Microstructure and Chemical Composition of Colletes halophilus Nest Cell Linings

Abstract

Bees of the genus Colletes have the unique ability to create what has been described as a cellophane-like nest cell lining material for the protection of their developing brood. Chemically, this material has been described as a linear polyester and has been noted for being naturally derived, robust and strongly resistant to chemical degradation as well as biodegradable. Despite these interesting properties little is known about the structure, chemistry or physical properties of the Colletes nest cell lining. This study investigates the nest cell linings of Colletes halophilus to addresses the discrepancies in the published literature on nest cell lining chemistry and structure. Using a variety of microscopical, analytical chemistry, mechanical and thermal characterization techniques a more complete model of the nest cell lining material is revealed. As opposed to simply being composed of a linear polyester as previously thought, the Colletes halophilus nest cell linings are shown to be biocomposite structures constructed from silk fibres laid down as a scaffolding for the application of a copolymer matrix composed of multiple ester containing compounds. Notably a composite structure has been revealed using SEM, TEM and confocal microscopy, and a more complex chemical composition revealed through FTIR and TOF techniques. Additionally, the Colletes halophilus nest cells show mechanical and thermal properties characteristic of a largely amorphous, thermoset polymer. These results advance the current understanding of the anatomy and behaviour of the Colletes bees as well as providing new information on the morphologyand chemistry of the nest cell lining material. The overall outcome of this study is a clearer understanding of the structure and composition of the nest cell lining itself as well its potential as biopolymer. Advances in the understanding of the structure and composition of this naturally derived composite may serve as a model for nonpetroleum derived polymers in the future.

Date of Award	1 Mar 2012
Original language	English
Awarding Institution	University of Bath
Supervisor	Irene Turner (Supervisor) & Martin Ansell (Supervisor)