Effects of diesel exhaust particles on the health and survival of the buff-tailed bumblebee Bombus terrestris after acute and chronic oral exposure

The diesel-powered transportation sector is a major producer of environmental pollution in the form of microand nanoscale diesel exhaust particles (DEP). Pollinators, such as wild bees, may inhale DEP or ingest it orally through plant nectar. However, if these insects are adversely affected by DEP is largely unknown. To investigate potential health threats of DEP to pollinators, we exposed individuals of Bombus terrestris to different concentrations of DEP. We analysed the polycyclic aromatic hydrocarbons (PAH) content of DEP since these are known to elicit adverse effects on invertebrates. We investigated the dose-dependent effects of those well-characterized DEP on survival and fat body content, as a proxy for the insects' health condition, in acute and chronic oral exposure experiments. Acute oral exposure to DEP showed no dose-dependent effects on survival or fat body content of B. terrestris. However, we could show dose-dependent effects after chronic oral exposure with high doses of DEP where significantly increased mortality was observed. Further, there was no dose-dependent effect of DEP on the fat body content after exposure. Our results give insights into how the accumulation of high concentrations of DEP e.g., near heavily trafficked sites, can influence insect pollinators' health and survival.