Pit relocation by antlion larvae: A simple model and laboratory test

• Published in: Evolutionary ecology 1991-04, Vol.5 (2), p.93-104
• Main Authors: Linton, M. C., Crowley, P. H., Williams, J. T., Dillon, P. M., Aral, H., Strohmeier, K. L., Wood, C.
• Format: Article
• Language: English
• Subjects: Myrmeleon immaculatus; Myrmeleontidae; Neuroptera
• ISSN: 0269-7653; 1573-8477
• DOI: 10.1007/BF02270826

We generated a computer model to analyse the effects of "shadow" competition for sit-and-wait predators, particularly antlion larvae. The model used a simple foraging assessment rule to determine the quality of an antlion's location, and antlions relocated randomly in theis habitat when a location proved to be of low quality. Shadow competition, or competition for food caused when one sit-and-wait predator intercepts moving prey before a second sit-and-wait predator is encountered, was incorporated into the model by restricting antlions to a bounded arena, and having prey for the antlions enter from the arena periphery. Antlions responded to shadow competition by relocating their pits to peripheral areas of their habitat. An experimental test with the antlion Myrmeleon immaculatus supported the importance of shadow competition as a cause of observed pit distributions. Only the treatment which incorporated shadowing had pit distributions near the periphery, while the pit distributions in the control treatments did not differ from randomly generated distributions. Shadowing can influence sit-and-wait predator distributions when the prey distributions and movement patterns generate the conditions necessary for shadowing.