# Fitness related effects of titanium dioxide nanoparticles and glyphosate exposure on Cardiocondyla obscurior

## TL;DR

This study examines how titanium dioxide nanoparticles and glyphosate affect the fitness of Cardiocondyla obscurior ants, revealing harmful and synergistic effects.

## Contribution

The study reveals novel synergistic effects of titanium dioxide nanoparticles and glyphosate on ant fitness and gut symbionts.

## Key findings

- Exposure altered brood distribution and queen size in a time-dependent manner.
- TiO2NPs and glyphosate together caused changes in gut endosymbiont densities and ROS accumulation.
- TiO2NPs were found to accumulate in ant tissues when combined with glyphosate.

## Abstract

Insects are essential for ecosystem functioning and their rapid decline is alarming. While it is evident that various pollutants such as pesticides play a crucial role in the disappearance of insects, knowledge on the effects of specific inorganic compounds such as nanoparticles (NPs) are less investigated and little is known about their direct and indirect impacts. Titanium dioxide nanoparticles (TiO2NPs) are abundantly found in the environment but their effects on insects is little known, as well as their role as vectors for other chemical stressors. In this study, we investigated lethal and sublethal effects of TiO2NPs on Cardiocondyla obscurior ants alone or combined with the herbicide glyphosate. We measured survival, brood production, gut endosymbiont densities, reactive oxygen species (ROS) accumulation, morphological features and elemental TiO2 distribution in ants chronically exposed to environmentally realistic concentrations of TiO2NPs and/or glyphosate. We found that proportional brood distribution was altered by the presence of the stressors and it was time dependent. Moreover, we observed a synergistic effect between TiO2NPs and glyphosate with bigger newly produced queens, altered gut endosymbionts densities and accumulation of TiO2NPs. These results shed light on the ecotoxicological effects of TiO2NPs ingestion and highlight the importance of understanding the synergistic effects of pollutants.

The online version contains supplementary material available at 10.1007/s11356-025-37388-y.