Table 1.

Response of Anopheles gambiae in an olfactometer to compounds identified in bacterial headspace samples.

Compound	Dilution	N	Treatment	Control	χ2-test (P-value)	Effect
1-butanol	1:100	167	34	39	0.56
	1:1,000	160	23	38	0.05
	1:10,000	163	32	17	0.03	+
2,3-butanedione	1:100	166	25	42	0.04	-
	1:1,000	166	25	39	0.08
	1:10,000	169	44	28	0.06
2-methyl-1-butanol	1:100	165	22	25	0.66
	1:1,000	164	24	45	0.01	-
	1:10,000	168	38	22	0.04	+
2-methylbutanal	1:100	174	33	49	0.08
	1:1,000	172	13	22	0.13
	1:10,000	171	31	18	0.06
2-methylbutanoic acid	1:100	167	49	25	0.01	+
	1:1,000	171	49	41	0.40
	1:10,000	166	38	43	0.58
3-hydroxy-2-butanone	1:100	168	21	29	0.26
	1:1,000	170	29	36	0.39
	1:10,000	170	36	17	0.01	+
3-methyl-1-butanol	1:100	163	29	31	0.80
	1:1,000	158	20	28	0.25
	1:10,000	157	41	25	0.048	+
3-methylbutanal	1:100	170	34	18	0.03	+
	1:1,000	168	24	21	0.65
	1:10,000	172	16	16	1.00
3-methylbutanoic acid	1:100	163	22	25	0.66
	1:1,000	161	33	24	0.23
	1:10,000	161	30	18	0.08
2-phenylethanol	1:100	162	24	30	0.41
	1:1,000	167	15	40	<0.001	-
	1:10,000	155	11	25	0.02	-

The ten test compounds were applied in three dilutions (1:100; 1:1,000; and 1:10,000) in LDPE sachets. The effect of the compounds on mosquito behaviour was examined by adding them individually to the attractive basic blend (treatment) and to test this combination against the basic blend (control). N = number of mosquitoes released. The effect (E) of the compound tested on the 'attractiveness' of the basic blend is indicated: + = significant increase of mosquito catches compared to the control, - = significant reduction of mosquito catches compared to the control.