Storage proteins in ants (Hymenoptera:Formicidae)

Storage proteins are a major feature of holometabolous development in insects, accumulating during the larval period and disappearing during metamorphosis. In ants (Hymenoptera:Formicidae), storage proteins also play important roles in adult females. Three types of storage proteins have been characterized from ants: hexamerins, proteins high in glutamine/glutamic acid, and very high density lipoproteins (VHDLs). The hexamerins have moderately high levels of aromatic amino acids and belong to the arthropod hemocyanin family of proteins. The proteins high in glutamine/glutamic acid can form hexamers under some conditions, but the subunit size is larger than that of typical hexamerins. The VHDLs are dimeric and share features with storage chromoproteins described from Lepidoptera. In Camponotus festinatus (Formicinae), storage proteins are found in adult ants in two situations. First, lack of brood stimulates workers to accumulate the same two storage hexamers found in larvae. Second, young virgin queens store large reserves of these proteins before mating. Protein storage by queens has been confirmed in two other subfamilies of ants, indicating it is widespread. The capacity to store proteins as adults enables queens to rear brood without leaving the nest and workers to store rich reserves and regulate larval diet seasonally.