No abstract

Moths exhibit different levels of fidelity to habitat, and some taxa are considered as bioindicators for conservation because they respond to habitat quality, environmental change, and vegetation types. In this study, we verified the effect of two phytophysiognomies of the Cerrado, savanna and forest, on the diversity distribution of moths of Erebidae (Arctiinae), Saturniidae, and Sphingidae families by using a hierarchical additive partitioning analysis. This analysis was based on two metrics: species richness and Shannon diversity index. The following questions were addressed: 1) Does the beta diversity of moths between phytophysiognomies add more species to the regional diversity than the beta diversity between sampling units and between sites? 2) Does the distribution of moth diversity differ among taxa? Alpha and beta diversities were compared with null models. The additive partitioning of species richness for the set of three Lepidoptera families identified beta diversity between phytophysiognomies as the component that contributed most to regional diversity, whereas the Shannon index identified alpha diversity as the major contributor. According to both species richness and the Shannon index, beta diversity between phytophysiognomies was significantly higher than expected by chance. Therefore, phytophysiognomies are the most important component in determining the richness and composition of the community. Additive partitioning also indicated that individual families of moths respond differently to the effect of habitat heterogeneity. The integrity of the Cerrado mosaic of phytophysiognomies plays a crucial role in maintaining moth biodiversity in the region.

No abstract

Specialist insects are more sensitive to spatial variations than generalists, which are able to exploit diverse hosts in various habitats. This study investigated whether specialist lepidopteran larvae feeding on a single host, Roupala montana Aubl. (Proteales: Proteaceae), maintain consistent abundance rates across spatial scales. We compared the abundance of specialist and generalist larvae at local and regional scales during the same period of collection, with equal sample efforts, and in the same type of vegetation, within a Brazilian savanna biome. Particularly, we focused on the following questions: Does spatial scale matter to the abundance of specialist larvae on a single host plant species? What is the relationship between the abundance of specialists and generalists among spatial scales? As predicted, in general, specialist larvae were present at higher densities on their specific host plants than generalists. However, we sought to learn how this abundance changed or did not change with spatial scale, as well as whether community similarity increased with spatial proximity. In this study, most larvae of specialist species on R. montana occurred at both local and regional scales, but they differed in abundance at different spatial scales. Moreover, although specialist larvae exhibited higher densities on R. montana than generalists, this pattern was not always consistent. The assemblage of larvae in neighboring areas showed greater mutual similarity, and there was a negative relationship between distance and similarity.

Insect herbivory is a critical top-down force structuring plant communities, and quantifying the factors that mediate damage caused by herbivores is fundamental to understanding biodiversity. As herbivory is the result of numerous ecological and evolutionary processes, including complex population dynamics and the evolution of plant defense, it has been difficult to predict variation in herbivory across meaningful spatial scales. In the present work, we characterized patterns of herbivory on plants in a speciose and abundant tropical understory genus (Piper) across forests spanning 44° of latitude in the Neotropics. We modeled the effects of geography, climate, resource availability, species richness and top-down pressure from parasitoids on the mean, dispersion, and skew of generalist and specialist herbivory. By examining these multiple moments of the distribution of herbivory, we were able to determine factors that increase biologically meaningful herbivory at the upper ends of its distribution. The strongest pattern that emerged at a large spatial scale was a roughly two-fold increase in herbivory in humid relative to seasonal forests. Site level variables such as latitude, seasonality and maximum Piper richness explained variation in herbivory at the local scale (plot level) better for communities of Piper congeners than for a single species. Predictors that varied between local communities, such as resource availability and diversity, best explained the distribution of herbivory within sites, dampening any broad patterns across latitude and climate and demonstrating why generalizations about gradients in herbivory have been elusive. The estimated population means, skew, and dispersion of herbivory respond differently to abiotic and biotic factors, demonstrating the need for careful studies to explore the distributions of herbivory and their effects on forest diversity.

No abstract

Declines in biodiversity generated by anthropogenic stressors at both species and population levels can alter emergent processes instrumental to ecosystem function and resilience. As such, understanding the role of biodiversity in ecosystem function and its response to climate perturbation is increasingly important, especially in tropical systems where responses to changes in biodiversity are less predictable and more challenging to assess experimentally. Using large scale transplant experiments conducted at five neotropical sites, we documented the impacts of changes in intraspecific and interspecific plant richness in the genus Piper on insect herbivory, insect richness, and ecosystem resilience to perturbations in water availability. We found that reductions of both intraspecific and interspecific Piper diversity had dramatic and site specific effects on herbivory, herbivorous insect richness, and plant mortality. Ecosystem responses to reduced intraspecific richness were often similar in magnitude to responses to reduced interspecific richness. Increased water availability reduced herbivory by 4.2% overall, and the response of herbivorous insect richness and herbivory to water availability was altered by both intra and interspecific richness in a site contingent manner. Our results underscore the role of intraspecific and interspecific richness as foundations of ecosystem function, and the importance of community specific contingencies in controlling function in complex tropical systems.

Declines in biodiversity generated by anthropogenic stressors at both species and population levels can alter emergent processes instrumental to ecosystem function and resilience. As such, understanding the role of biodiversity in ecosystem function and its response to climate perturbation is increasingly important, especially in tropical systems where responses to changes in biodiversity are less predictable and more challenging to assess experimentally. Using large scale transplant experiments conducted at five neotropical sites, we documented the impacts of changes in intraspecific and interspecific plant richness in the genus Piper on insect herbivory, insect richness, and ecosystem resilience to perturbations in water availability. We found that reductions of both intraspecific and interspecific Piper diversity had dramatic and site specific effects on herbivory, herbivorous insect richness, and plant mortality. Ecosystem responses to reduced intraspecific richness were often similar in magnitude to responses to reduced interspecific richness. Increased water availability reduced herbivory by 4.2% overall, and the response of herbivorous insect richness and herbivory to water availability was altered by both intra and interspecific richness in a site contingent manner. Our results underscore the role of intraspecific and interspecific richness as foundations of ecosystem function, and the importance of community specific contingencies in controlling function in complex tropical systems.