Approaching and rostrum protrusion behaviours ofRhynocoris marginatus on three prey chemical cues

摘要

Rhynocoris marginatus (F.) (Heteroptera Reduviidae) is a polyphagous predator predominantly found in agroecosystems, and theirbordering ecosystems like scrub jungles, semi-arid zones and forests in India. Although R. marginatus is a polyphagous predator, itexhibited a certain degree of host specificity. Due to its predatory potential, R. marginatus has been used as an important biologicalcontrol agent in India. Laboratory and field trials showed that R. marginatus feeds mainly on lepidopteran pests followed by coleop-teran pests. R. marginatus locates the preys by the chemical cues emanating from them. Approaching and rostrum protrusion behav-iours of R. marginatus life stages on hexane extract of three groundnut pests, Helicoverpa armigera (Hubner) (Lepidoptera Noctui-dae), Spodoptera litura (F.) (Lepidoptera Noctuidae) and Mylabris pustulata (Thunberg) (Coleoptera Meloidae). Significantly R.marginatus adult was found to be more responsive to the chemical cues of S. litura (62.5%) followed by H. armigera (60%) and Mpustulata (40%). R. marginatus showed minimal preference to M pustulata chemical cues as compared to H. armigera and S. liturachemical cusses. The prey's chemical cues elicited a quicker approaching behaviour of the predator than the control. Moreover therostrum protrusion time was also higher in the prey chemical cues categories as compared to the control. The results clearly showthe role of prey chemical cues in prey-predator interaction. GC-MS analysis of the prey chemical cues indicated H. armigera, Mpustulata and S. litura contains eight, eight and five saturated hydrocarbons, respectively.