Search

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.robot.2006.05.001 Byline: P. Valdastri (a), P. Corradi (a), A. Menciassi (a), T. Schmickl (b), K. Crailsheim (b), J. Seyfried (c), P. Dario (a) Abstract: Rapid advancements of both microsystem technology and multi-agent systems have generated a new discipline, arising from the fusion of microrobotics technologies and of swarm intelligence theories. Microrobotics contributes with new capabilities in manipulating objects in the microscale and in developing miniaturized intelligent machines, while swarm intelligence supplies new algorithms allowing sets of simple robotic agents to solve complex tasks. A microrobotic swarm that is able to collectively achieve a cleaning task in an arena has been developed. This paper presents a novel platform for microrobotic swarms with the goal to apply swarm intelligence results to practical micromanipulation tasks and describes in details two main features of the platform: an optical communication strategy between the microrobotic agents, in order to share information and to coordinate swarm actions, and a micromanipulation technique-based on electrostatic phenomena-which can be performed by each microrobotic agent. Author Affiliation: (a) Scuola Superiore Sant'Anna - CRIM Lab, V.le R. Piaggio 34-56025 Pontedera (PI), Italy (b) Department for Zoology, Karl-Franzens-Universitat Graz, Universitatsplatz 2, A-8010 Graz, Austria (c) Universitat Karlsruhe (TH), IPR, Building 40.28, KaiserstraAe 12-76128 Karlsruhe, Germany Article History: Received 18 April 2005; Revised 8 May 2006; Accepted 15 May 2006

Abstract: Butterflies of the genus Heliconius are well known for their peculiar habits of utilizing pollen as a source of amino acids. Saliva plays a major role in the process of extracting amino acids and proteins from the pollen grains. In this investigation, we obtained samples of saliva from adult Heliconius melpomene by placing pumpkin pollen or fine glass-beads on the proboscis, which stimulates the butterflies to release saliva. Proteolytic activity was determined in the saliva by an insoluble protein-dye that turns blue when cleaved by proteases. Its extinction value was measured with a spectrophotometer at 595nm. Both the saliva sampled with pollen and the saliva obtained from inert glass-beads exhibit proteolytic activity demonstrating that the saliva contains proteases. The proteolytic activity of the pollen/saliva samples was higher than that of the glass-bead/saliva samples, which we attribute to the stimulating effects of pollen, such as taste, smell, and texture, and not to proteases which might have been liberated from the pollen. This is indicated by the fact that pollen samples without saliva showed only a negligible indication for proteolytic activity. In general, females exhibit higher proteolytic activities than males, presumably due to their greater amino acid investment in reproduction. We present here first evidence for the existence of proteases in the saliva of a butterfly species and suggest that these enzymes are crucial for the use of amino acids and proteins from pollen in Heliconius butterflies. [Copyright &y& Elsevier]