Cuidado parental e incidência de predadores e parasitoides de ovos em ootecas de aranhas orbitelas (Araneae: Araneidae, Uloboridae) em Minas Gerais, Brasil

Abstract

Parental care is a trait present in many animals, increasing the offspring survival with the reduction of the mortality caused by biotic and abiotic factors. In spiders, parental care is quite diverse, being frequently efficient against some generalist predators, such as ants. For birds and other visually orientated predators, spiders have various strategies against predation, like camouflage and disguises (“masquerade”). However, some groups of predators and parasitoids (e.g. wasps, dipterans and mantispids) have species capable of surpassing the multiple lines of defense and attack the eggs of spiders. Still, little is known about the occurrence and impact of these natural enemies on offspring survival of spiders, and what potential effect parental care in this context. Thus, in this thesis we investigate the behavioral ecology of spiders from the families Araneidae and Uloboridae and their eggs, describing the natural enemies of each studied species. We demonstrate that parental care in Manogea porracea (Araneidae) is efficient for the survival of the eggs in a population on Cerrado, even in the presence of an egg predator that had not been described previously attacking the species. We investigated maternal care in the spider Miagrammopes unipus (Uloboridae) describing its behavior with the egg sacs, the variation in the egg sacs and the attack of the eggs by a parasitoid wasp. We also investigated camouflage in this species through the calculation of background matching between females, their egg sacs and substrates used to rest. We registered the insects associated with the egg sacs of 10 species of spiders, including the two previously mentioned. Only one species was not attacked by any natural enemy, the invasive spider Cyrtophora citricola (Araneidae), recently found in Brazil. All other nine species were attacked by some egg predator or parasitoids, such as wasps, diptera and mantispids. Finally, we describe a parasitoid wasp of the spiders attacking C. citricola, showing the use of a new host for a native wasp, but still without any records of predators or parasitoids attacking their egg sacs in the population studied. Many interactions between the spiders, their egg sacs and natural enemies were explored in this thesis, contributing to the understanding of the ecology and evolution of these animals.