Pentane

The dewatered DSS feedstock used in this study was provided by Bergen Water and their biogas facility in Norway. The DSS was used as received with no drying or homogenisation, hence there is a risk of a certain degree of inhomogeneity in the batches used for each experiment.
Ethyl acetate (EtOAc, > 99.5%), ethanol (absolute, 99.96%), formic acid (> 98%), sodium sulphate ( $\ge$  99.0%, anhydrous), dodecane (analytical standard), benzoic acid ( $\ge$  99.5%), pyridine ( $\ge$  99.5%), N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) w/1% trimethylchlorosilane (TMCS)) and pentane ( $\ge$  99%) were purchased from Merck (Saint-Louis, MO, USA) and used without further purification.
The oil yields are calculated by mass of oil produced relative to input mass of dry, organic feedstock. The energy recovery in the bio-oil is calculated relative to the organic matter input in the DSS. As formic acid does not contribute significantly to the oil yield^{31 (link)}, this input is not included in the yield calculations. When ethanol is included in the reaction medium, it can react with specific hydroxyl substituents^{32 (link)} or in esterification of carboxylic acids. However, such contributions were not included in the yield calculations due to challenges in quantification, and this gives an unknown uncertainty in the recovery values for the different systems.

The hydrodistillation (HD) procedure was obtained in a modified Clevenger apparatus for 2 h. Diethyl ether (J.T. Baker Inc., NJ, USA) and pentane (Fluka, Merck KGaA, Germany) were used as the solvent trap in a v/v ratio of 2:1 (1 mL). HD was performed separately on the prepared samples of fresh and air-dried D. vermicularis. The volatile oil dissolved and trapped in the solvent trap was carefully removed with a pipette avoiding taking the water part. It was then slowly concentrated by the gentle flow of nitrogen until the volume of 0.2 mL was reached. An amount of 2 µL of the sample was used for GC–MS analyses. HD was performed in triplicate.

Ant mimics were created by extracting cuticular hydrocarbons from ants and transferring them to 2 mm glass beads (Fisher Scientific). Cuticular hydrocarbons were extracted using standard methods [33 (link)–35 ]. Surface lipids were extracted from thawed ants that were killed by freezing at -20°C, by soaking them in 1 mL of 100% pentane (Aldrich Chemicals) for 10 minutes with periodic shaking. Long-chain hydrocarbons are unreactive and not susceptible to evaporation in storage; freezing does not significantly cause quantitative or qualitative changes in cuticular hydrocarbon profiles compared to fresh samples. Cuticular hydrocarbons were separated from more polar surface lipids by eluting extracts with 2 mL of 100% pentane through a 2 cm column of silica gel (Merck; grade 60, 70–230 mesh, 60Å) in a 5.75 inch glass Pasteur pipette. The extracts were added to a glass tube containing 2 mm glass beads equal in number to the ants extracted. The solvent was allowed to evaporate thus transferring one ant-equivalent of purified cuticular hydrocarbons from ants to each ant mimic.