The term “synergism” is used for cases where two compounds together show a more concerted activity than that predicted from the sum of their individual activities. Often one component is not toxic or far less active than the counterpart component at the dosage employed, but when combined with the latter markedly increases the activity and is called a “synergist.” As related to insecticides, a synergist is used at high doses (for example, 5-10 times more than the insecticide) in many cases and the cost justifies its use in limited cases like natural pyrethrum. The effectiveness of an insecticide synergist is commonly expressed by the ratio of the LD50 of an insecticide alone to the LD50 of the insecticide with the synergist (for reviews see Yamamoto 1973; Hodgson and Tate 1976; Wilkinson 1976a,b; Casida and Quistad 1995b).
KeywordsCatechol Carbene Carbamate GSSG Phosphonates
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