What insects are there in my field?

Dr Lawrence Malinga (Senior Research Entomologist) and Roshay Smith (MSc Student)

15th March 2025

What insects are there in my field?

Dr Lawrence Malinga (Senior Research Entomologist) and Roshay Smith (MSc Student)

15th March 2025

Dr Lawrence Malinga (Senior Research Entomologist) and Roshay Smith (MSc Student)

15th March 2025

Almost 45 years ago, SASRI conducted a study on the macro-arthropod community of sugarcane fields in four regions in KwaZulu-Natal as part of a project to assess the predators of eldana – 20 taxonomic groups of arthropods were recorded. Another study in 1996 investigated the effect that intercropping beans in sugarcane had on populations of arthropod predators of eldana. Since then, there has been no updated data on the diversity and abundance of insects in commercial sugarcane. Long-term changes in weather patterns, economic uncertainties, and social pressure to meet food demands have led farmers to adopt new crop cultivation practices, including extensive tillage, crop residue burning, and high external inputs. All of these new practices may have had an impact on insect biodiversity.

To establish how insect dynamics may have changed, a study was conducted to provide recent baseline data on the diversity and abundance of insects in conventional sugarcane based on two sugarcane fields in KwaZulu-Natal. Three sampling methods, namely pitfall, sticky and water pan traps, were used to sample insects in rainfed and irrigated sugarcane in Gingindlovu and Pongola from March to October 2022.

This study collected 12 493 insects belonging to 14 insect orders and 88 families in rainfed sugarcane and 22 309 insects belonging to 14 orders and 94 families in irrigated sugarcane. The most abundant insects in irrigated sugarcane were flies (Diptera – 41%), true bugs (Hemiptera – 29%) and Hymenoptera (sawflies, wasps, bees, and ants – 16%). The most abundant families were leafhoppers (21%) and dance flies (18%).

In rainfed sugarcane, Hymenoptera (29%) had the highest abundance of insects with 14 insect families, followed by beetles (Coleoptera – 20%) with 17 insect families and Diptera (17%) with 20 insect families. The most abundant families were ants (24%) and crickets (12%).

Results revealed significant differences in insect order and family abundance between irrigated and rainfed sugarcane. Irrigated sugarcane showed a higher overall insect count, with flies and true bugs dominating, while Hymenoptera was most prevalent in rainfed sugarcane. This research provides crucial baseline data on insect community changes potentially linked to modern agricultural practices.