Individual vs. Combined Short-Term Effects of Soil Pollutants on Colony Founding in a Common Ant Species

Abstract

Insects are integral to terrestrial life and provide essential ecosystem functions such as pollination and nutrient cycling. Due to massive declines in insect biomass, abundance, or species richness in recent years, the focus has turned to find their causes. Anthropogenic pollution is among the main drivers of insect declines. Research addressing the effects of pollutants concentrates on aquatic insects and pollinators, despite the apparent risk of contaminated soils. Pollutants accumulating in the soil might pose a significant threat because concentrations tend to be high and different pollutants are present simultaneously. Here, we exposed queens of the black garden ant Lasius niger at the colony founding stage to different concentrations and combinations of pollutants (brake dust, soot, microplastic particles and fibers, manure) to determine dose-dependent effects and interactions between stressors. As proxies for colony founding success, we measured queen survival, the development time of the different life stages, the brood weight, and the number of offspring. Over the course of the experiment queen mortality was very low and similar across treatments. Only high manure concentrations affected the colony founding success. Eggs from queens exposed to high manure concentrations took longer to hatch, which resulted in a delayed emergence of workers. Also, fewer pupae and workers were raised by those queens. Brake dust, soot and plastic particles did not visibly affect colony founding success, neither as single nor as multiple stressors. The application of manure, however, affected colony founding in L. niger negatively underlining the issue of excessive manure application to our environment. Even though anthropogenic soil pollutants seem to have little short-term effects on ant colony founding, studies will have to elucidate potential long-term effects as a colony grows.

Comparison of fitness effects in the earthworm Eisenia fetida after exposure to single or multiple anthropogenic pollutants

“…We found neither negative fitness effects on the queens themselves nor on their brood (Seidenath et al 2021). In contrast to ant queens and their brood, which only come into contact with the pollutants with their body surface, earthworms also ingest the pollutants when feeding on the substrate.…”

“…Some of them only use it as shelter and breeding ground and others take up food particles from the soil surface or ingest the soil as substrate feeders. This might be a reason why we observed larger lethal and sublethal effects in E. fetida than we reported earlier for ants (Seidenath et al 2021). In the earlier study we kept ant queens in soils with the same pollutant treatments used in the present experiment.…”

Diesel exhaust particles alter gut microbiome and gene expression in the bumblebee Bombus terrestris

“…Exposure of different invertebrate species to such particles showed mixed effects. Particulate matter contamination in soil did not affect colony founding in the ant Lasius niger (Seidenath et al 2021). However, soil-feeding earthworms (Eisenia fetida ) showed a strongly increased mortality when exposed to soil spiked with brake dust particles (Holzinger et al 2022).…”

Exposure Pathways and Toxicity of Microplastics in Terrestrial Insects

“…Negative impacts on reproduction, life cycles, and survival pose a risk to the population and, thus, the colony growth of terrestrial insects (Figures and ). Although many studies have examined these factors, few have investigated them together to assess the impact of microplastic exposure on the success of colony founding. , Terrestrial insects are adversely affected by plastic pollution because of the transfer of plastics within an insect colony, leading to decline in population. Therefore, it is critical to combine data to predict the impact of plastic pollution on insects.…”