Impact of Fumigation Made with Crataeva religiosa Forts, Azadirachta Indica A. Juss. and Senna occidentalis L. on Callosobruchus Maculatus Fab.

Comparing the effectiveness of certain plants fumigation (Crataeva religiosa Forts, Azadirachta indica L. and Senna occidentalis L.) on eggs and adults of Callosobruchus maculatus made us investigate in our study. The crushed leaves smoke substance of these plants have been applied to the external forms of this insect. For each of the plants we tested, the fumigation effect is gradual on the eggs. Thus, whatever the plant, the mortality of the eggs increases with the increase of the applied dose; But A. indica is found to be more effective on eggs than other plants. The adults of this species are more susceptible to the fumigation of crushed leaves of C. religiosa than to that of other plants. from 12 hours of impact all the doses (D1 (0.00364g/cm3), D2 (0.00728g/cm3), D3 (0.01456g/cm3) and D4 (0.02912g/cm3)) made of this plant, applied, induced 100% mortality whereas this effect was observed only on day 7 with S. occidentalis and day 11 of application with A. indica. The combined application of these plants fumigation would have a considerable impact on the protection of cowpea in the actual storage systems against the effect of C. maculatus

Assessment of the Genetic Diversity of Sitophilus Zeamais in Countries of the Sahelo-Sudanian Zone (Senegal, Mali, Niger, Burkina Faso, Guinea Conakry)

Maize is exploited substantially in the countries of the semi-arid zone of West Africa [5] where it plays essential economic and social functions. But these functions are seriously threatened by heavy losses, caused mainly by the corn weevil (Sitophilus zeamais) (Motschusky, 1855). This article aims to assess the genetic diversity of the insect in 5 countries in the semi-arid zone. This evaluation will highlight the country (ies) where the susceptibility of S. zeamais to survive or disappear is high, because the genetic diversity of a population is positively linked to its adaptive potential [12]. Exploitation of 60 sequences of the cytochrome b gene from insects from countries in the area (Senegal, Mali, Niger, Burkina Faso, Guinea Conakry) has led to the conclusion that genetic diversity is high in Senegal, Guinea Conakry but especially in Burkina Faso and Niger. These countries would therefore favor the adaptability of the insect. However, it is very low in Mali. Thus this country would be unfavorable to the survival of S. zeamais

Etude Phénotypique des Taurins Ndama du Centre de Recherches Zootechniques de Kolda (Sénégal)

Au Sud du Sénégal, du fait de la présence de glossines, le taurin Ndama ou Bos taurus taurus est la principale race bovine élevée par les agropasteurs. L’importance indéniable de ces bovins dans la vie socio-économique a conduit à la création du Centre de Recherches zootechniques de Kolda (CRZ-K) et l’initiation d’un programme de sélection à noyau fermé dès 1972 pour améliorer les performances des taurins. L’actuel noyau de sélection ouvert est constitué par des animaux appartenant au CRZ-K et ceux de la Coopérative des Agro-éleveurs Sélectionneurs de la Ndama (CASE-Ndama). L’objectif de cette étude est de caractériser phénotypiquement les taurins Ndama du noyau de sélection. La collecte des données phénotypiques composées de 15 variables qualitatives et 17 quantitatives a été réalisée sur 118 taurins adultes agés d’au moins quatre ans. L’évaluation des performances pondérales a été réalisée grâce à l’analyse des données longitudinales de 1970 bovins durant la période de 1973 à 2016. Les variables qualitatives ont été exprimées en pourcentages et pour les variables quantitatives, une analyse descriptive et une comparaison des moyennes ont été faites. Les résultats ont montré que la majorité des animaux présentait la même apparence avec une robe fauve uniforme, des cornes bicolores en lyre, des muqueuses peu pigmentées. Avec un dimorphisme marqué chez les bovins, les animaux adultes ont une hauteur au garrot moyenne de 106,9 ± 3,5 cm et un poids moyen de 230,9 ± 40,6 kg. Les moyennes de la longueur du corps et du périmètre thoracique étaient de 112,0 ± 7,9 cm et 150,0 ± 8,4 cm respectivement. Cette étude tout en montrant la hausse des mensurations corporelles des animaux par rapport à leurs congénères élevés dans les exploitations rurales souligne la baisse des performances pondérales survenue pendant certaines périodes durant lesquelles le programme a connu des contraintes. In southern Senegal, because of tsetse flies, Ndama taurine or Bos taurus taurus is the main bovine breed raised by farmers. The undeniable importance of these cattle in the socio-economic life led to the creation of the Centre de Recherches Zootechniques of Kolda (CRZ-K) and the initiation of a selection program since 1972 to improve animal productivity. The current open breeding nucleus is composed by animals belonging to the CRZ-K and those of farmers Ndama Agro-Breeders' Cooperative (CASE-Ndama). The aim of this study is to phenotypically characterize Ndama taurins of the selection nucleus. The phenotypic data collected for 15 qualitative and 17 quantitative variables was carried out on 118 adult bulls at least four years old. Longitudinal data from 1970 cattle during the period 1973 to 2016 were used to evaluate weight performances. The results showed that the majority of animals had the same appearance with a uniform fawn color, black and white lyre horns and fairly pigmented mucous membranes. Sexual dimorphism was marked. Adult animals had an average height of 106.9 ± 3.5 cm and average weight of 230.9 ± 40.6 kg. The mean of body length and chest perimeter were 112.0 ± 7.9 cm and 150.0 ± 8.4 cm respectively. This study showed the increase in body measurements of animals compared to those in rural farms and highlighted the decline in weight performances occurred during certain periods where the program had constraints

