Road-associated variation in insect abundance differs between three common orders

The ecological impacts of roads are well-researched for many vertebrates, but studies are relatively lacking with regards to invertebrates. Here, changes in the abundance of ground-dwelling species of the three most common insect orders, Hymenoptera (specifically ants), Hemiptera (true bugs) and Coleoptera (beetles), with distance from a gravel road in a grassland system in South Africa, are documented. Insects were collected by means of pitfall traps ( n  = 164) installed at 2, 5, 10 and 20 m perpendicular to a gravel road, and abundances of these three orders were compared statistically between the four distances. Whereas no significant differences in the numbers of Hymenoptera and Coleoptera were observed with distance from road, the abundance of Hemiptera was greater closer to the road. Our results show that quieter, low-traffic roads can affect the distribution of insect species at finer spatial scales.