Sour-Taste Tolerance in Four Species of Nonhuman Primates

The taste of most fruits is characterized by a mixture of sensations termed sweet and sour by humans, and the food selection behavior of primates suggests that they may use the relative salience of sweetness and sourness to assess palatability of potential food items. Therefore, taste responses of six squirrel monkeys, five pigtail macaques, four olive baboons, and four spider monkeys to sweet-sour taste mixtures were assessed in two-bottle preference tests of brief duration (2 min). Monkeys were given the choice between a reference solution of 50 mM sucrose and mixtures containing 10, 30, or 50 mM citric acid plus 10, 20, 50, 100, 200, 400, 800, or 1000 mM sucrose. We found that the four species differed markedly in their acceptance of physiological concentrations of sour-tasting citric acid. Whereas olive baboons showed the highest degree of sour-taste tolerance and actually preferred most of the sweet-sour taste mixtures over sweet-tasting reference solutions, squirrel monkeys showed the lowest degree of sour-taste tolerance and rejected most of the sweet-sour taste mixtures even when they contained considerably more sucrose than the reference solutions. Additional tests demonstrated that the preference for sweet-sour taste mixtures was not based on masking effects. Rather, the animals perceived both the sweetness and the sourness of the taste mixtures and made a trade-off between the attractive and aversive properties of the two taste qualities. The results of this study suggest that the proximate reason for the marked differences in acceptance of sweet-sour taste mixtures are differences among species in the hedonic evaluation of the sour taste of citric acid. Possible ultimate reasons, which do not necessarily exclude, but may complement each other, include evolutionary adaptation to dietary specialization, avoidance of competition pressure, and phylogenetic relatedness.     

Gustatory Responsiveness to Six Bitter Tastants in Three Species of Nonhuman Primates

Gustatory responsiveness of six adult squirrel monkeys, four spider monkeys, and five pigtail macaques to six bitter tastants was assessed in two-bottle preference tests of brief duration (2 min). Animals were given the choice between a 30-mM sucrose solution and defined concentrations of a bitter tastant dissolved in a 30-mM sucrose solution. With this procedure, Saimiri sciureus, Ateles geoffroyi, and Macaca nemestrina were found to significantly discriminate concentrations as low as 0.2, 0.05, and 0.1 mM quinine hydrochloride; 1, 1, and 0.05 mM caffeine; 20, 5, and 1 mM naringin; 5, 2, and 1 mM salicin; 0.01, 0.001, and 0.02 mM sucrose octaacetate; and 0.05, 0.01, and 0.5 mM denatonium benzoate, from the alternative stimulus. With the exception of naringin in the pigtail macaques, all three species rejected all suprathreshold concentrations of all bitter tastants tested. The spider monkeys and the pigtail macaques displayed the lowest taste avoidance thresholds with three of the six tastants each; in contrast, the squirrel monkeys displayed the highest taste avoidance thresholds with four of the six tastants. The across-tastant patterns of taste avoidance thresholds were identical in spider monkeys and squirrel monkeys; both species displayed the following order of sensitivity: sucrose octaacetate > denatonium benzoate > quinine hydrochloride > caffeine > salicin > naringin. All three primate species were more sensitive to the two artificial tastants (sucrose octaacetate and denatonium benzoate) compared to the four naturally occurring tastants. However, the concentrations detected by all three primate species with the four naturally occurring tastants are well below those reported in plants or arthropods consumed by these species suggesting that they may use bitterness as a criterion for food selection.     

Taste Preferences for Five Food-Associated Sugars in the Squirrel Monkey (Saimiri sciureus)

