Nano-La2O3 Induces Honeybee (Apis mellifera) Death and Enriches for Pathogens in Honeybee Gut Bacterial Communities

Reciprocal interactions between anthropogenic stressors and insect microbiota

Insects play many important roles in nature due to their diversity, ecological role, and impact on agriculture or human health. They are directly influenced by environmental changes and in particular anthropic activities that constitute an important driver of change in the environmental characteristics. Insects face numerous anthropogenic stressors and have evolved various detoxication mechanisms to survive and/or resist to these compounds. Recent studies highligted the pressure exerted by xenobiotics on insect life-cycle and the important role of insect-associated bacterial microbiota in the insect responses to environmental changes. Stressor exposure can have various impacts on the composition and structure of insect microbiota that in turn may influence insect biology. Moreover, bacterial communities associated with insects can be directly or indirectly involved in detoxification processes with the selection of certain microorganisms capable of degrading xenobiotics. Further studies are needed to assess the role of insect-associated microbiota as key contributor to the xenobiotic metabolism and thus as a driver for insect adaptation to polluted habitats.

Rare-earth metal oxide nanoparticles decouple the linkage between soil bacterial community structure and function by selectively influencing potential keystone taxa

Excessive production and application of rare-earth metal oxide nanoparticles warrants assessment of their environmental risks. Little is known about the impact of these nanoparticles on soil bacterial communities. We quantified the effects of nano-Gd₂O₃ and nano-La₂O₃, at the different concentrations and exposure regimes, on soil bacterial community structure and function as well as the structure-function relationship. Further, we constructed and analyzed a co-occurrence network to identify and characterize potential keystone taxa that were related to the enzyme activities and responded to the increasing concentrations of nanoparticles. Both nano-Gd₂O₃ and nano-La₂O₃ significantly altered the bacterial community structure and function in a concentration-dependent manner; however, these negative effects were observed on day 1 or day 7 but not on day 60, indicating that these effects were transient and the bacterial communities can mitigate the effect of these nanoparticles over time. Interestingly, the nanoparticle exposure decoupled the relationship between the structure and function of the soil bacterial communities. The decoupling was due to changes in the composition and relative abundances of potential keystone taxa related to bacterial community functions. Altogether, we provide insights into the interactions between the rare-earth metal oxide nanoparticles and soil bacterial communities. Our results facilitate the environmental risk assessment and safe usage of rare-earth metal oxide nanoparticles.