Effects of neem limonoids on the malaria vector Anopheles stephensi Liston (Diptera: Culicidae)

The effects of the neem (Azadirachta indica A. Juss) limonoids azadirachtin, salannin, deacetylgedunin, gedunin, 17-hydroxyazadiradione and deacetylnimbin on Anopheles stephensi Liston (Diptera: Culicidae) were investigated. In exploring advantages of pure neem limonoids, we studied the larvicidal, pupicidal, adulticidal and antiovipositional activity of neem limonoids. Azadirachtin, salannin and deacetylgedunin showed high bioactivity at all doses, while the rest of the neem limonoids were less active, and were only biologically active at high doses. Azadirachtin was the most potent in all experiments and produced almost 100% larval mortality at 1 ppm concentration. In general, first to third larval instars were more susceptible to the neem limonoids. Neem products may have benefits in mosquito control programs.     

rDNA-ITS2-PCR assay for grouping the cryptic species of Anopheles culicifacies complex (Diptera: Culicidae)

Anopheles culicifacies, a predominant vector of malaria in India exists as a complex of five sibling species A, B, C, D and E, of which, except species B, all the rest are vectors with varying vectorial capacities. With a combination of PCR assays, it is possible to identify all the five members of this species complex. These assays include amplification of the rDNA-ITS2 region followed by digestion of the ITS2 amplicon using restriction enzyme, Rsa I which groups the five members of the An. culicifacies complex into two categories: species A and D forming one category and species B, C and E forming another. The samples grouped thus are then subjected to two allele-specific PCR assays (AD-PCR and BCE-PCR), which has been designed using sequence differences in the mitochondrial cytochrome oxidase II (CO II) subunit. The AD-PCR assay distinguishes species A and D, whereas the BCE-PCR assay distinguishes species B, C and E. In the present study, the differences in the ITS2 region of the five species was used to design a PCR assay which groups the five members into the same two categories as obtained after digestion of the ITS2-PCR product. This assay uses a common forward primer based on the 5.8S region and two reverse primers, which is specific for the two categories. Amplification of a PCR product of size 253bp indicates the presence of species A/D, while a product of size 409bp indicates the presence of species B/C/E. By using this ITS2 PCR assay, the three-step procedure is reduced to two cutting down the time and cost involved. The ITS2 PCR assay has been validated on specimens collected from different regions of India and the results confirm to the earlier reports on the distribution of the members of the An. culicifacies complex.     

Bionomics of Anopheles stephensi Liston in the malarious area of Hormozgan province, southern Iran, 2002

Anopheles stephensi Liston is an important malaria vector in Hormozgan province, where it is the most prevalent anopheline mosquito. It shows two annual activity peaks, one in spring and another in the autumn. In mountainous areas the second peak starts earlier than in coastal regions. Adults are endophilic and endophagic, but in the hot season when people sleep outside buildings they frequently bite outdoors. Larvae are found in a wide-range of habitats, both natural and man-made. All three biological forms of the species, occur in the province, i.e. An. stephensi stephensi (type form), An. stephensi mysorensis, and the intermediate form. An. stephensi mysorensis is found only in rural-mountainous areas, whereas the type and intermediate forms occur in urban-coastal regions and the rural plains, with the type form predominant. The presence of the type form in urban areas and mysorensis in rural areas is consistent with the available epidemiological data for malaria in the region and with the finding in India that the type form is an efficient malaria vector inhabiting urban areas whereas mysorensis is rural and has a lower vectorial capacity. Insecticide susceptibility tests on field collected adult mysorensis and adults from laboratory strains of the type and intermediate forms were carried out according to WHO standard methods. These showed that all three forms are susceptible to bendiocarb, propoxur, malathion, fenitrothion, deltamethrin, permethrin, cyfluthrin, and lambdacyhalothrin, but are resistant to DDT and show low level of tolerance to dieldrin. Examination of the larvicidal activity of malathion, fenitrothion, temephos and chlorpyrifos at diagnostic doses showed that these stephensi forms are susceptible to all larvicides except fenitrothion. Irritability tests to pyrethroid insecticides showed high levels of irritability to permethrin and lambdacyhalothrin, but low irritability to cyfluthrin and deltamethrin. The importance of these findings for the epidemiology and control of malaria in the region are discussed.     