The taste preferences of six adult squirrel monkeys for sucrose, fructose, glucose, lactose, and maltose were assessed in two-solution choice tests of brief duration (5 min). In experiment 1 the monkeys were given the choice between all binary combinations of the saccharides presented in equimolar concentrations of 50, 100, 200, and 400 mM, respectively. Preferences for individual sugars were stable across the concentrations tested and indicate an order of relative effectiveness (sucrose > fructose > glucose ≥ maltose ≥ lactose), which is identical to the order of sensitivity found in this species and similar to findings on relative sweetness in man. In experiment 2 the squirrel monkeys were given the choice between a standard sucrose solution of 50 mM and ascending series of concentrations of the other saccharides in order to determine concentrations that were consumed in equal amounts compared to the standard. Solutions of 100 mM fructose, 300 mM glucose, and 200 mM lactose and maltose were found to be equally effective to the 50 mM sucrose, whereas other concentrations led to marked preferences for one of the alternatives. The finding of concentrations of equal effectiveness are consistent with findings on concentration-dependent loss of discrimination ability in man and support the hypothesis that for squirrel monkeys sucrose may indeed be indiscriminate from fructose, glucose, lactose and maltose when concentrations are suitably adjusted. The results suggest that squirrel monkeys and man share important features of sweet-taste perception.     

Taste Responsiveness to Food-Associated Acids in the Squirrel Monkey (Saimiri sciureus)

The taste responsiveness of six adult squirrel monkeys to five food-associated acids was assessed in two-bottle preference tests of brief duration (5 min). In experiment 1 the monkeys were given the choice between tap water and defined concentrations of citric acid, ascorbic acid, malic acid, acetic acid, or tannic acid dissolved in tap water. In experiment 2 the animals were given the choice between a 50 mM sucrose solution and defined concentrations of the same acids dissolved in a 50 mM sucrose solution. With both procedures Saimiri sciureus significantly discriminated concentrations as low as 10 mM ascorbic acid and acetic acid, 5 mM citric acid and malic acid, and 0.2 mM tannic acid from the alternative stimulus. The results showed: (1) that squirrel monkeys respond to the same range of acid concentrations as other nonhuman primate species tested so far, (2) that Saimiri sciureus detects food-associated acids at concentrations well below those present in most fruits, and (3) that the responsiveness of this New World primate to acidic tastants was largely unaffected by the addition of a sweet-tasting substance. The results support the assumption that squirrel monkeys may use sourness and/or astringency of food-associated acids as a criterion for food selection.     

The Frequency of Occurrence of Acyclic Monoterpene Alcohols in the Chemical Environment does not Determine Olfactory Sensitivity in Nonhuman Primates

Using a conditioning paradigm, the olfactory sensitivity of five spider monkeys, three squirrel monkeys, and three pigtail macaques for six acyclic monoterpene alcohols that differ markedly in their frequency of occurrence in plant odors was assessed. The results showed that: (1) all three primate species have a well-developed olfactory sensitivity for acyclic monoterpene alcohols; (2) squirrel monkeys are significantly more sensitive for members of this class of odorants than the other two species and are able to detect all six odorants at concentrations below 0.1 ppm; and (3) there is a lack of positive correlations between olfactory sensitivity and the abundance of the acyclic monoterpene alcohols in flower odors and etheric oils. The results lend support to the growing body of evidence that suggests between-species comparisons of the number of functional olfactory receptor genes or of neuroanatomical features are poor predictors of olfactory performance. The findings do not support the hypothesis that olfactory sensitivity for members of a chemical class may be related to the frequency of occurrence of such odorants in a species' chemical environment.     

Serum α-lipoprotein responses to variations in dietary cholesterol,protein and carbohydrate in different non-human primate species

Serum α-lipoprotein responses to variations in dietary cholesterol, protein, and carbohydrate were studied in different nonhuman primate species. Chimpanzee, rhesus, green, patas, squirrel and spider monkeys all showed significant interspecies differences in serum total cholesterol responses to 1.84 mg/kcal exogenous cholesterol. Dietary cholesterol significantly increased the α-lipoprotein cholesterol in all species except rhesus and chimpanzee. Among these species, there was no relationship between the basal serum lipoprotein profile and subsequent lipoprotein responses to dietary cholesterol. Although the level of dietary protein at 6%, 12%, and 37% of calories had no appreciable main effect on serum total cholesterol in spider monkeys, very low protein diet (6% of calories) produced a significant elevation in α-lipoprotein cholesterol. Serum α-lipoprotein responses to exogenous cholesterol (1.84 mg/kcal) was highest for the very low protein diet and lowest for low protein diet (12% of calories). Diets with high sucrose (76.5% of calories) and low saturated fat (12.5% of calories) containing no added cholesterol were tested in squirrel and spider monkeys and produced a consistent serum total cholesterol response; the α-lipoprotein response was significantly higher in squirrel monkeys than in spider monkeys. The above findings have implications in experimentally induced and comparative atherogenesis. Presented at the Lipoprotein Symposium AOCS meeting, St. Louis, Missouri, May 1978.     

