Fitness of two phenotypes of Harmonia axyridis (Coleoptera: Coccinellidae)

Antonio O Soares,Henrique Schanderl,Daniel Coderre

doi:10.14411/eje.2001.048

Abstract

The coccinellid H. axyridis shows considerable intraspecific variability of elytral patterns. In this paper, we suggest that a genotype that confers a specific pattern of elytra could also confer other specific autecological attributes. The aim of this paper is to compare fitness parameters of two phenotypes (aulica and nigra). Aulica is a common morph characterized by two light red areas that nearly cover the whole elytra, leaving a narrow black border, whereas nigra is completely black; the latter is a rare morph that was naturally obtained from mass cultures. Intraspecific differences occur between H. axyridis phenotypes. The aulica phenotype is more voracious than nigra. Consumption rate of males is higher in aulica than in nigra, but there is no difference for females. Larval biomass of aulica is generally higher than that of nigra. The maximum body-weights reached by larval instars and adults are significantly higher for aulica. Aulica also has greater longevity and reproductive capacity. Only life stage duration of eggs and pre-pupae differ between the two phenotypes. Nigra shows lower fecundity and fertility. Our study showed that the strong differences in phenotype traits of the coccinellid H. axyridis could affect its fitness.

Highlights

Fitness can be defined as the measure of the relative performance of genotypes of a species and their contribu tion to future generations (Begon et al, 1990)
Total pre-adult developmental time did not differ between the aulica and nigra phenotypes
Average daily voracity and 24 h-oldcoccinellid voracity of first, second, third, fourth instars as well as adult males and females were significantly higher for aulica than for nigra (Table 2)

Summary

Introduction

Fitness can be defined as the measure of the relative performance of genotypes of a species and their contribu tion to future generations (Begon et al, 1990). The direct evaluation of fitness has rarely been performed (Hoffman, 1994). Most researchers generally measure fitness indi rectly by using parameters such as body size, develop mental time, fecundity and fertility. Indirect measures of fitness are often used to evaluate the efficacy of a predator and its capacity population increase following field introduction. Performance may vary among phenotypes of the same species.

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