Vainillin

Reagents for extraction and other measurements were supplied by Sigma-Aldrich (St. Louis, MO). Oleuropein, verbascoside, luteolin-7glucoside, apigenin-7glucoside, rutin, apigenin, luteolin, tyrosol, hydroxytyrosol, vanillic acid, vainillin, p-coumaric acid, and ferulic acid were obtained from Sigma Chemical (St. Louis, MO, USA) and Extrasynthese (Genay, France). Non-commercial phenolic standards such as ligstroside, hydroxytyrosol-1-glucoside, or the main secoiridoids derivatives were obtained from olive leaves, fruits and oils using a high performance liquid chromatography (HPLC) preparative system.

Standard multi-ionic solution for plasma spectrometry is from Perkin-Elmer, Waltham, MA, USA. N-benzoyl-DL-arginine, +catechin, p-nitroanilide, β-glucosidase, bacterial protease, porcine pancreatic trypsin, bovine pancreatic α-chymotrypsin, porcine intestinal peptidase, trypsin, boron trifluoride, and vainillin were from Sigma (Sigma Chemical Co., St Louis, MO, USA). All the other chemicals were of analytical grade.

In the Reserva and Guinea sites, male euglossine bees were sampled for a period of 11 months from June 2006 through May 2007 (except April 2007). In Rio Claro, sampling was conducted from October 2007 to September 2008. At each site, we sampled bees at a single location once every month for 5 h between 08:00 AM and 1:00 PM. We used five chemical baits: cineole (CIN), 1,4-dimethoxybenzene (DMB), methyl cinnamate (MC), methyl salicylate (MS), and vainillin (VAI) (Sigma-Aldrich, St. Louis, MO). We applied each chemical to a small square (5 × 5 cm) of absorbent paper clipped to a tree trunk at a height of 1.5 m.
Baits were placed along an existing trail 10 m away from each other, along mountain ridges. CIN and VAI were replenished every 1.5 h, and the remaining baits were replenished every 2.5 h. Censuses were conducted only during sunny days or slightly cloudy days to avoid short-term variability between samplings rounds. We sequentially collected bees that visited each of the five chemical baits using entomological nets and placed bees in 95% ethanol. Specimens were pinned and deposited at the Museo de Historia Natural of the Universidad de Los Andes (Bogota, Colombia). Species identification was carried out using reference collections of regional euglossine bees as well as taxonomic keys (Bonilla-Gómez and Nates-Parra 1992 ; Roubik and Hanson 2004 ).