Perception des paysans sur la contrainte de la mineuse de l'épi Heliocheilus albipunctella De Joannis, ravageur important du mil en zone sahélienne

Heliocheilus albipunctella De Joannis est un important ravageur des épis du mil en zone sahélienne. Pour documenter la perception des paysans par rapport à ce ravageur, une enquête a été réalisée en avril 2016 avec un échantillon de 732 producteurs dans cinq principales régions agricoles du Niger. Les résultats obtenus ont montré que: 1) 17 % des répondants ont pu décrire le cycle biologique de H. albipunctella; 2) le ravageur cause en moyenne 43 à 82 % de perte de production, une moyenne obtenue depuis 28 ans selon les régions; 3) 37 à 78 % des producteurs savent que les infestations des épis du mil sont favorisées par les semis précoces, les sécheresses et la nature sableuse du sol; 4) d'après la moitié des répondants le plus de dégâts sont observés au stade grenaison du mil; 5) plus de 80 % des producteurs ne connaissent aucune méthode de lutte contre ce ravageur. Ces informations interpellent sur l'incidence négative de H. albipunctella sur le rendement du mil dans ces zones précaires. La nécessité de développer un programme participatif de gestion intégrée de ce ravageur est recommandée

Field performance of the parasitoid wasp, Trichogrammatoidea armigera (Hymenoptera: Trichogrammatidae) following releases against the millet head miner, Heliocheilus albipunctella (Lepidoptera: Noctuidae) in the Sahel

The effectiveness of the egg parasitoid Trichogrammatoidea armigera Nagaraja (Hymenoptera: Trichogrammatidae) in controlling Heliocheilus albipunctella de Joannis (Lepidoptera: Noctuidae), a major insect pest of pearl millet in the Sahel was assessed during two consecutive years in Niger on-station and on-farm conditions. We found that released T. armigera were able to find and parasitize host eggs within pearl millet fields both onstation and in farmers’ fields. On-station releases of T. armigera led to an average 4.86-fold increase in T. armigera parasitism compared to control fields, where no parasitoids were released. Likewise, on-farm releases of T. armigera led to up to 5.31-fold more egg parasitism by T. armigera in release fields than in control. Our results suggest the effectiveness of T. armigera and lays the groundwork for using T.armigera in augmentative biological control of H. albipunctella in the Sahel

Les malformations de Dandy-Walker : Aspects diagnostiques et apport de l’endoscopie : A propos de 77 cas

ObjectifDécrire les malformations kystiques de la fosse postérieure chez l’enfant et évaluer les indications et résultats thérapeutiques.MéthodeIl s’agit d’une étude prospective en série continue réalisée dans le service de neurochirurgie de l’hôpital national de Niamey (Niger) entre janvier 2007 et février 2012. Etaient inclus, les enfants de 0 à 5ans admis pour macrocranie ou retard psychomoteur sans antécédents de méningite chez qui un kyste malformatif de la fosse postérieure a été découvert au scanner. Une évaluation clinique et une classification scannographique a été réalisée pour chaque patient. L’indication opératoire a été retenue en présence de syndrome de la fosse postérieure associé ou non à une hydrocéphalie. En présence d’une hydrocéphalie le traitement était endoscopique de première intention (VCS + fenestration du kyste dans le ventricule latérale (VL) + cautérisation plexuelle partielle). Certains patients ont été classés selon les critères prédictifs des résultats de la VCS selon Warf. Une fontanelle non affaissée et tendue à 1mois post opératoire était considérée comme un échec. Seuls les patients suivis pendant au moins 6 mois ont été inclus dans l’étude.RésultatsLa série comportait 144 patients porteurs de kyste de la fosse postérieure soit 11,076% des enfants de 0 à 5 ans ayant réalisé un scanner en 5ans. La moyenne d’âge était de 8,7 mois (7 jours - 5 ans) avec un sexe ratio de 1,4. Il s’agissait de 67 cas de malformation de Dandy Walker (46,52%), de 21 cas de Dandy Walker variant (14,58%) et de 56 cas de kyste de la fosse postérieure considérés comme megacisterna magna ou kyste de la valecula ou Dandy Walker complex (38,88%). Sur les 144 patients porteurs de malformation kystique de la fosse postérieure l’hydrocéphalie était associée dans 128 cas soit dans 88,88% des cas. L’indication opératoire était retenue chez 77 patients suivis pendant au moins 6 mois (53,47%) dont 8 n’avaient pas d’hydrocéphalie (5,55%). Il s’agissait de 49 cas/ 67 de malformation de Dandy Walker, de 7 cas/21 de Dandy Walker variant, et de 21 cas/56 retenus comme des megacisterna magna ou de kyste de la valecula ou Dandy Walker complex. Le suivi moyen était de 16,4 mois (6 mois- 59 mois) avec au moins un scanner de contrôle à 6 mois post- opératoire. Le taux de succès du traitement endoscopique seul était de 57% à 6 mois.ConclusionLorsque l’indication opératoire est retenue pour une malformation kystique de la fosse postérieure associée à une hydrocéphalie, le traitement endoscopique peut être de première intention

