The mango tree in central and northern Benin: cultivar inventory, yield assessment, infested stages and loss due to fruit flies (Diptera Tephritidae)

Introduction. The mango tree is of prime importance to the rural economy of central and northern Benin since it provides food and crucial nutriments at the end of the dry season. However, mango producers in Benin are confronted with two problems that are closely connected: deterioration of fruit quality by fruit flies and the inadequacy of postharvest methods. In the Sudanian zone of Benin, fruit flies (Diptera Tephritidae) are highly responsible for major production losses. Materials and methods. An inventory of all present cultivars and yields of main mango cvs. (Gouverneur, Eldon, Dabshar, Kent, Smith, Keitt and Brooks) was carried out in Benin on 7 000 fruits near Parakou (Borgou) during the years 2005 and 2006. Sampling of 3 000 young fruits (length range 13–26 mm) was carried out in 2006 in order to detect some very early tephritid attacks. A loss assessment of pre-ripening and ripening fruits was also carried out on 7 750 fruits in 2006. Results and discussion. We identified 29 cultivars in the district of Borgou where 75% of the mango orchards of Benin are situated. Most of these use the ‘gatherer’ production system. The early Gouverneur cultivar had the lowest yield (1.8 t·ha–1), and the late Brooks cultivar had the highest yield (10.4 t·ha–1). Small and immature young fruits allowed development of both C. cosyra and B. invadens in February and March, i.e., before the mango season itself: this result could be a useful result for pest control. For the pre-ripening and ripening stages, average losses due to tephritid varied from 0.34 t·ha–1 to 6.5 t·ha–1 depending on cultivar type, resulting in considerable loss of income for small planters. Taking all cultivars together, losses stood at 17% in early April and exceeded 70% at mid-June. By the middle of the crop year, over 50% losses were recorded. The seasonal cultivar Eldon and late cultivars (Keitt and Brooks) were the most infested. Conclusion. In the Sudanian zone of Benin, the two main species of Tephritidae that have a high economic impact on mango trees are B. invadens and C. cosyra. Our preliminary observations and calculations will be used in a forthcoming article to calculate the economic injury level of these fruit flies.

Introduction. Le manguier occupe une place paniculitrement importante dans l'dconotnierumle des zones centrales et. septentrionales du Bdnin. Pendant la fin de la saison siche, l:r mangue cons-titue un apport nutritionnel fondamental par sa forte teneur en nutriments. NIais. au Bdnin, les producteursde mangues sont confront6s i deux contraintes €troitement li6es l'une ir I'autre : ddfaut de <.;ualit6 dtr fruitimputable aux motrches des fnrits et insuffisance de techniqtres ad6quates de . post-recolte ". I)ans la zonesoudanienne b€ninoise, les mouches des fhrits (Diptera'l'ephriticlae) sont la contminte majeure respon-sable de pertes consid6rables de producrion. Materieletm€thodes. L'inventaire des cultivars presentsau Mali ei les estinations de rendentents des principaux cultivars de manguier ((louverneut, Eldon, Dabs-har. I{ent, Smith, Keitt, Brooks) ont 6t6 men6s sur 7000 fruils autour de Parakou durant lcs ann€es 2(X)5et 2006. Des 6chantillonnages de 3000 petits fruils (de 13 mm l 26 r.r.rm) ont 6t6 r6alis6s en 2006 atln desavoir quels 6taient les stades les plus pr€coces i 6tre atrrqu€s. Des estimntions de pertes au nivcau clesstacles de pr€raturit6 err maturit6 de 7 750 fruits ont €t6 6galerncnt l)ites en 2006. Resultats €t discus-slon. Notis avons identifi€ 29 cultivars dans le ddpartement clu f3orgou qui concentrc environ 75 o'n desvergers de manguiers du B€nin. La pluparr d'entrc euK +.pllartiennent ) un.systdme de production de . type,cueillette '. Le cultivar pr€coce Gouverneur (1,8 t ha-r) e eu le plus faible endement t le cultivar tardifBrooks a eu le renclement le plus €lev€ (10,,1 f ha-l). Les petititiuits immaturcs ()nt pcnnis le d6vekrp-pernent complet <Je C. cosj,ra comrne de B. inuadens clurant les rnois de f6i,rier et mars, soit bien:lvantla campagne mangue ; cela pourrait avoir des applications sur la lutte. Pour les stadqs dc pr€-mrturiteet niattirii6 cles fiuiis, les pe.tbs t.oyennes dues aL" 'l'.ph.iti,1"" ont vari€ de 0.34 t htl ) 6,5't ha-l sclonles cultivars et elles ont occasionnd rlne perte de revenus consid6rable pour Ies petits planteurs. En prellallten compte la moyenne de tous les cultivars, les prtes atteigtrcnt 17 94r en d6but d'avril pttur d€passer700,odIa mi-juin. Plus de 50 9zo de pertes ont 6t€ enregistr6s au milieu de la campagne de mangue. Lecv. de saison Eldon et les cv. tllrdifs (Kein, Brooks) ont 6t6les plus infest€s. Conclusion. Les cleux espicesma jeures de'ltphritidae cl'inta:ret €conornique pour le rnanguier dans le Norcl du B€nin sont ts. inuaderset C. cosyra. Cette 6tude prdlirninaire devrait servir de base au calcul d'un seuil 6conomique de nuisibilitdde ces Tephritidae du manguier dans un prochain anicle.