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Indian Journal of Entomology
Year : 2008, Volume : 70, Issue : 3
First page : ( 206) Last page : ( 216)
Print ISSN : 0367-8288.

Functional response of Rhynocoris kumarii ambrose and livingstone and normal and synergy-505 exposed Rhynocoris marginatus (Fab.) to larva of Euproctis fraterna (Moore)

Ambrose Dunston P., Rajan S. Jesu, Raja J. Micheal

Entomology Research Unit, St. Xavier's College (Autonomous), Palayankottai, 627 002, Tamil Nadu.

Received:  January,  2008.


Functional response studies in the IV and V nymphal instars and the adult males and females of Rhynocoris kumarii Ambrose and Livingstone and R. marginatus (Fabricius) to the larvae of Euproctis fraterna (Moore) revealed similar Holling's type II curvilinear responses. The life stages of both R. kumarii and R. marginatus responded to the increasing prey density by killing more number of prey than prey killed at lower prey densities and exhibited the searching time decreased as the prey density was increased. The predation rate showed a steep rise from 1 to 16 prey densities. The maximum predations presented by ‘k’ values were always found restricted to the higher prey density. Attack ratios decreased as the prey density was increased. Negative correlations were obtained between the prey density and the handling and recovery times of the predator and the searching time. Though a curvilinear type II relationships were found between the number of prey killed and the prey density in both normal and Synergy-505 exposed life stages of R. marginatus, Synergy-505 reduced functional response parameters such as number of prey killed, attack rate and searching time, and prolonged handling and recovery times. The toxicological impacts were greater among the nymphal instar's than the adults. Among adult males were affected more than the females.


Key words

Rhynocoris kumariiR. marginatus, functional response, Euproctis fraterna, Synergy-505.


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