Development of an Optimum Diet for Mass Rearing of the Rice Moth, Corcyra cephalonica (Lepidoptera: Pyralidae), and Production of the Parasitoid, Habrobracon hebetor (Hymenoptera: Braconidae), for the Control of Pearl Millet Head Miner

The rice moth, Corcyra cephalonica Stainton, an alternate host for the production of the parasitoid, Habrobracon hebetor Say, was reared on different diets, including pearl millet [Pennisetum glaucum (L.) R. Br.] (Poales: Poaceae) flour only, and in combinations of flours of sorghum [Sorghum bicolor (L.) Moench] (Poales: Poaceae), peanut (Arachis hypogea L.) (Fabales: Fabaceae), and cowpea [Vigna unguiculata (L.) Walp.] (Fabales: Fabaceae) to identify the optimal and economical proportion to be used under the conditions of Niger. The addition of cowpea or peanut to the pearl millet diet slightly increased C. cephalonica larval development time. Likewise, the addition of cowpea or peanut to cereal diets yielded a higher C. cephalonica larval survival. Female moths emerging from larvae fed on cereal and legume mixed diets produced higher eggs compared to the ones fed on sole and mixed cereals. Among legumes, cowpea addition is most interesting in terms of cost/production of C. cephalonica larvae. However, female moths emerging from larvae fed on different millet cowpea mix (5, 25, and 50%) laid significantly more eggs than those fed on sole pearl millet. Further, individual C. cephalonica larvae fed on 75% pearl millet + 25% cowpea produced significantly more H. hebetor. With an initial 25 C. cephalonica larvae kept for a 3-mo rearing period, the number of H. hebetor parasitoids produced will reach 2.68–10.07 million. In terms of cost/production ratio, the 75% pearl millet: 25% cowpea yielded better results

Timing of releases of the parasitoid Habrobracon hebetor and numbers needed in augmentative biological control against the millet head miner Heliocheilus albipunctella

Heliocheilus albipunctella de Joannis (Lepidoptera: Noctuidae) is one of the major insect pests of pearl millet in the Sahel. The native parasitoid, Habrobracon hebetor Say (Hymenoptera: Braconidae), is currently being promoted for augmentative biological control of the pest in the Sahel. The current study was carried out to identify the right time for releases of the parasitoid using either pearl millet growing stage, or pest occurrence as reference, and to determine the optimal number of parasitoids needed to cover a given area. Our results indicate that release of parasitoids at the panicle emergence stage or six weeks after first sight of eggs of H. albipunctella lead to highest parasitism of H. albipunctella larvae by H. hebetor. The dose of 800 parasitoids for a distance of 3 km radius was enough for controlling H. albipunctella. The implications of the results are discussed toward cost effective and practical recommendation adapted to the Sahelian conditions

The parasitoid Trichogrammatoidea armigera Nagaraja (Hymenoptera: Trichogrammatidae) is a potential candidate for biological control of the millet head miner Heliocheilus albipunctella (de Joannis) (Lepidoptera: Noctuidae) in the Sahel

Pearl millet, Pennisetum glaucum (L.) R. Br., is a crop grown throughout West Africa, especially in the Sahel. Pearl millet is the major staple food for the population of the Sahel, particularly for household use. It is one of the world’s most resilient drought-tolerant cereal crops, surviving even in the poorest soils in the driest regions and in the hottest climates. Despite this extreme climatic adaptation, pearl millet suffers from many biotic constraints, including insect pests (Nwanze and Harris, 1992). Among these, the stem borer (MSB) Coniesta ignefusalis (Hampson) (Lepidoptera: Crambidae) and the millet head miner (MHM) Heliocheilus albipunctella (de Joannis) (Lepidoptera: Noctuidae) are the major chronic insect pests of millet in the Sahel, including Niger. The MSB develops on many species of the Poaceae family; in the Sahel, it develops 2–3 generations per year on pearl millet during the rainy season and diapauses in leftover pearl millet stems during the rest of the year (Youm et al., 1996). The damage from C. ignefusalis is due to the feeding of developing larvae in millet stalks; first generation larvae cause dead hearts and stand loss, while the second and third generations cause lodging, disruption of the vascular system, and inhibition of grain formation (Harris, 1962; Youm et al., 1996). The MHM is a univoltine and monophagous species, which develops on millet in the Sahel during the rainy season between July and October and spends the remainder of the season in diapause in the soil (Gahukar et al., 1986). Infestations of H. albipunctella are more severe in the drier zones of the Sahel (Nwanze and Harris, 1992). The damage from H. albipunctella is due to larvae that feed on the panicle and prevent grain formation (Nwanze and Harris, 1992). Almost every year, outbreaks of the MHM are observed in the Sahel, especially on millet planted early or earlymaturing cultivars, while millet planted later or late-maturing cultivars is more affected by MSB (Gahukar et al., 1986; Youm et al., 1996). Both insect pests inflict significant yield losses ranging from 15% to total crop failure for C. ignefusalis (Harris, 1962; Ajayi, 1990) and from 40% to 85% for H. albipunctella (Gahukar et al., 1986; Krall et al., 1995)..

