Relevance Study Of Pesticide Penetrating Agent Toxicity On Daphnia Magna And Synergism On Insecticides

Penetrant is a type of important adjuvant of pesticide formulations which is useful in promoting the effect of pesticide active ingredients in agricultural production and also in favor of delaying the resistance of pesticide on target organisms. In present study, the united toxicities of two insecticides, indoxacarb and acetamiprid, with different penetrants on target insects and the joint toxicities on Daphnia magna were evaluated to explore the relevance of combined toxicities of insectices and penetrants on target organisms and non-target Daphnia magna, meanwhile, to clear the feasibility if the Daphnia magna could be a model organism to screen the effective penetrant for agricultural production.1. The synergisms of indoxacarb and non-ionic penetrants, cationic penetrants, organic silicon penetrants to two insects, Spodoptera exigua and Agrotis ypsilon were determined with the dipping method. Meanwhile, the synergistic effects of acetamiprid and the penetrants to Aphis ciricola were also assessed with the same method. Results showed that synergisms of each penetrant were higher to acetamiprid than to indoxacarb. In the synergistic effect to indoxacarb, synergisms with the single long-chain alkyl benzyl ammonium chloride DDBAC and TDBAC were higher than others with the synergism ratio from 2.5 to 12.0, then was the organic silicon adjuvant with ratio 2.0-5.0, and the fatty alcohol-polyoxyethylene ether and the alkylphenol polyoxyethylene ether with less number of ethylene oxides also be synergistic to indoxacarb against Spodoptera exigua and Agrotis ypsilon which synergism ratio were 1.7-10.0 and 1.6~2.3 respectively.Compared with indoxacarb, the gynergisms of penetrants to acetamiprid were much higher. Almost all of the penetrants except the alkylphenol polyoxyethylene ether surfactants with the ethylene oxides number are or more than 30 were synergistic to acetamiprid. The organic silicon adjuvant showed the highest synergism to cetamiprid with the synergism ratio of 40-215, then were the fatty alcohol-polyoxyethylene ether and the alkylphenol polyoxyethylene ether with the ratio of 20-175 and 10-70 respectively, and the synergistic effect were higher with the decreasing of number of ethylene oxide. Synergisms of the quaternary ammonium cationic surfactants were lower than other penetrants with the ratio of 5-50.2. The 48 h EC50 values of indoxacarb and acetamiprid were 2.37×10-2 mg/L and 27.54 mg/L, be extremely high toxicity level and low toxicity level respectively. The independent toxicities of alkylphenol polyoxyethylene ether surfactants were moderate toxicities or low toxicities level, while almost all of the fatty alcohol-polyoxyethylene ether surfactants were high toxicities, and all of the tested quaternary ammonium cationic surfactants and organic silicon adjuvants were extremely high toxicities. The joint toxicities of pesticides and penetrants were evaluated with AI additive index method and the equivalent curve method. Joint toxicities results indicated that the higher the independent toxicity of penetrant was, the higher the joint toxicities with pesticides to Daphnia magna were. To the non-ionic penetrants, adjuvant with less number of ethylene oxides would be higher joint toxicity to Daphnia magna. All the quaternary ammonium cationic surfactants and organic silicon adjuvant were synergisitic effect or addictive effect to Daphnia magna with two pesticides. The joint toxicities of penetrants with acetamiprid were higher than with indoxacarb.3. Results of effects of penetrants on physical properties of water were determined that the organic silicon adjuvant showed the most remarkable effect on water, and then were the quaternary ammonium cationic surfactants. In the non- ionic penetrants, fatty alcohol–polyoxy ethylene ether surfactants were much higher in the effects on physical properties of water than the alkylphenol polyoxyethylene ether surfactants. In conclusion, a higher liposolubility adjuvants with a longer carbon chain or less number of ethylene oxides showed a lower effect on the decreasing of surface tension and increasing of expanded diameter but a higher maximum retention amount on the leaf.In conclusion, the relevance of combined toxicities of insecticides and penetrants on target organisms and non-target Daphnia magna was positive correlation. That is to say, the penetrant which showed a stronger united to xicity with insecticide on target organisms also has a higher joint toxicity on Daphnia magna, and vice versa. Therefore, it was feasible for Daphnia magna as a model organism to screen the effective penetrant for agricultural production.