Plant Spatial Distribution and Predator–Prey Ratio Affect Biological Control of the Twospotted Spider Mite Tetranychus urticae (Acari: Tetranychidae) by the Predatory Mite Phytoseiulus persimilis (Acari: Phytoseiidae)
Amoah, B., Anderson, J., Erram, D., Gomez, J., Harris, A., Kivett, J., Ruang-Rit, K., Wang, Y., Murray, L., & Nechols, J. (2016). Biocontrol Science and Technology, 26(4), 548–561.
A greenhouse experiment tested how plant spacing and predator–prey ratio affect the foraging efficiency of the predatory mite Phytoseiulus persimilis released to control twospotted spider mites. Plant damage stayed uniformly low when plant rows had no spacing gaps, but rose when rows were interrupted. Findings suggest point releases at a standard 1:10 predator-to-prey ratio are effective within roughly 65 cm of the release point, but gaps in plant rows can leave parts of a crop under-protected even with larger predator releases.