Population structure of the phytoseiid mite, Neoseiulus womersleyi, in an experimental organic tea field

Abstract: In order to control spider mites in tea plantations following reductions in chemical pesticide applications, it is necessary to use natural enemies such as the phytoseiid mite Neoseiulus womersleyi. Banker plants, which encourage proliferation of phytoseiid mites, can enhance the biological control characteristics of N. womersleyi; however, the optimum number and distribution of banker plants are uncertain. In this study, in order to provide insights into use of banker plants, we analyzed the population structure of N. womersleyi in an experimental organic tea field using microsatellite DNA markers. The results suggested mites migrated on several occasions into the field during the early summer. Nevertheless, the mites did not reach the centre of the field. Microsatellite analysis also suggests that movement in the field was strictly limited, indicating that the artificial spread of phytoseiid mites from banker plants to tea plants would be required to control spider mites effectively.