PROBLEM TO BE SOLVED: To provide a method of preventively or curatively combating crop pests and diseases and a method of improving crop yield.SOLUTION: A composition contains (a) strigolactone derivative at least represented by general formula (I) or (II) and (b) insecticidal compound, in the mass ratio (a)/(b) from 1/1 to 1/1013.COPYRIGHT: (C)2014,JPO&INPIT【課題】作物の有害生物及び病害と予防的又は治療的に闘う方法並びに作物の収量を増大させる方法の提供。【解決手段】少なくとも下記一般式(I)又は(II)で表されるストリゴラクトン誘導体(a)及び殺虫剤化合物(b)を1/1~1/1013の(a)/(b)の重量比で含んでいる組成物。【選択図】なし