Population structure of the malaria vector Anopheles funestus (Diptera: Culicidae) in Madagascar and Comoros

Microsatellites were used as markers for a study of the population structure of Anopheles funestus on Madagascar and Comoros. Mosquitoes were collected in four different localities on Madagascar and one on Comoros. There was a significant genetic differentiation between all samples from Madagascar and that from Comoros (P<0.05). With respect to the Madagascar mosquito samples, it was found that there were no significant genetic differences between samples that were collected at the east coast, and in the highlands, respectively. By contrast, the west coast sample exhibited significant genetic differences (with regard to all Madagascar samples). The results are discussed with respect to population distribution and migration of A. funestus from mainland Africa and the islands east of the mainland.     

Microsatellite DNA polymorphism and heterozygosity in the malaria vector mosquito Anopheles funestus (Diptera: Culicidae) in east and southern Africa

There has been an increase in malaria cases in southern African countries in recent years due to the presence of populations of Anopheles funestus that are resistant to the pyrethroid class of insecticides. Since A. funestus is one of the major African malaria vectors, knowledge of its genetic structure will benefit control strategies, such as the management of insecticide resistance, by allowing predictions to be made of possible spread of the resistance. This study uses microsatellite DNA markers to analyze samples from five countries in east (Kenya and Uganda), central (Malawi) and southern (South Africa and Mozambique) Africa. There were deviations from Hardy-Weinberg expectations for some loci in all population samples but this was probably due to the presence of null alleles. High levels of genetic diversity were observed (mean alleles per locus = 6.5-10; unbiased H=0.23-0.89). Low differentiation was observed between Kenya and Uganda (average F(ST)=0.002, R(ST)=0.0001) and between Mozambique and South Africa (F(ST)=0.0004, R(ST)=0.02), contrary to high differentiation among the central and southern Africa samples (average F(ST)=0.023, R(ST)=0.027). High differentiation was measured across the region (mean F(ST)=0.04, R(ST)=0.08), east versus Malawi (F(ST)=0.067, R(ST)=0.089) or southern Africa populations (F(ST)=0.068, R(ST)=0.15). A test of isolation by distance along the east-central-south transect gave evidence (R(2)=0.50, P<0.001) that geographic distance limits gene flow in A. funestus.     

Identification of four members of the Anopheles funestus (Diptera: Culicidae) group and their role in Plasmodium falciparum transmission in Bagamoyo coastal Tanzania

The role of Anopheles funestus group in malaria transmission was investigated in Bagamoyo coastal Tanzania, in the process of characterizing the area as a malaria vaccine testing site. Mosquitoes were sampled inside houses and multiplex PCR was used to identify 649 specimens. The following species were found: A. funestus s.s. (84.3%), A. leesoni (13.6%), A. rivulorum (1.5%) and A. parensis (0.6%). Multiplex PCR of 147 blood-fed specimens showed that over half (57.1%) of the identifiable blood meals were taken from human hosts, and human blood index in A. funestus and A. leesoni was 55% and 82% respectively. Plasmodium falciparum infection rate determined by nested PCR was 11% in A. funestus s.s. Although the abundance was low, 26 specimens of A. leesoni, two of A. rivolurum and one of A. parensis were found positive for P. falciparum. The presence of four A. funestus species in Tanzania emphasizes the relevance to define precisely their spatial and temporal distribution, specific behaviour, ecology and exact role in malaria transmission.     

