Abstract: Vibrio qinghaiensis sp. Q67 was used as an indicator strain to study the toxic effects of five common pesticides, pirimicarb (PIR), carbaryl (CAR), glyphosate (GLY), dimethoate (DIM), and acephate (ACE). The toxicities were evaluated by toxic unit and concentration addition model. The results showed that the toxicity of the pesticides decreased in the following order: PIR > GLY > CAR > DIM > ACE. Four of the 10 binary mixtures of these five pesticides showed antagonistic toxic effects, while the remaining six showed additive or synergistic toxic effects. Among the seven five-component mixtures designed by uniform design ray, four showed synergistic and then antagonistic effects, while the remaining three showed a consistent antagonistic effect. The toxicity of the five-component mixtures was strongly positively correlated with the concentration of CAR (r = 0.947). Based on this result, a linear model was established to predict the toxicity of pesticide mixtures. This method has the advantages of low cost, rapidity, simplicity and convenience, which can be used as a potential preliminary screening method for rapid detection of pesticide residues in agricultural products and foods.

Key words: V. qinghaiensis sp. Q67; joint toxicity; pesticides; acute toxicity; rapid test