BackgroundSleeping sickness, transmitted by G. p. palpalis, is known to be present in the Ivory Coast. G. p. palpalis has recently been reported to occur in several places within the town of Abidjan, including: (i) the Banco forest, (ii) the Abobo Adjamé University campus and (iii) the zoological park. Could these three places be treated sequentially, as separate tsetse populations, or should they be taken as one area comprising a single, panmictic population?MethodsThe amount of gene flow between these places provides strategic information for vector control. It was estimated by the use of both microsatellite DNA and morphometric markers. The idea was to assess the interest of the faster and much less expensive morphometric approach in providing relevant information about population structure. Thus, to detect possible lack of insect exchange between these neighbouring areas of Abidjan, we used both genetic (microsatellite DNA) and phenetic (geometric morphometrics) markers on the same specimens.Using these same markers, we also compared these samples with specimens from a more distant area of south Ivory Coast, the region of Aniassué (186 km north from Abidjan).ResultsNeither genetic nor phenetic markers detected significant differentiation between the three Abidjan G. p. palpalis samples. Thus, the null hypothesis of a single panmictic population within the city of Abidjan could not be rejected, suggesting the control strategy should not consider them separately. The markers were also in agreement when comparing G. p. palpalis from Abidjan with those of Aniassué, showing significant divergence between the two sites.ConclusionsBoth markers suggested that a successful control of tsetse in Abidjan would require the three Abidjan sites to be considered together, either by deploying control measures simultaneously in all three sites, or by a continuous progression of interventions following for instance the "rolling carpet" principle. To compare the geometry of wing venation of tsetse flies is a cheap and fast technique. Agreement with the microsatellite approach highlights its potential for rapid assessment of population structure.

Summary : ECO-DISTRIBUTION AND TRYPANOSOMA INFECTION OF GLOSSINA PALPALIS PALPALIS IN THE BANCO FOREST OF AND ITS RELICS, ABIDJAN (CÔTE D'IVOIRE)In order to implement an anti-vector programme in the suburb of Abidjan (Côte d'Ivoire), investigations were conducted to assess the tsetse fly densities as well as infection with trypanosomes. Catches were carried out during the rainy season and dry season with Vavoua traps laid during four consecutive days in different sites (Banco forest, Abidjan zoological park, area of the University of Abobo-Adjamé). One species of tsetse fly (Glossina palpalis palpalis) and two species of trypanosomes (Trypanosoma congolense, T. vivax) have been revealed. The apparent density per trap per day (DAP) is very high in the zoological park, 54.8 tsetse fly/trap/day during the dry season and 28.1 during the rainy season. At the University of Abobo-Adjamé, the DAP is respectively 13.5 and 8.1 tsetse fly/trap/day during the rainy season, and in the dry season it is only 0.9 and 0.8 in the Banco Forest. The physiological age on all sites is as follows: 57.5 % of old parous, 39 % of young parous and 3.6 % of nulliparous in the rainy season. These proportions vary to 51.9 % of young parous, 47.1 % of old parous and 1 % of nulliparous in the dry season. The overall infection rate is estimated at 20.7 % in the rainy season and 20 % in the dry season. Statistical analysis have showed a significant difference in the distribution of infection rates. Résumé

Après son apparition en 1989 à la frontière Est, la cochenille farineuse du manguier, Rastrococcus invadens Williams, 1986 (Homoptera ; Pseudococcidae) est devenue très rapidement une contrainte majeure à la production de mangues en Côte d'Ivoire. Les prospections et les enquêtes ont révélé que cet insecte très polyphage, confiné en 1992 au Sud-Est du pays, a envahi en 1996 toutes les régions à l'exception du Nord-Ouest. Dans la région nord qui produit les mangues d'exportation, il a occasionné en moyenne 53 % de pertes de rendement en station de recherche à Korhogo-Lataha. Ces pertes ont parfois atteint 100 % en milieu paysan, contraignant les planteurs à détruire les vergers ou les arbres attaqués. Les taux d'infestation des arbres dans cette région sont de 82 %, 36 % et 11 % respectivement dans les villes, les villages et les vergers des paysans; la propagation du ravageur ayant été favorisée par l'activité humaine. Les méthodes physiques et chimiques de lutte appliquées par les planteurs se sont avérées inefficaces et dangereuses. Partout, la cochenille a été associée à un complexe d'ennemis naturels dont les parasitoïdes Gyranusoidea tebigy Noyes et Anagyrus mangicola Noyes (Hymenoptera ; Encyrtidae) qui pourraient être utilisés dans un programme de lutte biologique.

RESUMEQuelques aspects écologiques de la dynamique spatio-temporelle des populations d'Altises Podagrica spp. ont été étudiés dans les zones cotonnières de la Côte d'Ivoire, en suivant l'évolution des effectifs et des dégâts sur deux types de variétés de cotonniers (cotonnier glandless et cotonnier classique) et sur deux plantes hôtes (le gombo et le jute). Il ressort de ce travail que selon les localités, 3 à 6 générations se chevauchent durant la campagne agricole. Les fluctuations et les niveaux des infestations dépendent des facteurs climatologiques (pluviométrie, humidité relative, ETP, température), de la date de semis, de la taille et la localisation de la parcelle ainsi que de la disponibilité des plantes-hôtes. Sur la base de ces résultats, des méthodes culturales de lutte appropriées contre les Altises ont été recommandées : culture des variétés glandless sur de grandes superficies, exclusivement au nord du 9 e parallèle et destruction des cotonniers après la récolte ainsi que les plantes-hôtes. Mots clés :Cotonnier glandless, Altise, dynamique des populations, lutte culturale, Côte d'Ivoire. ABSTRACT SPATIAL AND SEASONAL PROFILES OF POPULATION DYNAMICS OF THE FLEA BEETLES podagrica spp. (coleoptera : chrysomelidae) : AGRONOMIC IMPLICATIONS IN THE COTTON PRODUCTION AREA IN CÔTE D'IVOIRESome ecological parameters of the population dynamics of the flea beetles Podagrica spp. were studied in the cotton growing area of Côte d'Ivoire. Population densities and damaged plants were scouted on two cotton varieties (glanded and glandless cotton) and two host plants (okra and jute). Data revealed, according to localities, that 3-6 overlapping generations of flea beetles occurred during the cotton growing season. Fluctuations and infestation levels depended on climatic factors (rainfall, relative humidity, ETP, temperature), cotton sowing dates, size and location of cotton fields, as well as on the presence of host plants. Based on these results, appropriate cultural methods to control flea beetles are recommended : cultivation of glandless cotton on large plots exclusively in the northern region above the 9 th parallel, destruction of cotton plants after harvest and the host plants.

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