Online Supplementary Material

Table S1. The estimated release rates (in μmol/min) of the compounds tested in the dual-choice olfactometer at 27°C, and the weighted mean evaporation rate (μmol/min ± SEM) of each compound in Blend A and B from LDPE sachets during the two indoor trapping experiments.

Compound / Release rate1
(μmol/min) / Blend A5
(μmol/min) / Blend B5
(μmol/min)
Ammonia4 / 15 / 1.6 ± 1.0 / 0.1 ± 0.02
Lactic acid3 / 0.0001 / 0.26 ± 0.22 / 0.07 ± 0.03
Acetic acid / 0.005 – 1.03
Propanoic acid / 0.001 – 0.22 / 0.70 ± 0.47
2-Methylpropionic acid3 / 0.0007 – 0.13
Butanoic acid3 / 0.0003 – 0.07 / 0.21 ± 0.04
3-Methylbutanoic acid / 0.0002 – 0.002 / 0.10 ± 0.3
Pentanoic acid / 9.97E-5 – 0.02 / 0.05 ± 0.02
Hexanoic acid / 1.28E-5 – 0.003
Heptanoic acid2 / 0.28 ± 0.04
Octanoic acid / 2.72E-6 – 0.0005 / 0.19 ± 0.06
Nonanoic acid2
Decanoic acid / 1.7E-7 – 3.4E-5
Dodecanoic acid / 4.15E-7 – 8.3E-5
Tridecanoic acid / 5.18E-8 – 1.04E-5
Tetradecanoic acid / 5.59E-8 – 1.12E-5 / 0.03 ± 0.02 / 0.001 ± 0.0009
Hexadecanoic acid / 4.76E-8 – 9.53E-6

1 Calculation of the amount of odor (μmol) delivered in the main airstream of the olfactometer represented by the formula (Vp x Tst) / (R x Pst x T) (mol/L, after Ough and Stone 1961), multiplied by the air flow used to deliver a test compound and divided by the dilution by the main airstream of the olfactometer (100 times). Vp at 27°C has been estimated. A range is given for flow rates of 0.5 – 100 ml/min (except for 3-methylbutanoic acid: 0.5-5 ml/min) passing through the glass bottle containing the test compound. Ammonia, lactic acid, and C2–C9 carboxylic acids were liquids, C10–C16 carboxylic acids were solid compounds.

Vp= vapor pressure of test compound at operating temperature (in mm Hg) as calculated at 27°C on the website of J.A. Byers: http://www.chemical-ecology.net/java/jav-vp.htm (accessed 2 February 2009).

Tst= temperature in degrees Kelvin at standard conditions (298 K)

R= volume occupied by one mole of gas at standard conditions (22.4 L)

Pst= air pressure at standard conditions (760 mm Hg)

T= operating temperature in degrees Kelvin (300 K)

2 Vapor pressure of test compound not known

3 Vapor pressure of test compound estimated at 28°C by Dr M. Posthumus (personal communication).

4 The release rate of ammonia (136 ppm, 230 ml/min) was calculated based on the vapor pressure given at http://www.engineeringtoolbox.com/ammonia-d_971.html (accessed 2 February 2009).

5 LDPE sachets were weighted before and after each experiment (n= 4 and 6, respectively).

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