Reproduction and demography of an Aphidophagous ladybird, Hippodamia variegata on six aphid species

Abstract

We tested six aphid species, viz. Aphis gossypii, Aphis craccivora, Brevicoryne brassicae, Lipaphis erysimi, Myzus persicae and Uroleucon compositae as essential foods needed for the reproduction and demography of an aphidophagous ladybird, Hippodamia variegata. Females were highly fecund (1210.8 ± 55.31 eggs) with prolonged oviposition period (56.30 ± 2.36 days) and laying most viable eggs (92.91 ± 0.81%) when fed on A. gossypii (reared on Lagenaria vulgaris) with the highest net reproductive rate (449.45 ± 20.53 females / female). Aphis craccivora (raised on Dolichos lablab) supported optimal value for intrinsic rate of increase (0.183 ± 0.003) with the shortest generation time (32.40 ± 0.557 days). Other diets didn’t show improved performance but quantified as essential foods. Brassica hosted B. brassicae and L. erysimi were less suitable but not the rejected prey. Age-specific fecundity of female H. variegata was triangular in function with peak oviposition during her early reproductive age when fed on either A. gossypii, A. craccivora, U. compositae or M. persicae, while peak skewed towards later reproductive age when fed on B. brassicae or L. erysimi. Fecundity was positively correlated with egg-viability and oviposition period. We used jackknife technique to estimate and compare the demographic parameters within the groups. High values of intrinsic and finite rates of increase on A. gossypii and A. craccivora affirm their suitability for augmentative rearing of H. variegata. We conclude that both A. gossypii and A. craccivora on above respective host-plants are highly suitable aphid-diets for mass-multiplication of H. variegata.