Begomovirus disease management for sustainable production to tomato in Caribbean. Annual report covering the period from 1 February 2002 to 31 January 2003 : INCO : International Scientific Cooperation Projects (1998-2002). Contract number : ICA4-2001-10002

Begomovirus diseases transmitted by Bemisia tabaci are responsible for important economic losses in tomato crops in the Caribbean islands. Because of the limited resources of growers, the diversity of the agro-system and the fragility of the ecosystem, the management strategies must be multi component in nature and based on a thorough understanding of the pathosystem involved to ensure sustainable development. BETOCARIB aims to study the pathosystem Bemisia- begomovirus-host plants and their epidemics to develop models in order to identify keys factor involved in the development of epidemics. Integrated pest management strategies able to reduce the impact of the diseases on tomato crops will be developed from these models and tested in the various islands. This project will be achieved through three WPs: - WP A is devoted to the identification of begomoviruses, their relative incidence, their vectors and their respective host plants in order to develop specific tools for their detection. - WP B is focused on epidemiology studies in order to built an adequate agronomic model to predict begomovirus infestations. - WP C will define the adequate IPM strategies to control viruses based on the use of tolerant/resistant varieties, the cultural methods and prediction of infections due to the agronomic epidemic model developed. The results obtained during this first year concern the three WPs. Le viral status was clearly confirmed for Cuba and Dominican Republic where mixed infection by TYLCV/ToHMV and TYLCV alone occur respectively. Martinique and Guadeloupe have partially characterized a novel introduced begomovirus, TYLCV, in addition to PYMV already identified. Trinidad and Tobago has started to identify additional viruses different from begomovirus already characterized. Each partners had developed specific tools to begomoviruses already identified and had agreed on a unique common protocol to detect them, an hybridization using non radioactive probes. They have designed new primers for specific detection of NW and OW begomoviruses based on sequence alignment. These will be evaluated during the next year. All partners have selected Bemisia tabaci samples and sent them to the Partner P1 in France in order to precise the biotype using RAPDs and microsatelites markers. The first epidemic data collected from Guadeloupe was highly informative to adapt the I maximal model' proposed in order to define an ecosystem-based begomovirus disease risk prediction model. Protocols developed in Guadeloupe will be transferred and adapted to Cuba to test during the next year the hardiness of the keys factors suspected involved in the epidemics. In parallel, Cuba, Martinique and Trinidad were set up several trials to screen tomato varieties for their resistance to TYLCV and PYMV as well as resistance to nematodes and high temperature. At the beginning of the project, Partner P1 created a BETOCARIB Web site to formalise the interactions between consortium members and to keep us aware on the project progress. Due to these objectives, the Betocarib Web site has been divided into two parts: everybody can consult one and one restricted to members only. The web site can be accessed at the following address: htpp://betocarib.cirad.fr (Résumé d'auteur