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Open Access Research

Morphometrical diagnosis of the malaria vectors Anopheles cruzii, An. homunculus and An. bellator

Camila Lorenz1, Tatiani Cristina Marques2, Maria Anice Mureb Sallum2 and Lincoln Suesdek13*

Author Affiliations

1 Programa de Pós-graduação (Mestrado) em Ciências (Biologia da Relação Patógeno-Hospedeiro), Instituto de Ciências Biomédicas, Universidade de São Paulo, 1500, 05509–300 São Paulo-SP, Brazil

2 Departamento de Epidemiologia, Faculdade de Saúde Pública, Universidade de São Paulo, 1500, 05509–300 São Paulo-SP, Brazil

3 Laboratório de Parasitologia, Instituto Butantan, Avenida Vital Brasil, 1500, 05509–300 São Paulo-SP, Brazil

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Parasites & Vectors 2012, 5:257  doi:10.1186/1756-3305-5-257

Published: 13 November 2012

Abstract

Background

Anopheles (Kerteszia) cruzii is a primary vector of Plasmodium parasites in Brazil’s Atlantic Forest. Adult females of An. cruzii and An. homunculus, which is a secondary malaria vector, are morphologically similar and difficult to distinguish when using external morphological characteristics only. These two species may occur syntopically with An. bellator, which is also a potential vector of Plasmodium species and is morphologically similar to An. cruzii and An. homunculus. Identification of these species based on female specimens is often jeopardised by polymorphisms, overlapping morphological characteristics and damage caused to specimens during collection. Wing geometric morphometrics has been used to distinguish several insect species; however, this economical and powerful tool has not been applied to Kerteszia species. Our objective was to assess wing geometry to distinguish An. cruzii, An. homunculus and An. bellator.

Methods

Specimens were collected in an area in the Serra do Mar hotspot biodiversity corridor of the Atlantic Forest biome (Cananeia municipality, State of Sao Paulo, Brazil). The right wings of females of An. cruzii (n= 40), An. homunculus (n= 50) and An. bellator (n= 27) were photographed. For each individual, 18 wing landmarks were subjected to standard geometric morphometrics. Discriminant analysis of Procrustean coordinates was performed to quantify wing shape variation.

Results

Individuals clustered into three distinct groups according to species with a slight overlap between representatives of An. cruzii and An. homunculus. The Mahalanobis distance between An. cruzii and An. homunculus was consistently lower (3.50) than that between An. cruzii and An. bellator (4.58) or An. homunculus and An. bellator (4.32). Pairwise cross-validated reclassification showed that geometric morphometrics is an effective analytical method to distinguish between An. bellator, An. cruzii and An. homunculus with a reliability rate varying between 78-88%. Shape analysis revealed that the wings of An. homunculus are narrower than those of An. cruzii and that An. bellator is different from both of the congeneric species.

Conclusion

It is possible to distinguish among the vectors An. cruzii, An. homunculus and An. bellator based on female wing characteristics.

Keywords:
Culicidae; Kerteszia; Wing geometric morphometrics; Identification; Malaria vectors; Atlantic Forest