Preliminary study on the galectin molecular diversity in Moroccoan Phlebotomus papatasi sandfly population

CONTEXT

Galactose binding protein (PpGalec) plays an important role in the specificity of Phlebotomus papatasi sandfly for Leishmania major. The molecular diversity of this ligand is currently unknown but might have some influence on the ability of PpGalec to efficiently recognize L. major in natural sandfly populations.

OBJECTIVE

To explore the molecular diversity of the P. papatasi Galectin gene (PpGalec) in natural sandfly population of Morocco.

RESULTS & CONCLUSIONS

Sequence variations of PpGalec was analyzed in 31 P. papatasi specimens collected from endemic and non-endemic zoonotic cutaneous leishmaniasis foci of Morocco. Among the 211 amino acid positions analyzed, 11 are subjected to mutation. Interestingly, we observe that one mutation directly affect an amino acid known to be involved in the substrate recognition by galectin. The repercussion of this polymorphism on the capacity of the galectin to efficiently bind the L. major Lipophosphoglycane (LPG) awaits further investigations.

Bacterial flora as indicated by PCR-temperature gradient gel electrophoresis (TGGE) of 16S rDNA gene fragments from isolated guts of phlebotomine sand flies (Diptera: Psychodidae)

In this study, we tested the capacity of Temperature Gradient Gel Electrophoresis (TGGE)-based fingerprinting of 16S rDNA PCR fragments to assess bacterial composition in a single isolated sand fly gut. Bacterial content was studied in different life stages of a laboratory-reared colony of Phlebotomus duboscqi and in a wild-caught Phlebotomus papatasi population. Our study demonstrates that a major reorganization in the gut bacterial community occurs during metamorphosis of sand flies. Chloroflexi spp. was dominant in the guts of pre-imaginal stages, although Microbacterium spp. and another as yet unidentified bacteria were detected in the gut of the adult specimen. Interestingly, Microbacterium spp. was also found in all the adult guts of both species. We demonstrate that the analysis of bacterial diversity in an individualized sand fly gut is possible with fingerprinting of 16S rDNA. The use of such methodology, in conjunction with other culture-based methods, will be of great help in investigating the behavior of the Leishmania-bacterial community in an ecological context.

Malformations of the genitalia in male Phlebotomus papatasi (Scopoli) (Diptera: Psychodidae)

Phlebotomus papatasi (Scopoli, 1786) (Diptera: Psychodidae) is a major vector of Leishmania major (Kinetoplastida: Trypanosomatidae), a causative agent of zoonotic cutaneous leishmaniasis. Morphological characters of sand fly genitalia are key indicators for species identification. Various anomalies affecting male genitalia have been previously described. We take advantage of a large sand flies survey conducted in 32 stations in Central and Southern Morocco to systematically quantify the prevalence and spatial distribution of malformations affecting the genitalia of P. papatasi. Among 597 examined males, 122 were abnormal (20.4%). Malformations were widespread and largely concerned the number of spines in the lateral lobes and in the styles. Asymmetrical anomalies in lateral lobes were common. Correspondence analysis of our results highlighted the symmetrical anomalies observed in the lateral lobes, and abnormal styles of the male genitalia were found to be associated with environmental disturbances since they were prevalent in sewage dumps.

Habitat preferences of phlebotomine sand flies (Diptera: Psychodidae) in southwestern Morocco

Data from a 4-yr study of phlebotomine sand flies in 44 stations in southwestern Morocco are presented. Correspondence analysis is used to describe the habitat preferences of nine sand fly species on a meso-scale (station) and a micro-scale (biotope). This work, based on highly diversified data from various stations, comprising several biotopes sampled during different seasons, provides new information on the ecology of sand flies in southwestern Morocco. It highlights many natural and artificial factors that affect the abundance and distribution of sand fly populations. The impact of climate, urbanization, proximity of humans and domestic animals, organic matter in the soil, shelter, and vegetation type is discussed.

Population structure and geographical subdivision of the Leishmania major vector Phlebotomus papatasi as revealed by microsatellite variation

Multi-locus microsatellite typing (MLMT) has been employed to infer the population structure of Phlebotomus papatasi (Scopoli) (Diptera: Psychodidae) sandflies and assign individuals to populations. Phlebotomus papatasi sandflies were collected from 35 sites in 15 countries. A total of 188 P. papatasi individuals were typed using five microsatellite loci, resulting in 113 different genotypes. Unique microsatellite signatures were observed for some of the populations analysed. Comparable results were obtained when the data were analysed with Bayesian model and distance-based methods. Bayesian statistic-based analyses split the dataset into two distinct genetic clusters, A and B, with further substructuring within each. Population A consisted of five subpopulations representing large numbers of alleles that were correlated with the geographical origins of the sandflies. Cluster B comprised individuals collected in the Middle East and the northern Mediterranean area. The subpopulations B1 and B2 did not, however, show any further correlation to geographical origin. The genetic differentiation between subpopulations was supported by F statistics showing statistically significant (Bonferroni-corrected P < 0.005) values of 0.221 between B2 and B1 and 0.816 between A5 and A4. Identification of the genetic structure of P. papatasi populations is important for understanding the patterns of dispersal of this species and to developing strategies for sandfly control.

