Relationships between developmental instability in morphological characters and fitness of Aphis fabae population reared on two host plants

Fluctuating asymmetry (FA) and the coefficient of within-environment variation (CV ^sub e^) are often used as measures of developmental instability and indicators of developmental deviations. Aphis fabae genotypes generally manifest higher developmental instability on novel host plants, but there is genotypic variability in this respect. Some genotypes have manifested lower developmental instability on nasturtium, where their fitness is higher. At the population level, aphids reared on nasturtium have shown higher developmental instability and lower fitness. When large samples are analyzed and the nonsignificant pattern of correlations is taken into account, the results of the study do not support the hypothesis that developmental instability is always a reliable indicator of fitness.[PUBLICATION ABSTRACT]