Evolution du contenu énergétique des ouvrières et des sexués de la fourmi Leptothorax unifasciatus (Latreille) (Hymenoptera ; Formicidae).

Dry weights, energetic contents, fat and ash percentages were measured for the various castes of Leptothorax unifasciatus from egg to old imago. The changes of these parameters indicate many differences according to castes. Workers store fats during the pupal life, which are probably intended for the future feeding of young larvae. The energetic content of males decreases continuously from the prepupal stage and adults are virtually emptied of their fat content. Queens store a great amount of fat not only at the end of larval growth but after imaginal emergence as well. These differences are discussed in the context of the reproductive modalities of the species (nuptial flight and queen independent nest founding). Some facts indicate that the energetic cost of sexual making and the number of workers determine the time when a society begins to produce sexuals during its development.