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Palm swamp forests are wetland ecosystems typical of the Brazilian Cerrado, which in recent decades have undergone intense changes due to land use alterations and climate change. As a result of these disturbances, many palm swamps have been experiencing significant drying, which can also affect adjacent vegetation. In the present study, we evaluated whether the drying of palm swamps affects the structure of plant–herbivore networks located in adjacent savanna areas in Brazil. Our results show that savanna areas adjacent to dry zones of palm swamps have fewer interactions, fewer interacting species, and a less specialized topology, which corroborates our expectations. Our findings indicate that the drying of palm swamps also has propagated impacts on adjacent savanna vegetation, impairing more specialized interactions in these environments. On the other hand, contrary to expectations, plant–herbivore networks in dry zones displayed higher modularity, lower nestedness and lower robustness than those in wet zones, suggesting that in dry environments, species tend to compartmentalize their interactions, even with lower interaction specialization. This is the first study to investigate the impacts of environmental drying on the structure of plant–herbivore networks in tropical ecosystems, highlighting the complexity of these effects and their differential impact on specialized and generalized interactions. Understanding these dynamics is crucial for developing effective conservation and management strategies in the face of ongoing environmental changes. [ABSTRACT FROM AUTHOR]

Human-induced habitat modification can affect species interactions and ecological networks composed of specialized species may be more susceptible to these effects. Immature and adult insect herbivores have different mobility and specificity levels related to their host plants, which can affect their tolerance to anthropic disturbances. In the present study, we compared the structure of plant-herbivore networks composed of adult and immature insects in 16 Neotropical savanna sites under different land-use intensification levels. We compared insect species richness, insect abundance, connectance, specialization, generality, vulnerability, modularity, and nestedness in plant-immature insect and plant-adult insect networks occurring in preserved and non-preserved areas. In total we sampled 328 individuals of 98 species of host plants and 557 individuals of 310 species of insect herbivores (275 individuals of 143 species of immature insects and 479 individuals of 196 species of adult insects). Although the richness of insect species did not differ between the networks, plant-immature insect networks had a lower insect abundance, generality and nestedness than networks of adult insects. On the other hand, connectance was lower for networks of adults than for networks of immature insects. Our results also show that the effects of habitat modification are more pronounced for immature insects than for adults, as network connectance increases and network vulnerability decreases between preserved habitats and disturbed habitats. Our findings support previous warnings that habitat modification can alter plant–herbivore interactions, and advance the understanding of how these effects can be different for assemblages composed of adult and immature insects. Implications for insect conservation: Our results indicate more consistent effects of habitat modification on immature insect interactions, which showed more specialized networks in preserved environments. Thus, our results contribute to the understanding of how plant-insect interactions are structured in highly disturbed environments, such as Neotropical savannas. [ABSTRACT FROM AUTHOR]

Human-induced habitat modification is among the main factors that threaten biodiversity on the planet. For highly specialized herbivorous insects, such as galling insects, anthropogenic disturbances that affect plants can have great effects on insects. In this sense, in the present study, we investigated the diversity of host plants and gall-inducing insects in anthropized and preserved remnants of Neotropical savannas in the Brazilian Cerrado. Sampling was performed in 30 plots (10 × 10 m) distributed in six study areas. Of these total, fifteen plots were in areas with anthropized vegetation and fifteen plots in areas with preserved vegetation. Overall, we recorded 67 species of gall-inducing insects and 39 species of host plants. We found that the diversity of both host plant species and gall-inducing insects differed significantly between areas, being higher in preserved plots than in anthropized plots. Our results revelated that changes in the species richness and composition of gall-inducing insects from preserved environments to anthropized environments were mediated by changes in the richness and composition of the plant species, respectively. Our study stands out as the first to demonstrate that plant diversity drives responses of gall-inducing insects to human disturbance in Neotropical savannas. Our findings indicate that the preservation of natural vegetation is important for the conservation of plant assemblages and their gall-inducing insects in urban environments. [ABSTRACT FROM AUTHOR]