Parasites and invasions: changes in gastrointestinal helminth assemblages in invasive and native rodents in Senegal

Understanding why some exotic species become widespread and abundant in their colonised range is a fundamental issue that still needs to be addressed. Among many hypotheses, newly established host populations may benefit from a parasite loss ("enemy release" hypothesis) through impoverishment of their original parasite communities or reduced infection levels. Moreover, the fitness of competing native hosts may be negatively affected by the acquisition of exotic taxa from invaders ("parasite spillover") and/or by an increased transmission risk of native parasites due to their amplification by invaders ("parasite spillback"). We focused on gastrointestinal helminth communities to determine whether these predictions could explain the ongoing invasion success of the commensal house mouse (Mus musculus domesticus) and black rat (Rattus rattus), as well as the associated decrease in native Mastomys spp., in Senegal. For both invasive species, our results were consistent with the predictions of the enemy release hypothesis. A decrease in overall gastrointestinal helminth prevalence and infracommunity species richness was observed along the invasion gradients as well as lower specific prevalence/abundance (Aspiculuris tetraptera in Mus musculus domesticus, Hymenolepis diminuta in Rattus rattus) on the invasion fronts. Conversely, we did not find strong evidence of GIH spillover or spillback in invasion fronts, where native and invasive rodents co-occurred. Further experimental research is needed to determine whether and how the loss of gastrointestinal helminths and reduced infection levels along invasion routes may result in any advantageous effects on invader fitness and competitive advantage

Impact of genetic diversity on biological characteristics of Usutu virus strains in Africa

Usutu virus (USUV) previously restricted to Africa where it caused mild infections, emerged in 2001 in Europe and caused more severe infections among birds and humans with neurological forms, suggesting an adaptation and increasing virulence. This evolution suggests the need to better understand USUV transmission patterns for assessing risks and to develop control strategies. Phylogenetic analysis conducted in Africa showed low genetic diversity of African USUV strains except for one human and the USUV subtype (USUVsub) strains, which exhibited a deletion in the 3′UTR and nucleotide substitutions throughout the genome. Here we analyzed their viral replication in vitro in mosquito and mammalian cells, and vector competence of Culex quinquefasciatus, compared to a reference strain. Growth kinetics of the different strains showed comparable replication rates however variations in replication and translation efficiency were observed. Vector competence analysis showed that all strains were able to infect Culex quinquefasciatus the main peridomestic Culex species in Africa, with detection of USUV viral genomes and infectious particles. Dissemination and transmission were observed only for USUVsub, but infectious particles were not detected in Culex quinquefasciatus saliva. Our findings suggest that genetic variability can affect USUV in vitro replication in a cell type-dependent manner and in vivo in mosquitoes. In addition, the results show that Culex quinquefasciatus is not competent for the USUV strains analyzed here and also suggest an aborted transmission process for the USUVsub, which requires further investigations

IgG responses to the gSG6-P1 salivary peptide for evaluating human exposure to Anopheles bites in urban areas of Dakar region, Sénégal

<p>Abstract</p> <p>Background</p> <p>Urban malaria can be a serious public health problem in Africa. Human-landing catches of mosquitoes, a standard entomological method to assess human exposure to malaria vector bites, can lack sensitivity in areas where exposure is low. A simple and highly sensitive tool could be a complementary indicator for evaluating malaria exposure in such epidemiological contexts. The human antibody response to the specific <it>Anopheles </it>gSG6-P1 salivary peptide have been described as an adequate tool biomarker for a reliable assessment of human exposure level to <it>Anopheles </it>bites. The aim of this study was to use this biomarker to evaluate the human exposure to <it>Anopheles </it>mosquito bites in urban settings of Dakar (Senegal), one of the largest cities in West Africa, where <it>Anopheles </it>biting rates and malaria transmission are supposed to be low.</p> <p>Methods</p> <p>One cross-sectional study concerning 1,010 (505 households) children (n = 505) and adults (n = 505) living in 16 districts of downtown Dakar and its suburbs was performed from October to December 2008. The IgG responses to gSG6-P1 peptide have been assessed and compared to entomological data obtained in or near the same district.</p> <p>Results</p> <p>Considerable individual variations in anti-gSG6-P1 IgG levels were observed between and within districts. In spite of this individual heterogeneity, the median level of specific IgG and the percentage of immune responders differed significantly between districts. A positive and significant association was observed between the exposure levels to <it>Anopheles gambiae </it>bites, estimated by classical entomological methods, and the median IgG levels or the percentage of immune responders measuring the contact between human populations and <it>Anopheles </it>mosquitoes. Interestingly, immunological parameters seemed to better discriminate the exposure level to <it>Anopheles </it>bites between different exposure groups of districts.</p> <p>Conclusions</p> <p>Specific human IgG responses to gSG6-P1 peptide biomarker represent, at the population and individual levels, a credible new alternative tool to assess accurately the heterogeneity of exposure level to <it>Anopheles </it>bites and malaria risk in low urban transmission areas. The development of such biomarker tool would be particularly relevant for mapping and monitoring malaria risk and for measuring the efficiency of vector control strategies in these specific settings.</p

