title: Antagonistic interactions between an invasive alien and a native coccinellid species may promote coexistence.
abstract: Despite the capacity of invasive alien species to alter ecosystems, the mechanisms underlying their impact remain only partly understood. Invasive alien predators, for example, can significantly disrupt recipient communities by consuming prey species or acting as an intraguild predator (IGP). Behavioural interactions are key components of interspecific competition between predators, yet these are often overlooked invasion processes. Here, we show how behavioural, non-lethal IGP interactions might facilitate the establishment success of an invading alien species. We experimentally assessed changes in feeding behaviour (prey preference and consumption rate) of native UK coccinellid species (Adalia bipunctata and Coccinella septempunctata), whose populations are, respectively, declining and stable, when exposed to the invasive intraguild predator, Harmonia axyridis. Using a population dynamics model parameterized with these experimental data, we predicted how intraguild predation, accommodating interspecific behavioural interactions, might impact the abundance of the native and invasive alien species over time. When competing for the same aphid resource, the feeding rate of A. bipunctata significantly increased compared to the feeding in isolation, while the feeding rate of H. axyridis significantly decreased. This suggests that despite significant declines in the UK, A. bipunctata is a superior competitor to the intraguild predator H. axyridis. In contrast, the behaviour of non-declining C. septempunctata was unaltered by the presence of H. axyridis. Our experimental data show the differential behavioural plasticity of competing native and invasive alien predators, but do not explain A. bipunctata declines observed in the UK. Using behavioural plasticity as a parameter in a population dynamic model for A. bipunctata and H. axyridis, coexistence is predicted between the native and invasive alien following an initial period of decline in the native species. We demonstrate how empirical and theoretical techniques can be combined to understand better the processes and consequences of alien species invasions for native biodiversity.
authors.affiliation: The Department of Animal Plant Sciences, The University of Sheffield, Sheffield, S10 2TN, UK.|Centre for Ecology and Hydrology (CEH), Crowmarsh Gifford, Wallingford, Oxfordshire, OX10 8BB, UK.|The James Hutton Institute, Dundee, DD2 5DA, UK.|School of Biosciences, Cardiff University, Cardiff, CF10 3AX, UK.
authors.forename: William T
authors.initials: WT
authors.lastname: Hentley
authors.affiliation: CEH, Bush Estate, Penicuik, Midlothian, EH26 0QB, UK.
authors.forename: Adam J
authors.initials: AJ
authors.lastname: Vanbergen
authors.affiliation: The Department of Animal Plant Sciences, The University of Sheffield, Sheffield, S10 2TN, UK.
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Beckerman
authors.affiliation: The Department of Animal Plant Sciences, The University of Sheffield, Sheffield, S10 2TN, UK.|Centre for Ecology and Hydrology (CEH), Crowmarsh Gifford, Wallingford, Oxfordshire, OX10 8BB, UK.
authors.forename: Melanie N
authors.initials: MN
authors.lastname: Brien
authors.affiliation: Centre for Ecology and Hydrology (CEH), Crowmarsh Gifford, Wallingford, Oxfordshire, OX10 8BB, UK.
authors.forename: Rosemary S
authors.initials: RS
authors.lastname: Hails
authors.affiliation: School of Biosciences, Cardiff University, Cardiff, CF10 3AX, UK.
authors.forename: T Hefin
authors.initials: TH
authors.lastname: Jones
authors.affiliation: Hawkesbury Institute for the Environment, Western Sydney University, Hawkesbury Campus, Locked Bag 1797, Penrith, NSW 2751, Australia.
authors.forename: Scott N
authors.initials: SN
authors.lastname: Johnson
mesh_terms: D000818:Animals; D001042:Aphids / Q000254:growth & development / Q000502:physiology*; D001517:Coleoptera / Q000254:growth & development / Q000502:physiology*; D004739:England; D020387:Food Chain; D058865:Introduced Species; D007814:Larva / Q000254:growth & development / Q000502:physiology; D009758:Nymph / Q000254:growth & development / Q000502:physiology; D011157:Population Dynamics; D011235:Predatory Behavior
keywords: aphid; behaviour; biocontrol; intraguild predation; ladybird; ladybug; natural enemies; non-consumptive interactions