Functional response of the predatory mite, Typhlodromus bagdasarjani (Acari: Phytoseiidae) to protonymphs of Eotetranychus frosti (Acari: Tetranychidae) on four apple cultivars

Abstract

The functional response of natural enemies and their interactions may be affected by host plant characters. Functional response of the adult females of the predatory mite, Typhlodromus bagdasarjani Wainstein and Arutunjan to protonymphs of Eotetranychus frosti (McGregor) on four apple cultivars Imperial Gala, Kohanz Golab, Granny Smith and Lebanon Red was investigated. The protonymphs of E. frosti were offered to the adult female of the predator at densities of 2, 4, 8, 16, 32, 64 and 128 on apple leaf discs (4 cm²). The number and length of trichomes on the lower surface of each apple cultivar were measured. The highest and lowest number of trichomes were observed in Granny Smith and Kohanz Golab, respectively. Typhlodromus bagdasarjani adult females exhibited the type II functional response on E. frosti protonymphs regardless of apple cultivars. Also, the values of attack rate (a) and handling time (T_h) were determined using the Rogers's type II model. Adult females of T. bagdasarjani had the highest attack rate (a) (0.0747 h¹) and the shortest handling time (0.7005 h) on Kohanz Golab, and the lowest attack rate (0.0334 h¹) and the longest handling time (1.1189 h) was on Granny Smith. The theoretical maximum predation rate (T/T_h) on Kohanz Golab, Imperial Gala, Lebanon Red and Granny Smith were 34.26, 33.79, 26.85 and 21.45 prey/day, respectively. The estimated value of a/T_h indicated that T. bagdasarjani was most effective against E. frosti on Kohanz Golab with lowest number of trichomes. The finding of this study shows that the predation and searching activity of the predator was affected by trichome density and length of the apple leaves.