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. infestations. The aim was to identify promising varieties for local protein sourcing in the food industry. Fourteen varieties were assessed over two seasons, taking into consideration parameters such as protein production and bruchid infestations. A ranking methodology based on principal component analyses is presented, along with the varieties most suitable for the Walloon agro-climatic context. Factors promoting varietal resilience in European contexts were also identified. Chapter V focused on the semiochemical control of BBW, aiming to identify efficient traps for capturing BBWs, assess the traps' impact on BBW sex ratios, evaluate collateral effects on crop benefits, and examine the influence of crop stage on trap captures. White pan traps combined with floral kairomones were found to be the most effective. Crop phenology strongly influenced trap attractiveness, and no significant sex ratio trends were observed. However, semiochemical traps had a significant impact on beneficial insects, requiring further adaptation to minimize collateral effects, particularly for threatened species. Recommendations are provided for minimizing impacts on beneficial entomofauna. Chapter VI investigated in laboratory potential new biopesticides against BBW. Firstly, five strains of entomopathogenic fungi were screened for their lethal and sublethal effects on bruchid species. B. bassiana (GHA) exhibited the highest virulence in terms of TL50. Additionally, the study explores RNA interference with C. maculatus as a biotechnological tool for bruchid control. All the necessary proteins for gene silencing and the laccase 1 gene were successfully identified. Micro-injection of laccase 1 dsRNA resulted in a significant decrease in gene expression in treated adults. Although no significant mortality was observed, further research should focus on the larval stage or explore alternative target genes to induce lethal effects. The study demonstrates successful gene silencing in a bruchid species and highlights RNAi as a potential control method. Chapter VII summarizes the different control levers evaluated in the thesis for the development of integrated biocontrol strategies against B. rufimanus. The most suitable crop itinerary for minimizing BBW impacts is presented as well as areas for future research to further develop the main conclusions of the thesis.Projet FEVERPR

An update for Halyomorpha halys (Stål, 1855) (Hemiptera, Pentatomidae) distribution in Belgium

The brown marmorated stink bug, Halyomorpha halys, represents an important insect pest and subsequently an important agricultural threat due to its polyphagous feeding habits and adaptability to diverse climates. Native from East Asia, its recent establishment in various regions, including North America and Europe, has led to substantial yield losses and economic impacts, which highlight the need for comprehensive research efforts, based on data occurrence by combining those from expert entomologists and citizen scientists. We reported here 14 new occurrences of this insect pest in the three regions of Belgium. Then, these data were merged with data occurrences from other studies and GBIF datasets of Belgium. The combined dataset showed a peak of presence of Halyomorpha halys in October and a dominance of field observations from citizen scientists especially in the nothern part of Belgium, Flanders. Crowd-sourced data have provided valuable insights into the presence and distribution of Halyomorpha halys in Belgium. Given the importance of the generated dataset, it could be asserted that this pest is uniformly distributed across the entire country, which necessitates additional research to evaluate its impact on various crops

Des plateformes analytiques et technologiques pour le développement de nouveaux biostimulants et agents de biocontrôle (PHENIX_BIOCONTROL_ULIEGE)

The PHENIX-BIOCONTROL-ULIEGE project relies on the analytical and technological platforms of the PHENIX portfolio to develop new biostimulants and control agents, in connection with the IIS DigiBiocontrol. This project is coordinated by Pr. Philippe Jacques from Gembloux Agro-Bio Tech (University of Liège), who is also the leader of the IIS DigiBiocontrol initiative. Four Work Packages are brached to reinforce 6 key competence axes of innovation in biostimulation and biocontrol: new screening approaches, mode of action characterization, control mode activity, production processes, formulation and texturing, and greenhouse and field demonstration.Le projet PHENIX-BIOCONTROL-ULIEGE s'appuie sur les plateformes analytiques et technologiques du portefeuille PHENIX pour développer de nouveaux biostimulants et agents de contrôle, en lien avec l'IIS DigiBiocontrol. Ce projet est coordonné par le Pr. Philippe Jacques de Gembloux Agro-Bio Tech (Université de Liège), qui est également le chef de file de l'initiative IIS DigiBiocontrol. Quatre Work Packages sont mis en place pour renforcer 6 axes de compétences clés en matière d'innovation dans le domaine de la biostimulation et du biocontrôle : nouvelles approches de criblage, caractérisation du mode d'action, activité du mode de contrôle, processus de production, formulation et texturation, et validation en serre et en champ.Projet PHENIX Biocontrol ULiège-SP