Different food sources affect the gustatory response of Anaphes iole,an egg parasitoid of Lygus Spp

The gustatory response of female Anaphes iole wasps to naturally occurring carbohydrates, a commercial food source, and host (Lygus lineolaris) frass was determined. Wasps responded to all 14 of the sugars at the highest concentration tested (2 M). At this concentration, sucrose, glucose, maltose, melezitose, fructose, and erlose all elicited <90% acceptance. The lowest concentration that evoked a response (=acceptance threshold) for these sugars was >1/256 M, with the exception of glucose, which was 1/16 M. Raffinose, trehalose, mannose, galactose, melibiose, rhamnose, stachyose, and lactose led to >50% gustatory response by the wasps at 2 M, and were categorized as moderately stimulatory sugars. The acceptance threshold for these sugars was <1/4 M, with the exception of raffinose, which was 1/256 M. In trials with moderately stimulatory sugars combined with either sucrose or maltose, only the rhamnose+maltose mixture significantly inhibited the gustatory response of A. iole. Food and water deprived parasitoids readily accepted the moderately stimulatory sugars. Eliminade^TM, a commercial food supplement, was readily accepted (92%) by A. iole. Conversely, the wasps did not feed on host frass. Chemical analysis of L. lineolaris frass demonstrated the presence of glucose, sucrose, fructose, trehalulose, and melezitose, apparently at concentrations below those perceived by A. iole. The latter two compounds were previously known only from homopteran honeydew (trehalulose and melezitose) and bacteria (trehalulose). With respect to gustatory response to nectar and honeydew sugars, A. iole differs markedly from other hymenopterans that have been studied in that this parasitoid accepted all the naturally occurring sugars with which it was tested. Moreover, this parasitoid had lower acceptance thresholds than other hymenopterans for many of the sugars. This broad and sensitive range of gustatory perception might be helpful in the development of a food source for the wasp that is not exploited by the host.     

Comparison of cultivars of ornamental crop Gerbera jamesonii on production of spider mite-induced volatiles, and their attractiveness to the predator Phytoseiulus persimilis

We investigated whether volatiles produced by spider mite-damaged plants of four gerbera cultivars differ in attractiveness to Phytoseiulus persimilis, a specialist predator of spider mites, and how the mite-induced odor blends differ in chemical composition. The gerbera cultivars differed in resistance, as expressed in terms of spider mite intrinsic rate of population increase (r _m). In order of increasing resistance these were Sirtaki, Rondena, Fame, and Bianca. To correct for differences in damage inflicted on the cultivars, we developed a method to compare the attractiveness of the blends, based on the assumption that a larger amount of spider mite damage leads to higher attraction of P. persimilis. Spider mite-induced volatiles of cultivars Rondena and Bianca were preferred over those of cultivar Sirtaki. Spider mite-induced volatiles of cultivars Sirtaki and Fame did not differ in attractiveness to P. persimilis. Sirtaki plants had a lower relative production of terpenes than the other three cultivars. This was attributed to a low production of cis--bergamotene, trans--bergamotene, trans--bergamotene, and (E)--farnesene. The emission of (E)--ocimene and linalool was lower in Sirtaki and Fame leaves than in Bianca and Rondena. The importance of these chemical differences in the differential attraction of predatory mites is discussed.     

Tolerance of bitter compounds by an herbivore,Cavia porcellus

Many plant defensive chemicals are bitter to humans. Because of this taste characteristic, and because bitter compounds are often toxic, such substances, and the plants that contain them, are regarded as generally unpalatable to wildlife. These assumptions may be unwarranted. To test the hypothesis that herbivores are indifferent to bitter tastants, we investigated the responsiveness of guinea pigs (Cavia porcellus) to denatonium benzoate, denatonium saccharide, limonene,l-phenylalanine, naringin, quebracho, quinine, Ro-Pel (a commercial animal repellent containing denatonium saccharide) and sucrose octaacetate. Only quinine and sucrose octaacetate slightly but significantly reduced feeding (P<0.05). Our findings are inconsistent with the notion that herbivores generally avoid what humans describe as bitter tastes.Post doctoral fellow at the Monell Chemical Senses Center at the time of the experiment.     

