Comportamento de nidificação em Polybia platycephala Richards, 1978: dinâmica de temperatura e luminosidade

Abstract

Nests of social insects function as the interface between colonies and the environment, and studying how environmental factors relate to the nesting behavior is essential in order to understand these organisms’ success in settling and surviving in the urban area. On this sense, our work aimed to study the relation between the social wasp Polybia platycephala nest orientation and the incidence of environmental light, aside from describing its temperature dynamics regarding the microenvironment where it is set. In order to study nest orientation and light incidence, 22 nests were chosen in 2016 in the city of Juiz de Fora, MG, being 11 in the rainy season and 11 in the dry (n= 22). Nest orientation was verified and light incidence on each nest was assessed through the day (06:00h - 18:00h). Additionally, six nests had their orientation experimentally inverted and luminosity was assessed before and after the inversion in order to verify the effect of nest orientation on exposure to light. In order to study temperature dynamics, the same 22 nests were used, and the nest and ambient temperatures were assessed in parallel with the luminosity. In order to verify the effect of the wasp activity on colony temperatures, an abandoned nest and an active colony were observed for 24 hours. The results allowed us to conclude that P. platycephala shows nest orientation strongly biased towards east, increasing exposure to light during the morning; colonies are, however, able to perform modifications on this behavior in order to adapt themselves to their microenvironment and optimize this exposure. Nest temperatures are intensely related to the ambient, fluctuating in parallel with it, which indicates a great dependence of the colonies on the environment to assure their survival. Overall, we found that P. platycephala has an intimate relation with its microenvironment, which may help explain its success in settling urban areas, but also makes it sensible to environmental and climatic changes in them.