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Ecology and evolution of stingless bees: a multiscale approach with an emphasis on the Afrotropics

par Noiset, Pierre
Président du jury Hardy, Olivier J.
Promoteur Vereecken, Nicolas
Publication Non publié, 2025-03-13

Thèse de doctorat

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Résumé :

The exponential growth of human activities is disrupting the Earth system, threatening the integrity of the biosphere. The ongoing ‘6th extinction wave’ is reducing ecosystem resilience, with dramatic ecological, social and economic consequences. One of the most concerning aspects of biodiversity decline is the extent of our ignorance, both in terms of data and knowledge, even for the most abundant species.Stingless bees (Apidae:Apinae:Meliponini) are a group of eusocial bees producing honey that are predominantly found in the tropical and subtropical regions of the world. Stingless bees visit thousands of wild plants and crops in the Tropics, providing key ecosystem services that are increasingly threatened by the use of chemicals, land-use and climate change. Despite their importance, research has been largely focused on the Western Honey Bee Apis mellifera, on which we rely massively for agriculture and honey production.In this thesis, we provide a study of the ecology and evolution of stingless bees at different spatial scales, with a specific focus on Afrotropical species. We present four studies at global or continental scale that are followed by four local studies that apply some of the theoretical concepts developed in the initial studies.First, we compiled spatiotemporal occurrence records at an unprecedented scale from both public and private databases. We examined the relationship between stingless bee distribution and environmental factors, ultimately characterising their ecological niche and producing the first habitat suitability maps for the Meliponini tribe (Chapter 3). Predictions of habitat suitability, as well as interpretation of diversity and distribution patterns, were hindered by several knowledge shortfalls. These gaps include insufficient distribution data and limited ecological and evolutionary understanding, particularly in the Afrotropics.To fill this gap, we investigated the foraging ecology of four stingless bee species (Hypotrigona araujoi, Meliponula bocandei, Meliponula togoensis, and Meliponula ferruginea) across urban and rural landscapes in diverse environments of three African countries (Chapters 4 & 7). Our findings revealed a large variety of host plants for the collection of pollen and nectar, with a high reliance on mass-flowering trees driving significant niche overlap among social bees. Morphological and ecological differences resulted in species-specific foraging patterns, which have major implications for beekeeping, afforestation and conservation programmes.We further studied the impact of the interactions between stingless bees and their environment on hive products. We aimed to disentangle the roles of evolutionary and environmental drivers of stingless bee honey compositional variation. We used a sampling design that combines honey profiling by H1-NMR spectroscopy and physico-chemical characterisation with the collection of honeys from Honey Bees and stingless bees in different tropical regions and environments. We conducted 4 studies (Chapters 5, 6, 8 & 9) that showed clear differentiation between the chemical composition and functional diversity of Honey Bee and stingless bee honeys, mainly due to the production of a range of bioproducts during sugar fermentation. The study of compositional variation of stingless bee honey showed that the role of ecological and evolutionary drivers and their joint effects varied according to the spatial scale, preventing the identification of a clear continental, phylogenetic or ecological pattern. Our results shed light onvibroader and less explored eco-evolutionary theories and provide guidelines for the establishment of scientifically-informed standards for stingless bee honey.We finally studied previously unexplored aspects of Traditional Ecological Knowledge related to stingless bees and the non-food uses of their honeys in Kenya (Chapter 10) through conducting semi-structured questionnaire. Our results uncover the vast and hitherto unexpected diversity of Indigenous uses associated with stingless bee honey.This thesis offers a robust and comprehensive study on the ecology and evolution of stingless bees, notably by formally incorporating the Afrotropics — an area where these bees are least known — and emphasising their central role in maintaining environmental and human health. Our holistic approach integrated cutting-edge analytical methods to evaluate and quantify the ecosystem services provided by stingless bees across different regions and ecosystems. This work identifies critical gaps in our understanding of the ecology and evolution of this diverse clade and highlights the need for cross-sectoral & transdisciplinary efforts to conserve and sustainably manage these species. Addressing the shortfalls highlighted in this thesis is essential for preserving the health of ecosystems and the communities that depend on them.