Cannibalism in temporary waters. Simulations and laboratory experiments revealed the role of spatial shape in the mosquito Aedes albopictus

Cannibalism is a commonly observed phenomenon in arthropod species having relevant consequences for population dynamics and individual fitness. It is a context-dependent behaviour and an understanding of the factors affecting cannibalism rate is crucial to highlight its ecological relevance. In mosquitoes, cannibalism between larval stages has been widely documented, and the role of density, food availability and length of contact between individuals also ascertained. However, although mosquitoes can develop in temporary water habitats with very heterogeneous topologies, the role of the site shape where cannibals and victims co-occur has been instead overlooked. In this paper, we investigated this issue by using a simulation approach and laboratory cannibalism experiments between old (third- and fourth-instars) and young (first-instar) larvae of the tiger mosquito Aedes albopictus. Three virtual spaces with different shapes were simulated and the number of larval encounters was estimated in each one to assess whether the spatial shape affected the number of encounters between cannibal and victims. Then, experimental trials in containers with similar shapes to those used in the simulations were performed, and the cannibalism rate was estimated at 24 and 48h. Our results showed that the spatial shape plays a role on cannibalism interactions, affecting the number of encounters between individuals. Indeed, in the experimental trials performed, we observed the highest cannibalism rate in the container with the highest number of encounters predicted by the simulations. Interestingly, we found also that spatial shape can affect cannibalism not only by affecting the number of encounters, but also the number of encounters ªfavorableº for cannibalistic events. Temporary waters are inhabited by several species other than mosquitoes. Our results, showing an influence of the spatial shape on cannibalism in Ae. albopictus larvae, add a new critical factor to those affecting ecological interactions in these habitats

Cannibalism and infectious disease: Friends or foes?

© 2017 by The University of Chicago. Cannibalism occurs in a majority of both carnivorous and noncarnivorous animal taxa from invertebrates to mammals. Similarly, infectious parasites are ubiquitous in nature. Thus, interactions between cannibalism and disease occur regularly. While some adaptive benefits of cannibalism are clear, the prevailing view is that the risk of parasite transmission due to cannibalism would increase disease spread and, thus, limit the evolutionary extent of cannibalism throughout the animal kingdom. In contrast, surprisingly little attention has been paid to the other half of the interaction between cannibalism and disease, that is, how cannibalism affects parasites. Here we examine the interaction between cannibalism and parasites and show howadvances across independent lines of research suggest that cannibalism can also reduce the prevalence of parasites and, thus, infection risk for cannibals. Cannibalism does this by both directly killing parasites in infected victims and by reducing the number of susceptible hosts, often enhanced by the stage-structured nature of cannibalism and infection. While the well-established view that disease should limit cannibalism has held sway, we present theory and examples from a synthesis of the literature showing how cannibalism may also limit disease and highlight key areas where conceptual and empirical work is needed to resolve this debate

Zheng Yi. Scarlet memorial : tales of cannibalism in modern China

This article reviews the book Scarlet Memorial: Tales of Cannibalism in Modem China , written by Zheng Yi, translated and edited by T. P. Sym

\u27Since This is a Horrible Thing to Think About\u27: European Perceptions of Native American Cannibalism

Contemporary Italian playwright Dario Fo wrote a satirical play entitled Johan Padan and the Discovery of the Americas which purported to be the account of one Johan Padan, a contemporary of Columbus, who journeyed to the New World, was shipwrecked, and rescued by some friendly Indians. At one point, Padan and a group of his fellows discussed the hospitality of the Indians, who were quite generous. One of them expressed the fear that the Indians simply care for them so that they will make a splendid feast. Another man remarked, quite scathingly, “This is the third voyage I’ve made to the Indies and I’ve never met Indians with pieces of arms and legs hung up to dry in their huts, like those charlatans Amerigo Vespucci and Alfonso Gamberan talked about…They just told those stories to have an excuse for treating the Indians like animals: They’re cannibals, so we can make them slaves.” Although Fo is more concerned with literary conventions that with factual and historical accuracy, he succeeds in tapping into one idea which partially explains the proliferation of European literature about the Indians and their cannibalism, namely that cannibalism became a means whereby Europeans could justify their enslavement of the Indians. However, to say that the practice of cannibalism was simply used as justification for the enslavement of the Indians would be a grievous understatement, because cannibalism represented so much more to the Europeans. What was noted down originally as a new, curious, and revolting but fascinating practice, gradually transformed into a justification for enslavement of the Native Americans, a method of persuasion, and a device by which some Europeans critiqued their own countries

Cannibalism as a life boat mechanism

Under certain conditions a cannibalistic population can survive when food for the adults is too scarce to support a non-cannibalistic population. Cannibalism can have this lifeboat effect if (i) the juveniles feed on a resource inaccessible to the adults; and (ii) the adults are cannibalistic and thus incorporate indirectly the inaccessible resource. Using a simple model we conclude that the mechanism works when, at low population densities, the average yield, in terms of new offspring, due to the energy provided by one cannibalized juvenile is larger than one