Invertebrates and the complexity of tropical ecosystems

Dung beetles from two sustainable-use protected forests in the Brazilian Amazon

Background

The Amazon Forest is one of the world's most biodiverse ecosystems and yet its protected areas are understudied concerning insects and other invertebrates. These organisms are essential for tropical forests due to their ecological processes, with some species being very sensitive to habitat disturbances. Dung beetles (Coleoptera, Scarabaeidae, Scarabaeinae) have been used as bioindicators for more than 30 years and were surveyed to assess the insect biodiversity of two sustainable-use forest reserves in the Brazilian Amazon.

New information

We report inventories of dung beetles from two Amazonian forest reserves in Pará State, Brazil: the Tapajós National Forest and the Carajás National Forest. Surveys were carried out with baited-pitfall traps installed in 2010, 2016, 2017 and 2019. We collected a total of 3,772 individuals from 19 genera and 96 species. We highlight the importance of Amazonian protected areas as refugia for insect biodiversity, particularly dung beetles, which contribute to many key ecosystem processes.

Biodiversity of butterflies (Lepidoptera: Rhopalocera) in the protected landscape of Nandhour, Uttarakhand, India

An appraisal of butterfly species composition in terms of comparative diversity richness in various habitat types was conducted in and around the Nandhour Wildlife Sanctuary of Terai Arc landscape in Uttarakhand. During the two years of survey period (March 2018–February 2020), a total of 89 species of butterflies belonging to families Nymphalidae 43 species, Pieridae 15 species, Lycaenidae 13 species, Hesperiidae eight species, Papilionidae seven species, and Riodinidae three species were recorded, of which 46 species represented new records for the Nandhour Landscape. Butterfly diversity and richness were highest in dense moist & open dry riverine forests and lowest in human settlements & agricultural land. No significant differences in the number of species were found in moist mixed deciduous forest, subtropical Chir Pine forest, moist Bhabar Sal forest, moist Shiwalik Sal forest, and plantation forest. Eight species are endemic to the Indian Himalayan Region. 

Temperature and productivity distinctly affect the species richness of ectothermic and endothermic multitrophic guilds along a tropical elevational gradient

The diversity of endotherms and ectotherms may be differently affected by ambient temperature and net primary productivity (NPP). Additionally, little is known about how these drivers affect the diversity of guilds of different trophic levels. We assessed the relative role of temperature and NPP in multitrophic guilds of ectothermic (arthropods: ants, ground beetles, spiders, and harvestmen) and endothermic (large mammals) animals along a tropical elevational gradient. We sampled arthropods at eight elevation belts and large mammals at 14 elevation belts in Atlantic rainforest (ranging from 600 to 2450 m.a.s.l.) of Itatiaia National Park, Southeast Brazil. Overall arthropod species richness was more associated with temperature than overall large-mammal species richness, while the latter was more associated with NPP. When separated into trophic guilds, we found that the species richness associated with NPP increased across arthropod trophic levels from herbivores to predators. Conversely, although NPP influenced large-mammal herbivore species richness, its effects did not seem to accumulate across large-mammal trophic levels since the species richness of large-mammal omnivores was more associated with temperature and none of the variables we studied influenced large-mammal predators. We suggest that thermal physiological differences between ectotherms and endotherms are responsible for the way in which arthropods and large mammals interact with or are constrained by the environment. Furthermore, the inconsistency regarding the role of temperature and NPP on species richness across multitrophic guilds of ectotherms and endotherms could indicate that thermal physiological differences might also interfere with energy use and flux in the food web.

The importance of insects on land and in water: a tropical view

Tropical insects are astonishingly diverse and abundant yet receive only marginal scientific attention. In natural tropical settings, insects are involved in regulating and supporting ecosystem services including seed dispersal, pollination, organic matter decomposition, nutrient cycling, herbivory, food webs and water quality, which in turn help fulfill UN Sustainable Development Goals (SDGs). Current and future global changes that affect insect diversity and distribution could disrupt key ecosystem services and impose important threats on ecosystems and human well-being. A significant increase in our knowledge of tropical insect roles in ecosystem processes is thus vital to ensure sustainable development on a rapidly changing planet.