Taxonomy based on science is necessary for global conservation

Peer reviewe

Overview of Bruchus rufimanus Boheman 1833 (Coleoptera: Chrysomelidae): Biology, chemical ecology and semiochemical opportunities in integrated pest management programs

Promoting the cultivation of native legumes, such as faba beans (Vicia faba L.) within the European Union is anticipated to contribute to the sustainability of cropping systems and provide food and feed proteins as alternatives to unsustainable imports. However, efficient alternative control methods to pesticides must be implemented to combat key pests that devalue faba bean seeds (namely, Bruchus rufimanus Boheman 1833, Coleoptera: Chrysomelidae). This pest causes significant economic losses in faba bean crops as post-embryonic development (cf. seminovorous larvae) occurs inside forming seeds. While there has been extensive research on the biology and chemical ecology of B. rufimanus, efficient control methods are lacking. Here, we review this pest species to identify: (i) knowledge gaps on its biology that could enhance management tools; (ii) potential improvements to current semiochemical based control approaches; and (iii) other method of control based on semiochemicals that could be implemented.FEVERPR

FEVERPRO Project Development of biological control methods in alternative to pesticides to manage Bruchus rufimanus Boheman 1833 in field bean crops

Bruchus rufimanus Boheman 1833 (Coleoptera : Chrysomelidae) is a serious pest of Vicia faba L. (Fabaceae) preventing the valuation of crop products due to its post-embryonic development taking place inside forming seeds. However, the European Union, concerned about the sustainable development of its agriculture, promotes V. faba crops for its multiple services provided to cropping systems, and restricts at the same time the use of effective pesticides against B. rufimanus. This suggests the finding of alternative control methods, such as the use of semiochemicals. To date, some volatile organic compounds (VOCs) involved in the field colonization, feeding, mating and oviposition of B. rufimanus, taking place on different parts of V. faba and following its phenological stage, have already been identified. Further studies would, however, provide insight into other pheromonal means of communication that could be implemented in the semiochemical-based management of this pest, such as the assessment of oviposition or aggregation pheromones. Concerning the semiochemical-based control methods, only one study has been trying to implement a mass-trapping method; and no studies investigated other methods, such as the push-pull or attract-and-kill methods, in IPM strategy including new insight into pheromone identification, entomopathogenic agents or specific parasitoids. In this context, preliminary experimentations of entomopathogenic tests and odor samplings for the identification of new pheromones (aggregation or oviposition deterring pheromone) were carried out within the “FEVERPRO project”, and could suggest the implementation of innovative control methods of this specific pest in alternative to the use of pesticides.FEVERPR

Gene Silencing of <i>laccase 1</i> Induced by Double-Stranded RNA in <i>Callosobruchus maculatus</i> (Fabricius 1775) (Coleoptera: Chrysomelidae) Suggests RNAi as a Potential New Biotechnological Tool for Bruchid’s Control