Mythe ou réalité ? Le "principe de Hopkins" dans le cas de la Bruche de l'Arachide Caryedon serratus (Coleoptera, Bruchidae)

Myth or reality ? The "Hopkins principle" in the case of the groundnut seed beetle, Caryedon serratos (Coleoptera, Bruchidae). Our purpose is to study the bases of oviposition site selection by females of various groundnut seed-beetle strains, Caryedon serratus, bred from different hosts. Egg distributions among hosts are compared. The results indicate that strains may be considered as developing according to Hopkins' host selection principle because females lay preferentially their eggs on the host they were bred from. The behaviour of females artificially bred on corn seeds shows however that host selection is not under the sole influence of the nature of larval food.Nous étudions le déterminisme du choix du substrat de ponte par des souches de Bruche de l'Arachide, Caryedon serrants, issues d'hôtes différents. Les distributions des œufs sur les différents substrats de ponte sont comparées. Les résultats révèlent que, d'une manière générale, les souches évoluent selon le principe de sélection d'hôtes de Hopkins puisque la ponte se fait de manière privilégiée sur la plante d'où est issue la femelle. Cependant, le comportement de femelles élevées artificiellement sur grains de maïs montre que la sélection de la plante hôte n'est pas uniquement influencée par la nature de la nourriture larvaire.Sembène Mbacké, Delobel Alex. Mythe ou réalité ? Le "principe de Hopkins" dans le cas de la Bruche de l'Arachide Caryedon serratus (Coleoptera, Bruchidae). In: Bulletin de la Société entomologique de France, volume 109 (1), mars 2004. pp. 61-66

Genetic differentiation of groundnut seed-beetle population in Senegal. Entomologia Experimentalis et Applicata

Abstract Caryedon serratus, the groundnut seed-beetle, is a major pest of groundnut (Arachis hypogaea), an introduced legume in the subfamily Papilionoideae. Native hosts of C. serratus in Senegal include Bauhiizia rufescens, Cassia sieberiana, Piliostigma i-eticulatum and Tamarindus indica, all of which belong to the legume subfamily Caesalpinioideae. The biology and natural history of C. serratus suggest that it is a candidate for population differentiation via host-race formation. Evidence for host-tree associated differentiation in C. serratus would be important for the design of rational pest management practices. To test this possibility, we analyzed the genetic structure of 20 adult collections of C. serratus from six sites in Western Senegal, on its five hosts. Results show a strong differentiation of insects from different host trees, with specimens from C. sieberiarza possibly representing a sibling species and insects from B. rufescens a distinct host-race

Seed weight and oviposition site selection in the genus Caryedon (Coleoptera, Bruchidae)

Our purpose is to study the effect of seed weight on oviposition site selection by females of two African species of Caryedon. Egg distributions among hosts are compared. The results indicate a significant positive correlation between the number of eggs on a seed and its weight.Poids des graines et choix du site de ponte dans le genre Caryedon (Coleoptera, Bruchidae). Nous étudions l’effet du poids des graines sur le déterminisme du choix du site de ponte par deux espèces africaines de Caryedon. Les distributions des oeufs sur les différents substrats de ponte sont comparées. Les résultats révèlent une corrélation positive significative entre le nombre d’oeufs sur une graine et le poids de cette graine.Sembène Mbacké, Delobel Alex. Seed weight and oviposition site selection in the genus Caryedon (Coleoptera, Bruchidae). In: Bulletin de la Société entomologique de France, volume 113 (3), spetembre 2008. pp. 355-358

Seed weight and oviposition site selection in the genus Caryedon (Coleoptera, Bruchidae)

Our purpose is to study the effect of seed weight on oviposition site selection by females of two African species of Caryedon. Egg distributions among hosts are compared. The results indicate a significant positive correlation between the number of eggs on a seed and its weight.Poids des graines et choix du site de ponte dans le genre Caryedon (Coleoptera, Bruchidae). Nous étudions l’effet du poids des graines sur le déterminisme du choix du site de ponte par deux espèces africaines de Caryedon. Les distributions des oeufs sur les différents substrats de ponte sont comparées. Les résultats révèlent une corrélation positive significative entre le nombre d’oeufs sur une graine et le poids de cette graine.Sembène Mbacké, Delobel Alex. Seed weight and oviposition site selection in the genus Caryedon (Coleoptera, Bruchidae). In: Bulletin de la Société entomologique de France, volume 113 (3), spetembre 2008. pp. 355-358