No abstract

In the Brazilian savanna many plant species bear regular associations with patrolling ants that are aggressive towards insect herbivores. However, not only ants but also several species of predatory wasps are attracted to plants due to the extrafloral nectaries (EFNs). Such wasps feed on both herbivores and plant exudates. In this study we describe the foraging behavior of the social Polistinae wasp Brachygastra lecheguana in the extrafloral nectaried shrub Banisteriopsis malifolia, and investigated the influence of patrolling ants Camponotus blandus on the activity of the wasp. Brachygastra lecheguana fed on the endophytic larvae of Anthonomus (Curculionidae) beetles that developed inside flower buds. The wasp lacerated the bud layers to reach the beetle larvae located at the bud core. The wasp visits to Ba. malifolia were statistically related to the abundance of flower buds and beetles. Ant exclusion experiments revealed that the hunting behavior of B. lecheguana on beetles was not related to the absence of C. blandus. However we found that wasps spent more time consuming extrafloral nectar on branches where ants were excluded. This is the first study reporting extrafloral nectar consumption by B. lecheguana, as well as the predation on herbivores in natural areas. In cerrado vegetation, ants benefit the plant by reducing insect herbivores, and our study provides evidence that the B. lecheguana -Ba. malifolia system represents a potential interaction where the wasp may also benefit the host plant. The value of this wasp species as a plant-guard is discussed.

No abstract

In the Brazilian savanna, myrmecophilous lycaenids are often found in many shrubs feeding on plant reproductive structures while are tended by ants, but only recently the role of both ants and food on the occurrence of lycaenids have received attention. In this study, we investigated the influence of Camponotus blandus (Formicinae) and flower bud abundance on the occurrence of Parrhasius polibetes, a florivorous lycaenid species that occurs in Banisteriopsis malifolia (Malpighiaceae). We also examined to what extent larval florivory was deleterious to plant reproductive outputs. Ant-exclusion experiments revealed that most P. polibetes individuals were found on branches with free C. blandus access. Nonetheless, the occurrence of larvae was not related to the abundance of ants and flower buds, indicating that the presence, rather than the abundance of mutualistic ants and food, influenced the occurrence of P. polibetes. Larvae were attended by C. blandus, which antennated frequently the dorsal nectary organ of larvae. Larval florivory was not deleterious to the plant. Banisteriopsis malifolia produces thousands of buds simultaneously and larvae feed only on a small portion of flower buds. The occurrence of P. polibetes in B. malifolia is advantageous for the larvae, since this plant supports mutualistic ants and plenty of food resources.

The presence of aggregates of A. reticulatum on Bauhinia has been reported, but the insects were mainly attended by ants of the genus Camponotus, and stingless bees were not regularly recorded in aggregations. We observed a colony of thetreehopper A. reticulatum and stingless bees, Trigona branneri, interacting on Bauhinia forficata (Fabaceae). Agonistic behavior was observed in bees when another individual of the same species or ants approached. Although this is not proof that the interaction between stingless bees and treehoppers is mutualistic, the interactions between ants and this insect are common and mutualistic. Thus, if T. branneri effectively provides protection for the aphids, a new mutualism can be the focus of future research to determine if the bee-aphid interactions have same ecological functions as the ant-aphid interactions.