Ecologia comportamental e de interações: vespas sociais e suas colônias

Abstract

The selection of nesting sites by social wasps is influenced by two types of selective pressure: abiotic and predation factors, however, in recent years, the social wasps have “preferred” a larger plot of exotic plants as a nesting substrate. The natural enemies act in this selection, attracted mainly by the resources made available by the colonies, and consequently they cause their ruin, the inquilinism in nests of social wasps, in turn, is little known and documented. Thus, this work aimed to understand the choice of social wasps in using more exotic plants as a nesting substrate, and through the tools of interaction networks to understand the relationship between wasps and natural enemies and wasps and inquilines. For the first objective, social wasps colonies were collected in native and exotic plants from 2011 to 2017 and evaluated three characteristics: "Broad Leaves", "Perennial Leaves" and "Presence / Absence of Trichomes", in addition to 36 months of observations in Dracaena fragrans in order to record the number of colonies during each phase of their cycle and at each time of year. Finally, collections were carried out with entomological umbrella on specimens of D. fragrans, as an exotic specimen, and in Portea petropolitana, as a native specimen. For the second and third objective, active and abandoned colonies were collected randomly between 2016 and 2018 in urban and secondary forest samples from seven Brazilian cities. All colonies were inspected, stored in plastic containers covered with voile tissue and kept in the laboratory, adult individuals were inspected to verify the presence of ectoparasites. After 30 days, the arthropod emergence/presence was verified and the containers were opened for a new inspection. In order to compare the wasps-enemy networks and wasps-inquilines we use the following metrics: connectivity (C), network asymmetry (W), nesting (NODF), specialization (H2') and robustness (R). A total of 53 species of plants were recorded, being 32 exotic species with 245 colonies and 21 native species with 50 colonies. The most important characteristics for nesting were similar, however, the presence of trichomes was superior in native plants. The life cycle of D. fragrans was similar to that of native plants, not explaining the preference of wasps. A total of 336 individuals were collected with the entomological umbrella, most of them represented by the Formicidae family. The guilds of predators, herbivores and omnivores were represented uniformly. Of 44 colonies evaluated, 24 presented some natural enemy, being 11 species of wasps and 14 species of natural enemies. In general, the results show that the interactions between wasps and natural enemies tend to be asymmetric and have low specialization and both sides of the network indicate robust data. During the collection and survey of the colonies and nests, it was possible to register seven new records of interactions between natural enemies and social wasps: Elasmus polistis, Entedoninae, Eupelminae, Megaselia scalari, Melaloncha sp., Mirothrips arbiter and Leptus sp. In relation to the inquilines, of the 88 colonies collected, 49 had some associated inquilines: 15 in active colonies and 34 in abandoned colonies, 19 species of social wasps and 31 species of inquilines. In network metrics, the results obtained show that the interactions between wasps and inquilines tend to be asymmetric, more inquilines and present low specialization and robust results. Considering that each species recorded plays a fundamental role in the equilibrium of ecosystems and that the natural environment is suffering serious threats, we can say, based on the data of this work that, in addition to its recognized ecological role, social wasps can be pointed indirectly as important maintainers of a range of other species.