Ecology of the invasive ladybird Harmonia axyridis in Europe

Nick Berkvens

    Onderzoeksoutput: ScriptieDoctoraatsscriptie - Doctoraatsscriptiepeer review


    The invasive ladybeetle Harmonia axyridis was originally introduced in Europe as a biological control agent of aphids. The recent establishment and spread of the species in Europe has lead to questions concerning the sustainability and environmentally friendliness of this strategy. This study aims to exploit H. axyridis as a prominent case study to acquire fundamental information on ecological traits determining both the success of invasions by exotic biological control agents and the hazards associated to these invasions. A first part of the study demonstrated the ability of H. axyridis to exploit pollen and fruit as alternative foods. This ability may contribute to the species’ establishment potential by sustaining its populations in times of prey scarcity and may offer the polyphagous coccinellid a competitive advantage over other native ladybird species with a lesser nutritional plasticity. Furthermore, an insignificant impact of the native braconid Dinocampus coccinellae on the population dynamics of H. axyridis was shown. This supports the enemy release hypothesis stating that the success of an invasion may be related to the scarcity of natural enemies in the introduced range compared to the native range. If an invasive arthropod is to establish in temperate or cold regions, it must be capable of surviving the occurring winter temperatures. Measurements of the cold tolerance of overwintering adults in indoor and outdoor hibernaculi concluded that a strong cold hardiness aids the species’ potential establishment in large regions of Europe. The fitness of the melanic and non-melanic morphs of H. axyridis differed during several experiments during the study. Due to the specific attributes of each morph, H. axyridis can take optimal advantage of new niches during her establishment. Polyphagy, climatic adaptability, absence of natural enemies and polymorphism are functional traits that may contribute to a successful invasion of an exotic natural enemy. In addition, polyphagy is a key trait which can lead to significant risks in colonized areas. This study supports the implementation of a risk-assessment procedure for screening new exotic biological control agents prior to their introduction in the field.
    Oorspronkelijke taalEngels
    Plaats van publicatieGhent
    ISBN’s in drukversie9789059893535
    PublicatiestatusGepubliceerd - 29-jan-2010


    • B390-gewasbescherming

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