title: Lethal and sublethal costs of autotomy and predator presence in damselfly larvae.
abstract: We studied the costs of lamellae autotomy with respect to growth and survival of Lestes sponsa damselfly larvae in field experiments. We manipulated predation risk by Aeshna cyanea dragonfly larvae and lamellae status of L. sponsa larvae in field enclosures and compared differences in numbers, size and mass of survivors among treatments. In the absence of a free-ranging A. cyanea larva, about 29% of the L. sponsa larvae died. This was probably due to cannibalism. The presence of a free-ranging A. cyanea reduced larval survival by 68% compared to treatments in which it was absent or not permitted to forage on L. sponsa damselflies. Across all predator treatments, lamellae autotomy reduced survival by about 20%. The mean head width and mass of survivors was lower in the enclosures with a free-ranging A. cyanea compared to the other two predator treatments. This suggested that larvae grew less in the presence of a free-ranging predator, indicating that increased antipredator behaviours were more important in shaping growth responses than reduced population density. Mass, but not head width, of survivors was also reduced after autotomy. The fitness consequences of these effects for the adults may be pronounced. In general, these field data strongly suggest that lamellae autotomy affects population regulation of damselflies.
authors.affiliation: Evolutionary Biology Group, University of Antwerp (RUCA), Groenenborgerlaan 171, B-2020 Antwerp, Belgium e-mail: stoks@ruca.ua.ac.be, Fax: +32-3-2180474, , , , , , BE.
authors.forename: Robby
authors.initials: R
authors.lastname: Stoks
authors.affiliation: Evolutionary Biology Group, University of Antwerp (RUCA), Groenenborgerlaan 171, B-2020 Antwerp, Belgium e-mail: stoks@ruca.ua.ac.be, Fax: +32-3-2180474, , , , , , BE.
authors.forename: Marjan
authors.initials: M
authors.lastname: De Block
authors.affiliation: Evolutionary Biology Group, University of Antwerp (RUCA), Groenenborgerlaan 171, B-2020 Antwerp, Belgium e-mail: stoks@ruca.ua.ac.be, Fax: +32-3-2180474, , , , , , BE.
authors.forename: Hans
authors.initials: H
authors.lastname: Van Gossum
authors.affiliation: Evolutionary Biology Group, University of Antwerp (RUCA), Groenenborgerlaan 171, B-2020 Antwerp, Belgium e-mail: stoks@ruca.ua.ac.be, Fax: +32-3-2180474, , , , , , BE.
authors.forename: Famke
authors.initials: F
authors.lastname: Valck
authors.affiliation: Evolutionary Biology Group, University of Antwerp (RUCA), Groenenborgerlaan 171, B-2020 Antwerp, Belgium e-mail: stoks@ruca.ua.ac.be, Fax: +32-3-2180474, , , , , , BE.
authors.forename: Kris
authors.initials: K
authors.lastname: Lauwers
authors.affiliation: Evolutionary Biology Group, University of Antwerp (RUCA), Groenenborgerlaan 171, B-2020 Antwerp, Belgium e-mail: stoks@ruca.ua.ac.be, Fax: +32-3-2180474, , , , , , BE.
authors.forename: Ron
authors.initials: R
authors.lastname: Verhagen
authors.affiliation: Laboratory for Animal Ecology, University of Antwerp (UIA), Universiteitsplein 1, B-2610 Wilrijk, Belgium, , , , , , BE.
authors.forename: Erik
authors.initials: E
authors.lastname: Matthysen
authors.affiliation: Evolutionary Biology Group, University of Antwerp (RUCA), Groenenborgerlaan 171, B-2020 Antwerp, Belgium e-mail: stoks@ruca.ua.ac.be, Fax: +32-3-2180474, , , , , , BE.
authors.forename: Luc
authors.initials: L
authors.lastname: De Bruyn
keywords: Growth; Key words Autotomy; Lestes sponsa; Predation; Survival