A Chamber for Testing the Release of Volatile Substances Secreted by Animals,Especially Mammals,as Exemplified by Substances Released by Rats in Response to Stress

Abstract

The success of the testing of volatile organic compounds emitted by animals is dependent on the creation of appropriate conditions for air sampling subsequently used to assay and identify the compounds. These conditions play a particularly important role in the investigation of pheromones, which are secreted in extremely low concentrations. The authors have not come across any previous work which offers constructional solutions, which would allow avoidance of contamination of the air samples containing volatile substances secreted by animals.

A constructional solution was developed, which provides optimal conditions for their sampling and isolation. Its main advantages are as follows: the exposure chamber (the chamber in which the animal is studied) is filled with synthetic air; the exposure chamber is separated from the atmospheric air with a synthetic air “jacket”; the exposure chamber has been constructed using materials which do not release chemicals and absorb them in trace quantities.     

Comparison of Urinary Scents of Two Related Mouse Species, <Emphasis Type="Italic">Mus spicilegus</Emphasis> and <Emphasis Type="Italic">Mus domesticus</Emphasis>

Whereas the house mouse (Mus domesticus) has been studied extensively in terms of physiology/behavior and pheromonal attributes, the evolutionarily related mound-building mouse (Mus spicilegus) has received attention only recently due to its divergent behavioral traits related to olfaction. To date, no chemical studies on urinary volatile compounds have been performed on M. spicilegus. The rationale for our investigations was to determine if there are differences in urinary volatiles of intact and castrated M. spicilegus males and to explore further whether this species could utilize the same or structurally similar pheromones as the male house mouse, M. domesticus. The use of capillary gas chromatography/mass spectrometry (GC-MS) together with sorptive stir bar extraction sampling enabled quantitative comparisons between the intact and castrated M. spicilegus urinary profiles. Additionally, through GC-MS and atomic emission (sulfur-selective) detection, we identified qualitative molecular differences between intact M. spicilegus and M. domesticus. A series of volatile and odoriferous lactones and the presence of coumarin were the unique features of M. spicilegus, as was the notable absence of 2-sec-butyl-4,5-dihydrothiazole (a prominent M. domesticus male pheromone) and other sulfur-containing compounds. Castration of M. spicilegus males eliminated several substances, including δ-hexalactone and γ-octalactone, and substantially decreased additional compounds, suggesting their possible role in chemical communication. Some other M. domesticus pheromone components were also found in M. spicilegus urine. These comparative chemical analyses support the notion of metabolic similarities as well as the uniqueness of some volatiles for M. spicilegus, which may have a distinct physiological function in reproduction and behavior.     

Odor Detection in Insects: Volatile Codes

Insect olfactory systems present models to study interactions between animal genomes and the environment. They have evolved for fast processing of specific odorant blends and for general chemical monitoring. Here, we review molecular and physiological mechanisms in the context of the ecology of chemical signals. Different classes of olfactory receptor neurons (ORNs) detect volatile chemicals with various degrees of specialization. Their sensitivities are determined by an insect-specific family of receptor genes along with other accessory proteins. Whereas moth pheromones are detected by highly specialized neurons, many insects share sensitivities to chemical signals from microbial processes and plant secondary metabolism. We promote a more integrated research approach that links molecular physiology of receptor neurons to the ecology of odorants.     

Spatio-temporal analysis of trap catches of Tribolium confusum du Val in a semolina-mill, with a comparison of female and male distributions

By using food-bait traps, we evaluated the presence and the spatio-temporal distribution of insect pests in an industrial semolina-mill, with particular attention to Tribolium confusum du Val in which the spatio-temporal dynamics of females and males were also studied separately. A total of 1401 insect specimens was captured in the traps, belonging to 14 taxa, mainly Coleoptera. The most abundant species were T. confusum (with 1002 adults), followed by Typhaea stercorea (L.) (with 158 adults) and T. castaneum (Herbst) (with 110 adults). Of particular interest was the presence in the food-bait traps of T. confusum and T. castaneum adults in a mixed population with equal numbers of males and females. Furthermore, analysis of the spatio-temporal dynamics suggested that the distribution of the two sexes in T. confusum was almost the same during the entire sampling period. The findings of our study can usefully be applied to the management of Tribolium infestations, but further and more detailed studies are needed to better understand the ecology and behaviour of the species in association with searching for food and production of aggregation pheromones.     

Field monitoring Sitophilus zeamais and Sitophilus oryzae (Coleoptera: Curculionidae) using refuge and flight traps baited with synthetic pheromone and cracked wheat

Flight traps with open vertical baffles and refuge traps in the form of rectangular cardboard boxes were used to catch Sitophilus zeamais and S. oryzae in Kenya. Traps baited with the aggregation pheromone (Sitophilure), and for the first time traps baited with pheromone and food bait (cracked wheat), were field tested. Both traps types were effective in capturing Sitophilus spp and gave higher weevil catch when baited with pheromone and cracked wheat combined than with pheromone or cracked wheat alone. The combination of pheromone and cracked wheat had an additive effect on trap catch and not a synergistic effect as reported in earlier laboratory trials. Different pheromone loadings of 0.5, 1 and 2 mg were tested. The catch of S. zeamais in flight traps rose significantly with increasing dosage. For refuge traps, the same effect was observed although the difference between 1 mg and 2 mg was not statistically significant. The trend was for increasing S. oryzae catch with dosage, although total catches were very much lower than those for S. zeamais, and differences did not prove statistically significant. Traps placed on the floor near infested maize cribs captured significantly more Sitophilus spp than those actually placed in the cribs. Adult Sitophilus captured were sexed and in both flight and refuge traps the sex ratio was biased in favour of females even though the sex ratio of weevils from infested maize cobs, which were the source of the captured weevils, was approximately even.     

