An object of the present invention is to provide a pesticide composition which has a further excellent control effect against agricultural pests. The present invention relates to a synergistic insecticide composition comprising (A) a nitrophenol compound and (B) an insecticidally active compound. The present invention relates to an insecticidal method characterized in that the above-mentioned synergistic insecticide composition is used to treat the habitat of agricultural pests (except humans). The present invention relates to a plant protection method characterized by treating a plant parasitic to agricultural pests or the vicinity thereof with the aforementioned synergistic insecticide composition. The present invention relates to a method of using a nitrophenol compound for enhancing insecticidal activity. The present invention relates to an insecticidal activity enhancer comprising a nitrophenol compound.本發明之課題在於提供一種對於農業害蟲具有更進一步優異之防除效果之殺蟲劑組成物。本發明係關於一種協同性殺蟲劑組成物，其含有(A)硝基苯酚化合物及(B)殺蟲活性化合物。本發明係關於一種殺蟲方法，其特徵在於以前述協同性殺蟲劑組成物對農業害蟲之生存場所(人類除外)進行處理。本發明係關於一種植物保護方法，其特徵在於以前述協同性殺蟲劑組成物對農業害蟲所寄生之植物或其附近進行處理。本發明係關於一種硝基苯酚化合物之使用方法，其用以增強殺蟲活性。本發明係關於一種殺蟲活性增強劑，其含有硝基苯酚化合物。
