Developmental instability in a stem-mining sawfly: can fluctuating asymmetry detect plant host stress in a model system?

Fluctuating asymmetry (FA) may be a sensitive indicator of the stress experienced by organisms during their development. Its use in this manner is an intuitively appealing, frequently proposed, and potentially powerful tool but remains controversial partially because its underlying premise rarely has been critically tested. Such tests should include direct comparisons among individuals for which levels of FA, stress and fitness have been unambiguously quantified.