Using Photobacterium Phosphoreum To Research Joint Toxicity Of Two Kinds Of Pesticides

Methomyl and Myclobutanil are two common and very important chemical pesticide* which are widely used in agricultural production. Agricultural production activities have caused a lot of pesticide residue, which is severe pollution of the environment. We need know their biological toxicity in the environment to provide the basis for the formulation of pollution prevention and control.This thesis specifically described a method for testing biological toxicity, in which Photobacterium Phosphoreum was taken as indicator organism.Methomyl and Myclobutanil are very important and harmful to the human body and the environment. These two substances' independent toxicity and joint toxicity were discussed in this thesis.The research showed that the relationship between the concentration of Methomyl or Myclobutanil and the toxic response can be described with Generalized Logit I and ExpGro2 function model. Applying these models, the values of these two substances' EC50 were calculated:the Methomyl's is 5.13×10-3 mol·L-1, and the Myclobutanil's is 3.23×10-4mol·L-1. The concentration of Methomyl or Myclobutanil that do typical inhibition to Photobacterium Phosphoreum can be calculated by the same way.After the measurement of joint toxicity, we found that the ExpGro2 function model was still suit for describing the relationship between the concentration of mixture and the toxic response. Short-acting toxicity test shows that 25 minutes of experimental data can be more accurate description of the single damage of Methomyl,35 minutes toxicity test data can more accurately describe the single damage of Myclobutanil.Using four evaluation method of two kinds of pesticides joint toxicity assessment, four joint toxicity assessment methods show the joint role type of two kinds of pesticides is synergy.The result of joint toxicity that comes from experiments is similar with the results that are forecasted through concentration response model. The concentration action model can bring more accurate results because the independent action model willover-estimate the toxicity of mixture.