Documented patterns of specialization and species interactions often omit plasticity in resource use across space and time, yet such variation is an important part of species interactions. To examine temporal variation in resource use, we compared species‐ and community‐level patterns of host plant use by folivorous caterpillars between the dry and rainy seasons in four preserved areas of cerrado vegetation in the Distrito Federal, Brazil. We sampled plants and caterpillars in 10 m circular plots monthly from March 2010 to March 2011. At the community level, we found a significant increase in the mean diet breadth of dry season caterpillars relative to those collected in the rainy season. Families and species of moths varied in diet breadth, but most exhibited a seasonal expansion. In particular, intraspecific comparisons showed a 30% increase in the number of host plants used in the dry season compared to the rainy season. These results provide a clear example of how temporal variation in resource use is heterogeneous, and more generalized patterns of resource use can emerge from studies at large temporal scales. Thus, seasonal or annual heterogeneity may obscure ecologically relevant specialized interactions that occur at smaller scales.

β diversity of herbivorous insects in the tropics is usually very high, and there is often strong dissimilarity in herbivore species composition across different spatial scales and different abiotic gradients. Similarly, turnover is high for trophic interactions between herbivorous insects and their host plants. Two factors have been proposed to explain temporal or spatial differences in trophic interactions: changes in species composition and temporal changes in the behavior of shared species. The goal of this study was to evaluate determinants of high β diversity of trophic interactions between lepidopteran caterpillars and their host plants across dry and rainy seasons and their transitions. Over the course of a year, interaction diversity data were collected from 275 temporary plots in Cerrado vegetation, comprising 257 species of caterpillars, 137 species of host plants and 503 different trophic interactions. All these diversity parameters varied across seasons. Species assemblages of caterpillars and plants were different among the four seasons, and there was a high turnover of interactions between the seasons. The high temporal β diversity of trophic interactions was mostly due to interaction rewiring between co-occurring species, as opposed to changes in species composition over time.

Among the mechanisms that influence herbivorous insects, fires, a very frequent historical phenomenon in the cerrado, appear to be an important modifying influence on lepidopteran communities. The purpose of this study was to compare the richness, abundance, frequency, and composition of species of caterpillars in two adjacent areas of cerrado sensu stricto, one recently burned and one unburned since 1994, on the experimental farm "FazendaÁgua Limpa" (FAL) (15 • 55 S and 47 • 55 W), DF, Brazil. Caterpillars were surveyed on two plant species, genus Erythroxylum: E. deciduum A. St.-Hil. and E. tortuosum Mart. (Erythroxylaceae). We inspected a total of 4,196 plants in both areas, and 972 caterpillars were found on 13.3% of these plants. The number of plants with caterpillars (frequency) differed significantly between the areas. The results indicate that recent and accidental fires have a positive effect on the abundance of caterpillars up to one year postfire, increase the frequency of caterpillars associated with Erythroxylum species in the cerrado and do not affect the richness of caterpillars on these plants. Moreover, the fires change the species composition of caterpillars by promoting an increase in rare or opportunistic species.

ABSTRACT. Eloria subapicalis (Walker, 1855) is a rare species (61 individuals in four years of samplings) of Noctuidae (Lymantriinae) with a specific diet consisting of leaves of Erythroxylum P. Browne (Erytroxylaceae) species in Brasilia's cerrado. Generally, the rarity of a caterpillar species may have many explanations such as a generalist diet, being restricted to a host plant that is scarce in the area, or occurring in a limited geographical area. However, all the above explanations do not apply to E. subapicalis because it shows specificity of diet, uses a common host plant in the cerrado areas, and has a large geographical distribution.

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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.

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