Habitat structure and host plant specialization drive taxonomic andfunctional composition of Heteroptera in postfire successional habitats

Abstract

Changes in habitat structure are the main driving forces for responses of animal assemblages to fire. According to thedisturbance theory, generalist species are expected to outperform specialists in variable environments. Thus, we hypothesized thatomnivorous and polyphagous species will become more abundant in unstable postfire successional vegetation, whereas monophagous(specialists), due to their strong dependence on host plants, are expected to respond according to the responses of plant hosts. Wecompared the responses of true bug (Heteroptera) assemblages in stable (unburnt) versus unstable (postfire successional) environmentsas this group shows a high diversity of feeding strategies. Redundancy analysis fitted our hypothesis as omnivorous and polyphagousbugs responded positively to fire whereas oligophagous bugs did not. Thus, the most generalized bugs in terms of diet were found indisturbed (burnt) habitats whereas specialized bugs were found in undisturbed (unburnt) habitats. Moreover, the most specialized bugs(monophagous species) responded to fire in accordance to the responses of their specific host plants. Although based on small bipartitenetworks, the lower modularity in burnt sites corresponded to a scenario of lower segregation of plant resources and fits the higherpresence of generalist bugs in these sites. Our results suggest that plant–bug trophic interactions shape the response of Heteroptera tofire, and this response seems to be mediated by the degree of feeding specialization.