Genetic diversity and gene flow of humans, Plasmodium falciparum, and Anopheles farauti s.s. of Vanuatu: inferred malaria dispersal and implications for malaria control

A comparison of the patterns of gene flow within and between islands and the genetic diversities of the three species required for malaria transmission (humans, Plasmodium falciparum, and Anopheles farauti s.s.) within the model island system of Vanuatu, shows that the active dispersal of An. farauti s.s. is responsible for within island movement of parasites. In contrast, since both P. falciparum and An. farauti s.s. populations are largely restricted to islands, movement of parasites between islands is likely due to human transport. Thus, control of vectors is crucial for controlling malaria within islands, while control of human movement is essential to control malaria transmission across the archipelago.     

Chlorfenapyr: a pyrrole insecticide for the control of pyrethroid or DDT resistant Anopheles gambiae (Diptera: Culicidae) mosquitoes

Owing to the development and spread of pyrethroid resistance in Anopheles gambiae in Africa there is an urgent need to develop alternative insecticides to supplement the pyrethroids. Chlorfenapyr is a pyrrole insecticide first commercialized for the control of agricultural pests and termites. Performance against An. gambiae bearing kdr (pyrethroid and DDT resistance) or Ace-1(R) insensitive acetylcholinesterase (organophosphate and carbamate resistance) mechanisms was studied using a variety of adult bioassay tests including a simulated-experimental hut system (tunnel tests) that allows uninhibited mosquito behaviour/insecticide interactions. Strains resistant to pyrethroids and organophosphates showed no cross resistance to chlorfenapyr. In cone bioassays on treated netting the mortality of adult mosquitoes showed an unexpected curvilinear response, with highest mortality occurring at intermediate dosages. Adults expressed irritability to chlorfenapyr at higher dosages, which might explain the dosage-mortality trend. Toxic activity of chlorfenapyr was slow compared to conventional neurotoxic insecticides and additional mortality occurred between 24h and 72 h. In tunnel tests, the dosage-mortality trend showed a more typical sigmoid response and most mortality occurred during the first 24h. Mosquito penetration through the holed, treated netting showed only limited inhibition and blood-feeding was not inhibited. Mortality rates in the kdr strain exposed to chlorfenapyr treated netting in tunnel tests were much higher than with permethrin treated netting over the same 100-500 mg/m(2) dosage range. Chlorfenapyr has potential for malaria control in treated-net or residual spraying applications in areas where mosquitoes are pyrethroid resistant. For treated-net applications chlorfenapyr might be combined with pyrethroid as a mixture to provide personal protection as well as to give control of resistant mosquitoes.     

Insecticide resistance in Bemisia tabaci Gennadius (Homoptera: Aleyrodidae) and Anopheles gambiae Giles (Diptera: Culicidae) could compromise the sustainability of malaria vector control strategies in West Africa

Insecticides from the organophosphate (OP) and pyrethroid (PY) chemical families, have respectively, been in use for 50 and 30 years in West Africa, mainly against agricultural pests, but also against vectors of human disease. The selection pressure, with practically the same molecules year after year (mainly on cotton), has caused insecticide resistance in pest populations such as Bemisia tabaci, vector of harmful phytoviruses on vegetables. The evolution toward insecticide resistance in malaria vectors such as Anopheles gambiae sensus lato (s.l.) is probably related to the current use of these insecticides in agriculture. Thus, successful pest and vector control in West Africa requires an investigation of insect susceptibility, in relation to the identification of species and sub species, such as molecular forms or biotypes. Identification of knock down resistance (kdr) and acetylcholinesterase gene (Ace1) mutations modifying insecticide targets in individual insects and measure of enzymes activity typically involved in insecticide metabolism (oxidase, esterase and glutathion-S-transferase) are indispensable in understanding the mechanisms of resistance. Insecticide resistance is a good example in which genotype–phenotype links have been made successfully. Insecticides used in agriculture continue to select new resistant populations of B. tabaci that could be from different biotype vectors of plant viruses. As well, the evolution of insecticide resistance in An. gambiae threatens the management of malaria vectors in West Africa. It raises the question of priority in the use of insecticides in health and/or agriculture, and more generally, the question of sustainability of crop protection and vector control strategies in the region. Here, we review the susceptibility tests, biochemical and molecular assays data for B. tabaci, a major pest in cotton and vegetable crops, and An. gambiae, main vector of malaria. The data reviewed was collected in Benin and Burkina Faso between 2008 and 2010 under the Corus 6015 research program. This review aims to show: (i) the insecticide resistance in B. tabaci as well as in An. gambiae; and (ii) due to this, the impact of selection of resistant populations on malaria vector control strategies. Some measures that could be beneficial for crop protection and vector control strategies in West Africa are proposed.     

