Željka Lončarić

Tebuconazole (TEB), a widely used triazole fungicide, is effective against soil-borne and foliar fungal pathogens. Toxicants can exhibit varying effects depending on the life stage of organisms, although standard toxicity tests typically focus on adult individuals. This study aimed to assess TEB’s potential adverse effects on the earthworm Dendrobaena veneta throughout its life cycle. Effects were evaluated by exposing cocoons to varying TEB concentrations, monitoring hatching, newly hatched juvenile mass, and growth to adulthood. A reproduction test assessed impacts on adults, offering insights into how these results compared with cocoon exposure findings. Results revealed that TEB delayed hatching at concentrations of 25, 50, and 100 mg/kg by 6, 8, and 15.5 days, respectively. Newly hatched juveniles exhibited a 15.96% (50 mg/kg) and 27.37% (100 mg/kg) reduction in body mass compared to controls, with no subsequent compensation during growth. Results from the reproduction tests showed no adverse effects on adult survival, but the effects are observed on juveniles, indicating a higher sensitivity of this developmental stage. While several adverse effects were observed, it is important to note that these occurred at concentrations exceeding recommended application rates. TEB appears safe for earthworms when used correctly, but the presence of multiple contaminants and stressors warrants consideration.