1ICAR-Indian Institute of Rice Research, Rajendranagar-500 030, Hyderabad, Telangana State, India
Professor, Jayashankar Telangana State Agricultural University, Rajendranagar-500 030, Hyderabad, Telangana State, India
*E mail: pravallikarathod@gmail.com
Online published on 24 June, 2016.
The harpactorine assassin bug, Rhynocoris marginatus (Fabricius) is a predator of diverse insect pests. In the present study, the functional response of adult bug to the three lepidopteran pests viz., Spodoptera litura, Mythimna seperata and Sesamia inferens exhibited Holling's type II curvilinear functional response; increased rate of attack by predator was recorded as the prey density increased. Maximum predation represented by ‘k ’value was found at higher prey densities i.e., k =3.8, 4.0 and 2.4 for S. litura, M. seperata and S. inferens, respectively. The predation rate showed a steep rise from two to ten prey densities. But highest attack ratio (y/x) was obtained at two prey/predator density and lowest attack ratios at ten prey/predator density. Positive correlation was obtained between prey density and the prey killed and negative correlation between the prey density and searching time of the predator at all prey densities. At high prey density, the predators spent less time in searching, therefore spent more time in handling, whereas at low prey density it was reverse. However, handling time varied due to factors such as rate of pursuit of predator and prey escape or prey capture success.
Functional response, Rhynocoris marginatus, Spodoptera litura, Mythimna seperata, Sesamia inferens, attack ratio, handling time, searching time
