抄録
We practiced acute toxicity tests of fenobucarb（BPMC, a carbamate insecticide）on neonates（less than 24 h old）of nine cladoceran species. A positive relationship between 24-h LC50 values（range 3.7 to 130.1 μg/L）and neonate body length was recognized, although two species（Moina macrocopa, M. micrura）showed extremely large LC50 values. Effects of BPMC on reproduction（number of offspring）of six of the nine species were also investigated. Several small species were more susceptible to BPMC than larger species in the reproduction tests. EC50s ranged form 2.8（Daphnia ambigua）to 16.3（D. pulex） μg/L with an exceptionally high value 104 μg/L for M. macrocopa. The mean value of 24-h LC50/EC10 was 11.2±12.8 （n=6），the large variation mainly depending on the shape of the dose- response curve for the number of offspring. Inhibition of acetylcholinesterase （AChE）by BPMC in four cladoceran species（one being the most susceptible, one being M. macrocopa）was positively related to species’ BPMC-susceptibility（as 24-h LC50s）．Differences in BPMC susceptibility of cladoceran species may be mainly depending on AChE（its activity and tolerance to BPMC），although contribution through their body size was also suggested.
