Predator‐ and killed prey‐induced fears bear significant cost to an invasive spider mite: Implications in pest management

BACKGROUND The success of biological control using predators is normally assumed to be achieved through direct predation. Yet it is largely unknown how the predator‐ and killed prey‐induced stress to prey may contribute to biological control effectiveness. Here, we investigate variations in life‐history traits and offspring fitness of the spider mite Tetranychus ludeni in response to cues from the predatory mite Phytoseiulus persimilis and killed T. ludeni, providing knowledge for evaluation of the nonconsumptive contribution to the biological control of T. ludeni and for future development of novel spider mite control measures using these cues. RESULTS Cues from predators and killed prey shortened longevity by 23–25% and oviposition period by 35–40%, and reduced fecundity by 31–37% in T. ludeni females. These cues significantly reduced the intrinsic rate of increase (rm) and net population growth rate (R0), and extended time to double the population size (Dt). Predator cues significantly delayed lifetime production of daughters. Mothers exposed to predator cues laid significantly smaller eggs and their offspring developed significantly more slowly but these eggs had significantly higher hatch rate. CONCLUSION Predator‐ and killed prey‐induced fears significantly lower the fitness of T. ludeni, suggesting that these nonconsumptive effects can contribute to the effectiveness of biological control to a great extent. Our study provides critical information for evaluation of biological control effectiveness using predators and paves the way for identification of chemical odors from the predator and killed prey, and development of new materials and methods for the control of spider mite pests. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. Findings on the impact of predator‐ and killed prey‐induced fears on an important invasive pest, Tetranychus ludeni, help develop new materials and methods for controlling spider mite pests. Cues from predators and killed prey shorten female longevity by a quarter and reproductive fitness by a third, significantly reducing population growth.