Criação e manejo de duas espécies de abelhas solitárias das tribos Anthidiini e Megachilini (Hymenoptera: Megachilidae) no Nordeste do Brasil

Abstract

Solitary bees that nest in pre-existing cavities constitute important models for the study of reproductive biology and present potential for management strategies aimed at conservation and pollination. However, for many Neotropical species, especially in anthropized environments, there are still significant gaps in knowledge about their bionomics and response to management. In this context, this thesis investigated the nesting biology, reproductive traits, and rearing potential of two species of Megachilidae, Dicranthidium arenarium (Anthidiini) and Megachile (Ptilosarus) cf. xanthura (Megachilini), in an urban area in Northeast Brazil. The study was conducted between August 2021 and November 2023, through the installation of trap nests with cavities of different dimensions. Nesting activities were monitored daily, and females of both species were individually marked, allowing continuous tracking from cavity occupation to adult emergence of their brood. The study evaluated aspects related to nesting behavior, nest architecture, reproductive effort, sex ratio, mortality, seasonality, and the influence of environmental variables, as well as the species' response to management interventions, such as the provision of nesting materials. D. arenarium predominantly used plant resin in nest construction, with flexibility in the use of alternative materials such as meliponine wax and resin. It demonstrated a preference for longer cavities (10 cm), a sex ratio skewed towards males, and an absence of significant correlation between nesting activity and climatic variables. The availability of nesting materials mitigated robbing and favored an increase in nesting, highlighting the importance of these resources as a limiting factor. The species exhibited behaviors that are still poorly understood, such as the prolonged stay of females inside the nest after oviposition. On the other hand, Megachile (P.) cf. xanthura built nests exclusively with leaf fragments, exhibited high reproductive efficiency and strong seasonality, with activity concentrated in periods of higher temperature and lower humidity. This species showed a sex ratio biased towards females, low incidence of parasitism, and a high rate of return to the emergence site, characteristics associated with good performance in trap nests. These results indicate potential for use in management programs and directed pollination. In an integrated way, the results demonstrate that both species respond positively to the use of trap nests but differ in the factors that influence their reproductive success. While D. arenarium is more sensitive to the availability of nesting materials, M. (P.) cf. xanthura responds mainly to climatic conditions. These results highlight that management strategies must consider the specific ecological requirements of each species. Thus, this work expands knowledge about the biology of solitary bees in Northeast Brazil and provides practical support for the development of management techniques aimed at the conservation, monitoring, and potential use of these species in pollination and environmental restoration programs.