Hormones and Behaviour

CABI Publishing eBooks, 2005

Boston studies in the philosophy of science, 2012

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Boston studies in the philosophy of science, 2011

No part of this work may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, microfi lming, recording or otherwise, without written permission from the Publisher, with the exception of any material supplied specifi cally for the purpose of being entered and executed on a computer system, for exclusive use by the purchaser of the work.

The purpose of this study is to present a scientific literature review that promotes a better understanding of animal behavior in relation to disease; it is directed to the knowledge and comprehension of strategies that certain parasites have to find their hosts and how these act in order to avoid parasites, and in the case they become sick, the type of behavioral tools that are used to face disease and regain their health.

Ideas in Ecology and Evolution, 2009

No living organism seems left untroubled by parasites. Parasitologists study with increasing enthusiasm when and how parasites alter host behaviour. Elucidating the neurological, endocrinological and molecular mechanisms mediating possible changes in the host's behaviour is unlikely to explain how parasites induce forms of "bizarre", "odd" or "drastically new and strange behaviours". We argue that parasites make use of behaviour programs that already existed in their hosts rather than creating host behaviour de novo. From an evolutionary and/or ontogenetic point of view, parasites might 'fake' an everyday life signal, activate a silent sub-repertoire, or even free dormant (i.e. phylogenetically old) behaviours. We illustrate by means of a few, well-known phenomena how a thorough ethological approach will be essential in determining the origin of the shown host behaviour and to differentiate between superficially similar but separate behaviour syndromes. Parasites may even merit the label of scouts in behaviour research, unmasking behavioural capabilities not at hand in the host's standard repertoire, and occasionally they might be used as tools to draw attention to relevant nervous control areas.

The behavioral and physiological responses of 6-d-old Aedes aegypti (L.) adult females exposed to deltamethrin and DDT were characterized using a free-choice excito-repellency test system. Excluding varying pretest age and carbohydrate availability as possible confounders, insecticide contact (measuring irritancy) and noncontact (measuring repellency) behavioral assays were conducted on two nonbloodfed groups, either unmated or mated (nulliparous), and two blood-fed groups, either parous or newly full-engorged mosquitoes. The degree of escape response to deltamethrin and DDT varied according to the physiological conditioning. Escape rates from contact and noncontact chambers with deltamethrin were more conspicuous in nonbloodfed groups compared with mosquitoes previously bloodfed. There were no significant differences in escape responses between unmated and nulliparous test populations. With DDT, a more pronounced escape response was observed in unmated compared with other physiological conditions. More moderate escape response was seen in nulliparous mosquitoes, and the least was observed in full bloodfed test individuals, regardless of test compound. Ae. aegypti, regardless of pretest conditioning, was completely susceptible to deltamethrin, whereas showing high resistance to DDT. Despite profound differences in resistance, there was no significant difference in avoidance response between chemicals and mosquito conditioning. Moreover, pre- and postbloodmeals were found to influence assay outcome and thus to have relevance on the interpretation of usceptibility and excito-repellency assays.

Starting from the studies of H. S. Liddell, the experiments on behavior disorders in animals encouraged a great deal of interest during the 1930s, 1940s, and 1950s in the United States. Even though these studies were mainly carried out with non-human animals, the awarding of prestigious scienti c prizes to some of these investigations paved the way to the conviction that the laboratory revolution would reach to Psychopathology. In this paper, we will explore the contrasting approaches to the study of abnormal behavior in animals carried out by H. S. Liddell, W. H. Gantt, Norman R. Maier, and Jules Masserman. In order to understand the signi cance of these research programs, we will focus our analysis not only in the divergent methodologies and theoretical constructs proposed to explain these phenomena, but also in some of the convergent arguments used to justify the relevance of these animal studies for the understanding of human psychopathology -i.e. the observed similarity between the symptoms of the experimental animals and the human patients, with special reference to the symptoms observed in the psychiatric casualties during the World War II.

PLoS Biology, 2005

Do malaria parasites enhance the attractiveness of humans to the parasite's vector? As such manipulation would have important implications for the epidemiology of the disease, the question has been debated for many years. To investigate the issue in a semi-natural situation, we assayed the attractiveness of 12 groups of three western Kenyan children to the main African malaria vector, the mosquito Anopheles gambiae. In each group, one child was uninfected, one was naturally infected with the asexual (non-infective) stage of Plasmodium falciparum, and one harboured the parasite's gametocytes (the stage transmissible to mosquitoes). The children harbouring gametocytes attracted about twice as many mosquitoes as the two other classes of children. In a second assay of the same children, when the parasites had been cleared with anti-malarial treatment, the attractiveness was similar between the three classes of children. In particular, the children who had previously harboured gametocytes, but had now cleared the parasite, were not more attractive than other children. This ruled out the possibility of a bias due to differential intrinsic attractiveness of the children to mosquitoes and strongly suggests that gametocytes increase the attractiveness of the children. Citation: Lacroix R, Mukabana WR, Gouagna LC, Koella JC (2005) Malaria infection increases attractiveness of humans to mosquitoes. PLoS Biol. 3(9): e298.

Small Ruminant Research, 2012

Herbivores form preferences for substances that raise fitness such as nutritious foods and avoid those substances, which lower fitness such as plant secondary compounds (PSC). Nevertheless, some PSC at certain concentrations have the potential to raise fitness as they act against infective diseases such as parasitism. The objective of the present review is to assess whether parasitized farm animals are able to manifest self-medicative behaviors. The ability of herbivores to self-select these medicinal plant compounds emerges from the inherent adaptive nature of behavioral responses in living organisms. In order to manifest self-medication animals should experience discomfort caused by a certain illness and also relief associated with the mitigation of sickness brought about by the ingestion of a medicinal plant. Observational and controlled studies suggest such conditions, as well as self-medicative behaviors occur not only in wild but also in domestic herbivores. Selfmedicative behaviors may allow individuals seek medicinal plant products when infected by parasites, even at times when the manager is not aware of the existence of parasitism in the flock. Self-medication may also allow for proper nutrition as animals offered choices will consume PSC-containing plants as well as nutritious and safe forages. Management programs should be geared at enhancing in herbivores the likelihood of the association medicine-relief from sickness and at favoring the transmission of self-medicative behavior across generations.

The International Quarterly of Community Health Education, 1985

Guineaworm, a waterborne helminthic disease, affects a large portion of the population in Idere, Nigeria. Although preventive health education interventions are experiencing success, it is slow due to the low economic status of the community. In the meantime people suffer and seek treatment. The decisionmaking process during illness with guineaworm does not fit neatly into individual psychosocial theoretical models. Concepts of the disease and potential remedies are strongly influenced by the local culture. In the process of studying these cultural influences, suggestions for new models have arisen. These suggest a mediating role for health education between traditional and Western scientific viewpoints in promoting efficacious illness behavior in endemic tropical diseases. According to the elders, suffering from guineaworm, a waterborne helminthic disease, has been a daily part of life in the dry season since time immemorial in *This work was sponsored by a grant from the Social and Economic Scientific Working Group of the WHO/World Bank/UNDP Special Programme on Training and Research in Tropical Diseases.