Time allocation of Orius sauteri in attacking Thrips palmi on an eggplant leaf

Orius sauteri (Poppius) ( Heteroptera: Anthocoridae) is a polyphagous predator used as a biological control agent of palm thrips, Thrips palmi (Karny) (Thysanoptera: Thripidae). We studied O.sauteri's searching efficiency, time allocation on a leaf, leaving tendency, and attacking of prey. Approximately 78% of the encountered prey was eaten. Searching for prey was concentrated for 86% of the time on the lower leaf side, where palm thrips are usually found. Patch residence times on empty leaves were different from those on leaves with T. palmi larvae. Walking activity was not affected by the thrips density, and walking took place during 64% of the total search time. The leaving tendency of O. sauteri was affected by the time from patch entry and the presence or absence of palm thrips, but not by the thrips density. If prey were present, the leaving tendency decreased ( multiplication factor 0.327), resulting in longer giving-up times than when no prey was present. The fact that the leaving tendency increases when patch exploitation lasts longer suggests that not much time is wasted on patches where encounters with prey are scarce.