Geometrical games between a host and a parasitoid

Avoiding detection by parasitoids is nearly impossible for most leafminers in their visually striking mines, and they often suffer from a high mortali ty rate by a great variety of parasitoid species. The leafminer-parasitoid interaction bears a strong resemblance to the princess-monster game develop ed in game theory, in which a "monster" (parasitoid) selects an optimal sea rch strategy to capture the "princess" (leafminer), while the princess sele cts an optimal strategy to hide from the monster. This article attempts to illustrate and to quantify the additional complexity that occurs when the p rincess can modify the arena in which the monster searches. Feeding activit y of the leafminer Phyllonorycter malella creates feeding windows, which ar e spots on the mine. Its main parasitoid Sympiesis sericeicornis is able to insert its ovipositor only through these feeding windows. Parasitism risk depends both un the leafminer-feeding pattern, which determines the structu re of the arena in which the parasitoid searches, and on the position of th e leafminer within the mine. The adaptive value of observed patterns of min e development and leafminer behavior is evaluated by comparing them to pred ictions from a simulation model of random patterns and leafminer positions. The leafminer creates a heterogeneous environment by leaving a central are a of uneaten tissue. This area acts as a protecting shield and greatly dimi nishes the risk of parasitism. Hence, by controlling the structure of the a rena in which the princess-monster game is played, the leafminer defines so me of the rules of the game.