【Background】The herbicide application is one of mainly methods to control the alligator weed Alternanthera philoxeroides. However, biological control by the beetle Agasicles hygrophila was also attempted in China. A safe use of the herbicides requires knowledge of their impact on the biological control agent.【Method】A.hygrophila adults and third instar larvae were fed on A.philoxeroides leaves that were sprayed with fluroxypyr, glyphosate and penoxsulam at various concentrations. Leaf consumption and survival of A.hygrophila adults and larvae, pupation rate, and female fecundity were compared.【Result】Female fecundity was suppressed significantly by glyphosate, whereas fluroxypyr had no significant impacts on female fecundity, the impacts of penoxsulam was inbetween. After feeding on herbicidestreated leaves for five consecutive days, leaf consumption of A.hygrophila adults decreased significantly mostly on fluroxypyr, followed by glyphosate and penoxsulam. Leaf consumption of A.hygrophila larvae were also significantly affected by glyphosate. When the larvae fed on host plant leaves treated by high concentrations of glyphosate for three days, larvae stopped feeding. Penoxsulam had no significant impacts on larval feeding. The tested herbicides had little impacts on female survival rates. 【Conclusion and significance】These results indicated that among the tested herbicides, penoxsulam was relatively safe for A.hygrophila, and its optimal concentration for the integrated management strategy of A.philoxeroides with A.hygrophila was 0.[KG-*8]9 L[KG-*4]·[KG-*8]ha-1.