GC-EAG

Coupled gas-chromatography-electroantennography (GC-EAG) was performed as described by Logan et al.³⁷. Briefly, 2 µl of the pooled volunteer foot volatile collection was injected on to an HP1 column (50 m, 0.32 mm ID, 0.52 film thickness) with a cool-on column injector, and split so that half the sample was detected by the GC-FID (Chemstation, Agilent, Santa Clara, U.S.A.) and the other half was passed over the antennae of the mosquito. This formed a combined trace (Fig. 2) where mosquito responses were directly aligned with the chemicals causing them. The mosquito was prepared as above, and for the GC method, the oven started at 30 °C, was held for 1 min, then raised by 5 °C/min to 100 °C, then by 10 °C/min to 230 °C and held for 1 min. 4–6 replicates were carried out for P. falciparum infected and uninfected An. gambiae mosquitoes at day 8–10 (oocyst stage) and 15–16 days (sporozoite stage) post-bloodmeal. Conserved responses to FID peaks across replicates were aligned using a lightpad.