Rice plants infected with bacterial endophytes, Herbaspirillum sp. and Azospirillum sp. show moderate resistance against one of most serious rice pests, the brown planthoper (BPH). Production and application cost of the endophytes is estimated to be much less than any control measures so far employed in paddy fields. Moreover, it has been shown that harmful side-effects of the endophytes on non-target organisms are negligible. Despite these favorable properties, our simulation experiments have revealed that making use of the endophytes frequently fails to suppress BPH density to an acceptable level on the occurrence of massive BPH immigration, unless additional tactics are incorporated into the management system. We developed a simulation model of BPH population dynamics to evaluate the combined effects of endophyte application and another control measure on BPH regulation. The results indicated that, if BPH mortality is dependent upon the ratio of natural enemy density to BPH density, then conservation biological control is most promising under the cultivation of endophyte-infected rice plants. It was also suggested that the enhancement of biocontrol works to prevent BPH from rapidly developing a biotype resistant to endophyte-infected rice plants.