Vitamin a deficiency modifies response of predatory miteAmblyseius potentillae to volatile kairomone of two-spotted spider mite,Tetranychus urticae

A volatile kairomone of the two-spotted spider mite,Tetranychus urticae, elicits a searching response of the phytoseiid predatorAmblyseius potentillae, only when the predator is reared on a carotenoid-free diet. However, after addition of crystalline -carotene or vitamin A acetate to the predator's rearing diet this searching response was absent. Because vitamin A and -carotene are indispensable nutrients for diapause induction, the carotenoid-deficient predators increase their fitness by searching for two-spotted spider mites, when other spider mites are unavailable. Two-spotted spider mites, among others, contain the carotenoids required for diapause induction, but are an inferior prey due to the dense webbing they produce. When the predators have carotenoids at their disposal, they do better by searching for other spider mites that are more profitable in terms of reproductive success. Such a prey is the European red spide mite,Panonychus ulmi. The volatile kairomone of this prey elicits a searching response of the predator whether it has a carotenoid deficiency or not.     

Electroantennogram response of alfalfa seed chalcid,Bruchophagus roddi (Hymenoptera: Eurytomidae) to host- and nonhost-plant volatiles

The alfalfa seed chalcid (ASC),Bruchophagus roddi, is a monophagous pest of alfalfa that parasitizes developing seeds. To further understand the olfactory basis of host-plant recognition by ASCs, we recorded electroantennograms (EAGs) from females and males to 39 volatiles from both alfalfa and red clover. The chemoreceptive sensitivity of ASCs was selective for certain general classes of compounds, defined by their carbon-chain length (C₆ and C₈), structure (aliphatics and phenolics), isomerism, and/or functional group (acetates, ketones, and alcohols). The compounds that elicited the largest EAGs were ranked as follows: (Z)-3-hexenyl acetate > hexyl acetate acetophenone octan-3-one methyl salicylate > octan-3-ol > oct-1-en-3-one > oct-1-en-3-ol (E)--ocimene (Z)- and (E)-3-hexen-1-ols. Over half the test compounds elicited significantly different responses between the sexes, and female antennal responses exceeded those of males for twice the number of these volatiles. Relationships of the tested volatiles to host-plant composition, EAG responses, and ASC behaviors showed no consistent correlations. However, nearly all of the host-plant volatiles known to stimulate behavioral activity also elicited moderate to potent EAG responses.     

Solution volume and seed number: Often overlooked factors in allelopathic bioassays

Cucumber seeds were germinated under various combinations of solution volume and seed number with a range of ferulic acid concentrations. At each concentration, radicle growth decreased as the relative amount of ferulic acid available per seed increased from (25 seeds/5 ml) to 5 (5 seeds/5 ml) to 19 (25 seeds/95 ml). With 2.0 mM ferulic acid in buffered solution, radicle lengths after 48 hr ranged from 71 to 47% of control. The amount of ferulic acid remaining in 2.0 mM solution after 48 hr was directly proportional to the amount initially available per seed, and ranged from 9 to 91%. Solution volume and seed number also significantly affected inhibition by vanillic acid, caffeic acid, and juglone. With 0.1 mM juglone, radicle lengths after 48 hr were 88% of control with 25 seeds/5 ml, 68% with 5 seeds/5 ml, and 56% with 25 seeds/90 ml. The data demonstrated that lower phytotoxin concentrations can produce equivalent or greater inhibitory effects than higher concentrations when the amount available per seed for uptake is greater. Equivalent inhibition of radicle growth was observed with 1.0 mM (5 seeds/5 ml) and 2.0 mM (25 seeds/5 ml) ferulic acid. Available literature on herbicides indicates that similar effects occur in greenhouse and field studies.     

