Comparison of the demographic parameters and survival of two phenotypes of Harmonia axyridis (Coleoptera: Coccinellidae)

Abstract

This paper reports the results of a comparative study of the demographic parameters of two phenotypes of Harmonia axyridis Pallas, reared on the black bean aphid, Aphis fabae Scopoli at 25 ± 1°C, 65 ± 2% RH and a photoperiod of 16L : 8D. The values of the intrinsic rate of increase and the finite rate of increase, which were obtained by bootstrapping, were greater for the succinea morph (0.182 females/female/d and 1.200, respectively) than the spectabilis morph (0.168 females/female/d and 1.183, respectively). The net reproductive rates and mean generation times of the two morphs did not differ. The risk of death of the succinea morph was significantly greater. However, there was no significant difference between the estimated survival times. Mean survival times were 95.2 d and 89.3 d for the spectabilis and succinea morphs, respectively.

Keywords

• coleoptera
• coccinellidae
• harmonia axyridis
• succinea morph
• spectabilis morph
• bootstrap
• life tables
• survival curves