Antoine Abel Missihoun

A growing number of studies has highlighted the importance of coinfections in eco‐evolutionary processes underlying host–parasite interactions and the resulting epidemiology of zoonotic agents. Small mammals, and particularly rodents, are known to be important reservoirs of many zoonotic pathogens, such as Toxoplasma gondii and Trypanosoma lewisi , that are responsible for toxoplasmosis and atypical trypanosomiasis in humans, respectively. Laboratory experiments on rodent models have shown that primary infection with T. lewisi increases the host sensitivity to other parasites, including T. gondii , following an alteration in the immune response. However, data on potential interactions between these parasites in wild small mammals remain scarce. In this study, we determined the T. lewisi prevalence in 553 small mammals from four localities of Cotonou city, Benin. The results were then combined with T. gondii data previously collected for the same individuals in order to investigate the influence of T. lewisi on T. gondii infection, and vice versa, using co‐occurrence tests and generalized linear mixed models (GLMMs). Despite quite high overall prevalence (32.5% and 15.2% for T. lewisi and T. gondii , respectively), we observed a clear and significant segregation between the two parasites. This may be explained by (i) differences in the species‐specific receptivity and/or sensitivity of small mammal host species to infection by these two parasites, with Rattus rattus (Rra), Rattus norvegicus (Rno), and Mastomys natalensis (Mna) being the main hosts of T. lewisi , while Crocidura olivieri (Cro) and Mus musculus domesticus (Mus) were the main hosts for T. gondii ; and/or (ii) a possibly high mortality in coinfected animals in the wild. Although dedicated experimental studies are required to confirm this pattern, as they stand, our data fail to support that in nature, the infection of small mammals by one of these two parasites favors widespread infection by the second one.

International trade has been favouring the dissemination of a wide suite of invasive alien species. Upstream prevention through the monitoring of entry points is identified as an appropriate strategy to achieve control of bioinvasions and their consequences. Maritime transportation has been responsible for the introduction worldwide of exotic rodents that are major pests for crops and food stocks as well as reservoirs of many zoonotic pathogens. In order to limit further dissemination, the International Health Regulation constrains decisions makers and socio‐economic stakeholders to manage ship‐mediated import/export of rodents within seaports. Unfortunately, eco‐evolutionary insights into rodent introduction events that could guide preventive actions in seaports are very scarce. In order to bridge this gap, we here describe the results of a 3 year‐long survey of small mammals conducted in the Port of Cotonou, Benin. Our aim was to assess the spatiotemporal distribution, diversity and relative abundance of invasive and native rodents. 960 small mammal individuals were captured in nine within‐seaport sites. We found (i) a marked predominance of invasive species (84% of the individuals belonging to Mus musculus, Rattus rattus, R. norvegicus), (ii) with native species (i.e. Mastomys natalensis and the shrew Crocidura olivieri) essentially restricted to peripheral non‐industrial areas, as well as (iii) a fine‐scale spatial segregation stable over time between the invasive Norway rats and house mice on the one hand, and the black rats and shrews on the other hand. Furthermore, trapping before and after two successive rodent control campaigns indicates that they were ineffective and that subsequent rodent recolonisation occurred 6–12 months following intervention. Synthesis and applications. Our results are discussed in terms of ecological processes at play (e.g. interspecific interactions) and operational recommendations (e.g. assessment of proper eradication units, environmental modifications).

In Benin, Xanthomonas oryzae pv. oryzae (Xoo) causing bacterial blight (BLB) was first described in 2013 on wild rice Oryza longistaminata. No studies have been conducted on Beninese Xoo strains and resistant rice varieties. The aim of this study is to check whether Xoo has already spread to cultivated varieties and to screen some rice accessions for the main resistance genes detection. To achieve this aim, rice leaves showing typical BLB symptoms were collected from various rice fields in Benin and analyzed by PCR to identify Xoo-specific sequences. In addition, seventy-five rice accessions were examined to identify Xoo resistance genes. The results showed that Xanthomonas oryzae (Xo) had been identified in Banikouara and Malanville. In addition, Sphingomonas sp was detected in several rice fields. A Xo-Sphingomonas Sp co-infection was also noted. 47 of 75 rice accessions examined (62.66%) carried Xoo resistance genes with 3 (4%) and 40 (53.33%) of xa5 and Xa21 respectively. None of the accessions had neither Xa7 nor Xa13 resistance genes. Three accessions had both xa5 and Xa21 genes. In addition, the rice isogenic lines IRBB60 and IRBB21used as positive controls, were found to be susceptible. These results indicate that Xo has evolved from a wild rice to cultivated varieties in northern Benin. Consequently, a varietal improvement program must be implemented with varieties having resistance genes to prevent a BLB pandemic in Benin.

