Responses of Wild Norway Rats (Rattus norvegicus) to Predator Odors

If rats could be shown to avoid the odors of predators, then conservation managers could manipulate this behavior to exclude rats from important conservation sites. We evaluated the ability of six predator odors to elicit avoidance responses by wild-caught Norway rats (Rattus norvegicus) from two New Zealand populations (Kapiti Island and North Island). Kapiti Island is free of mammalian predators, while the North Island has established populations of felids, canids, and mustelids. Three of the predator odors were real and three were synthesized volatile ingredients of real animal feces or urine. We compared the rats' responses to predator odors with their responses to three natural herbivore odors. We used a Y maze, and rats were offered the choice of an odor in one arm of the maze and distilled water in the other arm. Each choice arm was ducted at the entrance to remove air and the odor. We recorded: (1) the time until the rat left the first arm of the maze, (2) the time until the rat visited each arm, (3) the number of visits to each arm, (4) the amount of time spent in each arm, and (5) a total activity score for each rat. Kapiti rats showed an aversion to five of the six predator odors, despite never having encountered them before. Kapiti rats visited herbivore odors more often than carnivore odors and were less active in the presence of carnivore odors than they were when tested with herbivore odors. In addition, Kapiti rats approached some herbivore odors more quickly than they approached carnivore odors. North Island rats appeared to avoid cat urine, but despite being predator experienced, did not show a consistent aversion to the carnivore odors we tested. Both samples of rats, but particularly the North Island group, showed high individual variation. We conclude that predator odors are unlikely to be an effective management tool for all populations of this species of rat because of this high individual variability and the likelihood that each island population will differ in its responses to a given odor.     

Death Anxiety and the Emotion-Processing Mind.

Death anxiety, a critical influence on human life and its psychotherapies, has been relatively neglected by psychoanalytic writers. The author proposes several reasons for this oversight and introduces the communicative or strong adaptive approach to psychotherapy and psychoanalysis, which has recently begun to explore this issue. The features of the approach are described, with emphasis on a revised version of Freud's topographic model of the mind. Three forms of death anxiety are postulated: existential, predatory, and predator. The author explores the effects of each form on emotional adaptations and the psychotherapy experience, and their role in the evolution of the emotion-processing mind-the postulated mental module with which people adapt to emotionally charged events and their meanings. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Olfactory responses of yellowfin tuna (Thunnus albacares) to prey odors: Chemical search image

Yellowfin tuna can detect and distinguish between odors of intact prey organisms, responding to odor quality of various prey rinses with different amino acid profiles. Chemical fractions of natural prey odors and synthetic mixtures of amino acids are less effective than whole natural rinses. Assuming uniform dilution, tuna can detect amino constituents of prey odors at about 10^–11 M. Intensity of the behavioral response is modified by hunger. Feeding experience with new prey causes a gradual shift to maximum responses to its odor. We propose that one of the functions of the tuna's olfactory system is to form chemical search images which focus food search behavior for specific prey. The search image is thought to be modifiable and to be induced by prevailing prey abundance, so as to optimize the predator's feeding efficiency.     

不同吸附剂对白酒异嗅物质去除的研究

实验对比了三大类共27种吸附剂对白酒中的16种异嗅物质（4-甲基苯酚、4-乙基苯酚、4-乙烯基苯酚、苯酚、愈创木酚、4-甲基愈创木酚、4-乙基愈创木酚、4-丙基愈创木酚、4-乙烯基愈创木酚、土味素、2-庚醇、3-辛醇、1-辛烯-3-醇、1-辛烯-3-酮、反式-2-辛烯-1-醇、反式-2-壬烯醛）的去除情况。采用浸入式固相微萃取（DI-SPME）结合气相色谱-质谱联用（GC-MS）技术对处理前后的酒样进行快速检测,计算其去除率。结果发现树脂的去除效果优于凹凸棒土、硅藻土、皂土和酒用活性炭,其中大孔阴离子交换树脂D730、D202和SD333对异嗅物质的总体去除效果最好。      

