Functional response of the predatory mite Amblyseius swirskii (Acari: Phytoseiidae) to Eotetranychus frosti (Tetranychidae) and Cenopalpus irani (Tenuipalpidae)

Abstract

Eotetranychus frosti and Cenopalpus irani Dosse are pests of apple trees that are widely distributed in apple orchards in Iran. The functional responses and predation rates of Amblyseius swirskii, one of the most commonly utilized phytoseiid mites for biological control, on these two pests were evaluated at 25 ± 1 °C, with 16:8 h L: D, and a relative humidity of 60 ± 10 % on apple leaves. The results of predation rate experiments on the two prey species indicated that the predator consumed significantly more eggs than larvae and protonymphs whereas consumption of deutonymphs were very rare. Likewise, the results of logistic regression analysis showed that A. swirskii exhibited a Type II functional response on all immature stages of E. frosti and C. irani. Handling time (Th) increased as prey size enlarged; the lowest handling times were determined as 0.4858 and 0.3819 h on eggs of E. frosti and C. irani, respectively, whereas the highest were found to be 1.4007 and 1.0190 h on deutonymphs, respectively. Amblyseius swirskii had the higher attack rate coefficient (α) on immature stages of C. irani than E. frosti. Attack rate coefficients (α) varied significantly between life stages of both pests with the highest attack rate obtained on eggs, followed by larvae, protonymphs, and deutonymphs. Results of this study suggest that A. swirskii could be a highly efficient biological control agent of E. frosti and C. irani at least at low prey densities.

Intraspecific interactions at high predator densities affect the predation efficiency ofNeoseiulus californicus(Acari: Phytoseiidae) when prey density is low

“…In general, type II functional responses seem to prevail in phytoseiids. It is recorded in several species, such as Euseius finlandicus and Amblyseius andersoni preying on Panonychus ulmi larvae and adult females (Koveos & Broufas, 2000), Euseius scutalis preying on T. urticae and Eutetranychus orientalis (Acari: Tetranychidae; Stathakis et al, 2021); Amblyseius swirskii preying on Eotetranychus frosti (Acari: Tetranychidae) and Cenopalpus irani (Acari: Tenuipalpidae) (Bazgir et al, 2020); Iphiseius degenerans preying on T. urticae and E. orientalis (Fantinou et al, 2012). However, it should be noted that predatory arthropods' feeding may be affected by plant species and/or cultivars characteristics for example via the impediment of their movement or indirectly via the quality of their prey (e.g., Cédola et al, 2001;Messina & Hanks, 1998;Merlin et al, 2022;Paspati et al, 2021), indicating that functional responses should be also evaluated in several environmental scenarios.…”