Résumé
Vietnam is considered as a good candidate for supplying the deficit of the world market in cocoa beans. Fertile soils in the South East and Central Highlands regions and western part of the southern region are particularly suitable for cocoa growing and enable yield between 1.5 and 2.0 tons. Yet, cocoa production is reduced by emerging pests like plant bugs, also called mirids, of the genus Helopeltis. For the moment, these pests are not well known on cocoa in Vietnam and pest management recommendations do not exist. We were contacted by Mars Inc. to conduct a support mission, with the global objectives to evaluate the situation in terms of species involved, damage, farmer practices, and to consider the possibility of conducting projects on cocoa mirids in Vietnam. The mission consisted of (i) inspecting cocoa plantations in three regions of Vietnam: the Dong Nai province, near Ho Chi Minh City, the Dak Lak province, in the highlands, and the Ben Tre province, in the Mekong Delta; (ii) running a workshop in order to train Vietnamese students, agronomists and entomologists in experimentation with cocoa mirids and to develop project proposals on IPM for cocoa mirids in Vietnam. Our investigation showed that Helopeltis spp. was present in all inspected farms, yet damaging cocoa with very variable levels. Damage was much more severe in the Dak Lak province, despite the fact that farms were usually regularly sprayed with insecticides. In the more diversified cocoa farms of the Mekong Delta, lower mirid damage was noticed, in spite of the absence of chemical control. Natural enemies, especially ants, were usually numerous in farms of this region. Farmer's spraying practices were very heterogeneous, regarding chemicals and spraying calendars and evidence has been given that recommendations for chemical control of cocoa mirids do not exist in Vietnam. Twenty participants belonging to seven organizations took part of the workshop on cocoa mirids in Vietnam, in Nong Lam University. PowerPoint presentations dealing with activities conducted on cocoa mirids in Cameroon were read. Demonstration was given for the rearing of cocoa mirids and for the assessment of cocoa resistance to mirids. Training was given on identification of the different development stages of Helopeltis sp. collected on cocoa. Finally, a brainstorming session gave the basis for a project proposal, involved organizations, expected funding and main components of which are briefly presented in this report. (Résumé d'auteur)