Polymorphism and polyethism in the formicinae ant Cataglyphis niger (Hymenoptera)

Worker polymorphism and its relation to colony size and polyethism was stud ied in the formicine ant, Cataglyphis niger. This species exhibited a sligh t dimorphism between the female castes and amonophasic allometry along a wi de continuum of size among the workers. Worker polymorphism, however, was e stablished progressively throughout colony development. Following the gener al rule in ants, the mean body size of the workers increased with colony si ze, and the range of worker size expanded. In the same way, the setting of individual growth parameters changed so that the allometric growth characte rized by an enlargement of the head proportionally to thorax width only occ urred in mature nests. In such a situation, the large workers contributed a major part of the nest guarding and foraging activities, whereas the small ones mostly performed nursing behaviors. Results were discussed with refer ence to previous works on other Cataglyphis species and to optimization cas te theory.