem services for us we would probably struggle to survive. So yes, we do need insects.