First record of the Asian malaria vector Anopheles stephensi and its possible role in the resurgence of malaria in Djibouti,Horn of Africa

Anopheles stephensi is an important vector of urban malaria in India and the Persian Gulf area. Its previously known geographical range includes southern Asia and the Arab Peninsula. For the first time, we report A. stephensi from the African continent, based on collections made in Djibouti, on the Horn of Africa, where this species’ occurrence was linked to an unusual urban outbreak of Plasmodium falciparum malaria, with 1228 cases reported from February to May 2013, and a second, more severe epidemic that emerged in November 2013 and resulted in 2017 reported malaria cases between January and February 2014. Anopheles stephensi was initially identified using morphological identification keys, followed by sequencing of the Barcode cytochrome c-oxidase I (COI) gene and the rDNA second internal transcribed spacer (ITS2). Positive tests for P. falciparum circumsporozoite antigen in two of six female A. stephensi trapped in homes of malaria patients in March 2013 are evidence that autochthonous urban malaria transmission by A. stephensi has occurred. Concurrent with the second malaria outbreak, P. falciparum-positive A. stephensi females were detected in Djibouti City starting in November 2013. In sub-Saharan Africa, newly present A. stephensi may pose a significant future health threat because of this species’ high susceptibility to P. falciparum infection and its tolerance of urban habitats. This may lead to increased malaria outbreaks in African cities. Rapid interruption of the urban malaria transmission cycle, based on integrated vector surveillance and control programs aimed at the complete eradication of A. stephensi from the African continent, is strongly recommended.     

库态按蚊(昆虫纲:双翅目)的研究现状:从生态学研究到其传疟作用

库态按蚊是一个由五种亲缘种型组成的按蚊复合体,分别被命名为A、B、C、D和E型,其中除B型以外,其他各型均属于传疟媒介.库态按蚊广泛分布于埃塞俄比亚及其以东的亚洲地区,包括印度和中国南部等.在某些南亚国家,库态按蚊既是当地的优势按蚊种,也是主要的传疟媒介之一,对当地疟疾的流行起着非常重要的作用.通过多线染色体技术和PCR能鉴定出按蚊复合体中的所有成员.该文对库态按蚊的生态学、传疟作用及其相关问题的研究文献进行综合的评述,主要包括:(1)最近所涉及的库态按蚊传疟媒介领域的研究,(2)库态按蚊的地理分布、生态学和库态按蚊幼虫及成虫的生态特征研究,以及每个种型的媒介能量等,(3)有关库态按蚊的媒介控制方面的研究进展,(4)对今后库态按蚊研究的展望.     

