Sustainable intensification of fruit production systems through innovative pest biological control technologies – Pest free fruit

Here, we propose to release entomopathogen and fungicide-coated sterile male fruit flies in orchards to reduce losses due to fruit flies and anthracnose, through (1) epidemic transmission of entomopathogens and (2) induction of sterility among wild fruit fly populations, and (3) dissemination of antagonistic fungi. With this ‘three-in-one’ technology relying on a sterile insect technique program (SIT), fruit growers will benefit from the biological control of both fruit fly and anthracnose. The SIT is an environmentally-friendly control method involving the mass-rearing and sterilization, using radiation, of a target pest, followed by the area-wide release of the sterile males over defined areas, where they mate with wild females resulting in no offspring and a declining pest population. The smart combination with specific entomopathogenic fungi have great potential for biocontrol because they reproduce in the insects they kill, resulting in epizootic in target pest populations. This approach has been recently tested with success to control medflies in Mexico. We will also test the transfer of antagonistic fungi (Trichoderma) by sterile B. dorsalis males to control mango anthracnose. One famous application of the concept of entomovectoring, developed earlier by UHEL team, is the use of bumblebees (flying doctors®) to bring fungicide to strawberry flowers to control diseases. We also propose a complementary approach based on auto-dissemination, in which wild males attracted to stations baited with male-specific lures and fungal spores, transfer fungal spores to target habitats and counterparts via mating and other social behaviors. This method was tested in Kenya (Real IPM) to control fruit flies but needs some more optimization to reach field effectiveness, and has to be tested to disseminate anthracnose-antagonist fungi.

Reporting in social media
? Chailleux A (2019) Pest Free Fruit : une mission de collaboration sur la gestion des mouches des fruits au Sénégal. Published online 12/11/2019.
? Muriithi B, Belmin R (2019) Household-level Field Survey of the Pest-Free Fruit Project in Embu County, Kenya. www.divecosys.org/en/actualites/pest-free-fruit-enquete-aupres-des-menages. Published online 12/02/2019.
? Belmin R, Muriithi B (2019) Visite du site expérimental Pest-Free Fruit au Kenya. www.divecosys.org/actualites/pest-free-fruit-au-kenya. Published online 05/16/2019.
? Chailleux A (2019) Visite des experts mondiaux de l’entomovectoring au Sénégal. www.divecosys.org/actualites/visite-des-experts-mondiaux-de-l-entomovectoring-au-senegal. Published online 04/26/2019.
? Brévault T (2018) Lancement du projet Pest-free fruit (LEAP-Agri), du 7 au 9 novembre 2018 à Dakar. afrique-ouest.cirad.fr/actualites/lancement-du-projet-pest-free-fruit-leap-agri-du-7-au-9-11-a-dakar. Published online 11/12/2018.

Networks and collaborations fostered by the research activities
Scientific networks
? dP (Dispositif d’enseignement et de recherche en partenariat) Divecosys (Conception de systèmes agroécologiques par la gestion des bioagresseurs et l’utilisation de résidus organiques). www.divecosys.org. Collaboration on pest management approaches, capacity building and training for PhD students and researchers.
? GDRI-Sud (Groupement de recherche international – Sud) Wan@bi (West African Network on Biological Invasions in West Africa). www.ird.fr/la-recherche/groupement-de-recherche-international-sud-gdri-sud/wan-bi-west-african-network-on-biological-invasions. Collaboration on research issues on biological invasion, capacity building and training for PhD students and researchers.
? Collectif TIS. Think tank which brings together stakeholders around the sterile insect technique (SIT) as a complementary means of controlling agricultural pest and disease vectors. www6.inrae.fr/consortium-biocontrole/Groupes-de-Travail/Collectif-sur-l-essor-de-la-Technique-de-l-Insecte-Sterile. Working groups and trainings ().
Scientific partnerships
? UMR CBGP (Montpellier, France): Setting up of two collaborative research projects on (i) dispersal of fruit flies in agricultural landscapes to improve management strategies (DISLAND, ANR 2020) and (ii) migration patterns of insect pests (BALLON, CIRAD CreSi 2020). Funding (10 k€) was obtained from the SCAC of the French Embassy in Senegal to support international mobility for two researchers from UMR CBGP to Senegal (field visit, seminar and workshop for proposal writing) and two PhD students to France (one to two-week trainings).

