No abstract

Predatory social wasps are well studied in several aspects; however, foraging behaviour, especially that which takes place away from the nest at often unpredictable locations, or specialized behaviours to find and subdue prey are not well understood. In the Brazilian tropical savanna, the Polistinae wasp Brachygastra lecheguana is specialized in preying on some endophytic weevil larvae which develops inside floral buds. We hypothesized that these wasps utilize a combination of different mechanisms such as visual, chemical (odour) and possible tactile cues to find the weevil larvae. Using a combination of experimental manipulations (visual; chemical; visual/chemical) we tested the wasp’s ability to detect the endophytic larvae in the field. Additionally, we checked the ability of this wasp to detect vibrations produced by the weevils inside the buds. Our results suggest that the B. lecheguana wasp utilizes a sequence of eco-physiological mechanisms to find the endophytic larva inside floral buds: sight, smell, and perhaps touch. The use of multiple cues by this wasp guarantees such a high rate of predation on endophytic beetles that the wasp may have positive implications (reduction in weevils’ infestation) for the future of the host plant’s reproduction.

Ants can interact with plants in several ways, being one of the most common visitors of extrafloral nectaries (EFNs). However, pericarpial nectars (PNs) may represent to the ant community a similar resource as EFN would do. Here, we investigate how an ant community interacts with PNs by an individual-based network, using Tocoyena formosa as a model. We hypothesized that plants with more PN’s would present a higher ant richness in comparison to plants with less PNs and will occupy a central position in the network interaction. We observed 36 individuals of T. formosa in November of 2016. We recorded both the ant species and abundances on each plant, as well as the number of active PNs. To test our hypothesis, we performed a linear regression between PNs and ant richness. We performed a bipartite network analysis to obtain both the specialization and centrality metrics of each plant, and we also conducted linear regressions between the number of PNs and both the specialization and centrality. We confirmed our hypothesis, in which the ant community was more rich in individuals of T. formosa with more active PNs, and these individuals were more central, being important for the maintenance of the interactions with ants. We believe that coexistence between ants foraging is possible in T. formosa due to the seasonality and short time prevalence of the PNs, whose dominant ants do not have able time to master the resource and exclude the others, allowing different species to use the same plant.