Toxin-free honey despite the alien Senecio inaequidens DC. invasion – a pilot study

Senecio inaequidens , a fast-spreading perennial herb native to Southern Africa, is increasingly common in disturbed habitats across Europe, including urban areas. This species contains pyrrolizidine alkaloids (PAs), natural toxins harmful to humans and animals. In this pilot study, we investigated the potential for PA contamination in honey from hives located near large S. inaequidens populations in Prague, Czechia. Pollen analysis of honey, hive-stored pollen and honeycomb samples indicated a low and infrequent presence of Asteraceae-type pollen, which could be, but not definitively, attributed to S. inaequidens . Chemical analysis using liquid chromatography–mass spectrometry (LC-MS) detected trace amounts of the PA echimidin in three honey samples, likely originating from Echium vulgare . No other PAs were detected above quantifiable levels. Our findings suggest that, under current conditions, S. inaequidens contributes minimally to PA contamination in honey and does not present a significant health risk. However, potential shifts in flowering phenology warrant continued monitoring to assess future risks.