Table of Contents
ISRN Entomology
Volume 2013, Article ID 281476, 7 pages
Research Article

The Effect of Prey Density on Life Table Parameters of Hippodamia variegata (Coleoptera: Coccinellidae) Fed on Aphis gossypii (Hemiptera: Aphididae) under Laboratory Conditions

Department of Plant Protection, Faculty of Agriculture, University of Guilan, P.O. Box 41635-1314, Rasht, Iran

Received 14 May 2013; Accepted 18 June 2013

Academic Editors: C. J. Bidau, J. Serrano, and C. Silva-Torres

Copyright © 2013 Soodeh Davoodi Dehkordi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Life table gives the most comprehensive explanation of the survivorship, development, and reproduction of a population. The life table parameters of ladybeetle, Hippodamia variegata (Coleoptera: Coccinellidae), on different densities (20, 40, 60, 80, and 100) of third instar nymphs of Aphis gossypii were studied in a growth chamber ( °C, % RH, and a photoperiod of 16L: 8D h). The adult preovipositional period and the total preovipositional period of female H. variegata were reduced as the prey density increased. The oviposition period was longer when prey density increased. Female longevity also increased significantly with increasing prey density. Fecundity was dependent on prey density. The lowest fecundity was obtained at density of 20 prey ( ) and the highest at density of 100 ( eggs). Intrinsic rate of increase was dependent on prey density and ranged from to  d−1 (female/female/day) with increasing prey density. Net reproductive rate and gross reproductive rate were also increased with increasing prey density. The peak reproductive values were dependent on prey density. However, mean generation time decreased as prey density increased. It was concluded that the increase in the density of A. gossypii nymphs had positive and significant effects on reproductive parameters of H. variegata.