The relation between fecundity and reproductive investment in aphids (Aphis fabae).
Mechanistic models of embryo growth are described and tested using the results of experiments on Aphis fabae. Increasing reproductive investment during nymphal development (measured as ovariole number) increases potential fecundity on nutrient-rich hosts. Increasing ovariole number increases the total cost of embryo maintenance and thus reduces the resources available for embryo growth. This means that on poor hosts the correlation between fecundity and ovariole number is negative.