Implications of Temperature and Prey Density on Predatory Mite Amblyseius swirskii (Acari: Phytoseiidae) Functional Responses

Amblyseius swirskii are predaceous mites that feed on phytophagous mites, pollens, and
plant exudates and are known as one of the most potent biological pest management agents.
Tetranychus urticae is a global mite that is difficult to manage because of its high population
growth rates, necessitating alternative management measures like biological control. Regarding
the functional response, the effects of temperature and prey density are some of the essential
behaviors of natural enemies. This study investigates the effect of varying temperatures and prey
densities on A. swirskii, a biological control agent for T. urticae. The present results demonstrated
the change in the functional response estimates when A. swirskii was reared at various temperatures
and different prey densities. The results of the estimates regarding the searching efficiency (a′)
showed the highest value (a′ = 0.919) at 26 ◦C and the lowest value (a′ = 0.751) at 14 ◦C. The
handling time per prey item (Th) for the predatory mites changed with the temperature and
prey density, showing the shortest handling time at 26 ◦C (Th = 0.005) and the highest value
at 14 ◦C (Th = 0.015). The functional response curves matched the type II functional response
model, demonstrating the inverse dependence of temperatures and prey density with a positive
quadratic coefficient. The predation curves for A. swirskii showed a significant difference between
the mean numbers of T. urticae consumed at various prey densities and temperatures, illustrating a relationship between A. swirskii and T. urticae. Therefore, the results of this research may be utilized
to forecast the behavior of A. swirskii and its usefulness in controlling T. urticae populations.