Gene expression in Ephemera danica in response to chlorantraniliprole exposure
Pesticides are important agricultural stressors for freshwaters, but the physiological mechanisms induced by pesticide exposure are largely unknown for most aquatic non-target organisms. The insecticide chlorantraniliprole, an agonist of the ryanodine receptor, has been reported to be highly selective for target pest species, which comprises representatives of the order Lepidoptera (butterflies). Using RNA sequencing data, we quantified the insecticide effect on the gene expression profiles of the mayfly Ephemera danica and other freshwater invertebrates. Organisms were exposed for 48 hours to three different concentrations of chlorantraniliprole. RNA extracts were pooled from 3 larvae to one library, irrespective of their sexe and developmental stage. Per concentration, 9 libraries (replicates) were sequenced on an Illumina Novaseq 6000, resulting in 36 RNA-seq libraries (9 x control, 9 x low concentration treatment, 9 x medium concentration treatment, 9 x high concentration treatment). We detected a strong cellular stress responses in E. danica and another insect species, implying that conserved cellular mechanisms are affected. However, the induced response pathways were not expected based on the insecticides' described mode of action. We found evidence for alterations of the developmental program, but the induced regulatory pathways were species-specific. If transcriptional changes in the developmental program induce alterations of emergence phenology, pronounced effects on food web dynamics in a cross-ecosystem context are expected.