Mohammadali Mirhosseini

The two-spotted spider mite (TSSM), Tetranychus urticae Koch (Acari: Tetranychidae), is one of the noxious pests on a wide range of crops over the world. In this study, the temperature-dependent functional response of 24 hours old adult female of acarophagous ladybird, Stethorus gilvifrons (Mulsant) on nymphal stages of TSSM was assessed at five temperatures including 15, 20, 25, 30 and 35 ± 1 ° C, under controlled conditions (60±5% RH and photoperiod of 16L:8D h) on bean plants (Phaseolus vulgaris) for 24 hours. Densities of 2, 4, 8, 16, 32, 64, and 128 prey were provided in each temperature. The maximum daily consumption of predator at all temperatures was observed in density of 128 prey (82.0, 77.6, 83.6, 93.0 and 103.2 prey/day for 15-35 ° C, respectively). The predator functional response at all temperatures fitted type II. The highest (0.2285 h-1) and lowest (0.0719 h-1) attack rate were belonged to 20 and 30 ° C, respectively. The longest handling time (0.997 h) observed at 15 °C, whereas the shortest handling time and highest value of maximum attack rate (T/Th) were associated with 30 °C (0.0624 h and 384.61 prey/d, respectively). The strong functional response and predation capacity of S. gilvifrons on nymphal stage of TSSM indicated the high potential of this predatory coccinellid as an effective biological control agent against this pest especially at 30 ° C and also when higher prey densities are present.