Ecoepidemics with infected prey in herd defence: the harmless and toxic cases

We consider a predator–prey population model with prey gathering together for defence purposes. A transmissible unrecoverable disease affects the prey. We characterize the system behaviour, establishing that ultimately either only the susceptible prey survive, or the disease becomes endemic, but the predators are wiped out. Another alternative is that the disease is eradicated, with sound prey and predators thriving at an equilibrium or through persistent population oscillations. Finally, the populations can thrive together, with the endemic disease. The only impossible alternative in these circumstances is predators thriving just with infected prey. But this follows from the model assumptions, in that infected prey are too weak to sustain themselves. A mathematical peculiarity of the model is the singularity-free reformulation, which leads to three entirely new dependent variables to describe the system. The model is then extended to encompass the situation in which ingestion of diseased prey is fatal for the predators and to the cases where the predators find the infected prey less palatable.     

Ovipositional behavior of lesser peachtree borer in presence of host-plant volatiles

Reactions of lesser peachtree borer [Synanthedon pictipes (G&R)] to volatiles of peach wood, either natural or chemically fractionated, were observed. Mated females were stimulated by and responsive to such materials and deposited significantly more eggs on substrates, including unnatural hosts, that had been treated with aqueous mixtures of bark-canker materials. Stimulation to oviposit occurred even when the female was blinded, indicating the presence of chemical cues. Natural canker-bark extracts immediately stimulated ovipostion and for a few hours significantly increased the number of eggs laid. However, average fecundity was not increased. Antennectomy did not significantly decrease response to volatiles by gravid females, and alternate sites of such chemoreception were not located. Complex mixtures derived by solvent extraction, steam distillation, and volatiles trapping from bark, canker, and gum all had activity. Observations of insect behavior in outdoor cages and also in the laboratory indicated that visual, chemosensory, and mechanosensory receptors are involved in host finding and oviposition.Mention of firm or product names does not imply recommendation or endorsement by USDA over others not mentioned.     

一类具有扩散和比例依赖响应函数捕食模型解的稳定性

主要研究一类具有扩散和比例依赖响应函数捕食模型．主要讨论了反应扩散系统和交错扩散系统正平衡点的稳定性．     

Effect of conspecific and heterospecific feces on foraging and oviposition of two predatory ladybirds: role of fecal cues in predator avoidance

Growing evidence suggests a flow of chemical information from higher to lower trophic levels that affects foraging and oviposition of prey in response to potential risks from predators. This was investigated in two species of ladybird predators of aphids, Harmonia axyridis and Propylea japonica. H. axyridis is known to be the stronger intraguild predator and P. japonica to be the more frequent intraguild prey in interactions of these two species. These ladybirds share aphid prey on mugworts, hibiscus, and Italian ryegrasses in fields of northern Japan but largely avoid each other on the same plant. Fecal cues of these ladybird predators were found to contribute in their assessment of predation risk from conspecific and heterospecific competitors in common habitats. Gravid females of H. axyridis reduced rates of feeding and oviposition when exposed to feces of conspecifics, but not when exposed to feces of P. japonica. In contrast, gravid females of P. japonica reduced feeding and oviposition when exposed to feces of both H. axyridis and its own species. Females of both ladybird species exhibited similar behavior in response to water extracts of feces. For P. japonica, the influence of heterospecific feces was greater than that of conspecific feces. Our results demonstrate that feces of ladybirds contain odors that have the potential to deter the feeding and oviposition activities of conspecific as well as heterospecific ladybirds. Such deterrence allows these insects to avoid predation risk. Differences in responses of the two predators are discussed.     

Receptor contributions to configural and elemental odor mixture perception.

Odor mixture perception can be configural (the mixture is qualitatively different from the components) or elemental (the components are recognizable). Some have argued that configural properties are dependent on chemical similarity and possible overlap at the receptor level. The authors show that a binary mixture in which both components activate the same receptor (17) has a configural odor, whereas a mixture that suppresses overlap has elemental odor properties. Rats trained to recognize mixtures of citronellal and octanal (strong 17 agonists) in many ratios rarely recognize the components, supporting configural representation of the odor mixture. However, when trained to recognize mixtures of citral (partial 17 agonist, inhibitor) and octanal, rats recognize 1 or both components over a wide range of ratios. (PsycINFO Database Record (c) 2010 APA, all rights reserved)