2 research outputs found
Incidence et regulation naturelle de la chenille mineuse de lâepi de mil, Heliocheilus albipunctella de joannis (Lepidoptera, Noctuidae) a bambey dans le bassin arachidier au Senegal
Au SĂ©nĂ©gal, la mineuse de lâĂ©pi, Heliocheilus albipunctella (Lepidoptera, Noctuidae) a commencĂ© Ă causer des dĂ©gĂąts dans les cultures de mil suite Ă une longue pĂ©riode de sĂ©cheresse au dĂ©but des annĂ©es 70. Le suivi dâun rĂ©seau de 45 parcelles de producteurs Ă Bambey en 2013, a permis dâĂ©valuer la situation du ravageur : abondance relative (oeuf et larve), parasitisme associĂ©, potentiel de rĂ©gulation naturelle et pertes de rendement liĂ©es aux dĂ©gĂąts. Les rĂ©sultats ont montrĂ© une distribution trĂšs hĂ©tĂ©rogĂšne du ravageur dans la zone avec des moyennes dâinfestation des Ă©pis en oeufs de 40 % et en larves 76 %. Un taux moyen de parasitisme des oeufs par TrichogrammatoĂŻdea sp estimĂ© Ă 2 % est notĂ© (n = 2281 oeufs). Le parasitisme larvaire est dominĂ© par des cocons dâendoparasitoĂŻdes de la famille des Ichneumonidae (8,6 %), des larves de Tachinidae (5,2 %) et des morphotypes non encore identifiĂ©s (4,6 %). Une faible mortalitĂ© larvaire due au Bracon sp. (1,5 %, n = 1567 larves) est observĂ©e. Ce faible taux de parasitisme, comparĂ© au potentiel rĂ©el de la rĂ©gulation naturelle observĂ©e (59 %, n = 45 parcelles) montre lâimportance probable des ennemis naturels dans le contrĂŽle du ravageur. Les pertes en grains sont estimĂ©es Ă 10 %.Mots clĂ©s : Heliocheilus albipunctella, mil, rĂ©gulation Ă©cologique, ennemis naturels, dĂ©gĂąt
A contrasting seasonality of wind erosivity and wind erosion between Central and Western Sahel
International audienceWind erosion is a major phenomenon in the Sahel, and can affect soil fertility. Studies of Sahelian aeolian erosion or erosivity are scarce and have been mainly focused on the Central Sahel. Since February 2020, the number of saltating particles and the horizontal flux of aeolian sediment were monitored in Bambey (Senegal) in combination with long-term 5-minutes wind measurements (2014-2021). These datasets enabled to assess the consistency of wind erosion and wind erosivity estimates, and thus to further analyze wind erosivity over pluriannual periods, as wind speed time-series are available over longer terms than horizontal aeolian flux. As a result, the seasonality of wind erosivity largely differs between Western and Central Sahel. In Western Sahel, wind erosivity is related to medium wind speeds during the dry season, while in Central Sahel it is mostly due to high wind speeds occurring at the monsoon onset. Additionally, horizontal flux of aeolian sediments during the dry season are of the same order in Senegal as in Western Niger, but lower than in Eastern Niger. Horizontal flux of aeolian sediments during the rainy season are lower in Senegal than in Western Niger and Eastern Niger