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

Abstract

AbstractBackgroundAnopheles(Kerteszia)cruziiis a primary vector ofPlasmodiumparasites in Brazil’s Atlantic Forest. Adult females ofAn. cruziiandAn. 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 withAn.bellator, which is also a potential vector ofPlasmodiumspecies and is morphologically similar toAn. cruziiandAn. 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 toKertesziaspecies. Our objective was to assess wing geometry to distinguishAn. cruzii,An. homunculusandAn. bellator.MethodsSpecimens 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 ofAn. cruzii(n= 40),An. homunculus(n= 50) andAn. 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.ResultsIndividuals clustered into three distinct groups according to species with a slight overlap between representatives ofAn. cruziiandAn. homunculus. The Mahalanobis distance betweenAn. cruziiandAn. homunculuswas consistently lower (3.50) than that betweenAn. cruziiandAn. bellator(4.58) orAn. homunculusandAn. bellator(4.32). Pairwise cross-validated reclassification showed that geometric morphometrics is an effective analytical method to distinguish betweenAn.bellator,An. cruziiandAn. homunculuswith a reliability rate varying between 78-88%. Shape analysis revealed that the wings ofAn. homunculusare narrower than those ofAn. cruziiand thatAn. bellatoris different from both of the congeneric species.ConclusionIt is possible to distinguish among the vectorsAn. cruzii,An. homunculusandAn. bellatorbased on female wing characteristics.