12/08/2026
Research demonstrating off-target negative effects of macrocyclic lactones impact plants as well as insects.
"Direct harmful effects of MLs on non-target organisms have been demonstrated, for example in dung beetles, where they primarily impair the survival of larvae...and in coprophagous flies, where they reduce the survival of both adults and larvae as well as pupation rates. In the case of the most thoroughly studied ML ivermectin, negative impacts on the reproduction of dung beetles have been reported, including reduced egg-laying, reduced larval size, and behavioral disorders such as impaired locomotion and sensory functions in reproductive adults. Only recently, direct detrimental effects of MLs on plants were discovered. These include impaired seed germination and seedling emergence as well as a reduction in aboveground biomass, photosynthetically active leaf area, and fruit number and weight. Several studies have shown that MLs, including MOX, are absorbed by roots or leaves and distributed throughout the plant. This suggests that insects that consume plant resources such as nectar, pollen, or phloem sap may also be exposed to MLs that are originally present in the soil and are transferred via the plant as parent compounds, their metabolites, and/or in the form of changes in plant metabolic pathways and products. Obregon et al. (2024) were able to demonstrate the transfer of the ivermectin metabolite abamectin along the food chain — via plant pollen to bees.
