Tending-ants increase survivorship and reproductive success of Calloconophora pugionata Drietch (Hemiptera, Membracidae), a trophobiont herbivore of Myrcia obovata O. Berg (Myrtales, Myrtaceae).

Abstract

The trophic relations between ants and hemipterans are very common in the Neotropical Region, but rarely explored in dry montane ecosystems. Given the diversity of outcomes of this type of interactions influenced by variation in biotic conditions (i.e. seasonality, spatial distribution, identity of species involved), new examples in different ecosystems can provide important data for a more general understanding of their impact in communities. We investigated the outcomes (direct benefits: survivorship and reproduction) of the relationship between the trophobiont herbivore Calloconophora pugionata (Membracidae) and its tending ants. The interaction occurs on Myrcia obovata (Myrtaceae), a common tree in montane forests and rupestrian fields of southeastern Brazil, and has never been studied before. Between 2008 and 2009, we selected and manipulated (ant-exclusion) trees in a pairwise experiment performed on plant branches infested by C. pugionata. This Membracidae laid its eggs peculiarly on the leaf margins, a behaviour that increased egg survival even when ants were absent. All life stages of the hemipteran exhibited higher survival rates (two-fold) and increased fecundity (four-fold higher oviposition rates) when attended by ants. This study shows that this ant-hemipteran interaction occurs in dry montane biomes in a way that is similar to other tropical ecosystems in which ants protect the hemipterans against predators, thus increasing their survival and reproductive fitness.