Implementation of biological solutions for controlling the tomato russet mite, Aculops lycopersici (Acari : Eriophyidae) on tomatoes – BIOLYCTOM

Laboratory tests were carried out to characterise the predator's biology. In order to gain a better understanding of its diet, several food sources were studied in addition to A. lycopersici: Tetranychus urticae, T. evansi, Trialeurodes vaporarorium, Tuta absoluta. Choice tests were used to characterise the factors affecting the predator's dispersal behavior. Movements between banker plants and tomato plants were also studied in the laboratory on a fine scale. The risks associated with the banker plants studied were tested to determine whether they were favorable to tomato pests. In greenhouses, several experiments were carried out to study the methods of supplying predators, using branches of banker plants placed on the tomatoes at different supply densities, and using pots of banker plants placed at the bottom of the tomatoes, in two production contexts at the CTIFL (soilless) and at INRAE Alenya (in soil). Finally, surveys of growers were carried out to determine the obstacles and levers to the implementation of these solutions and their potential acceptability for large-scale development

Major results of the project
The predator consumes and develops on pollen, A. lycopersici and T. urticae, but also T. absoluta and T. vaporarorium. The two plant banks are favourable to T. urticae and T. turkestani but not to T. absoluta and T. vaporarorium. The predator disperses from the pots of banker plants to the tomatoes, attracted by A. lycopersici, with better colonization when M. suaveolens is used as a banker plant. When A. lycopersici is introduced via branches placed on the tomatoes, the pest is controlled and damage is reduced with M. suaveolens. Profitability is at the heart of growers' decisions, and technical support is essential.

New projects are already being funded at European level (NextGenbioPest) and French level (Casdar GAMHA), in which most of the BioLyctom project partners are involved.
The work carried out and the results obtained during the BioLyctom project are opening up new academic and applied research questions.
On the biology and behaviour of the predator, concerning its host plants, its feeding on other prey and other types of pollen, and its ability to co-habit with other predators. We also plan to carry out metaborcoding studies to characterise the diet of T. (A.) recki in in situ situations, on tomatoes and banker plants, in order to refine our knowledge of its diet. Our results also open up prospects for the selection of small individuals for better dispersal on the stem, studies that need to be completed to determine the biological and predation characteristics of these small individuals, in addition to the lability of this trait. The appearance of a new virus transmitted by A. lycopersici opens up new prospects for studying and applying the results of this project.
On the development and integration of the new strategy, in particular by identifying plants that are repellent to mite pests on the basis of work carried out on undercropping with garlic in strawberry crops in Brazil. The idea would be to develop a push-pull strategy against mite pests and potentially also against other pests that are prey to T. (A.) recki.
On socio-economic aspects, to link the decisions taken by growers with the expectations of downstream players in the sector (marketing players). For each grower, various indicators could be put into perspective: economic indicators (income, yield, organisation of working time, etc.), agronomic indicators (respect for the environment, plant health) and social indicators (expectations downstream, arduousness, the way society views the work, local development, etc.) to gain a more detailed understanding of growers' decision-making processes.

The project has produced both scientific and technical results, with 5 scientific publications, 13 communications in national and international conferences, 3 technical papers, 6 presentations in professional events, youtube videos…. Several brochures were produced and sent to the producers surveyed. Finally, a final workshop was organized in 2024 for producers and advisers. All the documents produced are available to everyone on the project website

Tomatoes are attacked by different pests, mites and insects. One of the most important pests, uncontrolled biologically still today, is Aculops lycopersici, the tomato russet mite. Its control is based on the use of pesticides with adverse effects on environment, biodiversity and health. Phytoseiidae are the most effective predators of pest mites; some species are also predators of insects. On tomato, the predators used are not efficient enough, while Phytoseiidae are reported on Solanaceae. In a previous project funded by Ecophyto (Acarosol project 2014-2018), a predatory species, endemic from Europe, has shown a never observed efficiency to control this pest in laboratory and semi-field conditions (greenhouse). In addition, we observed high densities of this predator on mints and Phlomis fructicosa and that it could disperse from mints to tomato plants infested with A. lycopersici. The present project aims to deepen the results obtained during this previous project, whose TRL obtained was 3-4. The aim here is to determine the efficiency factors of two biological control strategies: (i) by augmentation and (ii) by biodiversity conservation within agro-ecological approaches. The expected TRL is between 5-6. The solutions investigated are based on the use and enhancement of endemic biodiversity, to avoid any risk associated with the introduction of exotic natural enemies. This 36-month project, consisting of 6 WPs, aims to (i) deepen knowledge on predator biology, (ii) characterize predator integration factors in control management strategies (side-effects of pesticides, predation on other tomato pests, reservoir effect of companion plants for pests), (iii) determine the operational factors for the implementation of the two strategies in semi-field conditions (ie release strategies, companion plant densities) and (iv) characterize the technical and socio-economic levers for the acceptability of the proposed solutions. Particular attention will be paid to dissemination with repercussions for the student’s formation (future professionals) and by the mobilization of the professionals, through an advisory committee and field demonstrations with the final aim of carrying out large-scale experiments in the DEPHY farm network. This project is based on an interdisciplinary approach and integrated methodologies (field collection, farmer surveys, laboratory and field experiments). It includes 4 partners with complementary expertise, UMR CBGP specialists in mites and food webs, UMR MOISA specialists in socio-economic aspects, the Alenya experimental unit and CTIFL (centre of Balandran), specialists in greenhouse biological control. The expected results are the proposal of biological solutions to control Aculops lycopersici, and the integration of these solutions in the technical itineraries and the economic production model. There are no biological solutions to control this pest and the expectations of the profession are very important. The results will be exploited by all, with a preferred target towards producers and development organizations since special attention is given to the autonomy of producers and wide result dissemination. Private companies have not been deliberately integrated into this project to avoid any blockage in dissemination, due to a highly competitive market, and they will also be free to exploit the results obtained.