Area dependent searching efficiency of Scymnus syriacus (Col.: Coccinellidae) feeding on Aphis craccivora (Hem.: Aphididae)

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Abstract

Searching efficiency is a key parameter of functional response which is in turn the major components in the selection of predators and parasitoids for biological control. Searching efficiency of Scymnus syriacus Mulsant feeding on Aphis craccivora Koch was determined at five different experimental arenas (i.e. 195, 247, 304, 385 and 650 cm2) on broad bean (Vicia fabae L.). To do this, functional response of the predator to different densities (i.e., 10, 20, 30, 40 and 60) of the third instar nymphs of A. craccivora was studied. At each experiment, one 48-h.-old female was introduced to the aphid density in a container (as an experimental arena) and replicated five times. The experiments were carried out at 25˚ ± 1C, 65 ± 5% RH and a photoperiod of 16L: 8D h. Using the logistic regression, a type III functional response was determined for S. syriacus in the entire five experimental arenas. Searching efficiency was found to be area dependent as it decreased as the area of experimental arena increased. The maximum expected predation rates (T/Th) were 48.56, 42.44, 40.77, 38.09 and 34.88 in the five experimental arenas, respectively. The area searched as a function of prey density indicated that as prey density increased, the area searched by the predator decreased. It is concluded that the size of searching area and prey density, both influence foraging behavior of S. syriacus.

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Journal of Entomological Society of Iran
Volume 31, Issue 1
September 2011
Pages 1-16

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