Comprehension of the causal mechanisms that shape the structure of ecological communities through trophic interactions is one of the most important themes in ecology. A basic tool used to study how communities are established and organized is the investigation of the direct trophic relationships influencing species interactions and biodiversity in natural systems. In a community, species may be linked directly or indirectly through resources and consumption. The major part of the fixed energy in terrestrial systems is processed autotrophically by plants, and almost all terrestrial fauna depends on this production. In systems involving three trophic levels, such as plants, herbivores, and predators, a trophic cascade describes the positive topdown effects of the third trophic level on the biomass, richness, or composition of the producer species. Predators frequently cause significant impact on density, spatial distribution, and diversity of herbivore assemblages, thereby altering the patterns and levels of herbivory in plant communities. These consequences are also observed for pollinator guilds influenced by predators. On the other hand, plant quality and herbivore action (bottom-up effects) on plant architecture, distribution, and population dynamics can also produce great impact on the associated fauna. Thus, in light of the importance of plant-animal interactions and due to the enormous advances that this research field has been experiencing over the last two decades, in both tropical and temperate areas, we invite you to submit a paper to this special issue. However, recent papers have revealed the direct and indirect importance of other arthropods in plant-animal interactions, such as spiders and isopods. Also, behavioral aspects of relationships between the second and third levels in the associated trophic chain are thought to be the basis of a better comprehension of the mechanisms maintaining the complexity and diversity in these associations. Potential topics include, but are not limited to:

• Arthropod-plant interactions considering aspects of life history
• Behavior that involves experimental manipulation

Before submission authors should carefully read over the journal's Author Guidelines, which are located at http://www.hindawi.com/journals/psyche/guidelines/. Prospective authors should submit an electronic copy of their complete manuscript through the journal Manuscript Tracking System at http://mts.hindawi.com/ according to the following timetable: