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Senegalia macrostachya is a wild legume whose seeds are highly prized by the Burkinabe population. Unfortunately, they are severely depreciated during storage by the main pest Caryedon furcatus. However, very few studies have looked at the impact of the amount of S. macrostachya seeds on major biological parameters such as egg laying and development of C. furcatus. These data could contribute to better control of this pest. The aim of the study was to evaluate the impact of the quantity of S. macrostachya seeds on the egg laying behaviour of C. furcatus and on the ability of the larvae to weave their cocoons. Pairs of C. furcatus up to 24 hours old were placed separately with Petri dishes containing 5, 10, 20, 50, 100 and 200 seeds of S. macrostachya in four replicates per treatment. The seeds were renewed daily until the females died. After egg laying, the seeds were incubated until adult emergence. Our results showed that the rate of egg-bearing seeds increased significantly from 77.60% when the female had 5 seeds to 100% when she had 100 seeds. Similarly, the rate of larvae that were able to weave their cocoons increased significantly with the number of seeds. The variation in the amount of seeds and the number of pairs of C. furcatus has a strong impact on the behaviour and development of C. furcatus. The results suggest the need to control C. furcatus on S. macrostachya especially in case of mass storage for the benefit of the consumers.

We investigated the diversity and the population dynamics of insects attacking seed stocks of Acacia macrostachya, an indigenous legume tree whose seeds constitute an important food source for rural and urban populations in Burkina Faso. For this purpose, six thousand four hundred and two seeds were collected from newly harvested dry pods in spontaneous vegetation around the research station of Saria, while 50kg of naturally infested seeds of A. macrostachya were purchased from nearby markets. To assess pest diversity and initial infestation, seeds collected from pods were divided into 3 batches of 2134 seeds, each batch representing a replication. Insect emergence in the laboratory was monitored for 45 days. The population dynamics of the pests was studied by incubating the seeds purchased on the market in 4 batches of 12.5kg each in polypropylene bags, which were kept under laboratory conditions and monitored for 8 months. Insects emerged from the samples included Coleoptera from three (3) families: Bruchidae (the most abundant), Tenebrionidae and Silvanidae, and Hymenoptera from four (4) families: Eulophidae, Pteromalidae, Eupelmidae, Eurytomidae. The initial seed infestation rate of the newly harvested pods was 50.67% with 47.14% caused by Bruchidius silaceus, 2.70% by Caryedon furcatus and 0.83% by Bruchidius sp. The most abundant species observed during the two first months of storage of the seeds obtained from the market was B. silaceus, but it disappeared from the stocks after March. Conversely, Caryedon furcatus populations remained steady and increased in February. Among the secondary pests observed, Oryzaephilus mercator was the most important. The initial seed perforation rate and weight loss were 16% and 2.8%, respectively, and increased to 35% and 7% after eight months of storage. The hymenopteran Eupelmus sp. was the most abundant parasitoid observed in storage. Our study allowed us to assess the diversity of A. macrostachya seed pests and their natural enemies. These results will contribute to a better understanding of their population dynamics and hence provide cues for further studies towards effective control methods.

The beetle Caryedon furcatus (Coleoptera: Chrysomelidae) attacks and destroys the seeds of Senegalia macrostachya (Fabales: Mimosaceae), thereby limiting their availability as food throughout the year. Very few studies have focused on the ability of this pest to develop on S. macrostachya seeds. The objective of this study was to determine some bio-demographic parameters of C. furcatus on the seeds of S. macrostachya. The results of this study showed that the peak of female oviposition occurs on the second day after emergence. The female laid during her lifetime, an average of 37 eggs of which an average of 35 hatched, while larval survival until imago was 87.14 %. The weight and size of emerged adults did not differ statistically by sex. However, the sex ratio was female-biased. The mean development time for C. furcatus to complete its development on the seeds of S. macrostachya was 50 days. With a population that doubles every 4.75 days, C. furcatus could cause significant damage to the seed stocks of S. macrostachya.

