The role of an attractive brood pheromone in the obligatory,slavemaking ant,Polyergus breviceps (hymenoptera: Formicidae)

Freeliving workers of Formica occulta, an ant species enslaved by the obligatory slavemaking ant Polyergus breviceps, retrieve and nurse Polyergus pupaejust as well as conspecific pupae in a choice test. No such attraction was found toward pupae of the facultative slavemaker; Formica wheeleri,which also enslaves F. occulta. Formica neogagates,a sympatric species which is not parasitized by either slavemaker, preferentially retrieves and tends conspecific brood over that of Polyergusand F. wheeleri.It is proposed that brood of obligatory slavemaking species must possess an attractive pheromone for slavemaker colony foundation to be successful, since slavemaker brood must be nursed by adult slave workers with no prior exposure to slavemaker brood. An attractive pheromone is not necessary in the brood of facultative slavemakers, since this brood is cared for by newly eclosed slave workers who imprint on the slavemaker brood.