[Effects of avermectin B1a on soil microorganism and earthworm (Eisenia fetida)]

Avermectins are the pesticides widely applied in agriculture. This paper studied the effects of different concentration avermectin B1a (AVM B1a) on soil bacteria and fungi, soil respiration, and soil earthworm (Eisenia fetida). The results showed that in 4 test soils, bacteria were significantly inhibited when the AVM B1a concentration was higher than 83.3 mg x kg(-1), while fungi were less impaired. Soil respiration was also inhibited by high concentration AVM B1a, which differed with soil types. The half lethal dosage (LD50) of AVM B1a to soil earthworm was estimated as 4.63 microg x cm(-2) in filter paper contact test, and as 24.13 and 17.06 mg x kg(-1), respectively after treated 7 and 14 days in artificial soil.