Demographic traits of Hippodamia variegata (Goeze) (Coleoptera: Coccinellidae) fed on Sitobion avenae Fabricius (Hemiptera: Aphididae)

Lady beetles are the most important predatory species among arthropods, so studying their population parameters gives a clear picture about their life span. the life histories of variegated lady beetle, hippodamia variegata (goeze), fed on the english grain aphid, sitobion avenae fabricius, on different host plants were studied under laboratory conditions, at 25 ± 1 °c, 65 ± 5%relative humidity and a photoperiod of 16:8 (light: dark) h. developmental, survival and fecundity data were analyzed using the age-stage, two-sex life table method. according to the age-stage, two-sex life table, the net reproductive rates (r_0) of ladybird fed on s. avenae reared on triticum aestivum var. tajan, hordeum vulgare var. dasht, zea mays var. single cross 704 and sorghum durra var. speed feed were estimated to be 235.38 ± 36.15, 190.74 ± 33.37, 293.54 ± 46.66 and 137.46 ± 23.66 female offspring / female, respectively. based on the results, the intrinsic rate of increase as an index of population increase of h. variegata, was 0.181 ± 0.006, 0.179 ± 0.006, 0.163 ± 0.006 and 0.162 ± 0.006 h^-1 preyed on host reared on t. aestivum var. tajan z. mays var. single cross 704 s. durra var. speed feed and h. vulgare var. dasht, respectively. our findings demonstrate that by using the age-stage, two-sex life table we can accurately describe the growth, survival and development of the predator. our finding may provide basic information for developing aphid biological control programs.