Agroecological Protection of Mango Orchards in La Réunion

International audienceMango is one of the world’s major tropical crops. In Réunion, the crop is plagued by pests, which have, over several decades, led to an over-reliance on agrochemicals. These expensive treatments have limited efficacy, and negative effects on the environment are associated with health risks and ecological imbalances. In addition, these agroecosystems are not ecologically sustainable. That is why in recent years, Agroecological Crop Protection has been applied to mango production in Réunion. The Biophyto project (2012–2014) was co-designed between 2010 and 2011 and brought together a number of agricultural partners in a collective approach to the crisis. It was followed until 2017 with further studies and experiments, as well as an extension phase to transfer knowledge to production areas. The experience broke new ground in Agroecological Crop Protection. A large quantity of data was collected which enabled comparisons between conventional and agroecological orchards. The results of this pioneering experience were very encouraging and the major points are (1) The Agroecological Crop Protection practices, mainly the suppression of pesticides, use of prophylaxis and permanent vegetal cover, which are the bases of conservation biological control, have been widely adopted by farmers. (2) These practices were found to reduce populations of pests and damage caused, e.g. mango bug, mealybugs, and had no negative impact on flowering level. (3) The treatment frequency index (TFI) decreased from 22.4 before the project to 0.3 after the project. Production costs were reduced by 35% without any loss of yield, except in a few specific circumstances. (4) The 124,001 arthropods identified from the 126,753 arthropods collected in orchards belong to 4 classes, 23 orders, 215 families, 451 genera and 797 morphotypes. The parasitoids formed the richest trophic group. (5) Bottom-up and top-down controls of biodiversity within a single community of arthropods were observed, and the role of ants, including invasive species, was quantified. (6) There was a negative effect of parasitoid diversity on the abundance of the Seychelles mealybug; the proportion of mango orchards in the landscape had a positive effect of on the abundance of South African citrus Thrips. (7) This experience also produced a large number of transfer assistance tools, particularly in the field of professional training. For example, a University Certificate of Professional Qualification (UCPQ) entitled “Agroecological Crop Protection”, and aimed at growers, technicians and agricultural advisers, has been available since 2013. (8) Other tools have been implemented by agricultural agencies and policy makers in order to facilitate the extension of agroecological practices: demonstration Dephy Ferme plots, a Biophyto Agri-Environment and Climate Measure and an Economic and Environmental Interest Group