Les biopesticides sont de plus en plus recommandes dans la production du niebe comme alternative a l‟utilisation des insecticides chimiques de synthese. La presente etude a pour objectif de determiner la periode d‟epandage des huiles de neem qui reduit le niveau des populations des thrips et de Maruca vitrata Fabricius en culture de niebe. La variete amelioree de niebe „tiligre‟ a ete semee dans six parcelles elementaires de 48 m2 chacune et correspondant aux traitements suivants : un temoin sans insecticide, un temoin de reference utilisant l‟insecticide de synthese le Pacha 25 EC (Acetamipride 10g/l + Lambda-Cyhalothrine 15g/l) et deux periodes d‟epandage dont une precoce (stade boutons floraux) et une tardive (stade 25% floraison) pour les deux huiles. Le nombre de larves et adultes de thrips, de larves de M. vitrata et les rendements gousse et graine ont ete les parametres mesures. Les resultats ont montre que lorsque l‟huile locale de neem et le TopBio sont epandus de facon precoce en culture de niebe, ils ont reduit de facon significative le nombre des thrips comme l‟insecticide chimique. L‟huile locale de neem, le TopBio n‟ont pas reduit le nombre de larves de M. vitrata comparativement aux deux temoins. Lorsque l‟huile locale et TopBio ont ete appliques de facon precoce, il y a eu une augmentation significative des rendements grains, respectivement de 1647,4 kg/ha et 1554 Kg/ha contre des rendements de 550 Kg/ha et de 600 Kg/ha pour les applications tardives. Au regard de ces resultats, l‟huile locale de neem en application precoce peut etre recommandee comme biopesticide dans la production familiale du niebe. Mots cles : Biopesticide, traitements precoce et tardif, insectes ravageurs. English Title: Effects of neem (Azadirachta indica L.) oils spraying periods on the populations of Megalurothrips sjostedti Trybom and Maruca vitrata Fabricius in the cowpea field Biopesticides are increasingly use in cowpea production as alternative to the use of synthetic chemical pesticides. The current study was aims to determine the period on which the application of neem oils significantly reduces trips and Maruca vitrata Fabricius populations level in the field. Cowpea variety « tiligre » was planted in six plots of 48 m2 each corresponding to the following treatments: a control without insecticide spray, a control using chemical insecticide Pacha 25 EC (Acetamiprid 10g/l + Lambda-Cyhalothrin 15g/l) and two spraying periods of two types of neem oils both at early (budding stage) and late (25% of flowering) stages. The number of larvae and adults trips, larvae of M. vitrata and pod and seed were the measured parameters. The results obtained showed that when local neem oil and TopBio were applied early in the cowpea field, they significantly reduced trips populations to the similar level to those of the chemicals insecticide. Local neem oil and TopBio didn‟t reduce the number of the larvae of M. vitrata compare to both controls. When local neem oil and TopBio were early applied, there led to a significant yield increasing of 1647.4 kg/ha and 1554 Kg/ha, respectively versus the yields of 550 Kg/ha and de 600 Kg/ha for late application. Considering this result, local neem oil, early applied, can be recommended as biopesticide for family cowpea production. Keywords : Biopesticide, early spray, late spray, insect pests.

Objectifs: Les objectifs de cette etude etaient d’inventorier les differentes pratiques post-recoltes d’ A. macrostachya ; les contraintes liees au stockage ; les methodes de protection des stocks et les differents usages des graines. Methodologie et resultats: une enquete a ete realisee dans vingt villages de la province du Boulkiemde aupres des acteurs de la gestion post recolte des graines d’ A. macrostachya . Les resultats ont montre que 52,13% des repondants conservent leurs graines dans les sacs en polypropylene, 24,47% dans les bidons de 20l de contenance et 20,21% dans les jarres. Les insectes sont percus comme les principaux ravageurs des graines. Leurs degâts commencent avant la recolte des gousses et se poursuivent dans les stocks tout au long du stockage. La methode de protection la plus utilisee pour faire face aux ravageurs est la precuisson a la chaleur. En l’absence de methode de lutte, des degâts importants sont observables des la premiere semaine de stockage. La conservation des graines repond a l’objectif de satisfaire les besoins de consommation et de commercialisation. Conclusion et application: Cette etude a permis de mieux apprehender les pratiques paysannes en gestion post recolte et les contraintes de stockage des graines de A. macrostachya . Elle ouvre les perspectives d’une gestion plus efficiente de cette importante denree alimentaire. Mots cles: Graines de zamne, gestion post-recolte, methodes de conservation, insectes ravageurs, perception paysanne, Burkina Faso English Title: Post-harvest management of the seeds of Acacia macrostachya Reichenb. ex DC. in the Boulkiemde province in Burkina Faso : participatory survey among farmers English Abstract Objectives: The objectives of this survey were to inventory the different post-harvest practices of A. macrostachya ; the storage problems; control methods use to protect A. macrostachya during storage and the different uses of seeds Method and results: A survey was conducted in 20 villages in the province of Boulkiemde among the actors of A. macrostachya seeds post-harvest management. The results showed that 52.13% of respondents kept their seeds in polypropylene bags, 24.47% in cans of 20l capacity and 20.21% in jars. Insects are considered as the main pests of A. macrostachya seeds. Damage begins before the harvest of the pods and continues during post-harvest storage. The most widespread method of protection for pests is pre-cooking with heat. In the absence of a control method, a lot damage can be observed from the first week of storage. Seed conservation serves the purpose of meeting consumer and marketing needs. Conclusion and application: This study made it possible to better understand farmers' practices in the postharvest management and the storage problems of A. macrostachya seeds. It opens up prospects for more efficient management of this important food. Keywords: zamne seeds, post-harvest management, conservation methods, insect pests, farmer perception, Burkina Faso

La conservation post recolte des denrees alimentaires demeure un probleme majeur en Afrique subsaharienne. Une enquete visant a apprehender la perception paysanne de la conservation post recolte des cereales et une evaluation d’echantillons preleves dans les stocks de six localites du Burkina Faso ont ete realisees. Les resultats de l’enquete montrent que la majorite des producteurs conservent leurs recoltes de mil, de mais et de sorgho dans des greniers. L’usage de substances vegetales est la methode la plus repandue pour la conservation des cereales. De l’avis des producteurs, le mil serait la cereale qui se conserve le mieux (P