Effect of nectar-foraging ants and wasps on the reproductive fitness of Turnera ulmifolia (Turneraceae) in a coastal sand dune in Mexico.
We evaluated the effect of different ant species on the reproductive fitness (estimated as end-of-season fruit set per treatment) of T. ulmifolia over two years (1991-93) on a sand dune matorral on the coast of Veracruz, México. The results show that (i) plants associated with the larger ant species (Camponotus abdominalis) produced more fruits than plants associated with the smaller ant species, and (ii) plants associated with ants were subject to lower levels of herbivory, than plants without ants. Consequently, ant presence is not synonymous of plant protection, and the level of protection by ants will depend on the size of the worker ants in a guild of ant visitors. Moreover, when ants were excluded, wasps and bees increased their visits, exerting a higher level of protection than that offered by the smaller ant species. However, the differential effect of wasps needs further attention.