Shemilt, Susan Jayne (2021) An investigation into the biosynthesis of cuticular hydrocarbons in British ants using isotopically labelled diets and gas chromatography - mass spectrometry. Doctoral thesis, Keele University.

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Ants are one of only four groups which can be classed as being truly social, that is they demonstrate altruistic behaviours towards nestmates. However in order to do this there must be a complex nestmate recognition signal at work. This signal is generally poorly understood, however it is accepted that it makes up a small part of the overall chemical profile present on the cuticle of the ant. This cuticle is coated with a variety of long chain hydrocarbons; the biosynthesis of which is a complex, multi-step process which is generally not well studied in social species. Many of the biosynthetic pathways already discovered have been done so using other insect species which are traditionally easier to work with. Therefore the main aim of this study was to test whether these biosynthetic pathways were also applicable to our studied British ant species.

In order to aid the elucidation of the biosynthetic routes, simple feeding experiments were devised. These experiments involved feeding a variety of species of common Britsh ants artificial diets. The species chosen for these experiments belonged to the subfamilies Formicinae and Myrmicinae and the diets were modified by adding an isotopically labelled substrate. The experiments of this type explored the incorporation of these labels into the final biosynthesised hydrocarbon product. Successful incorporation suggested that the substrate was a biologically important molecule to the biosynthetic process; either used as a precursor or later in the biosynthetic process. The results presented within this thesis showed that the incorporation of these labelled substrates depended on a number of factors. The amount of incorporation appeared to vary by species, substrate and label type, as well as possible environmental and instrumental factors such as ant health and instrument sensitivity.

It was generally found that the labels based on deuterium atoms were less reliable as their more labile nature meant that any trends were less discernible. More reliable and insightful results were gained when using carbon-13 labels. The incorporation appeared to vary with some species showing different responses to others, however the reasons behind this difference are unknown. It could be down to subtle differences between the biosynthetic pathways or a previously unconsidered factor could be important, such as the health of the colony or rate of hydrocarbon production.

The main challenge of this work was sourcing both the correct species of ant, and labelled substrates that were cost effective to use. Custom organic synthesis was used in order to produce a wide range of labelled fatty acids, however ultimately experimental design was dependant on commercial substrate availability.

The results shown within this thesis indicate that there is a lot of unknown knowledge surrounding biosynthetic processes in ants and that models gained from other species cannot necessarily be applied to ants. However, it is also clear that there are many possible dependant factors in uencing this work and that far more research needs to be carried out in order to understand the underpinning biosynthetic processes more clearly.

Item Type: Thesis (Doctoral)
Subjects: Q Science > QC Physics
Divisions: Faculty of Natural Sciences > School of Chemical and Physical Sciences
Contributors: Drijfhout, FP (Thesis advisor)
Depositing User: Lisa Bailey
Date Deposited: 18 Oct 2021 11:48
Last Modified: 18 Oct 2021 11:49

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