The Arrow Macambira (Encholirium spectabile: Bromeliaceae) as an Important Habitat for the Arthropod Fauna in Rocky Outcrops of the Brazilian Semi-Arid Region.

Bromeliads play a vital role in preserving biodiversity in the Neotropical region. To understand their impact on arthropod diversity in Brazil's semi-arid region, we studied the rupicolous bromeliad Encholirium spectabile. From 2011 to 2018, we observed the arthropod fauna in E. spectabile clumps, documenting the associated taxa, their abundance, and interactions. We also investigated how seasonality affects arthropod richness and composition during the dry and rainy seasons. Over the observation period, 15 orders and 57 arthropod families were recorded in association with E. spectabile. Insecta dominated, followed by predatory chelicerates. Eight usage categories were identified, with Shelter being the most prevalent, followed by Predators, Nesters, and Nectarivores. Significant differences in taxonomic richness were noted between rainy and dry seasons, with the rainy season exhibiting higher diversity. Seasonal variation was also observed in species composition. Clumps of E. spectabile emerged as crucial habitats for surrounding arthropod fauna. This research underscores the importance of non-phylotelm bromeliads, particularly in high abiotic stress environments like semi-arid regions. The taxonomic diversity observed aligns with findings from diverse environments, shedding light on the relevance of E. spectabile for associated arthropod fauna. These results prompt further exploration of non-phylotelm bromeliads in semi-arid settings, providing a fresh perspective on their significance in shaping arthropod communities.

Semi-arid's Unsung Heroes: Hymenoptera and the Vital Ecosystem Services Enabled by Encholirium spectabile, a Rupicolous Bromeliad in the Brazilian Semi-arid Region.

The concept of Ecosystem Services (ES) recognizes the importance of natural ecosystems in supporting human well-being. Hymenoptera, a diverse group of insects including ants, bees, and wasps, play crucial roles in providing ESs. Despite their significance, the provision of ESs by Hymenoptera is often undervalued, leading to ecosystem degradation and loss of important services. This study focuses on the association between Hymenoptera and a rupicolous bromeliad species (Encholirium spectabile) and explores the ESs promoted directly and indirectly by these insects. The study area is located in the Caatinga region of Brazil, characterized by irregular rainfall and a dry season. The results show that Hymenoptera, particularly bees, ants, and wasps, provide a range of ESs including pollination, honey production, pest control, cultural symbolism, and educational value. These services are vital for plant reproduction, food production, and ecosystem functioning in both seasons; there are no differences in species richness between seasons, but rather in species composition. Understanding the importance of Hymenoptera for ESs is crucial for informing conservation and management practices to ensure the sustainability of natural ecosystems. The study highlights the need for conservation actions to protect the intricate ecological relationships between Hymenoptera and bromeliads, which indirectly support ESs by providing habitat and resources, especially during droughts when resources are scarce in the region. By recognizing the importance of bromeliads in supporting Hymenopteran communities, conservation efforts can focus on preserving these critical ecological interactions and maintaining ES provision.

Interactive effects of predation risk and conspecific density on the nutrient stoichiometry of prey.

The mere presence of predators (i.e., predation risk) can alter consumer physiology by restricting food intake and inducing stress, which can ultimately affect prey-mediated ecosystem processes such as nutrient cycling. However, many environmental factors, including conspecific density, can mediate the perception of risk by prey. Prey conspecific density has been defined as a fundamental feature that modulates perceived risk. In this study, we tested the effects of predation risk on prey nutrient stoichiometry (body and excretion). Using a constant predation risk, we also tested the effects of varying conspecific densities on prey responses to predation risk. To answer these questions, we conducted a mesocosm experiment using caged predators (Belostoma sp.), and small bullfrog tadpoles (Lithobates catesbeianus) as prey. We found that L. catesbeianus tadpoles adjust their body nutrient stoichiometry in response to predation risk, which is affected by conspecific density. We also found that the prey exhibited strong morphological responses to predation risk (i.e., an increase in tail muscle mass), which were positively correlated to body nitrogen content. Thus, we pose the notion that in risky situations, adaptive phenotypic responses rather than behavioral ones might partially explain why prey might have a higher nitrogen content under predation risk. In addition, the interactive roles of conspecific density and predation risk, which might result in reduced perceived risk and physiological restrictions in prey, also affected how prey stoichiometry responded to the fear of predation.