A lot of research work remains to be done in each task to reach our In Task 1, additional experiments are to be conducted to identify the determinants of male mating success, particularly ME feeding, and the effect of methyl eugenol (ME) feeding on pheromone production and composition.
In Task 2, field observations will be conducted to locate specific sites where mating occurs, as disease transmission (for fungal entomopathogens) likely occurs primarily during male courtship (with wild males) and mating (with wild females).
In Task 3, multi-stakeholder workshops will be held to co-design an integrated and coordinated strategy for fruit fly management. This strategy will combine entomovectorate with a coherent set of actions at the three levels of the plot (e.g., prophylaxis, traps, etc.), the territory (treatment of fly reservoirs), and the supply chain (post-harvest innovations, commercial incentive for farmers to treat fruit flies). Specifically, we will combine (i) a territory-wide SIT/entomovectoring approach with (ii) an integrated orchard-level fruit fly management strategy, including recommended methods and grassroots innovations.
In Task 4, as work progresses on the modeling and development of the simulation tool, a few weeks must be spent to properly define the exploration possibilities to be done with the model. Indeed, many possibilities for analysis present themselves, but there will not be enough time to explore them all. Therefore, a prioritization analysis must be done first in order to stay within the objectives of the project but also to hit the most interesting questions that can be addressed. We plan to prepare a first manuscript to present version 1 of the simulation model and an evaluation of entomovectoring within the next year.
In Task 5, a first pilot experiment on self-dissemination of fruit fly traps using Metarhizium will be conducted in Kenya during the 2020/2021 mango season. By the end of 2021, we will conduct a follow-up survey targeting households that were initially interviewed to assess the impact of the tested biotechnology on selected economic, social, and environmental outcomes. In addition, mango infestation data, similarly targeting the same farms where similar data were collected this year, will be obtained in early 2021 to access the effect of the tested biotechnology on mango infestation rates. The infestation data will also be incorporated into modeling the economic, social and environmental impact of the technology.

Publications, conference papers, posters and presentations
? Diop S, Brévault T, Faye E, Chailleux A (2019) Triggering fungal epizootics in Oriental fruit fly populations using entomovectoring. Poster. 2nd Conference on Sustainable Intensification (CID 2019). Sustainable Intensification levers for agroecological transition of production systems in sub-Saharan Africa. Dakar, Senegal, October 8-10, 2019.
? Ndiaye D, Brévault T, Belmin R (2019) Freins à la diffusion des technologies de lutte biologique contre la mouche des fruits Bactrocera dorsalis. Poster. 2ème Conférence intensification durable (CID 2019). Leviers d'intensification pour une transition agroécologique des systèmes de production en Afrique Sub-Saharienne. Dakar, Sénégal, 8-10 octobre 2019.
? Brévault T, Clouvel P (2019) Pest management : Reconciling farming practices and natural regulations. Crop Protection, 115, 1-6.
? Diop S, Dosso F, Brévault T, Chailleux A (2020) Horizontal and vertical transmission of an entomopathogenic fungus, Metarhizium anisopliae, among Bactrocera dorsalis fruit flies. Poster. XXVI International Congress of Entomology, Helsinki, Finland, July 19-24, 2020 (This congress was postponed to 2021 due to coronavirus pandemic).
? Chailleux A, Sene Thiao D, Diop S, Bouvery F, Diatta P (2020) How Bactrocera dorsalis is caught by attract and kill traps in Sub-Saharan mango orchards ? In prep.
? Ndiaye D, Brévault T, Belmin R (2020) Perception and management of mango fruit flies in Senegal. In prep.
? Wangithi CM, Muriithi BW, Belmin R (2020). Analysis of farmers’ innovations, knowledge, and perceptions on fruit fly management in the Kenyan mango farming system. In prep.
? Muriithi B (2020) Barriers and opportunities for scaling up sustainable agricultural innovations: A case of fruit fly IPM technologies in the Kenyan Mango Farming Systems. In prep.