Impact of a social parasite on ant host populations depends on host species, habitat and year

Parasites often affect the abundance and life-history traits of their hosts. We studied the impact of a social parasite - a slavemaking ant - on host ant communities using two complementary field manipulations. In the first experiment, we analysed the effect of social parasite presence on host populations in one habitat. In a second experiment, conducted in two habitats, we used a cross-fostering design, analysing the effect of sympatric and allopatric social parasites. In the first experiment, host colonies benefited to some extent from residing in parasite-free areas, showing increased total production. Yet, in the second experiment, host colonies in plots containing social parasites were…