Occurrence of chlorpyrifos and organochlorine pesticides in a native bumblebee (Bombus pauloensis) living under different land uses in the southeastern Pampas, Argentina

Enhanced bioaccumulation and toxicity of Fenpropathrin by polystyrene nano(micro)plastics in the model insect, silkworm (Bombyx mori)

BACKGROUND

Nano(micro)plastics (NMPs) and agrochemicals are ubiquitous pollutants. The small size and physicochemical properties of NMPs make them potential carriers for pollutants, affecting their bioavailability and impact on living organisms. However, little is known about their interactions in terrestrial ecosystems. This study investigates the adsorption of Fenpropathrin (FPP) onto two different sizes of polystyrene NMPs and examines their impacts on an insect model, silkworm Bombyx mori. We analyzed the systemic effects of acute exposure to NMPs and FPP, individually and combined, at organismal, tissue, cellular, and gut microbiome levels.

RESULTS

Our results showed that NMPs can adsorb FPP, with smaller particles having higher adsorption capacity, leading to size-dependent increases in the bioaccumulation and toxicity of FPP. These effects led to higher mortality, reduced body weight, delayed development, and decreased cocoon production in silkworms. Additionally, the pollutants caused physical and oxidative damage to the midgut and altered gene expression related to juvenile hormone (JH) and silk protein synthesis. The gut microbiome analysis revealed significant changes and reduced abundance of potentially beneficial bacteria. Thus, the aggravated toxicity induced by NMPs was size-dependent, with smaller particles (NPs) having a greater impact.

CONCLUSIONS

This study demonstrates the role of NMPs as carriers for contaminants, increasing their bioavailability and toxicity in terrestrial ecosystems. These findings have significant implications for ecosystem health and biodiversity.

The effect of lambda-cyhalothrin nanocapsules on the gut microbial communities and immune response of the bee elucidates the potential environmental impact of emerging nanopesticides

Emerging nanopesticides are gradually gaining widespread application in agriculture due to their excellent properties, but their potential risks to pollinating insects are not fully understood. In this study, lambda-cyhalothrin nanocapsules (LC-NCs) were constructed by electrostatic self-assembly method with iron mineralization optimization, and their effects on bee gut microbial communities and host immune-related factors were investigated. Microbiome sequencing revealed that LC-NCs increase the diversity of gut microbial communities and reduce the complexity of network features, disrupting the overall structure of the microbial communities. In addition, LC-NCs also had systemic effects on the immune response of bees, including increased activity of SOD and CAT enzymes and expression of their genes, as well as downregulation of Defensin1. Furthermore, we noticed that the immune system of the host was activated simultaneously with a rise in the abundance of beneficial bacteria in the gut. Our research emphasizes the importance of both the host and gut microbiota of holobiont in revealing the potential risks of LC-NCs to environmental indicators of honey bees, and provides references for exploring the interactions between host-microbiota systems under exogenous stress. At the same time, we hope that more research can focus on the potential impacts of nanopesticides on the ecological environment.

Changes in thermal sensitivity of Rhinella arenarum tadpoles (Anura: Bufonidae) exposed to sublethal concentrations of different pesticide fractions (Lorsban® 75WG)

The intensive use of agrochemicals and the rapid increase of global temperatures have modified the thermal conditions of aquatic environments, thus increasing amphibians' vulnerability to global warming and positioning them at great risk. Commercial formulations of chlorpyrifos (COM) are the pesticides most widely used in agricultural activities, with a high toxic potential on amphibians. However, little is known about the separate effects of the active ingredient (CPF) and adjuvants (AD). We studied the thermal sensitivity at different concentrations and pesticide fractions in Rhinella arenarum tadpoles, on thermal tolerance limits (CTmax = Critical thermal maximum and CTmin = Critical thermal minimum), swimming speed (Ss), Optimum temperature (Top), and Thermal breadth 50 (B50). Our results demonstrate that the pesticide active ingredient, the adjuvants, and the commercial formulation of chlorpyrifos differentially impair the thermal sensitivity of R. arenarum tadpoles. The pesticide fractions affected the heat and the cold tolerance (CTmax and CTmin), depending on the concentrations they were exposed to. The locomotor performance (Ss, Top, and B50) of tadpoles also varied among fractions, treatments, and environmental temperatures. In the context of climate change, the outcomes presented are particularly relevant, as mean temperatures are increasing at unprecedented rates, which suggests that tadpoles inhabiting warming and polluted ponds are currently experiencing deleterious conditions. Considering that larval stages of amphibians are the most susceptible to changing environmental conditions and the alarming predictions about environmental temperatures in the future, it is likely that the synergism between high temperatures and pesticide exposure raise the threat of population deletions in the coming years.