Threshold gustatory

Worker honey bees (Apis mellifera) were caught at the hive entrance and maintained with food and water ad libitum in small Plexiglas boxes until the beginning of the experiments. To evaluate the gustatory threshold and for learning and metabolism experiments, honey bees were immobilized individually in small plastic tubes with a drop of wax-collophane mixture laid between the dorsal part of the thorax and the tube. The head and the prothoracic legs were free to move, allowing the honey bee to clean its antennae from the repeated sucrose stimulations. Honey bees underwent a... 

The aim of this experiment was to study the effect of IMl on the gustatory perception. The gustatory threshold was defined as the lowest concentration of a sucrose solution applied to the antennae able to elicit a proboscis extension. The threshold was defined twice for each honey bee first before any treatment and then after IMl or vehicle application. Several doses of IMl were used with several time-intervals between the application of the drug and the test. 

An increase in the gustatory threshold was observed between the first and the second determinations whatever the treatment (Figure 6.2). A very slight increase of less than one-half unit was found for the vehicle and for the lowest doses of IMI (1.25 and 2.50ng/bee). Animals treated with the vehicle (controls) were not different from those receiving no treatment (data not shown). Groups that received 1.25 and 2.50ng IMI were not different from controls, so in subsequent habituation experiments, both doses could have been used. A loss of sensitivity was noticed for the dose of 5 ng after 1 hour. This delayed effect seems not to be related to the time needed by imidacloprid to reach the brain from the thoracic application... 

Figure 6.2 Variations of the gustatory threshold (arbitrary units) 15 min, 30 min, or 1 h after thoracic application of DMSO (n = 20 for each time) or imidacloprid at different doses (1.25, 2.5, 5ng/bee). The number of imidacloprid-treated animals is indicated on the graph. P<0.05.

Homologous series of aliphatic n-alcohols and -fatty acids are useful to test the latter possibility, since manerous studies on membranes involve such compounds (e.g. X> ) Previous studies using alcohols and fatty acids indicated that olfactory and gustatory thresholds for these compounds are closely related to chemotactic thresholds The purpose of the present study... 

The studies cited in this paper show that for n-aliphatic alcohols (C1-C12) and -acids (C2 Cg), olfaction and taste act in similar ways as chemotaxis and anesthesia. Jain et al. ( ) came to a similar conclusion for many other membrane systems. Alcohols and fatty acids were used in the present study since olfactory and gustatory data on these compounds could be compared with those on many other systems. It should be kept in mind that threshold... 

A major roadblock in identifying gustatory properties of stearic acid is the absence of a delivery system that can present high concentrations or amoimts of hydrophobic stimuli in the absence of tactile (and olfactory) cues. For example, Chale-Rush et al. [4, 22] and Mattes [2] foimd that the detection of smell and taste thresholds of fatty acid stimuli differed with presentation conditions. This absence of a suitable delivery system ciurently limits suprathreshold studies on fatty acid chemosensation in the oral cavity. 

Consummatory Behavior - Rats treated with moderate doses of PCPA consume laboratory food and water normally,10b,19c,22 ut appear to be more finicky or responsive than controls in their consumption of solutions of alcohol, 22, 23 saccharin,23c dextroselOh or quinine,18 suggesting that gustatory or olfactory thresholds may be lowered by PCPA. 

As stated earlier, taste, chemicals that initiate a gustatory response, and smell, chemicals that function as odorant molecules have been extensively studied, first with arthropods and more recently with vertebrates. Since the development of very efficient separation techniques and high sensitive detection systems, we are no longer limited to taste panels and threshold odor detection by humans. Table I shows some examples of the behavior response as shown by certain species for a specific chemical. 

---