Invitation B. Fassotte - Gembloux Agro-Bio Tech

Le Corps professoral de
Gembloux Agro-Bio Tech - Université de Liège vous prie
de lui faire l'honneur d'assister à la défense publique de la dissertation originale que
Madame Bérénice FASSOTTE,
Titulaire d’un diplôme de master bioingénieur en sciences agronomiques,
à finalité spécialisée
présentera en vue de l'obtention du grade et du diplôme de
DOCTEUR EN SCIENCES AGRONOMIQUES ET INGENIERIE BIOLOGIQUE,
le 28 avril 2016, à 15 heures, en l'auditorium de Zoologie (Zl),
Passage des Déportés,2 à 5030 GEMBLOUX.
Cette dissertation originale a pour titre :
« Sexual attraction in lady beetles : fundamentals and applications »
Le jury est composé comme suit :
Présidente : Prof. M.-L. FAUCONNIER : Présidente du Département AgroBioChem,
Membres: Prof. F. VERHEGGEN (Promoteur), F. FRANCIS, G. LOGNAY, B. BODSON,
P. DE CLERCQ (Université de Gand), T. HANCE (UCL).
UNIVERSITE DE LIEGE – GEMBLOUX AGRO-BIO TECH – SERVICE INSCRIPTIONS ET APPARITORAT
Passage des Déportés, 2 - 5030 Gembloux - Belgique
Téléphone +32(0)81 62 23 45 - Fax +32(0)81 62 21 68 - www.gembloux.ulg.ac.be
Abstract
Sustainable agriculture relies on the development of environmentally friendly methods of crop
production. Therefore, alternative solutions are required to decrease insecticide use and to promote
the efficacy of natural enemies against insect pests. Investigating the sexual behavior of lady beetles
is of practical relevance, because these insects could be used to reduce plant-feeding insect
populations in crop fields by taking advantage of their predatory behavior.
In this context, the objective of this PhD thesis was twofold: (1) a fundamental research that
focuses on the identification of the sex pheromone of Harmonia axyridis (Pallas) and (2) an applied
approach aimed at elaborating semiochemicals slow-release dispensers with these compounds, in
order to attract individuals in cultivated fields.
We have demonstrated that virgin females of H. axyridis display a typical male-calling
behavior in presence of prey, which is associated with the release of a pheromonal blend that is
highly attractive for conspecific males. Dynamic headspace sampling and subsequent chemical
analyses allowed the characterization of this sex pheromone. Finally, we focused on the
development of a formulation releasing a combination of semiochemicals that attract aphid
predators. The formulation, composed of alginate beads, was optimized under laboratory
conditions. The release rate of the formulation was assessed by dynamic headspace sampling
coupled with adsorbent trapping. The formulation was efficient at attracting two natural enemies of
aphids.
All these results are discussed in the context of sustainable agriculture, with the use of
semiochemicals, and especially pheromones, as potential tools to enhance current cropping systems.
In near future, the application of such molecules, based on strong knowledge of insect olfaction, is
expected to increase considerably with the development of new methods aimed at attracting
predators and/or parasitoids. In addition, improvements of experimental devices, such as the
elaboration of slow release dispensers, are suggested in the last chapter of this PhD thesis.
UNIVERSITE DE LIEGE – GEMBLOUX AGRO-BIO TECH – SERVICE INSCRIPTIONS ET APPARITORAT
Passage des Déportés, 2 - 5030 Gembloux - Belgique
Téléphone +32(0)81 62 23 45 - Fax +32(0)81 62 21 68 - www.gembloux.ulg.ac.be