Table 1. Quantification using GC–MS and FTIR of the role of bacteria in the transformation of caffeine in H. hampei.

Experiment	Treatment*	Caffeine in frass†, mean±s.e
		GC–MS‡	FTIR‡
Control	H. hampei—normal microbiome	0.348±0.038 (b)	BDT§ (b)
Antibiotic	H. hampei—antibiotic-treated	2.154±0.127 (a)	1.757±0.410 (a)
Antibiotic-reinfection	H. hampei—antibiotic-treated, reinfected with P. fulva	0.639±0.022 (b)	BDT§ (b)

ANOVA, analysis of variance; BDT, below detection limits; FTIR, Fourier transform infrared spectroscopy; GC–MS, gas chromatography–mass spectrometry; LSD, least significant differences.

^*After treatment, insects were transferred to antibiotic-free fluorosphere-labelled diet (minimal diet) and left to feed for 4 h before frass collection. N=6 (measured samples) for FTIR and N=4 for GC–MS. Caffeine values per treatment were statistically compared with one-way ANOVA and least significant difference test.

^†In milligram of caffeine per gram of diet.

^‡Values with same letter are not statistically different from each other, LSD test (P<0.05).

^§For ANOVA analysis, these values were defined as zero.