Effect of host plants on the functional response of the acarophagous ladybird beetle, Stethorus gilvifrons to Tetranychus turkestani

The strawberry spider mite, Tetranychus turkestani Ugarov and Nikolski, is an important pest of various field and glasshouse crops in Iran. This study aimed to determine the functional response of adult females of Stethorus gilvifrons Mulsant to different densities of T. turkestani on three fabaceous host plant species: cowpea (Vigna unguiculata L.), white bean (Phaseolus lunatus L.), and red bean (Phaseolus calcaratus Roxb.) at 30±2 °C, 60±10 % RH, and a photoperiod of 16L: 8D. Beetles were starved for 24 h before testing and then isolated singly for 24 h in 9-cm Petri dishes with 4, 8, 12, 24, 48, or 96 adult females of T. turkestani. Logistic regression analysis revealed a type III response on cowpeas. Constant (b) and handling time were 0.00718 and 0.3299 h, respectively. In contrast, a type II response was observed in white beans and red beans. The maximum attack (0.1219 h-1) and the minimum handling time (0.2301 h) were recorded on white beans and red beans, respectively. The maximum attack rates (T/Th) were 72.74, 60.42, and 104.30 eggs/day on cowpeas, white beans, and red beans, respectively. This laboratory study suggests that the plant features affect the capability of S. gilvifrons to respond to changes in a high T. turkestani density.