Olfactometer studies on preference of Rhynocoris marginatus Fabricius to three lepidopteran preys

The assassin bug, Rhynocoris marginatus is a generalist predator and can be deployed across agro ecosystems. In a study to assess its interactions with three polyphagous lepidopteran pests, the predator showed significantly higher preference to Spodoptera litura (F.) (50%) over Mythimna separata (25.3%) and Sesamia inferens (24.7%). The prey predator interaction of three prey species and R. marginatus was assessed in a Y-arm olfactometer and a six-arm olfactometer. Though R. marginatus responded to all the hexane extracts of tested insect pests, it showed maximum preference to S. litura (85.7%) followed by M. separata (57.1%) and S. inferens (42.8%) in the Y arm olfactometer compared to control. The approaching time and handling time were more for S. litura i.e., (10.9±1.99 min) and (18.3 ± 2.62 min) when compared to M. separata (10.2 ± 2.49 min), (17.7 ± 2.92 min) and S. inferens (7.33 ± 2.51 min) (17.6 ± 3.51 min) respectively. Similarly in a multi choice test, R.marginatus highly preferred the hexane extract of S. litura (42.8%) followed byM. seperata (28.5%) and least preference was to S. inferens (21.4%) which was on par with hexane extract alone.