Genetic variability in geographical populations of Culex quinquefasciatus Say (Diptera: Culicidae) from India based on random amplified polymorphic DNA analysis

Genetic variability and environmental factors may influence the refractiveness, propagation of pathogen and transmission of disease. Random amplified polymorphic DNA (RAPD) is one of the widely used molecular markers for population genetic diversity studies. In present study, RAPD is used to ascertain the genetic variability in Culex quinquefasciatus populations collected from various Indian geographical locations. Out of 50 RAPD primers screened, 14 primers exhibited clear, concrete and distinct banding pattern showing up to 100% polymorphism. Primer OPBD3 was tested with DNA of 14 geographical populations from India (including one laboratory population) showed 21 loci representing 14 populations with 100% polymorphism. The genetic diversity among the populations indicated the Shannon index (I) and gene diversity index (H_ST), 0.48 and 0.31, respectively among the population, displaying rich genetic variation among the Cx. quinquefasciatus populations. Consensus tree showed two clusters indicating the genetic variation among the various geographical populations. The findings of this study may be useful to understand the population variation under different ecological conditions and development of effective vector management strategies.     

Population genetic structure of the malaria vector Anopheles moucheti in south Cameroon forest region

We used recently developed microsatellite DNA markers to explore the population genetic structure of the malaria vector, Anopheles moucheti. Polymorphism at 10 loci was examined to assess level of genetic differentiation between four A. moucheti populations from South Cameroon situated 65-400 km apart. All microsatellite loci were highly polymorphic with a number of distinct alleles per locus ranging from 9 to 17. Fst estimates ranging from 0.0094 to 0.0275 (P < 0.001) were recorded. These results suggest a very low level of genetic differentiation between A. moucheti populations. The recently available microsatellite loci revealed useful markers to assess genetic differentiation between geographical populations of A. moucheti in Cameroon.     

Species B of Anopheles culicifacies (Diptera: Culicidae) is reproductively less fit than species A and C of the complex

Anopheles culicifacies, the most important malaria vector of peninsular India exist as a complex of five sibling species. The member species of the complex have various biological differences including their susceptibility to malaria parasites. The present attempt is made to study and compare the fecundity of the differentially susceptible members of the An. culicifacies complex. Gravid female mosquitoes of species A, B and C were allowed to lay their eggs individually during first and second gonotrophic cycle. The eggs were counted after hatching and categorized as ‘hatched eggs’, ‘unhatched eggs’, ‘embryonated eggs’, ‘unembryonated eggs’ and ‘non/partially melanized eggs’. The data was analyzed using Student's t test, ANOVA, Chi-square and Pearson's correlation analysis. All females that were visually categorized as ‘gravid’ did not lay eggs. Species C laid maximum number of eggs per female. The eggs laid per female mosquito of each species were found to be significantly higher during second gonotrophic cycle as compared with the first gonotrophic cycle. The eggs hatched per female in species C were found to be significantly higher than that of species A and B. The poor-vector species B mosquitoes were found to be the least fecund among the members of the species complex. The unembryonated eggs constitute the biggest proportion of the unhatched eggs in species A, B and C of the species complex.     

Comparison of the effects of extracts from three Vitex plant species on Anopheles gambiae s.s. (Diptera: Culicidae) larvae

Acetone and methanol extracts of different parts of three Vitex species (leaves and stem bark of Vitex trifolia, leaves, stem bark and root bark of Vitex schiliebenii and stem and root bark of Vitex payos) were evaluated for their potential to control Anopheles gambiae Giles s.s. larvae (Diptera: Culicidae). The extracts gave different levels and rate of mortality of the larvae. Some (methanol extract of V. trifolia leaves, acetone extracts of stem bark and leaves of V. schiliebenii, acetone extract of root bark of V. payos) caused 100% mortality at 100 ppm in 72 h, with those of V. schiliebenii and V. payos showing faster rate of mortality (LT₅₀ = 8 h) than that of V. trifolia (LT₅₀ = 14 h). At lower doses of these extracts (≤50 ppm), most of the larvae failed to transform to normal pupae but gave larval–pupal intermediates between 4 and 14 days of exposure. Some pupated normally but the adults that emerged appeared to be weak and died within 48 h. Extracts of the stem bark of V. payos showed interesting effects on the larvae. Initially, the larvae were relatively hyperactive compared to those in control treatments. Later, the ones that did not transform to larval–pupal intermediates became stretched and inactive and died and floated in clusters on the surface. These observations suggest some interesting growth-disrupting constituents in the plants, with possible application in the practical control of mosquito larvae in aquatic ecosystems.     

