4 methylphenol

Artificial selection experiments were conducted for behavioral responses to four odorants: 4-ethylguaiacol (Sigma-Aldrich; St. Louis, MO), 4-methylphenol (Sigma-Aldrich), methyl hexanoate (Sigma-Aldrich), and ethyl acetate (Sigma-Aldrich), using Flyland as the base population [45 (link)]. All behavioral assays were performed at 0.01%. To commence selection, we measured behavioral responses of virgin females and males to each odorant. Upon completion of each assay, flies were collected from the odor- and non-odor sides of the T-maze. Flies collected from the odor side were used to establish the high lines, while files from the non-odor side were used to establish the low lines. Behavioral tests were performed until a minimum of 25 females and 25 males for each of three replicate high and low responding lines were obtained for each odorant. To establish the control lines, assays were conducted in which there was no odor present in the T-maze. Flies were then collected from one side of the T-maze, selected at random. This selection regime was repeated each generation for 30 generations. Symmetrical responses to selection were assessed at generation 18.

Chemical standards of acetone, butane-2,3-dione, butan-2-one, thiophene, dimethyl disulfide, hexanal, heptan-4-one, heptan-2-one, 2-pentylfuran, dimethyl trisulfide, 6-methylhept-5-en-2-one, benzaldehyde, octanal, d-limonene, trans-3-octen-2-one, linalool, 4-methylphenol, 1,3-di-tert-butylbenzene, internal standard (4-methylpentan-2-ol), and sodium chloride (NaCl, ≥99.5%) were supplied by Sigma-Aldrich (Saint Louis, MO, USA). MilliQ water (Millipore, Bedford, MO, USA) was used for the preparation of standards. Hydrochloric acid (HCl, 37%) was purchased from Chempur (Piekary Śląskie, Poland). The 75-μm carboxen/polydimethylsiloxane (CAR/PDMS) (stable flex) solid-phase microextraction (SPME) fibers were purchased from Supelco (Bellefonte, PA, USA).