A growing human population, warming climate, conflicts, and rising prices are threatening the already fragile supply of food to people around the world. This challenge is recognised by the annual declaration of 16 October as World Food Day by the United Nations.

Food insecurity is when people do not have continuous access to sufficient, safe and nutritious food that meets their needs. Fruits are important sources of vitamins and minerals that reduce the risk of non-communicable diseases, but their production and availability are compromised by many insect pests.

In the University of Pretoria Department of Zoology and Entomology, Professor Christopher Weldon and his research group are working to secure access to fruit. They are doing this by finding better ways to monitor insect pest populations, reduce pest populations without relying on widespread use of insecticides, and limit the damage caused by pest insects.

Pest monitoring

Prof Weldon’s team is currently working to improve early detection of insect pests that have not yet arrived in South Africa. Odours are being used to improve sticky traps for detection of citrus psyllids that can transmit the devastating Asian citrus greening disease. An artificial intelligence system is also being developed to make it easier to find the tiny psyllids on traps.

Research is also being done to better understand how weather and other environmental variables affect the effectiveness of traps to catch thrips in avocado and macadamia orchards and fruit flies in citrus orchards. “Temperature is really important for whether an insect will be caught in a trap because their flight is restricted when it is cool or very hot,” Prof Weldon explains.

Dylan Pullock, an MSc Entomology student in the Department of Zoology and Entomology, helping to improve monitoring of citrus psyllids by adding odours to traps and detecting the pests on traps using artificial intelligence.

Pest management

Fruit flies are recognised globally as among the most destructive pests of fruit. To limit the risk of fruit flies damaging fruit, a control tactic called “attract-annihilate” can be used to reduce fruit fly numbers. This tactic uses the attraction of flies to the smell of food or other chemicals (or baits) to small spots of insecticide, and is being studied by Prof Weldon’s team to improve how farmers use it. “Farmers need to put the baits in tree canopies because flies rarely visit spots on the ground,” Prof Weldon says.

In addition, Prof Weldon’s team is researching the potential for sterile insect technique for the invasive oriental fruit fly (Bactrocera dorsalis). In sterile insect technique, large numbers of sterile fruit flies are released into the wild to mate with the pest population, leading to no fertilised eggs being laid. This is a proven way to control some fruit fly species but, says Prof Weldon, “A lot of testing and optimisation is needed to sterilise and release high-quality oriental fruit flies for the method to be used successfully.”

Msizi Ramaoka is an MScAgric (Entomology) student working out why fruit flies visit protein baits and how they should be applied to make them more effective.

This research, which involves international collaboration and close cooperation with agriculture industries, shows how entomologists at the University of Pretoria are helping to improve the sustainable production of high quality, nutritious food by managing insect pests.

Interested in entomology?

What is entomology?
The scientific study of insects.

What is applied entomology?
It is the use of knowledge of insects to benefit humans. This includes working out the best way to control insect pests, helping to promote crop pollination by insects, and identifying insects that indicate environmental health. Furthermore, it includes using insects to rehabilitate degraded land like former mine sites and solving criminal cases using insects on bodies as evidence.

How can I become an entomologist?
Register for the BSc Entomology degree at the University of Pretoria!

Is there work as an entomologist?
BSc Entomology graduates are highly sought after by the agriculture industry and government agencies, particularly to work on pest detection and management. Postgraduate study in entomology at honours or higher levels opens more opportunities with higher levels of responsibility, involvement in solving entomological problems and higher salaries.