Bio-based control strategies of Bruchus rufimanus in faba bean crop ; Stratégies de contrôle bio-basées de Bruchus rufimanus en culture de féverole

This thesis broaches the promotion of faba bean cultivation (Vicia faba L., Fabaceae) for food uses in Wallonia and the challenge posed by the broad bean weevil, Bruchus rufimanus Boheman 1833 (Coleoptera : Chrysomelidae). Faced with no effective control methods against this pest, biocontrol strategies and alternatives to pesticides were investigated. Five approaches were adressed, including the improvement of the pest bio-ecological knowledge, the identification of optimal varieties for seed valorization in food industries, the evaluation of most effective semiochemical traps, and the development of specific control methods based on entomopathogenic fungi and RNA interference. Chapter I provided an overview of faba bean cultivation and the challenges posed by Bruchus rufimanus (BBW) infestations in Europe. The chapter reviews the biology and chemical ecology of BBW, identifies knowledge gaps, and explores potential improvements to semiochemical-based approaches and alternative control methods. This chapter lays the groundwork for the subsequent research areas of the thesis. Chapters II focused on the ecology and the biology of BBW in Wallonia. Field monitoring studies were conducted to gather comprehensive data about adult infestations, addressing the lack of region-specific information. The diversity of bruchids and their parasitoids in faba bean crops are described, including their spatial distribution and the damage they cause to seeds. Bruchus rufimanus was identified as the predominant bruchid species, along with four larval parasitoids: Triaspis luteipes, T. thoracica, Pteromalus sequester, and P. fasciatus. Infestation rates and emergence timing of BBW varied across different bioclimatic areas. Chapter III provides a methodological description of rearing Bruchus rufimanus and models the influence of temperature on the pest's embryonic and post-embryonic development. Chapter IV evaluated faba bean varieties and the combined influence of climate on crop productivity, seed quality, and Bruchus spp. ...