Estruturas sutis com funções não tão sutis: efeitos indiretos dos construtores de abrigos na organização das comunidades de artrópodes de plantas terrestres em diferentes escalas espaciais, temporais e nas interações tróficas

Abstract

This thesis is the result of a study that investigated the importance of different structures created by arthropods on plants for the organization of terrestrial arthropod communities, as well as the effects of ecosystem engineering at different spatial and temporal scales and their indirect consequences on trophic interactions. It is divided into three chapters. Initially, in Chapter 1, we provided an extensive database that included more than 1000 unique records of ecosystem engineering by arthropods, in the form of structures built on plants, such as galls, leaf rolls and leaf ties. All records were published in the literature, and cover both natural structures (91% of records) and structures artificially created by researchers (9% of records). The data was collected between 1932 and 2021, in more than 50 countries and various ecosystems, from polar zones to tropical zone. In addition to data on host plants and engineers, we aggregate data on the types of buildings and the identity of the secondary colonizers using these structures. This dataset highlighted the importance of these subtle structures for the organization of terrestrial arthropod communities, enabling hypothesis testing in ecological studies that address ecosystem engineering and shelter-mediated facilitation. In the second chapter, we evaluated whether the leaf structures created by the galler Ditylenchus gallaeformans Oliveira, Santin, Seni, Dietrich, Salazar, Subbotin, Mundo-Ocampo, Goldenberg & Barreto, 2013 (Anguinidae) in the species Miconia ligustroides (DC.) Naudin (Melastomataceae), contribute to changes in the diversity and composition of the arthropod community at different spatial scales (plant and leaf level). We also evaluated the effects of shelter occupancy on the choice of secondary colonizers, and the influence of these structures on herbivory levels on host plants. Arthropod abundance, richness and biomass were higher in leaf shelters compared to intact leaves. These effects were observed at similar magnitudes at the plant and leaf scales. Arthropod composition differed between plants with shelters and plants without shelters, and between unoccupied shelters and intact leaves. Shelters increased arthropod abundance, richness and biomass by almost 100% compared to intact leaves. However, occupied shelters had a decrease in arthropod abundance, richness and biomass by almost 60% compared to unoccupied shelters. Finally, plants without shelters exhibited higher levels of leaf herbivory than plants with shelters. Our findings demonstrated the strong and positive indirect effects of gall induction that facilitated shelter creation and the indirect effects of shelters on diversity, species composition and leaf herbivory, and should be replicated in other systems involving plants and their respective gallers. Finally, in the third chapter, we evaluate the consequences of the facilitation generated by D. gallaeformans leaf shelters on arthropod communities in M. ligustroides at the leaf and plant level in an environment subject to strong climatic seasonality during two consecutive years. The shelters increased arthropod diversity and modified the species composition on M. ligustroides at the leaf and plant level, and in the dry and rainy seasons. Comparing shelters in different seasons, the shelters of dry season exhibited higher abundance, richness and biomass of arthropods compared to rainy season shelters in both years evaluated. Finally, the overall effects of shelters on the diversity of the arthropod community associated with M. ligustroides were positive and moderately strong in the dry season, increasing arthropod abundance, richness, and biomass by an average of 65% in both years. Our study contributed to a better understanding of the patterns of variation and magnitude of ecosystem engineering at different spatial and temporal scales, and provided new insights into the importance of shelters for aridity-sensitive species.