Mosquitoes of the Maculipennis complex in Northern Italy

Abstract

The correct identification of mosquito vectors is often hampered by the presence of morphologically indiscernible sibling species. The Maculipennis complex is one of these groups that include both malaria vectors of primary importance and species of low/negligible epidemiological relevance, of which distribution data in Italy are outdated. Our study was aimed at providing an updated distribution of Maculipennis complex in Northern Italy through the sampling and morphological/molecular identification of specimens from five regions. The most abundant species was Anopheles messeae (2032), followed by Anopheles maculipennis s.s. (418), Anopheles atroparvus (28) and Anopheles melanoon (13). Taking advantage of ITS2 barcoding, we were able to finely characterize tested mosquitoes, classifying all the Anopheles messeae specimens as Anopheles daciae, a taxon with debated rank to which we referred as species inquirenda (sp. inq.). The distribution of species was characterized by Ecological Niche Models (ENMs), fed by recorded points of presence. ENMs provided clues on the ecological preferences of the detected species, with An. daciae sp. inq. linked to stable breeding sites and An. maculipennis s.s. more associated to ephemeral breeding sites. We demonstrate that historical Anopheles malaria vectors are still present in Northern Italy.

Figure 1

Location of sampled sites on the Northern Italy map, with reference to the boundaries of the Pianura Padana, type of sampling and the geometric mean of mosquitoes of the Maculipennis complex collected per night in the 2017–18 seasons. Map created using QGIS 3.10 (www.qgis.org).

Figure 2

Proportion of different species identified in sampled sites. Abbreviations of Italian provinces (NUT3) with identified specimens are shown. The points of presence of every species are reported in Supplementary Figure S1. Map created using QGIS 3.10 (www.qgis.org); raster layers: Globe DEM (www.ngdc.noaa.gov), EU-Hydro (www.copernicus.eu).

Figure 3

Maximum likelihood tree obtained by ITS2 haplotypes from this work (in bold with EBI accession numbers) and reference sequences from GenBank (accession number reported). Bootstrap values on 1000 replicates reported near the node, only values over 700 are shown.

Figure 4

(a) Site of detection of An. atroparvus (red) and An. melanoon (green). Output of ENM obtained by Maxent for An. daciae sp. inq. (b) and An. maculipennis s.s. (c). Map created using QGIS 3.10 (www.qgis.org); raster layers: Globe DEM (www.ngdc.noaa.gov), EU-Hydro (www.copernicus.eu).