Abstract: The aims were to investigate the safety of 42.4% fluxapyroxadpyraclostrobin SC on mulberry and silkworm. The harm to mulberry and residual toxicities to silkworm of different concentration of 42.4% fluxapyroxadpyraclostrobin SC were evaluated. The results showed that all treatments were not phytotoxic to mulberry. At 20 d after spraying， the developmental duration of 2 instar of Bombyx mori showed no difference among the groups feeding on mulberry leaf treated with 141 and 212 mg·L-1 fluxapyroxadpyraclostrobin SC and the water control， but the development period of 3， 4， and 5 instar larvae were delayed. The development periods of silkworms were delayed and body weights of tetramolter were reduced after feeding on mulberry leaf treated with 283 and 565 mg·L-1 fluxapyroxadpyraclostrobin SC. After feeding mulberry leaf treated with 141 and 212 mg·L-1 fluxapyroxadpyraclostrobin SC， the economic characters of silkworm showed no significant difference compared with the water control and 10% difenoconazole WDG group， while feeding 283 and 565 mg·L-1 processing mulberry leaf， its cocoon weight， cocoon shell， cocoon shell rate and pupa weight were significantly lower than those of the water control. Therefore， 42.4% fluxapyroxadpyraclostrobin SC was unfavorable in mulberry field and surrounding farmland during the sericulture， and its safety interval period for silkworm was longer than 20 d.

Key words: fungicide, mulberry, toxicity, silkworm, safety