Niche Modeling May Explain the Historical Population Failure of Phytoseiulus persimilis in Taiwan: Implications of Biocontrol Strategies

SIMPLE SUMMARY: Phytoseiulus persimilis Athias-Henriot, a mite species widely used in pest management for the control of spider mites, has been commercialized and introduced to numerous countries. In the 1990s, P. persimilis was imported to Taiwan, and a million individuals were released into the field. However, none have been observed since then. In this study, we explored the ecological niche of this species to determine reasons underlying its establishment failure. The results indicate that P. persimilis was released in areas poorly suited to their survival. To the best of our knowledge, the present study is the first to predict the potential distribution of phytoseiids as exotic natural enemies. This process should precede the commercialization of exotic natural enemies and their introduction into any country. ABSTRACT: Biological control commonly involves the commercialization and introduction of natural enemies. Phytoseiulus persimilis Athias-Henriot, a mite species widely used in the control of spider mites, was imported to Taiwan in the 1990s and was mass-reared and released into the field. However, none have been observed in comprehensive surveys of phytoseiid mites for over 30 years. In this study, the distribution of P. persimilis in Taiwan was predicted, and environmental variables that affect its distribution were analyzed. The mountainous region of southcentral Taiwan was determined to be suitable for the establishment of this species, whereas the four sites at which it was released in the 1990s, particularly those in southwestern Taiwan, exhibited low suitability. Notably, the minimum temperature of the coldest month was identified as a crucial limiting factor affecting the distribution of P. persimilis, indicating that a Mediterranean climate is more suitable for this species. To the best of our knowledge, this study is the first to predict the suitable distribution of exotic predatory mites in a biological control program. The present findings serve as a pivotal assessment framework for the commercialization and foreign introduction of natural enemies.