Dioscorea rotundata Poir. is mainly dioecious but it also produces monoecious individuals. Recently two genetic markers were proposed to determine the sex in this species. We tested them in 119 individuals from 101 different cultivars of the national collection of Benin to verify whether they can predict the sex observed in the field. Among the analyzed individuals, 72 were male, 37 were female, 7 were monoecious and 3 were non-flowering. Our results showed that the marker sp16, associated with the W allele (female allele), was present in all female individuals but also in more than 42% of male individuals. Thus, while the absence of sp16 confirmed the male sex of the individuals, its presence did not allow sex discrimination. The marker sp1 allowed the identification of four genotypes (AA, AB, BB and AC) in the analyzed individuals with AA and AB being the most represented. Although AA was observed in 62.16% of female individuals and AB in 83.33% of male individuals, we did not observe a clear correlation between sp1 genotypes and sex identity. We concluded that the tested markers did not allow a clear sex discrimination in Beninese Dioscorea rotundata cultivars. Our results also suggest that Beninese D. rotundata cultivars have adopted a male XX/XY heterogametic system that is undergoing reorganization.

Antimicrobial resistance is a real public health problem. All over the world, it has a considerable impact in hospitals. The present study was conducted to ascertain the bacterial ecology in two hospitals in Benin as well as the resistance genes present in the recovered isolates. A total of 146 environmental and catheter samples were collected at the University Hospital Center of Abomey-Calavi / So-Ava and at the Beninese Army Hospital of Cotonou. These samples were inoculated on Mannitol Salt and Eosin Methylene Blue agars. The colonies obtained were identified and their sensitivity to antibiotics were tested, using the Kirby Bauer technique. Four resistance genes encoding the production of extended-spectrum beta-lactamases (blaCTX-M1, blaCTX-M2, blaCTX-M9, blaCTX-M15) and the gene coding for methicillin resistance (mecA) were screened. The gene coding for methicillin resistance (mecA) was sought in staphylococci. A total of 69 (53,49%) and 60 (46,51%) strains belonging to Enterobacteriaceae family and staphylococci were identified, respectively. A predominance of Staphylococcus aureus (25.6%) followed by Enterobacter cloacae (21.0%) and coagulase negative staphylococci (21.0%) was observed. These bacterial strains showed multidrug-resistance, particularly to beta-lactams, fluoroquinolones, aminoglycosides, and macrolides. Beta-lactamases were identified in the genome of bacterial strains with a predominance of blaCTX-M15 (42.8%). The frequency of the mecA gene in staphylococci was 50%. These results show the magnitude of the antimicrobial resistance situation in the hospitals investigated. They can be used to support advocacy for urgent action at the national level, especially with regards to the management and efficient use of antimicrobials in Benin.

The understanding of genetic diversity within local crop varieties constitutes an important step in the preservation of their genetic potential. The objective of this study was to assess the genetic diversity of sorghum (Sorghum bicolor (L.) Moench) cultivated in the Northwest of Benin and to reveal certain fundamental evolutionary mechanisms. A total of 61 accessions of sorghum landraces belonging to the four identified races in Benin were estimated using 20 microsatellite markers. For all the loci analyzed, 140 polymorphic alleles were detected with a mean value of 7.00 per locus and polymorphic information content (PIC) average value was 0.33 for all the 20 simple sequence repeats (SSRs), suggesting an important genetic diversity within the cultivated sorghum germplasm used. An unweighted pair group method arithmetic average (UPGMA) clustering and principal coordinate analysis (PCoA) based on DICE coefficient revealed three major genetic groups supported by two main components: the botanical race and the morpho-physiological characteristics of the grains (colour and degree of bitterness). It was thus recommended that further research on genetic diversity of sorghum should integrate these genetic parameters for a better preservation of the genetic resources of this important crop in Benin. Key words: Genetic diversity, simple sequence repeats (SSRs) markers, Sorghum bicolor, Benin.