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 the disturbance theory, generalist species are expected to outperform specialists in variable environments. Thus, we hypothesized that omnivorous 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. We compared the responses of true bug (Heteroptera) assemblages in stable (unburnt) versus unstable (postfire successional) environments as this group shows a high diversity of feeding strategies. Redundancy analysis fitted our hypothesis as omnivorous and polyphagous bugs responded positively to fire whereas oligophagous bugs did not. Thus, the most generalized bugs in terms of diet were found in disturbed (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 bipartite networks, the lower modularity in burnt sites corresponded to a scenario of lower segregation of plant resources and fits the higher presence of generalist bugs in these sites. Our results suggest that plant-bug trophic interactions shape the response of Heteroptera to fire, and this response seems to be mediated by the degree of feeding specialization.

Linear Landscape Elements and Heteropteran Assemblages within Mediterranean Vineyard Agroecosystems

“…In vineyard agroecosystems, linear habitats have been shown to support high levels of heteropteran diversity, community structure being largely determined by plant abundance and diversity or vegetation architecture [39,[60][61][62]. Hedgerows are structurally diverse and botanically complex elements that potentially provide a wide range and a high amount of resources [51,[63][64][65].…”

“…In phytophagous and predatory heteropterans, more limited than omnivores in encountering food resources [71,84], the slight shift toward longer wings as the season progresses might be driven by higher mobility and food resources accessibility in the surrounding habitats [52,85]. This is in contrast with omnivorous heteropterans, which use a wider range of resources and are more tolerant to habitat change and disturbance [62], and for which we would expect wing length to remain constant (similar to that occurring with other morphological traits), instead of showing lower mean values over the season. Nevertheless, again the low abundances could limit the identification of patterns in omnivores.…”