The effect of adult diet on the biology of butterflies : 1. The common imperial blue, Jalmenus evagoras.

This study examines the effect that sugars and amino acids in the adult diet of Jalmenus evagoras can have on female feeding behaviour, somatic maintenance, longevity, fecundity and egg weight. The presence of sugars in their adult food stimulated butterflies of this species to feed, and they appeared to compensate for low (1% wt/wt) sugar diets by feeding for longer periods. Butterflies were also more likely to feed on diets containing amino acids than on water controls. The availability of sugar allowed females to maintain or even increase their body weight and fat body size, but amino acids had no effect on these variables. Individuals on the medium (25% wt/wt) sugar diet attained the greatest longevity. Female fecundity was increased as much as threefold by the availability of sugar. However, amino acids in the diet had no effect on either longevity or fecundity. Egg weight was not affected by the concentration of sugars or amino acids in the adult diet, but was correlated with the weight of the female butterfly. These results demonstrate that the availability of carbohydrates in the adult diet could play an important role in the population dynamics of this species. However, the presence of amino acids had little effect on most of the variables measured, nor was there any interaction effect between sugars and amino acids.