Autotomy shapes the trade-off between seeking cover and foraging in larvaldamselflies

Animals commonly choose between microhabitats that differ in foraging retur n and mortality hazard. I studied the influence of autotomy, the amputation of a body part, on the way larvae of the damselfly Lestes sponsa deal with the trade-off between foraging or seeking cover. Survival of Lestes larvae when confronted with the odonate predator Aeshna cyanea was higher in a co mplex than in a simple microhabitat, indicating that this more complex micr ohabitat was safer. Within the simple microhabitat, larvae without lamellae had a higher risk for mortality by predation than larvae with lamellae, sh owing a long-term cost of autotomy. When varying the foraging value (food p resent or absent) and predation risk (encaged predator or no predator) in t he simple microhabitat, larvae with and without lamellae responded differen tially to the imposed trade-off. All larvae spent more time in the simple m icrohabitat when food was present than when food was absent. Larvae without lamellae, however, only sporadically left the safe microhabitat, irrespect ive of the presence of the predator. In contrast, larvae with lamellae shif ted more frequently towards the risky microhabitat than those without lamel lae, and more often in the absence than in the presence of the predator. Th ese decisions affected the foraging rates of the animals. I show for the fi rst time that refuge use is higher after autotomy and that this is associat ed with the cost of reduced foraging success. The different microhabitat pr eferences for larvae with and without lamellae are consistent with their di fferent vulnerabilities to predation and demonstrate the importance of intr insic factors in establishing trade-offs.