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Genetic differentiation among natural populations of the vector of onchocerciasis, Simulium ochraceum in Guatemala

Published online by Cambridge University Press:  19 September 2011

Takeshi Agatsuma
Takeshi Agatsuma
Affiliation:
Department of Parasitology, Kochi Medical School, Oko-Cho, Nankoku City 781–51, Japan
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Abstract

Electrophoretic studies of Guatemalan blackflies, Simulium ochraceum, the main vector of Central American onchocerciasis, were performed using isozyme patterns. A total of six larval and adult populations originating from four localities (a non-endemic area, Finca La Ruda, a low-endemic area, Finca Rincon, and two high-endemic areas, Finca Brote and Finca Recreo) were analyzed. The enzymes examined were adenylate kinase (AK), alkaline phosphatase (ALP), glucose phosphate isomerase (GPI), hexokinase (HK), isocitrate dehydrogenase (IDH), leucine aminopeptidase (LAP), malic enzyme (ME), and phosphoglucomutase (PGM). Of these, six enzymes, AK, ALP, HK, IDH, LAP, and ME showed no variation either within or among populations. GPI and PGM were found to be highly polymorphic in all of the six populations. χ2-test for fit to Hardy-Weinberg equilibrium (HWE) revealed that the distribution of the phenotypes of the two polymorphic enzymes was not significantly out of the HWE. A verages of values of proportion of polymorphic loci (P) and heterozygosity per individual (H) of the six populations were 0.234 and 0.084, respectively, each of which was similar to the values reported for different groups of organisms (Nei, 1975). Genetic diversity among populations was measured by FST and GST and both parameters showed that the non-endemic population from the Finca La Ruda (Dl) was greatly differentiated genetically from the other five populations. Estimates of genetic distance (Nei, 1975) showed that the Dl population was furthest from the other populations.

Résumé

Des études électrophorétiques ont permis de comparer les spectres d'isoenzymes de la mouche noire du Guatémala, Simulium ochraceum, vecteur principal de l'onchocercose en amérique centrale. Au total 6 populations de larves et d'adultes, provenant de 4 localités (une région où l'onchocercose n'est pas endémique, Finca La Ruda; une région à faible endémie, Finca Ricon et de régions à haute endémie, Finca Brote et Finca Recreo) ont été analysées.

Les enzymes suivants ont été examinés: adénylate kinase (AK), alcaline phosphatase (ALP), glucose phosphate isomérase (GPI), hexokinase (HK), isocitrate déhydrogénase (IDH), leucine amino-peptidase (LAP), enzyme malique (ME) et la phosphoglucomutase (PGM). Dans les populations testées aucun polymorphisme n'a été montré pour les 6 enzymes suivants: AK, ALP, HK, IDH, LAP et ME. En revanche GPI et PGM sont hautement polymorphes dans toutes les populations.

Un test de χ2 pour l'analyse de l'équilibre Hardy-Weinberg (HWE) révèle que la distribution des phénotypes des deux enzymes polymorphes n'est pas significativement hors du HWE. Des valeurs moyennes de loci polymorphes (P) et d'hétérozygotie par individu (H) des 6 populations sont de 0,234 et 0,084 respectivement, chacune étant similaire aux valeurs reportées pour différents groupes d'organismes (Nei, 1975). Des diversités génétiques parmi les populations ont été mesurées par FST et GST. Les deux paramètres montrent que la population de la Finca La Ruda (Dl) est génétiquement très différenciée des cinq autres populations.

Des estimations de distance génétique (Nei, 1975) ont montré que la population Dl est plus récente que les autres populations.

Keywords

Blackfliesenzyme electrophoresisisozymespopulation geneticsonchocerciasisGuatemala
Type
Symposium II: Biotypes, Polymorphism and Co-evolution in Tropical Insects
Information
International Journal of Tropical Insect Science , Volume 8 , Issue 4-5-6: Recent Advances in Research on Tropical Entomology , December 1987 , pp. 465 - 469
Copyright
Copyright © ICIPE 1987

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References

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