| Popis: |
Strobilurins, a commonly used class of fungicides, are known to impact an embryonic development of aquatic organisms and show toxicity to different soil organisms. Standard tests for soil invertebrates are usually limited to the assessment of endpoints like survival and number of juveniles, while hatching and embryotoxicity tests have emerged recently. Besides earthworms, enchytraeids are the most commonly used bioindicators of soil contamination. Their size and short life cycle makes them suitable for this type of research. The main aim of the study was to assess the impact of strobilurins on reproduction and hatching delay of enchytraeid Enchytreus crypticus. Standardised OECD reproduction tests with azoxystrobin (AS), pyraclostrobin (PS) and trifloxystrobin (TS) were conducted. A decreased number of juveniles and an increased number of unhatched cocoons in strobilurin treatments were recorded. TS was the most toxic in terms of reproduction (EC50 0.04 mg a.i./kg soil), followed by PS (EC50 1.85 mg a.i./kg soil) and AZ (EC50 93.10 mg a.i./kg soil). The use of synchronised cocoons enabled monitoring of hatching dynamics. After a standard 11-day exposure more than 90 % of cocoons were hatched in the control while in treated soil those values were lower. However, as hatching was monitored after that period (up to the 19th day) the percentage of hatched cocoons significantly increased with the time of exposure. Consequently, EC50 values changed. These results show that supplementary endpoints such as hatching success included in standard tests could increase tests sensitivity and accuracy |
