Life table and predation capacity of Hippodamia variegata (Coleoptera: Coccinellidae) feeding on Aphis fabae (Hemiptera: Aphididae)

Abstract

The life history and predation rate of variegated lady beetle, Hippodamia variegata (Goeze), fed on the black bean aphid, Aphis fabae Scopoli, were studied under laboratory conditions. Developmental, survival, fecundity, and predation rate data were analyzed using the age-stage, two-sex life table and the traditional age-specific female life table. Means and standard errors of population growth parameters were calculated using the jackknife method. Using the age-stage, two-sex life table, the intrinsic rate of increase (r), net reproductive rate (R0), mean generation time (T) and finite rate of increase (λ) were 0.2031d−1, 389.0 offspring, 29.4d, and 1.2252d−1, respectively. The population parameters r, R0, T, and (λ) calculated using the female age-specific life table were 0.2045d−1, 387.6 offspring, 29.16d, and 1.2269d−1, respectively. Although no statistically significant differences were found between population parameters of the two methods, the female age-specific life table could not include the male population and its contribution to predation, nor was it possible to describe the stage differentiation. The net predation rate (C0) using the age-stage, two-sex life table was 1127.1 aphids, and 1503.1 aphids when using the female age-specific life table. The higher net predation obtained when using the female age-specific life table was an overestimation caused by ignoring the male population. Our results demonstrate that by using the age-stage, two-sex life table we can accurately describe the survival, development, and predation capacity of the predator.