Learned aversion

A repetition of in situ experiments with the yellowhead wrasse, partially in response to the above criticisms, again showed that fish developed a learned aversion to otherwise palatable food that had been adulterated with 15P-PGA2 [99], This was presumably due to the emetic properties of PGA2. It was pointed out that methyl esters of prostaglandins are also known to possess emetic properties [104], and reasoned that if the 15-acetoxy ester inhibits the emetic properties of PGA2, then it is likely to be quickly lost because of its known lability, especially in the presence of coral esterase. Further, the acidic environment in the stomachs of predatory fish would promote hydrolysis of these labile esters. 

Gerhart, D. J., Emesis, learned aversion and chemical defense in octocorals a central role for prostaglandins , Am. J. Phys., 260, R839, 1991. 

Liss PS, Malin G, Turner SM, Holligan PM (1994) Dimethyl sulphide and Phaeocystis a review. J Mar Syst 5 41 Long JD (2004) Plasticity of consumer-prey interactions in the sea chemical signaling, learned aversions, and ecological consequences. Biology. Georgia Institute of Technology, Atlanta, pill... 

Herbivores and omnivores select the diet containing the higher level of protein or AA mixtures when the choices contain balanced lAA profiles (Peters and Harper, 1984). Indeed, rats can select levels of protein that are considerably higher than their requirement (Makarios-Lahham et al., 2004). Although the mechanism for selection of high levels of dietary protein is not known, it appears that it occurs in the absence of the learned aversion that accompanies avoidance of an lAA-deficient diet (Tome, 2004). 

Food preferences also can be learned, and, like learned aversions, conditioned preferences can be used to evaluate chemosensory abilities. Typically, preferences are induced by pairing the ingestion of a novel flavor with calories (Bolles et al. 1981 Messier White 1984 Booth 1985 Mehiel Bolles 1984, 1988 Simbayi et al. 1985), recovery from nutritional deficiency (Garcia et al. 1967 Zahorik et al. 1974), and recovery from malaise (Green Garcia 1971 Zahorik 1977 Sherman et al. 1983). The novel flavor is subsequently preferred, as are other flavors that subjects perceive as similar to the conditioned stimulus. However,... 

Smotherman, W.P. (1982) Odor aversion learning by the rat fetus. Physiol. Behav. 29, 769-771. 

Visual and chemical cues interact in foraging by natricine snakes. Even visual cues alone can elicit prey attack, especially in aquatic foraging (Drummond, 1985). Aposematic color patterns of prey enhance the learning of prey that induces illness. Garter snakes, Thamnophis radix hay deni, were exposed to fish and earthworms presented on black-and-yellow forceps, and then inj ected with lithium chloride (LiCl). Control prey was offered on green forceps. Later, the snakes avoided food from either forceps, but the aversion to prey paired with black-andyellow was stronger (Terrick etal, 1995). 

Brown-headed cowbirds, Molothrus ater, and red-winged blackbirds, A. phoeniceus, removed 95-98% less rice seeds sown in flight pens if the seeds had been treated with methiocarb. The effect was the same whether 100% or only 50% of the seeds had been treated. This shows that an entire prey population can be protected even if only a portion is unpalatable. Such automimicry may permit partial treatment of crops with repellents, which would be effective, environmentally sound, and economical (Avery, 1989). Batesian mimicry offers advantages over food aversion learning (Reidinger and Mason, 1983). 

Flavor consists of taste and odor combined. Animals often avoid tastes after only one experience if delayed illness follows it, but odors are not avoided under such circumstances. If an odor and a taste are presented together before an illness is induced experimentally (e.g. with lithium chloride), animals can learn to avoid the odor after just one such experience. When the odor is intensified in such a combined presentation, only the odor aversion increases, not the taste aversion. If the taste is made more intense, both odor and taste aversions increase. As a rule, the odor aversion strength depends on the taste experience, but not vice versa (Garcia etal, 1986). 

Social learning can modify conditioned aversions. Spotted hyenas conditioned by lithium chloride treatment lost their aversion in the presence of naive conspecifics (Yoerg, 1991). The reverse occurs in rats a conditioned aversion is transmitted to naive animals (Strupp and Levitsky, 1984). 

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