Appendix B. Mobile olfactometer: technical details and pictures.
For the biotests, we used a newly established mobile olfactometer (Fig. B1). The system allowed us to conduct the tests in the field with scents from naturally growing, unpicked flowers and insects that did not live in captivity and just recently foraged for resources. The airstream was produced by a battery driven electronic pump (Thomas Gardner Denver, G 24/08 30W; Fig. B3 p). Air was sucked in through a particle filter (Fig. B3 fi). Teflon tubes lead the airstream via a valve (Fig. B3 v) into a flask filled with charcoal (Fig. B3) to clean the air which was than directed into a flask filled with distilled water (Fig. B3) to moisten the air. The valve needs to be opened before switching off the pump in order to reduce the pressure in the system. The cleaned and moistened air was than directed to four flowmeters (Analyt-MTC, 112-08SA; Fig. B3 f) that allowed adjusting a constant flow [mL/min]. Scent application was accomplished in the following way (Fig. B2): flower or inflorescence stems were wrapped with Teflon tape and a hose of oven bag (Toppits, PET, Fig. B1 A o; Fig. B3 o) was tightly affixed at the Teflon tape using masking tape without damaging the plant tissue. The top end of the hose was thrust through the top part of washing flask which was clearly cut at the top (Fig. B2). Into the overlapping hose a Teflon washing flask topping (Fig. B3 w/t) was tightly pressed into the top part of the cut washing flask. The Teflon topping had two connections for spiral Teflon tubes: One supplied the air from the flowmeters the other one transported the scented air to the arenas (Fig. B3 arena). The whole assemblage was carried by a post and a laboratory clamp (Fig. B2).
We used a smaller version of the four field arena as described in Junker and Blüthgen (2008) (Fig. B4). A glass plate covered the arena. All holes for aerial in and out flow in the arena were obstructed with metal sieves to prevent ants from escaping. Air flew off a central hole. The whole apparatus was fitted into an aluminium box so that the whole setup can be transported to the field site.
FIG. B1. Mobile Olfactometer.
|FIG. B2. Odor source that supplies the arena of the olfactometer with floral scent.|
|FIG. B3. Schematic drawing of the mobile olfactometer, showing the battery (12 V), power button, electric pump (p), filter (fi), valve (v), washing flasks filled with charcoal and pure water, flowmeters (f), assemblage to apply the scent (w/t , o) and the Y-shaped arena. The two remaining flowmeters are used only when the four field arena is operated.|
|FIG. B4. Dimensions of the arena used for the biotests.|
Junker, R. R., and N. Blüthgen. 2008. Floral scents repel potentially nectar-thieving ants. Evolutionary Ecology Research 10:295308.