Development of reference transcriptomes for the major field insect pests of cowpea: a toolbox for insect pest management approaches in West Africa

Cowpea is a widely cultivated and major nutritional source of protein for many people that live in West Africa. Annual yields and longevity of grain storage is greatly reduced by feeding damage caused by a complex of insect pests that include the pod sucking bugs, Anoplocnemis curvipes Fabricius (Hemiptera: Coreidae) and Clavigralla tomentosicollis Stål (Hemiptera: Coreidae); as well as phloem-feeding cowpea aphids, Aphis craccivora Koch (Hemiptera: Aphididae) and flower thrips, Megalurothrips sjostedti Trybom (Thysanoptera: Thripidae). Efforts to control these pests remain a challenge and there is a need to understand the structure and movement of these pest populations in order to facilitate the development of integrated pest management strategies (IPM). Molecular tools have the potential to help facilitate a better understanding of pest populations. Towards this goal, we used 454 pyrosequencing technology to generate 319,126, 176,262, 320,722 and 227,882 raw reads from A. curvipes, A. craccivora, C. tomentosicollis and M. sjostedti, respectively. The reads were de novo assembled into 11,687, 7,647,10,652 and 7,348 transcripts for A. curvipes, A. craccivora, C. tomentosicollis and M. sjostedti, respectively.Functional annotation of the resulting transcripts identified genes putatively involved in insecticide resistance, pathogen defense and immunity. Additionally, sequences that matched the primary aphid endosymbiont, Buchneraaphidicola, were identified among A. craccivora transcripts. Furthermore, 742, 97, 607 and 180 single nucleotide polymorphisms (SNPs) were respectively predicted among A. curvipes, A. craccivora, C. tomentosicollis and M.sjostedti transcripts, and will likely be valuable tools for future molecular genetic marker development. These results demonstrate that Roche 454-based transcriptome sequencing could be useful for the development of genomic resources for cowpea pest insects in West Africa

Native parasitoids recruited by the invaded fall army worm in Niger

Surveys of fall army worm Spodoptera frugiperda (J. S. Smith) on maize and sorghum in Niger revealed the occurrence of egg parasitoids (Trichogrammatoidea sp., Trichogramma sp., and Telenomus sp.), egg-larval parasitoids (Chelonus sp.), and larval parasitoids (Cotesia sp., and Charops sp.)

Evaluation of the effect of farmer field school approach on the adoption of improved production technologies for millet and cowpea in central southern Niger

La diffusion des technologies améliorées par l’approche champ école paysan (CEP) interroge sur le taux d’adoption par les producteurs. L’objectif de cette étude et de connaître les déterminants de l’adoption des technologies et son impact sur le rendement et le revenu agricole. Il a été interviewé 380 producteurs dont 150 apprenants de CEP, 150 producteurs n’ayant pas participé au processus mais résidants des villages CEP et 80 producteurs des villages témoins. Le modèle de régression Logit a été utilisé pour l’analyse des données. Il ressort de cette étude que l’approche CEP influence l’adoption des technologies. Cette adoption a permis une augmentation de rendement du mil de 99 % et de celui du niébé de 136 % ainsi qu’une hausse de revenu de 97 % pour le mil et 120 % pour le niébé. Les facteurs déterminant les résultats de ce travail pourront être mis à profit pour renforcer les programmes de vulgarisation de technologies agricoles de production. Mots clés: Diffusion, pratique agricole, CEP, Maradi, ZinderThe dissemination of improved technologies through the farmer field school approach (CEP) asks about their adoption by producers. The objective of this study is to know the determinants of technology adoption and its impact on agricultural yield and income. 380 producers were interviewed including 150 CEP learners, 150 producers who did not participate in the process but residents of the CEP villages and 80 producers from the control villages. The logit regression model was used for data analysis. This study showed that CEP approach influences the adoption of technologies. This adoption resulted in an increase in yield of millet by 99% and cowpea by 136 %, as well as a 97 % increase in revenue for millet and 120 % for cowpea. The determining factors of this work the results may be used to strengthen extension programs for agricultural production technologies. Keywords: Diffusion, agricultural practice, CEP, Maradi, Zinde

Management of the pearl millet head miner through releases of the parasitoid wasp Habrobracon hebetor Say in Niger

Millet head miner Heliocheilus albipunctella De Joannis is one of the main insect pests of millet in the Sahel. In 2015 and 2016, a large-scale biological process was initiated with the parasitoid Habrobracon hebetor Say released in five regions of Niger. Regional teams, including farmers’ organizations, were set up for promoting producers’ awareness, identifying infested areas and placing 9177 release bags. The surface covered was estimated to be 1 417 680 ha in 2015 and 1 521 330 ha in 2016, about 21% of the millet cropped area in the regions concerned. Evaluations conducted during two years showed an increase of 168% to 1398% for the parasitism rate on MHM larvae in the villages where parasitoids were released compared to control villages. Survey about farmers’ perception revealed that the operation is beneficial for more than 77% of respondents. They estimated an average 76% larvae mortality rate and a 50% increase in millet yield due to the parasitoid release