A Parasitoid of Aphids Manipulates Host Mummification Site, With Effects on Survival but Not Hyperparasitism

Abstract

Many parasites change the behavior of their host. Parasitoid wasps, for example, frequently engage in body guard manipulation to induce behaviors in their hosts that enhance parasite survival after pupation. Parasitoids of aphids have repeatedly been found to alter host location on the plant, thereby influencing the location where their host mummifies, that is their pupation site. Potential benefits of this behavior for the parasite, however, remain under debate. Combining experiments in the laboratory and the field, we tested whether the parasitoid Aphelinus chaonia induces behavioral changes in its aphid host to influence its mummification location and whether these reduce hyperparasitism, an important source of mortality to the developing parasitoid. Aphelinus chaonia clearly caused aphids to move either off the plant or into the leaf axil prior to mummification and host death. However, movement to the leaf axil did not result in any reduction of hyperparasitism. Nevertheless, in the field, mummies situated on the stem were less likely to survive than those elsewhere on the plant, including in the leaf axil. We discuss our findings in the light of potential host manipulation.