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

Abstract

BackgroundAnopheles (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.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 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.ResultsIndividuals 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.ConclusionIt is possible to distinguish among the vectors An. cruzii, An. homunculus and An. bellator based on female wing characteristics.

Morphogenetic characterisation, date of divergence, and evolutionary relationships of malaria vectors Anopheles cruzii and Anopheles homunculus

“…Some of the landmarks in the wings were more variable than others and were consequently more useful in species identification. Lorenz et al (2012) observed that female An. cruzii and An.…”

“…Geometric morphometrics of the wing were analysed according to the procedure described by Lorenz et al (2012). We analysed the right wings of 133 An.…”

Landmark and outline-based geometric morphometrics analysis of three Stomoxys flies (Diptera: Muscidae)

“…Geometric morphometrics is increasingly applied to medically and economically important insects to distinguish morphologically similar species, especially cryptic taxa, and to detect intraspecific variation (Dujardin 2008, Ruangsittichai et al 2011, Lorenz et al 2012, Dujardin and Kitthawee 2013, Morales Vargas et al 2013, Demari-Silva et al 2014, Jaramillo-O et al 2015, Sumruayphol et al 2016). Wing veins provide many well-defined landmarks suitable for the landmark-based approach (Villegas et al 2002).…”

Comparative Vector Bionomics and Morphometrics of Two Genetically Distinct Field Populations of Anopheles darlingi Root from Belize, Central America and Zungarococha, Peru, South America

“…homunculus, and An. bellator to the appropriate species 78-88% of the time (104). Again in Colombia, a study on members of the Albitarsis complex found 2 molecular operational taxonomic units (MOTUs) using COi DNA bar-coding; An.…”