Behavioral Ecology Advance Access published online on April 25, 2008
Behavioral Ecology, doi:10.1093/beheco/arn046
Programmed versus stimulus-driven antiparasitic grooming in a desert rodent
a Department of Life Sciences, Ben-Gurion University of the Negev, 84105 Beer-Sheva, Israel b Mitrani Department of Desert Ecology, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus, 84490 Midreshet Ben-Gurion, Israel c Ramon Science Center, 80600 Mizpe Ramon, Israel d Desert Animal Adaptations and Husbandry, Wyler Department for Dryland Agriculture, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus, 84490 Midreshet Ben-Gurion, Israel
Address correspondence to H. Hawlena, who is now at Department of Biology, Indiana University, Bloomington, IN 47405, USA. E-mail: hadashaw{at}gmail.com.
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Abstract |
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We tested 2 hypotheses concerning regulation of grooming in flea-infested rodents and examined if 2 grooming components, scan and scratch grooming, are controlled by programmed and stimulus-driven regulation, respectively. The programmed grooming hypothesis proposes central programming that periodically evokes a bout of grooming to remove ectoparasites before they are attached and predicts that juvenile rodents 1) regardless of infestation status will invest more time in grooming (the body size principle) and 2) sustain lower flea densities than adults. The stimulus-driven grooming hypothesis postulates a direct response to irritation from ectoparasite bites and predicts that under flea-free conditions, 1) the stimulus-driven grooming regulation will not be activated, thereby neither juveniles nor adults will engage in grooming, but under flea infestation, 2) adults will invest more time in grooming than juveniles and sustain similar flea densities. We recorded the behavior of adult and juvenile flea-parasitized and nonparasitized rodents and quantified the frequency and duration of the 2 grooming components. Flea infestation increased the time devoted to grooming, supporting the existence of a regulation mechanism. However, the results did not support the dominance of neither hypothesis. Both forms of grooming were affected similarly by flea infestation and host age, hence may not necessarily be linked to a given regulation mechanism. Regardless of infestation status, time devoted to grooming was lower in juveniles, and both age groups sustained fleas at similar densities. We suggest that the assumptions and predictions of the 2 hypotheses should take into account the morphology and natural history of the host organism.
Key words: body size principle, ectoparasites, programmed grooming, stimulus-driven grooming, time budget.
Received 11 January 2008; revised 19 March 2008; accepted 22 March 2008.