Action of malathion plus lindane pesticide on crustacean populations.

The effects of malathion + lindane biocide on Moina and Acanthocyclops populations were tested under experimental conditions. The LD50,24 for Moina is 0.00034 ml.liter-1. Percentages of Acanthocyclops surviving different biocide doses within the range 0.0002-0.0006 ml.liter were not significantly different from each other. The biocide dose used by the farmers in rice fields in the Ebro River Delta (0.00057 ml.liter-1) against crustaceans is high enough to control cladoceran and copepod populations. Here it is suggested that a lower dose would also be successful. Recovery of the zooplankton populations in rice fields after biocide use is initially accomplished by Rotifera spp. and then by crustaceans. This takes place mainly through the irrigation channel.