Mosquitocidal properties of Morinda citrifolia L. (Noni) (Family: Rubiaceae) leaf extract and Metarhizium anisopliae against malaria vector,Anopheles stephensi Liston. (Diptera: Culicidae)

ObjectiveTo evaluate the mosquito larvicidal and pupicidal activity of the ethanolic extracts from Morinda citrifolia (M. citrifolia) plant and entomopathogenic fungi Metarhizium anisopliae (M. anisopliae) against malaria vector, Anopheles stephensi (An. stephensi).MethodsM. citrifolia leaves were collected in and around Alleppy districts, Kerala, India. M. citrifolia leaf was washed with tap water and shade dried at room temperature. An electrical blender powdered the dried plant leaves. A total of 500 g leaf powder was macerated with 1.5 L of ethanol sequentially for a period of 72 h and filtered. The crude plant extracts were evaporated to dryness in rotary vacuum evaporator. The larvicidal and pupicidal activity was assayed at various concentrations ranging from 100 to 500 mg/L under the laboratory conditions. The LC₅₀ and LC₉₀ values of the M. citrifolia leaf extract and M. anisopliae fungi were determined by Probit analysis.ResultsThe plant extract showed larvicidal and pupicidal effects after 24 and 48 h of exposure; all larval instars and pupae have considerably moderate mortality; however, the highest larval and pupal mortality appeared in combined treatment at 24 and 48 h. The LC₅₀ and LC₉₀ values of M. citrifolia and M. anisopliae and their combined treatment against the first to fourth instars larvae and pupae of the malaria vector were assessed. M. citrifolia had values of LC₅₀=202.47, 95.75, 57.52, 18.30 and 97.78 mg/L; LC₉₀=384.37, 482.91, 631.22, 757.55 and 944.96 mg/L at 48 h. M. anisopliae had values of LC₅₀=1.40, 3.99, 5.56, 8.77 and 11.49%; LC₉₀=13.84, 17.62, 22.20, 25.71 and 30.78% at 48 h; Combined treatment had values of LC₅₀=3.71, 16.73, 29.71, 40.60 and 138.10 mg/L; LC₉₀=122.29, 150.15, 156.90, 211.99 and 806.67 mg/L at 48 h, respectively.ConclusionsThe plant and the fungi are promising larvicidal and pupicidal agents against malaria vector, An. stephensi. This is a new eco-friendly approach for the control of vector. Therefore, this study provides first report on the combined treatment of this plant extract and fungi from India.     

Indirect effects of cigarette butt waste on the dengue vector Aedes aegypti (Diptera: Culicidae)

Despite major insecticide-based vector control programs, dengue continues to be a major threat to public health in urban areas. The reasons for this failure include the emergence of insecticide resistance and the narrowing of the spectrum of efficient products. Cigarette butts (CBs), the most commonly discarded piece of waste, also represent a major health hazard to human and animal life. CBs are impregnated with thousands of chemical compounds, many of which are highly toxic and none of which has history of resistance in mosquitoes. This study was performed to examine whether exposure to CB alters various biological parameters of parents and their progeny. We examined whether the mosquito changes its ovipositional behaviors, egg hatching, reproductive capacity, longevity and fecundity in response to CB exposure at three different concentrations. Females tended to prefer microcosms containing CBs for egg deposition than those with water only. There were equivalent rates of eclosion success among larvae from eggs that matured in CB and water environments. We also observed decreased life span among adults that survived CB exposure. Extracts of CB waste have detrimental effects on the fecundity and longevity of its offspring, while being attractive to its gravid females. These results altogether indicate that CB waste indirectly affect key adult life traits of Aedes aegypti and could conceivably be developed as a novel dengue vector control strategy, referring to previously documented direct toxicity on the larval stage. But this will require further research on CB waste effects on non-target organisms including humans.     