Effect of ewe urine and vaginal secretions on ram investigative behavior

Urine from estrous ewes increased the investigative premating activity of the ram. Estrous vaginal tampons resulted in a decrease. The flehmen response of the ram was closely associated with urination by the ewe.     

Multi-agent Physical A* with Large Pheromones

Physical A* (PHA*) and its multi-agent version MAPHA* are algorithms that find the shortest path between two points in an unknown real physical environment with one or many mobile agents [A. Felner et al. Journal of Artificial Intelligence Research, 21:631–679, 2004; A. Felner et al. Proceedings of the First International Joint Conference on Autonomous Agents and Multi-Agent Systems, Bologna, Italy, 2002:240–247]. Previous work assumed a complete sharing of knowledge between agents. Here we apply this algorithm to a more restricted model of communication which we call large pheromones, where agents communicate by writing and reading data at nodes of the graph that constitutes their environment. Previous works on pheromones usually assumed that only a limited amount of data can be written at each node. The large pheromones model assumes no limitation on the size of the pheromones and thus each agent can write its entire knowledge at a node. We show that with this model of communication the behavior of a multi-agent system is almost as good as with complete knowledge sharing. Under this model we also introduce a new type of agent, a communication agent, that is responsible for spreading the knowledge among other agents by moving around the graph and copying pheromones. Experimental results show that the contribution of communication agents is rather limited as data is already spread to other agents very well with large pheromones     

An Antiaphrodisiac in Heliconius melpomene Butterflies

Gilbert (1976) suggested that male-contributed odors of mated females of Heliconius erato could enforce monogamy. We investigated the pheromone system of a relative, Heliconius melpomene, using chemical analysis, behavioral experiments, and feeding experiments with labeled biosynthetic pheromone precursors. The abdominal scent glands of males contained a complex odor bouquet, consisting of the volatile compound (E)-β-ocimene together with some trace components and a less volatile matrix made up predominately of esters of common C₁₆- and C₁₈-fatty acids with the alcohols ethanol, 2-propanol, 1-butanol, isobutanol, 1-hexanol, and (Z)-3-hexenol. This bouquet is formed during the first days after eclosion, and transferred during copulation to the females. Virgin female scent glands do not contain these compounds. The transfer of ocimene and the esters was shown by analysis of butterflies of both sexes before and after copulation. Additional proof was obtained by males fed with labeled D-¹³C₆– glucose. They produced ¹³C-labeled ocimene and transferred it to females during copulation. Behavioral tests with ocimene applied to unmated females showed its repellency to males. The esters did not show such activity, but they moderated the evaporation rate of ocimene. Our investigation showed that β-ocimene is an antiaphrodisiac pheromone of H. melpomene.     

Identification and Characterization of Cuticular Hydrocarbons from a Rapid Species Radiation of Hawaiian Swordtailed Crickets (Gryllidae: Trigonidiinae: <Emphasis Type="Italic">Laupala</Emphasis>)

A previous investigation of cuticular hydrocarbon variation among Hawaiian swordtail crickets (genus Laupala) revealed that these species differ dramatically in composition of cuticular lipids. Cuticular lipid extracts of Laupala species sampled from the Big Island of Hawaii also possess a greatly reduced number of chemicals (as evidenced by number of gas chromatography peaks) relative to ancestral taxa sampled from the geologically older island of Maui. One possible explanation for this biogeographic pattern is that reduction in chemical diversity observed among the Big Island taxa represents the loss of ancestral hydrocarbons found on Maui. To test this hypothesis, we characterized and identified the structures of cuticular hydrocarbons for seven species of Hawaiian Laupala, two from Maui (ancestral) and five from the Big Island of Hawaii (derived) by using gas chromatography-mass spectrometry. Big Island Laupala possessed a reduced number of alkenes as well as a reduction in the diversity of methyl-branch positions relative to species sampled from Maui (ancestral), thus supporting our hypothesis of a founder-induced loss of chemical diversity. The reduction in diversity of ancestral hydrocarbons was more severe within one of the two sister lineages on the Big Island, suggesting that post-colonizing processes, such as drift or selection, also have influenced hydrocarbon evolution in this group.     

Lizard Epidermal Gland Secretions I: Chemical Characterization of the Femoral Gland Secretion of the Sungazer, <Emphasis Type="Italic">Cordylus giganteus</Emphasis>

The giant girdled lizard or sungazer, Cordylus giganteus, is endemic to South Africa. It has been suggested that in this species, as in other lizard species, epidermal glands in the femoral, pre-cloacal regions, and cloacal glands are the main sources of semiochemicals and that these secretions could play an important role at different levels of the social biology of the animals. To gain a better understanding of the nature of the femoral gland secretions of the sungazer, characterization of the constituents of the secretions was carried out. By using GC-MS analysis, in conjunction with auxiliary techniques, such as solventless sample introduction and trimethylsilyl derivatization, 53 relatively involatile compounds, including carboxylic acids, alcohols, ketones, esters, and steroids, were identified in the secretions of both sexes. The study showed that the secretions of male and female sungazers contain only semi-volatile chemicals.