Repellents excretions

The search for environmentally benign pest repellents has spawned many experiments with excretions and gland secretions from felids, canids, and mustelids. 

Secretions and excretions from the same species can be used as repellents as well as attractants to traps or bait. Repellents are based on territorial exclusion and same-sex competition, while attractants exploit general gregariousness and preference for the opposite sex. 

Each of these observations or sightings has chemical ecology implications that will be discussed. The instructor will lead students to pertinent literature. Topics include, but are not limited to, feeding attractants and repellents palat-ability detoxication of plant secondary compounds marking with secretions or excretions chemical defense. 

The biological functions of such plant secondary metabolites (PSMs) have been debated for a long time. They often have antimicrobial functions, but also serve as repellents and feeding inhibitors against herbivorous insects and vertebrates, notably birds and mammals. Animals have evolved many mechanisms to cope with phenolics in their diet. These start with food processing. For instance, beavers consume experimental sticks of the phenolics-rich witch hazel only after leaving them in the water for 2-3 days, apparently to leach out unpalatable compounds (Miiller-Schwarze et al. 2001). Many birds and mammals eat clay to adsorb phenolics so they never will be absorbed in the intestines. If they are taken up in the blood stream, such PSMs will eventually be rendered harmless by oxidation and other processes, followed by conjugation, in the liver. They then will be excreted in the urine. 

BPH settling response on tillers of the susceptible VTN1V variety sprayed with the steam distillate extracts of resistant varieties showed the same pattern of response as when actual resistant plants were used. This indicated that treatment of the susceptible variety with steam distillate extracts of resistant varieties conferred resistance at least temporarily. The low amount of honeydew excreted by BPH females on the tillers of TNI plants treated with the extract of ARC 6650 resistant or Ptb 33 variety confirmed that the insect was unable to settle down for sustained feeding (Figure 3). Nymphs caged on similarly treated TNI plants were unable to settle on them and suffered high mortality. Thus, restlessness of BPH nymphs and adults on resistant plants could be attributed to exposure to the plant volatiles which have a repellent or toxic effect on the insect. 

In alchemy, vile terms about excretions tend to repel the nonadept. However, they bring humorous delight to the alchemist who even uses dung s soft exothermic heat to warm his flask and urine to provide nitrate and ammonia. The alchemist also calls his reaction residues by the name faeces or excrement. Nicholas Flamel s 1629 Original du Desire or Thresor de Philosophie identifies that the Philosophers Stone is in the messy chemical substrate of the Alchemists cmcible ... 

The first compares the ratio of the two areas under the curve (AUC) for topical versus intravenous dosing. The area estimates are from zero to 168 hours and do not use extrapolated areas beyond this time. This gave a value of 1.64 percent. For the 12 cm exposure experiment, the value was 1.85 percent. A second comparison is obtained by comparing total excretion for each experiment, topical versus intravenous. This gave an absorption estimate of 1.89 percent for the first experiment, 4.0 percent for the second experiment, and 1.78 percent for the third experiment (0.1 mg/kg). These data demonstrate that no significant change in absorption estimates occurred when the application area was doubled or when the surface dose was reduced 20-fold. This is in contrast to what is usually expected in percutaneous absorption studies,(22) but was also observed by Reifenrath, al. for mosquito repellents as seen in Table IV. 

Male mice communicate their gender and social status by means of chemical signals excreted in urine. These substances usually attract adult females and repel adult male mice. 

An androgen-dependent family of proteins (Major Urinary Proteins, MUPs) is excreted in urine by males. Since MUPs bind small volatile molecules, they have been suggested to be pheromone-binding proteins. After purification, MUPs still retain their ligands in a behavioral test of attractiveness, these molecules attract adult females and repel adult males. Prepubertal animals show the opposite pattern of results males prefer MUPs-associated cues and females do not. These findings match those obtained using whole urine from adult males, therefore we conclude that MUPs ligands can indicate the presence of an adult male mouse to conspecifics. 

The large, flightless grasshopper, Romalea microptera excretes a novel sesquiterpenoid allenic ketone in its defensive secretionsJ Meinwald and Hendry confirmed the proposed structure and stereochemistry of this ant-repellant substance by stereospecific synthesis from isophorone. 

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