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Annual population dynamics of mango fruit flies (Diptera: Tephritidae) in West Africa: socio-economic aspects, host phenology and implications for management
- Jean-François Vayssières, Antonio Sinzogan, Appolinaire Adandonon, Jean-Yves Rey, Elhadj Oumar Dieng, Koumandian Camara, Morodian Sangaré, Sylvain Ouedraogo, N’klo Hala, Adama Sidibé, Youssouf Keita, Guy Gogovor, Sam Korie, Ousmane Coulibaly, Cinthia Kikissagbé, Alliance Tossou, Max Billah, Koffi Biney, Oswald Nobime, Paterne Diatta, Robert N’Dépo, Moussa Noussourou, Lanciné Traoré, Symphorien Saizonou, Manuele Tamo
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Introduction. Losses in West African commercial mango orchards due to fruit fly infestations have exceeded 50% by the middle of the crop season since 2005, resulting in considerable income loss for the growers. Materials and methods. In 2009, weekly monitoring of adult fruit fly species of economic significance was carried out in eight West African countries at 12 sites across five agro-ecological zones: (i) Humid Forest, (ii) Guinean savanna, (iii) Southern Sudan, (iv) Northern Sudan, and (v) Sahelian. Trapping was performed using methyl eugenol and terpinyl acetate in 288 Tephri-traps, targeting Bactrocera invadens and Ceratitis cosyra. Results. The data showed that B. invadens was present throughout the year in the Forest zone, abundant for 7 months, with a peak in May at the end of the mango season, C. cosyra being totally absent. In the Guinean savanna zone, B. invadens was abundant for 6-7 months, with a peak at the beginning of June coinciding with the season, with a few C. cosyra. In the Southern Sudan zone, B. invadens was abundant for 6 months, with a peak in mid-June during the season, C. cosyra peaking in April. In the Northern Sudan zone, B. invadens was abundant for 5 months, with a peak at the end of June at the end of the season, C. cosyra peaking in May. In the Sahelian zone, B. invadens was abundant for 4 months, peaking in August during the season, C. cosyra peaking just before. These preliminary results showed that the exotic species, B. invadens, was present at high levels [mean peak of 378 flies per trap per day (FTD)] in all agro-ecological zones, while the native species, C. cosyra, preferred the drier zones of West Africa, with lower population levels (mean peak of 77 FTD). Conclusion. Detection trapping of male flies with parapheromones is a useful indicator of field population levels and could be used to deploy control measures (IPM package) in a timely manner when the Economic Injury Level is reached. Control strategies for these quarantine mango fruit fly species are discussed with respect to agro-ecological zones and the phenological stages of the mango tree.
Fruit phenology of citruses, mangoes and papayas influences egg-laying preferences of Bactrocera invadens (Diptera: Tephritidae)
- Paterne Diatta, Jean-Yves Rey, Jean-François Vayssieres, Karamoko Diarra, Emile Victor Coly, Mathieu Lechaudel, Isabelle Grechi, Saliou Ndiaye, Ousmane Ndiaye
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Introduction. African fruit production, as well as regional and international fruit trade, have experienced heavy economic losses over the past decade due to the damage caused by fruit flies, especially B. invadens Drew Tsuruta & White (Tephritidae: Diptera). Bactrocerainvadens attacks fruits belonging to numerous botanical families, several of which are of great economic importance. The females of these flies generally lay their eggs in mature fruits, but some can lay in green-immature fruits. Materials and methods. The influence of the species, variety and phenology of fruits on the fruit attractiveness to B. invadens and the elicitation of B. invadens egg-laying behaviour were studied in the laboratory. Fruits harvested regularly during the years 2008 and 2009 from orchards in the Niayes area (Senegal) were exposed to gravid females in cages set for the different factors tested. The exposed fruits were then incubated and the pupae emerging from them were counted. Results and discussion. Bactrocera invadens females laid eggs in ripe fruits. Within the same fruit species, the variety plays an important role in egg-laying preference. Hence, among the mango varieties tested, the Pêche variety hosted the highest number of pupae per fruit, while the Palmer variety hosted the lowest number. Comparison among different fruit species showed that mature papaya was more infested than mature mango or citrus. Furthermore, flies were unable to develop on lime. Conclusion. Our study showed that B. invadens can infest green and ripe host fruits, and even immature abscised fruits. Consequently, management of this pest must include preventive measures in the development and implementation of an integrated management system.
Seasonality and range of fruit fly (Diptera: Tephritidae) host plants in orchards in Niayes and the Thiès Plateau (Senegal)
- Ousmane Ndiaye, Jean-François Vayssieres, Jean Yves Rey, Saliou Ndiaye, Papa Madialéké Diedhiou, Cheikh Tidiane Ba, Paterne Diatta
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Introduction. Senegal produces up to 150,000 t of fruit, of which 60,000 t are mangoes. Fruit production is important for the Niayes region, where 60% of total production is of mangoes, with citrus production coming next at 24%. Mango losses have become more substantial since the arrival of Bactrocera invadens in Senegal. The pest population increases in the mango ripening period, but little is known about its secondary hosts. Materials and methods. Fruits of cultivated and wild plants were collected regularly from April to December 2008 inside and around 19 orchards in eleven localities in the Niayes and Thiès areas in Senegal. The samples were monitored to identify any fruit flies present so that a list of host plants could be compiled. For mango, the study focused on establishing the influence of certain parameters such as the variety, the fruit size, the color, the flowering pattern and the physiological levels of infestation due to B. invadens and Ceratitis cosyra. Orchards were classified either as traditional (many mango varieties and many fruit species grown together in a stand) or intensive (fields of monovarietal mango trees), according to their composition and how they were managed. Results and discussion. A total of 663.2 kg of fruit, including those of 24 mango varieties, 13 citrus species with five lime varieties, two orange varieties and four pomelo varieties along with other cultivated and wild plants, were sampled both as fallen fruit and from the trees. Traditional orchards were more infested than the modern ones. B. invadens was significantly dominant over the other flies emerging such as C. cosyra, C. capitata, C. punctata, C. bremii, Bactrocera cucurbitae, Capparimyia bipustulata, Carpomyia sp. and Dacus sp. B. invadens was found on the 24 varieties of Mangifera indica, the 13 citrus species, and the other cultivated plants and wild plants sampled. Some host plants supported a relatively high level of fruit flies before the mango ripening period. Mangifera indica was infested principally by B. invadens and C. cosyra. C. cosyra was significantly present on the first fruit trees to flower, mostly in early varieties, while B. invadens infested all the varieties whatever the fruit development stage, the color, or the flowering pattern. Conclusion. Because of the host plants' diversity and varieties the traditional orchards were more infested than the modern ones. The management of this pest needs an Integrated Pest Management system based on a back-to-basics study of the infesting fruit flies, existing parasitoids and their hosts.