title: Temporal autocorrelation in host density increases establishment success of parasitoids in an experimental system.
abstract: Environmental variation is classically expected to affect negatively population growth and to increase extinction risk, and it has been identified as a major determinant of establishment failures in the field. Yet, recent theoretical investigations have shown that the structure of environmental variation and more precisely the presence of positive temporal autocorrelation might alter this prediction. This is particularly likely to affect the establishment dynamics of biological control agents in the field, as host-parasitoid interactions are expected to induce temporal autocorrelation in host abundance. In the case where parasitoid populations display overcompensatory dynamics, the presence of such positive temporal autocorrelation should increase their establishment success in a variable environment. We tested this prediction in laboratory microcosms by introducing parasitoids to hosts whose abundances were manipulated to simulate uncorrelated or positively autocorrelated variations in carrying capacity. We found that environmental variability decreased population size and increased parasitoid population variance, which is classically expected to extinction risk. However, although exposed to significant environmental variation, we found that parasitoid populations experiencing positive temporal autocorrelation in host abundance were more likely to persist than populations exposed to uncorrelated variation. These results confirm that environmental variation is a key determinant of extinction dynamics that can have counterintuitive effects depending on its autocorrelation structure.
authors.affiliation: INRA, UMR 1355 Institut Sophia Agrobiotech 06900, Sophia Antipolis, France ; Université Nice Sophia Antipolis, UMR 7254 Institut Sophia Agrobiotech 06900, Sophia Antipolis, France ; CNRS, UMR 7254 Institut Sophia Agrobiotech 06900, Sophia Antipolis, France.
authors.forename: Elodie
authors.initials: E
authors.lastname: Vercken
authors.affiliation: INRA, UMR 1355 Institut Sophia Agrobiotech 06900, Sophia Antipolis, France ; Université Nice Sophia Antipolis, UMR 7254 Institut Sophia Agrobiotech 06900, Sophia Antipolis, France ; CNRS, UMR 7254 Institut Sophia Agrobiotech 06900, Sophia Antipolis, France.
authors.forename: Xavier
authors.initials: X
authors.lastname: Fauvergue
authors.affiliation: INRA, UMR 1355 Institut Sophia Agrobiotech 06900, Sophia Antipolis, France ; Université Nice Sophia Antipolis, UMR 7254 Institut Sophia Agrobiotech 06900, Sophia Antipolis, France ; CNRS, UMR 7254 Institut Sophia Agrobiotech 06900, Sophia Antipolis, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Ris
authors.affiliation: INRA, UMR 1355 Institut Sophia Agrobiotech 06900, Sophia Antipolis, France ; Université Nice Sophia Antipolis, UMR 7254 Institut Sophia Agrobiotech 06900, Sophia Antipolis, France ; CNRS, UMR 7254 Institut Sophia Agrobiotech 06900, Sophia Antipolis, France.
authors.forename: Didier
authors.initials: D
authors.lastname: Crochard
authors.affiliation: INRA, UMR 1355 Institut Sophia Agrobiotech 06900, Sophia Antipolis, France ; Université Nice Sophia Antipolis, UMR 7254 Institut Sophia Agrobiotech 06900, Sophia Antipolis, France ; CNRS, UMR 7254 Institut Sophia Agrobiotech 06900, Sophia Antipolis, France ; INRIA, Biocore 06902, Sophia Antipolis, France.
authors.forename: Ludovic
authors.initials: L
authors.lastname: Mailleret
keywords: Environmental noise; Trichogramma; introduced populations; propagule pressure; red noise; transitory dynamics; white noise