Predispersal seed predation in leguminous species: seed morphology and bruchid distribution [seed shape, review]

We measured and calculated seed morphological parameters [axonometric linear measures, weight, volume and minimum-maximum seed size ratio (SMIMA)] of 110 leguminous plant species occurring in Hungary. We collected seed samples, reared the predispersal seed predators from the samples, took morphological data from the bruchids (elytra length, body width, thorax length) and calculated the body size ratio (BSR). We found that SMIMA and BSR were fairly good predictors of bruchid infestation patterns at plant tribe, species and sample (locality) levels. Bruchid body length was much less variable than the parameters (e.g., volume) of seeds from which they were reared. We also found that the closer the shape of the seeds of a leguminous plant species to a sphere, or the larger the seed volume, the higher the probability of bruchid infestation. Seed morphological traits (weight, volume and SMIMA) clearly separated the hosts of the genera Bruchus and Bruchidius. For the three related bruchid genera studied, phylogenetic and ecological effects (regarding seed shape preference) were also separated. We concluded that the evolution of the seed size of plant species studied is not likely driven by bruchids or by other seed predators.