Intraspecific variation within Phlebotomus sergenti Parrot (1917) (Diptera: Psychodidae) based on mtDNA sequences in Islamic Republic of Iran

An intraspecific study on the morphological and molecular characteristics of Phlebotomus sergenti s.l., the main vector of Leishmania tropica, was performed on 28 Iranian populations from 11 provinces and a few samples from Greece, Morocco, Lebanon, Turkey, Pakistan, and Syria. Three morphotypes were identified as A, B and C, with some intermediate forms in the samples under investigation. Based on the number of setae and the width of basal lobe of coxite, differences between A and B morphotypes were highly significant. Excluding one unusual haplotype, sequence analysis of approximately 439 bp of mtDNA (a fragment of cytochrome B gene, tRNA for serine gene, and a fragment of NADH1 gene) revealed a 6-7% genetic distance within the Iranian populations and among the specimens of other countries. Neighbor-Joining (NJ) analysis confirmed the existence of three main groups within our samples. Although there was no consistency between morphotypes and genotypes, but an interrelationship was found between morphometry and morphotypes. Morphotype A, which was considered as P. sergenti sergenti, was the most prevalent in collection sites. Morphotype B, which was identified as Phlebotomus sergenti similis, is the first record of this subspecies in Iran, and was found to be sympatric with other morphotypes. Morphotype C had an elongated style in comparison with P. sergenti sergenti. Molecular database showed three main genetic structures. This is the first combined morphological and molecular studies on P. sergenti s.l. in Iran.     

Geometric morphometric analysis of Colombian Anopheles albimanus (Diptera: Culicidae) reveals significant effect of environmental factors on wing traits and presence of a metapopulation

Anopheles albimanus is a major malaria mosquito vector in Colombia. In the present study, wing variability (size and shape) in An. albimanus populations from Colombian Maracaibo and Chocó bio-geographical eco-regions and the relationship of these phenotypic traits with environmental factors were evaluated. Microsatellite and morphometric data facilitated a comparison of the genetic and phenetic structure of this species. Wing size was influenced by elevation and relative humidity, whereas wing shape was affected by these two variables and also by rainfall, latitude, temperature and eco-region. Significant differences in mean shape between populations and eco-regions were detected, but they were smaller than those at the intra-population level. Correct assignment based on wing shape was low at the population level (<58%) and only slightly higher (>70%) at the eco-regional level, supporting the low population structure inferred from microsatellite data. Wing size was similar among populations with no significant differences between eco-regions. Population relationships in the genetic tree did not agree with those from the morphometric data; however, both datasets consistently reinforced a panmictic population of An. albimanus. Overall, site-specific population differentiation is not strongly supported by wing traits or genotypic data. We hypothesize that the metapopulation structure of An. albimanus throughout these Colombian eco-regions is favoring plasticity in wing traits, a relevant characteristic of species living under variable environmental conditions and colonizing new habitats.     

Genetic variability of Brazilian populations of Lymnaea columella (Gastropoda: Lymnaeidae), an intermediate host of Fasciola hepatica (Trematoda: Digenea)

In Brazil, Lymnaea columella is the most important intermediate host of Fasciola hepatica, the etiological agent of fasciolosis, which is a parasitic disease of veterinarian and human importance. Random amplified polymorphic DNA (RAPD) was used to investigate the genetic variability within and among nine Brazilian populations of L. columella comprising 205 individuals. A number of four primers were used for analysis of molecular variance (AMOVA). Out of 83 RAPD markers, 63 (76%) were polymorphic and revealed 119 unique RAPD profiles. The levels of genetic variability found in the populations were low and most of the genetic variation was interpopulational (81.6%) when compared to intrapopulational variability (18.4%). These results are in accordance with the dynamics and distribution of the populations analyzed.