This means that the ant who is suited for the best caste for the job, is the one who gathers the most vegetation with the least expenditure of energy. The most efficient group of leaf carriers proved out to be the ones whose heads were 2.0 to 2.2 millimeters in width. When soldiers were given leaf carrying jobs, they use much more energy.

The sex of a leaf-cutter ant is very easily determined. If the queen fertilizes an egg it produces a female and an unfertilized egg produces a male. Since the male progeny come from unfertilized eggs, they are haploid; that is, they inherit one of the mother’s two sets of chromosomes and nothing from the father (Hoyt 1996). The female on the other hand is diploid. They receive one of the mother’s two sets of chromosomes and the father’s one set (only one set of chromosomes exist in a gamete or sperm). The key is that one set – the half of the genes that daughters get from their haploid father. It is identical to every other set every female gets, and thus the sisters must be at an absolute minimum of 50% related to each other. The genes from their mother, depending on which of the two sets of chromosomes is inherited, may or may not be the same. On average, based on chance, sisters share 75 % of their genes with each other – more than 50 % they share with either parent. Thus sister ants in a colony can best ensure the survival of their own genes by helping each other. Males, meanwhile, with only one of the mother’s two sets and nothing from a father, share only 25 % of their genes with their sisters, on average, and predictably contribute less labor than females to the colony welfare; their purpose is reproduction through a single mating, after which they die (Hoyt 1996).

This is one of the main differences that separates the ant species from other insects. For all hymenopterans are haplodiploid. Also a difference within hymenoptera is that the Atta group is a social insect while most hymenopterans are solitary. Now you must be asking yourself, what causes a female to grow into a fertile queen instead of a sterile worker? Holldobler & Wilson (1994) said that the deciding factors are environmental rather than genetic. All the females of a colony possess the same genes with respect to caste – and any female after conception [as previously mentioned, most ants in the nest are female] can turn into either a queen or a worker. The genes merely provide the potential to develop into either a worker or a queen. The controlling environmental factors are several in kind, varying among species. On is the amount and quality of food received by the larva.