Comparing the plant–herbivore network topology of different insect guilds in Neotropical savannas

Abstract

1. Herbivorous insects can be classified into several trophic guilds with different levels of specialisation on their host plants, which may influence the topological structure of their trophic networks. The present study tested the hypothesis that the structure of plant–herbivore networks differs between guilds of galling, sucking, and chewing insects. 2. Six areas of Neotropical savannas were studied in two localities in the North of the state of Minas Gerais, Brazil. In each area, interactions between plant and insect species were used to build networks for different guilds. 3. In total, 18 plant–herbivore networks were built, comprising 317 insect morphospecies, 50 plant species, and 489 distinct interactions. The networks were characterised using species richness and different network topological measures (connectance, modularity, nestedness, and specialisation). 4. The results obtained showed no difference in species richness, network size, and connectance between distinct insect herbivore guilds. However, it was found that modularity was higher for exophagous than galling insect networks and nestedness was higher for chewers than for other guilds. On the other hand, galling insect networks showed higher specialisation than exophagous insect networks, and sucking insect networks were more specialised than chewing insect networks. 5. The findings of the present study indicate that, although species richness did not differ between insect guilds of herbivores in Neotropical savannas, the topological structure of networks is sensitive to biological and ecological differences between these herbivore groups. The present study stands out as the first to systematically compare the network structure of different herbivore guilds in Neotropical savannas.