Male european corn borer,Ostrinia nubilalis (Hübner), antennal responses to analogs of its sex pheromone

Experiments were conducted to (1) determine whether the electroantennogram (EAG) can detect differences among the responses of antennae from males derived from the three strains ofOstrinia nubilalis (Hübner), and (2) characterize the EAG responses of each strain to isomeric forms of the natural pheromone, (E)- and (Z)-11-tetradecen-1-ol acetate (TDA), and analogs possessing differences in the terminal alkyl group, cyclopropyl (CPA), ortert-butyl (TBA).EAG responses differed among the strains in two ways: (1) Antennae fromZZ males always produced an EAG to (Z)-TDA with an extended duration of response. This signature EAG response was found to be unique to the antennal response ofZZ males to (Z)-TDA, thus providing a relatively easy method of distinguishing liveZZ males fromEE orZE males. Correlated with this longer EAG response was a longer disadaptation time, i.e., the EAG response ofZZ antennae disadapted more slowly (ca. 10 min) than the response ofEE antennae. (2) Strain differences in the relative EAG amplitudes to isomers and analogs were observed at the stimulus amounts eliciting the peak EAG amplitude as follows: TDA CPA > TBA forZZ males and both isomers; TDA > CPA TBA and CPA TDA > TBA forEE males and theE andZ isomers, respectively; CPA > TBA TDA forZE males and both isomers. Dose—response relationships were seen for all compounds if amplitude (peak height) of the EAG was used as a measure of response. However, if width of the EAG at half the peak height (peak width) was used, then only theZZ antennal response to (Z)-TDA resulted in a meaningful dose-response relationship. For all strains, the EAG amplitudes elicited by theZ isomers of any of the tested compounds were greater than those elicited by the correspondingE isomers. Therefore, correlations between the relative EAG and upwind flight responses were observed in theZZ (r = 0.86) andZE (r = 0.80) strains but were not correlated in theEE strain (r = 0.18). Temporal studies showed that adaptation, not postexcision deterioration, was responsible for the observed decreases in the EAG amplitude after repetitive stimulation or after stimulation with amounts in a descending order. Disa-daptation required at least 20 min for a moderate dose (10 g for 1 sec). Developmental studies showed that antennae from 2-day-old adults had the greatest EAG response.     

Chemosensory stimuli for the walking legs of the crayfish Procambarus clarkii

Studies of chemoreception in crustaceans have shown that flesh-eating species can detect amino acids, nucleotides and derivatives, and amines, while most herbivorous and omnivorous species are additionally sensitive to carbohydrates. We used extracellular recording techniques to evaluate the effectiveness of a range of nitrogen-containing compounds (mostly amino acids), bile acids, and carbohydrates in stimulating chemoreceptor cells present in the second and third pereopods of the omnivorous crayfish Procambarus clarkii. When applied at a final concentration of 100 M, effective stimuli were trehalose, leucine, cellobiose, glycine, sucrose, maltose, and ammonium (from most to least effective). The other 17 compounds tested, many chosen because they are potent stimuli for other crustaceans, were ineffective stimuli for P. clarkii. Concentration–response functions were determined for three single cells that were sensitive to ammonium, for five multiunit fibers sensitive to glycine, and for six multiunit fibers sensitive to leucine. Thresholds ranged from 10 nM to 10 M, functions were generally linear when plotted against the log of the stimulus concentration, and there was little evidence of saturation. While P. clarkii is sensitive to only seven of 24 compounds tested, the compounds that proved stimulatory should serve as cues for location and identification of food items preferred by this omnivorous crustacean.     

Experimental investigation of the combustion of hydrogen-kerosene fuel in an air-direct flow channel

Conclustions In conditions of the supersonic flow of air in the chamber investigated, with p_c=(0.2–0.4)×10² kPa and M=1.5–2, the spontaneous ignition of hydrogen streams, flowing along the air stream, occurs at T _A ^* 1050°K.Stabilization of the combustion of kerosene, atomized in air (or in a hydrogen-air flame core), is achieved in the conditions considered with _{H 2} 0.004, and for ignition of the kerosene it is necessary that _{H 2} 0.04. In the case of combustion stabilization of the atomized hydrocarbon fuel with a hydrogen flame core, a significant improvement of ignition of the liquid fuel occurs with intensification of its combustion.Moscow. Translated from Fizika Goreniya i Vzryva, Vol. 18, No. 2, pp. 30–36, March–April, 1982.     