Altitudinal structuring of sand flies (Diptera: Psychodidae) in the High-Atlas mountains (Morocco) and its relation to the risk of leishmaniasis transmission

This paper presents the results of entomological surveys on phlebotomine sand flies (Diptera: Psychodidae) in the Haouz of Marrakech and High-Atlas mountains (Morocco). Sand flies were captured with sticky traps from 25 stations with altitudes ranging between 400 and 1400 m. A total of 2742 specimens belonging to nine phlebotomine species was collected, Phlebotomus (Larroussius) perniciosus Newstead being the predominant species. There was a remarkable difference in the diversity of the sand fly fauna among the altitudes. Two associations of sand fly faunas were determined, the first one in lower altitude and the second one in higher altitude. The significance of the predominant species at any altitude range was discussed in terms of the risk of transmission of leishmaniasis.

Nocturnal activity of phlebotomine sandflies (Diptera: Psychodidae) in a cutaneous leishmaniasis focus in Chichaoua, Morocco

The nocturnal activity of phlebotomine sandflies (Diptera: Psychodidae) was studied "at an epidemic focus" on human cutaneous leishmaniasis due to Leishmania tropica Wright in Chichaoua province, in Morocco. Sandflies were collected using light and sticky-paper traps changed at 2-h intervals, inside and around houses, in August and October 2004. Overall, 633 sandflies, belonging to six species of Phlebotomus and three of Sergentomyia, were collected. Sandfly activity was nocturnal and higher at twilight. Several activity patterns were observed according to the species. Phlebotomus (Paraphlebotomus) sergenti Parrot, 1917, the suspected vector of L. tropica in this focus, was caught during each collection performed from 1900 to 0500 hours, the numbers of species caught peaked at 1900-2100 hours. There were seasonal variations of the nocturnal activity, which could be related to the variations in temperature and relative humidity.

Seasonal fluctuations of phlebotomine sand fly populations (Diptera: Psychodidae) in the urban area of Marrakech, Morocco

Phlebotomine sand flies (Diptera: Psychodidae) were collected continuously, using sticky traps, during 1 year from October 2002 to September 2003, in an urban area of Marrakech city (Morocco). A total of 3277 specimens were collected belonging to five species. Phlebotomus (Phlebotomus) papatasi (54.6%) is the predominant species followed by Sergentomyia (Sergentomyia) minuta (20%), S. (S.) fallax (11.3%), P. (Paraphlebotomus) sergenti (10.3%) and P. (Larroussius) longicuspis (3.8%). Data analyses showed a mono-modal annual pattern for P. sergenti and a bi-modal one for the other species. P. papatasi, the proven vector of Leishmania major in Morocco, was active throughout the year. This species did not diapause in this region. P. papatasi population peaked in June and November, which relating to the periods of risk in this area. Its preferred temperature ranged between 32 and 36 degrees C but no significant correlation was found between its density and the temperature. Considering the high density and long activity period of P. papatasi, the area of Marrakech should be regarded as a potential focus for L. major. This suggests the need for a continuously surveillance to prevent risk of zoonotic cutaneous leishmaniasis.

Entomological investigations in Chichaoua: an emerging epidemic focus of cutaneous leishmaniasis in Morocco

Cutaneous leishmaniasis due to Leishmania tropica Wright seems to be an emerging disease in Chichaoua, a province located in southwestern Morocco. In this study, sand flies (Diptera: Psychodidae) were collected from 12 stations. Sticky traps were placed in domestic, peridomestic, and sylvatic sites. In total, 3,787 specimens consisting of 10 species (seven Phlebotomus and three Sergentomiya) were identified. Phlebotomus perniciosus Newstead, the predominant species, was abundant, especially in mountainous areas. Phlebotomus sergenti Parrot (12%) was found in all studied villages where it was associated with domestic and peridomestic habitats. On the basis of its abundance, distribution, and notable anthropophily, P. sergenti, a proven vector of L. tropica elsewhere, is considered the cutaneous leishmaniasis vector in this emerging focus.

Distribution of phlebotomine sandflies, of the subgenus Larroussius, in Morocco

Adult sandflies (Diptera: Psychodidae) of the genus Phlebotomus and of the subgenus Larroussius were collected with sticky traps from thirty-four localities in central and south-western Morocco. Four Larroussius species were present in this area, Phlebotomus perniciosus Newstead, being the most widespread and abundant species particularly in the mountainous area, was sympatric with the closely related species Phlebotomus longicuspis Nitzulescu. Only one male of P. perniciosus displayed the bifid copulatory valves characteristic of the species. All specimens showed copulatory valves curved at their apex. The number of coxite hairs is a taxonomical tool that differentiates this morph of P. perniciosus from P. longicuspis. Phlebotomus ariasi Tonnoir was collected from six mountainous stations. Phlebotomus mariae Rioux et al. was scarce; only five males were collected and were often associated with P. ariasi.