Efficacy of releases of phytoseiid mites (Acari: Phytoseiidae) on spider mite control on raspberry in high tunnel production, and implication on control strategy through a population model of Tetranychus mcdanieli (Acari: Tetranychidae)

Field experiments were conducted to determine the establishment and the effectiveness of certain predatory mites in controlling spider mites in raspberry grown under high tunnels. First, the efficacy of Neoseiulus fallacis and N. californicus releases combined with Phytoseiulus persimilis was compared to an acaricide (clofentezine). Weather and low release rates being unfavourable to predator establishment, release strategies were not as effective as the acaricide. Second, the effect of adding an artificial mist on the establishment of P. persimilis was measured. Control was achieved more rapidly by treatment with artificial mist, but the difference in prey and predator density was not significant. Third, a population dynamics model was developed and calibrated with the aim of better understanding spider mite dynamics under tunnel production. The model fits the field data well, is useful for sizing up the impact of different parameters on the population dynamic and shows that temperature is a critical parameter in the management of spider mites.