• control techniques;
  • biocides;
  • invasive crayfish species;
  • natural pyrethrum


BACKGROUND: The crayfish Procambarus clarkii inflicts severe ecological and economic damages in Europe. To develop an efficient method for its control, four experiments were carried out to assess the impact of natural pyrethrum (i.e. Pyblast) on crayfish: (1) the 24 h LC100 and LC50 were quantified on crayfish; (2) the breakdown time of the 24 h LC100 was assessed using Daphnia magna as a bioindicator; the effects of 24 h LC100 on crayfish were investigated by applying the biocide into burrows (3) and in a drainage channel (4).

RESULTS: Pyblast concentrations of 0.05 and 0.02 mg L−1 corresponded to 24 h LC100 and LC50 respectively. The concentration of 0.05 mg L−1 broke down after 72 h, whereas 0.02 mg L−1 did not cause any significant mortality in D. magna after 24 h. However, 0.05 mg L−1 had no effect on crayfish when introduced into the burrows, but led to a mortality of 95% when applied in the water.

CONCLUSION: Experimental evidence is provided for the efficacy of Pyblast to control invasive crayfish. Obviously, before its use on a large scale, further studies are needed to find a concentration that will achieve the target 100% mortality with the shortest recovery time of the environment. Copyright © 2012 Society of Chemical Industry