BackgroundThe tsetse fly Glossina palpalis gambiensis is the main vector of sleeping sickness (Human African Trypanosomiasis - HAT) in West Africa, in particular in littoral Guinea where this disease is currently very active. The Loos islands constitute a small archipelago some 5 km from mainland Guinea, where G. p. gambiensis is well known as a nuisance and potential disease vector by inhabitants of the three main islands, Fotoba, Room, and Kassa. The National Control Program against HAT of Guinea has decided to eradicate tsetse in Loos islands in order to sustainably protect humans and economic activities. After baseline data collection, tsetse control began on the islands in 2006. On each of the three islands a specific combination of control methods was implemented according to the entomological situation found.ResultsStarting densities before control operations were 10, 3 and 1 tsetse/trap/day in Kassa, Room and Fotoba respectively, but by July 2010, tsetse were no longer caught in any of the sentinel traps used for monitoring. The reduction rate was faster where several control methods were implemented as a combination (impregnated traps and targets ITT, selective groundspraying, epicutaneous insecticide treatment of pigs, and impregnated fences around pig pens), whereas it was slower when ITT were used as the only control method.ConclusionsThis 100% suppression is a promising step in the eradication process, but G. p. gambiensis may still occur at very low, undetectable, densities on the archipelago. Next step will consist in assessing a 0.05 probability of tsetse absence to ascertain a provisional eradication status. Throughout these operations, a key factor has been the involvement of local teams and local communities without whom such results would be impossible to obtain. Work will continue thanks to the partners involved until total eradication of the tsetse on Loos islands can be declared.
-Introduction. The appearance of cercosporiose due to Phaeoramularia angolensis in 1993 in Guinea nowadays constitutes one of the limiting factors of citrus cultivation in this country. The lack of knowledge of the sensitivity of the locally-present citrus species or varieties concerning the pathogen is slowing down the planned revival for this crop. Faced with this stake, in situ studies on the varieties' sensitivity and tests of the disease's chemical control were undertaken. Materials and methods. Citrus trees in collections and village plantations were followed from 1995 to 1999 in the main citrus-producing areas of Guinea to evaluate the sensitivity to Phaeoramularia angolensis of almost sixty varieties. In addition, a chemical control test was carried out in 1999 to define doses and frequencies of treatments to be recommended to the growers to control the disease. The rate of affected organs and the losses of production due to the pathogenic fungus were assessed. Results and discussion. Sensitivity varied according to the site, but especially according to the species and their varieties. Almost all the orange and all the tangelo and pomelo trees were very sensitive to the disease, with depreciation rates of the whole production (leaves and fruits) often over 30 %. The sensitivity rates of the mandarin trees were contrasted with tolerant varieties (Ponkan) to very sensitive ones (Hansen). Tangors, lemon, lime, kumquat and grapefruit trees appeared to be tolerant in all sites, except Tahiti lime and Meyer lemon trees over 800 m altitude. During the chemical control test, the dose of 100 g active matter · 100 L -1 of water applied every 10 days allowed the raising of the potentially marketable fruit rate to about 90%. In addition, the profitability of the orchards quickly decreased as soon as the rate of fruit attacks was higher than 20%. Conclusion. Our results show that new research undertaken in the current context of Guinean citrus cultivation could lead to answering the problems of control strategies to be adopted, of products, doses or periods to be recommended, and of varieties to be promoted in the country.Guinea / Citrus / variety trials / disease control / blotches / Phaeoramularia angolensis / disease resistance / chemical control Vers une lutte contre la cercosporiose des agrumes en Guinée.Résumé -Introduction. L'apparition de la cercosporiose due à Phaeoramularia angolensis en 1993 en Guinée constitue de nos jours l'un des facteurs limitants de la culture des agrumes dans ce pays. Le manque de connaissance sur la sensibilité, vis-à-vis du pathogène, des espèces ou varié-tés d'agrumes présentes localement freine la relance projetée pour cette culture. Face à cet enjeu, des études sur la sensibilité in situ et des essais de contrôle chimique de la maladie ont été entrepris. Matériel et méthodes. Des agrumes en collections et en plantations villageoises ont été suivis de 1995 à 1999 dans les principales régions productrices d'agrumes de Guinée afin d'évaluer la sensibilité à Phaeoramularia ...
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