Bruchids are the most important pests of leguminous seeds in the world. In this study, the focus was done on Callosobruchus maculatus, a serious pest of Vigna unguiculata seeds. As no efficient control methods preventing collateral effects on beneficials currently exist, this study investigated whether RNA interference (RNAi) could provide a new biotechnological and selective tool for bruchids control. Three principal objectives were followed including (i) the identification of all RNAi machinery core components and a key protein to silence in C. maculatus genome (c.f., dicer-2, argonaute-2, R2D2, and laccase 1), (ii) the identification of suitable reference gene for RT-qPCR analyses, and (iii) the micro-injection of dsRNA coding for laccase 1 to adults of C. maculatus to assess gene expression levels by RT-qPCR and potentially related mortalities. Phylogenetical analyses performed from transcriptomic information successfully identified all necessary proteins in the RNAi mechanism and also the open reading frame of laccase 1 in C. maculatus. A new reference gene was identified (i.e., alpha-tubuline 1) and coupled with glutiathone S transferase for RT-qPCR analyses. Double-stranded RNAs coding for laccase 1 and green fluorescent protein (control) were produced and 400 ng of each dsRNA were micro-injected into C. maculatus adults. RT-qPCR analyses revealed a stable significant decrease in laccase 1 expression in about 80% of adults treated with laccase 1 dsRNA after three days post-injection. No significant mortalities were observed which is probably related to the non-exposure of adults to anti-nutritional factors that are usually regulated by laccase. Further research should focus either on the feeding larval stage which is directly exposed to anti-nutritional factors, or on other target genes to induce dead phenotypes. This study is the first gene silencing report on a bruchid species and supports RNAi as a potential future method of control

Susceptibility of Bruchus rufimanus Boheman 1833 (Coleoptera: Chrysomelidae) to three entomopathogenic fungi: Limits of conidial suspensions sprayings and potential alternatives in integrated pest management strategy

peer reviewedBruchus rufimanus Boheman 1833 is a serious pest of Vicia faba L. preventing the valuation of seeds. Limited control methods against this pest suggested few alternatives, out of which entomopathogenic fungi were proposed as promiscuous control levers, but no data precisely describe the optimal method of application on large scale crops. First results from laboratory bioassays on this pest showed a “conidial quantity” dependent lethal response which is not compatible with classical crop spraying. These results are therefore discussed to highlight other application methods, such as attract and infect and endophytic fungi, which could integrate IPM strategyFEVERPR

Impacts of Semiochemical Traps Designed for Bruchus rufimanus Boheman 1833 (Coleoptera: Chrysomelidae) on Nontarget Beneficial Entomofauna in Field Bean Crops

Broad bean weevils (BBWs&ndash;Coleoptera: Chrysomelidae) are serious pests of field bean seeds that hamper the promotion of this crop in the diversification of European cropping systems. Recent research has identified different semiochemical lures and trap devices for the development of semiochemical-based control strategies of BBWs. In this study, two field trials were carried out in order to provide necessary information supporting the implementation of sustainable field use of semiochemical traps against BBWs. More particularly, three principal objectives were followed including (i) the identification of the most efficient traps for BBWs capture and the influence of trapping modality on BBWs sex-ratio, (ii) the assessment of eventual collateral effects on crop benefits including aphidophagous and pollinator insects such as Apidae, Syrphidae and Coccinellidae, (iii) the assessment of the crop developmental stage influence on the capture by semiochemical traps. Three different semiochemical lures were tested in combination with two trapping devices across two field trials in early and late flowering field bean crops. The crop phenology and climate parameters were integrated into the analyses to interpret the spatiotemporal evolution of the captured insect populations. A total of 1380 BBWs and 1424 beneficials were captured. White pan traps combined with floral kairomones were the most efficient traps for the capture of BBWs. We demonstrated that the crop phenology (c.f., the flowering stage) exerted strong competition on the attractiveness of semiochemical traps. Community analysis revealed that only one species of BBWs was captured in field bean crops (i.e., Bruchus rufimanus), and no trend was highlighted concerning the sex ratios according to the trapping devices. The beneficial insect community included 67 different species belonging to bees, hoverflies and ladybeetles. Semiochemical traps manifested a strong impact on beneficial insect communities that included some species under extinction threats and need to be further adapted to minimize such collateral effects. Based on these results, recommendations are provided for the implementation of the most sustainable BBWs control method that minimizes the impact on the recruitment of beneficial insects, which is an important ecosystem service for faba bean crops