Aggregation response of Orius niger (Hem.: Anthocoridae) to different densities of Thrips tabaci (Thys.: Thripidae) under laboratory conditions

Aggregation response of the predatory bug Orius niger (Wolff) at different densities (۵, ۱۰, ۲۰, ۳۰, ۴۰ and ۵۰) of the second instar nymphs of Thrips tabaci Lind. was examined on a cucumber leaf disc as a patch. The number of predatory bugs and their allocated time per patch was recorded. The index (µ), in Hassell & May, at all densities of the predator (۱, ۲, ۴, ۸, ۱۶ and ۳۲) appeared greater than zero and, was indicative of its tendency to aggregate in the patches where a higher density of prey occurred. The percentage time spent by the predatory bug at different patch densities of T. tabaci showed that it allocated more time in patches with higher densities of prey.