Enzyme Polymorphism and Genetic Variability of One Colonized and Several Field Populations of Phlebotomus papatasi (Diptera: Psychodidae)

Abstract

The Alexandria laboratory colony and five field populations of Phlebotomus papatasi (Scopoli) from Egypt were analyzed for genetic variation at 17 enzyme loci. The laboratory colony was characterized by a low level of genetic variation as measured by the average number ofalleles per loctus i(A = 1.70 t 0. 16) and the average expected heterozygositv dfie = 0.06 t 0.02). Polymorphismn was observed at 23.5% of the examined loci, and genotype frequencies at tawo loci P(PGM. AK-2) were tound to deviate slightly from the Hardy-Veinberg, equilibriumn. In contrast, the average nunmber of alleles per locus for field populations ranged fron A = 2.35 ± 0.20 to 2.76 " 0.10, and fie ranged from 0.15 = 0.03 to 0.21 ± 0.05. All hlci of field populations exhibited polymorphism, ranging from 47.0% to 76.5%. and four to seven loci in each population were found to deviate from the HardyWeinberg equilibrium. Deviations in both colonized and field populations were caused by heterozygote deficiency. Despite geographic isolation and some individual deviations from the Hardy-Weinberg equilibrium, no evidence of significant genetic difference was obtained for any of the populations sampled. Calculated indices of genetic distance and genetic identity for the five field populations showed minor variation but were collectively representative of a single, genetically uniform population. KEY WORDS Phlebotomus papatasi. genetic variation, polymorphismPhlebotomus papatasi (Scopoli) has been reHuman cases of cutaneous leishmaniasis (CL) corded in Egypt from habitats ranging from heav-caused by Leishmania major (Mansour et al. ily populated urban centers to barren desert.1987. 1991) have been reported frequently from Given the extremely limited flight range of this the sparsely populated North Sinai, but few sand fly (WHO 1984), it is reasonable to consider cases originate along the Mediterranean coast or that Egyptian populations of P. papatasi from in the Nile Delta (Morsy et al. 1985(Morsy et al. . 1991. P. different habitats and locations may differ genet-papatasi, the recognized vector of L. major in ically. Variable morphological characters of some Egypt (Wahba et al. 1990), is found commonly in Egyptian populations of P. papatasi have been each of these areas. Recent work with P. papatasi noted (Schmidt & Schmidt 1962, Lane 1986 and from Egypt and Israel has shown that genetically may result from reproductive isolation or ecolog-stable strains, susceptible and refractory for L. ical partitioning. At one location, 30% of the major infection, can be selected within 13 genadult male P. papatasi examined were found to erations, and that selection for refractoriness to have atypical genitalia (Kassem et al. 1988), and infection is associated with a shift from polymor-P. papatasi from the Sinai express some morpho-phism to monomorphism at certain enzyme loci logical characteristics similar to a closely related (Wu 1989, Wu & Tesh 1990a .44). xatithine dehvdro----------------------------- .9). tions' genetic variability (Lorenz et al...

Genetic structure of Mediterranean populations of the sandfly Phlebotomus papatasi by mitochondrial cytochrome b haplotype analysis

“…Therefore, genetic differences were expected between widely separated P. papatasi populations. Previous experiments carried by Kassem et al (1993) and Ghosh et al (1999), using isoenzyme electrophoresis of sandflies from Egypt and the Jordan Valley, documented the presence of polymorphisms at 14 of 25 loci in Egyptian strains and seven of 20 loci in the Jordan Valley strains.…”

“…A variety of methods have been employed in the past to evaluate spatial components of genetic diversity among P. papatasi populations. Genomic allele frequency estimates have been used to calculate genetic diversity using allozyme (Kassem et al , 1990, 1993), mtDNA (Parvizi et al , 2003) and microsatellite loci (Hamarsheh et al , 2006).…”

Interspecific hybridization and genetic variability of Phlebotomus sandflies

“…They found polymorphism at 14/25 loci in P. papatasi . Kassem et al . (1993) extended their study to field populations of P. papatasi in Egypt and found no diagnostic alleles or significant gene frequency differences among five field populations and a laboratory strain, although they noted that 4–7 loci in each population deviated from the Hardy–Weinberg equilibrium.…”

Population structure and geographical subdivision of theLeishmania majorvectorPhlebotomus papatasias revealed by microsatellite variation

“…The geographical distribution of P. papatasi includes different climatic and ecological discontinuities, where insecticide usage varies greatly, and may set different selection patterns that are favourable to local adaptation among geographically distant P. papatasi populations and are associated with patterns of population divergence (Pener & Wilamovsky, 1987; Dhiman & Mittal, 2000). When different genetic markers were used to study genetic variation in P. papatasi , such as c ytochrome b (Esseghir et al , 1997; Parvizi et al , 2003; Hamarsheh et al , 2007a), internal transcribed spacer 2 (ITS2) (Depaquit et al , 2000, 2008; Hamarsheh et al , 2007b) and isoenzyme electrophoresis (Kassem et al , 1993; Ghosh et al , 1999), it was concluded that widely separated populations of P. papatasi were genetically quite homogenous.…”