Particular Levels of Odors Released by Virgin Females Attract Conspecific Males of the Funnel-Web Spider <Emphasis Type="Italic">Allagelena difficilis</Emphasis>

Female-released chemical signals are crucial clues for mate-searching males to locate and gain sexual receptivity of conspecific females. Abundant behavioral evidence indicates that female spiders release sex pheromones to guide mate-searching behavior of conspecific mature males. However, the chemical nature of spider pheromones is poorly understood. Females of the funnel-web spider, Allagelena difficilis, employ sit-and-wait tactics for mating. Field observations indicate that males leave their retreats to search for potential mates during the breeding season. Therefore, we investigated whether virgin females release a sex attractant to conspecific males and then explored the chemical nature of the female pheromone. Four fatty acids extracted from the female bodies (palmitic acid, linoleic acid, cis-vaccenic acid and stearic acid) constitute a multiple-component sex attractant to conspecific males in A. difficilis. Unexpectedly, mated females also produce the same fatty acids, but at trace levels. Two-choice experiments showed that males were significantly attracted by the blend of the four fatty acids in appropriate concentrations while avoiding the blend consisting of the same acids at very low concentrations, suggesting that mate-searching males are able to discriminate virgin females from mated females by the quantities of female-specific fatty acids in the funnel-web spider A. difficilis.     

Electrospun Micro/Nanofibers as Controlled Release Systems for Pheromones of <Emphasis Type="Italic">Bactrocera oleae</Emphasis> and <Emphasis Type="Italic">Prays oleae</Emphasis>

New systems for the controlled release of 1,7-dioxaspiro[5.5]undecane and (Z)-7-tetradecenal, the sex pheromones of olive fruit fly, Bactrocera oleae, and olive moth, Prays oleae, respectively, were developed utilizing electrospun micro/nanofiber matrices from inexpensive, biodegradable polymers, namely polycaprolactone, cellulose acetate and polyhydroxybutyrate. The incorporation of the pheromones in 5, 10 and 20% w/w in the electrospinning polymer blends allowed for the production of fiber mats with variable loading levels and release rates, ensuring however in all cases the release of pheromones for more than 16 weeks. Laboratory bioassays and field trapping tests showed that the fiber mats obtained from electrospinning of polyhydroxybutyrate solution containing 5% w/w 1,7-dioxaspiro[5.5]undecane and polycaprolactone solution containing 5% w/w (Z)-7-tetradecenal were almost twice as effective in attracting B. oleae and P. oleae males, respectively, in comparison to the positive controls used.     

Polymerization of carbazolyl-containing epoxides with triphenylcarbenium salts

Summary Polymerization of 9-(2,3-epoxypropyl) carbazole (EPC) and 1,2-epoxy-6-(9-carbazolyl)-4-oxahexane (ECOH) with triphenylcarbenium hexachloroantimonate and triphenylcarbenium tetrafluoroborate have been studied by the microcalorimetric technique. Triphenylcarbenium salts have turn out to be more efficient catalyst for the polymerization of carbazolyl-containing epoxides than Lewis acids, giving high yields at low initial concentration of the catalyst. Using comparatively restricted conditions of reaction ([triphenylcarbenium saltyda]_o0.02 mol/l t50° C) transition from the conventional active chain end mechanism to the activated monomer mechanism has been observed at a sufficiently high degree of conversion of monomer.     

Volatile compounds from interdigital gland of male white-tailed deer (Odocoileus virginianus)

Interdigital secretions were collected from eight male white-tailed deer of various ages. Analysis of volatiles was performed by gas chromatography-mass spectrometry with a modified headspace technique. Forty-six volatile compounds were found including alkanes, arenes, aldehydes, ketones, aliphatic acids, esters, pyrroles, furans, and sulfur compounds. Eleven occurred in higher concentrations (P0.10) in dominant (3.5-year-old) than in subordinate (1.5-year-old) animals. Dominant males typically have higher serum testosterone levels, and fatty acids and esters fluctuate with sebum production, which is under hormonal control. Therefore, these compounds may reflect testosterone levels and act as chemical signals indicating the presence of a dominant male. Interdigital volatiles also may act as generalized scent trail markers.