Diversity of mosquitoes (Diptera: Culicidae) collected in different types of larvitraps in an Amazon rural settlement

Abstract

Anthropogenic environments provide favorable conditions for some species, which is especially true of mosquitoes that present eclecticism at the moment of choice for the site of oviposition. In the present study, the diversity of mosquitoes was assessed by providing plastic containers, bamboo internodes, and tires in a forest, the forest edge, and peridomicile environments in a rural settlement area. Eighteen sampling points were chosen, delimited by a buffer of 200 m, placed in three environments: forest, forest edge, and peridomicile. In each environment, larvitraps were installed, separated by a minimum distance of 7 m and 1 m from the ground. A total of 10,131 immature mosquitoes of 20 species were collected. The most abundant species was Culex urichii (29.5%), followed by Trichoprosopon digitatum (27.1%), and Cx. (Melanoconion) spp. (10.4%). There was a difference in the composition of immature mosquito populations between larvitraps (p < 0.0005), and the plastic container hosted a greater diversity of species, whereas tires presented a greater abundance of individuals. The forest, forest edge, and peridomicile environments were also different with regard to diversity of immature mosquito populations (p < 0.0010). The forest edge was the environment with the greatest diversity of species, followed by the peridomicile and forest environments. In the forest and peridomicile, plastic container larvitraps had the greatest diversity, whereas the forest edge tire presented the largest number of individuals. Further, tire larvitraps collected the largest number of individuals in all environments. Ten species associated with the bamboo internode and tire were identified. The preference of species for artificial larvitraps, such as the plastic container and tire, even in wild environments was noted. These artificial objects may represent a risk factor for the population living in this region, as all vector species found in the study were present in plastic containers and tires.

Fig 1. Study area geographical information system.

A—In different shades of grey; South America, Brazil, and the municipality of Presidente Figueiredo. B—Delimitation area of the Presidente Figueiredo municipality, pointing to the agrovillage of Rio Pardo. C—Rio Pardo agrovillage and, in particular, roads where larvitraps were distributed for immature mosquito collection. D—Location of collection points along agrovillage roads: the numbers represent the geographic coordinates of the collection points: 1 (01º48’37.6” S, 060º16’27.1” W); 2 (01º48’26.7” S, 060º16’26.1” W); 3 (01º48’23.5” S, 060º16’25.7” W); 4 (01º48’13.6” S, 060º16’25.2” W); 5 (01º45’51.6” S, 060º17’08.2” W); 6 (01º47’33.3” S, 060º17’42.7” W); 7 (01º48’30.4” S, 060º18’46.8” W); 8 (01°48’15.9” S, 060°19’06.3” W); 9 (01°48’31.6” S, 060°19’05.3” W); 10 (01°48’51.9” S, 060°19’ 06.9” W); 11 (01°49’00.9” S, 060°19’09.5” W); 12 (01°47’06.1” S, 060°19’15.9” W); 13 (01°46’36.3” S, 060°19’22.5” W); 14 (01º48’37.5” S, 060º20’24.2” W); 15 (01º48’37.3” S, 060º20’39.4” W); 16 (01º48’15.0” S, 060º21’20.4” W); 17 (01°47’18.2” S, 060°21’31.6” W); 18 (01°47’17.4” S, 060°21’53.3” W). Reprinted from Maxar under a CC BY license, with permission from Instituto Leônidas e Maria Deane—Fiocruz, original copyright 2008.

Fig 2. Larvitrap installations in the Rio Pardo agrovillage, Presidente Figueiredo, Amazonas, Brazil.

A—bamboo internode. B—tire. C—plastic container. D—trap installation. The arrows point to the installed larvitraps for the collection of immature mosquitoes.

Fig 3. Collected species of mosquitoes.

Rarefaction curves representing the accumulated richness of the immature mosquito species collected in plastic container, tire, and bamboo internode traps in the agrovillage of Rio Pardo, Presidente Figueiredo, Amazonas, Brazil periods of November 2017 and January–February 2018.

Fig 4. Rényi diversity profiles of immature mosquitoes.

A—Diversity of species found in bamboo internodes, plastic containers, and tire larvitraps. B—Diversity of species found in bamboo internodes, plastic containers, and tire larvitraps installed in the forest environment. C—Diversity of species found in bamboo internodes, plastic containers, and tire larvitraps installed in the forest edge environment. D—Diversity of species found in bamboo internodes, plastic containers, and tire larvitraps installed in the peridomicile environment. X axis: Alpha (α) zero = log wealth, 1 = Shannon Index, 2 = Simpson Index, Inf = Berger Parker Index. Rio Pardo, Presidente Figueiredo, Amazonas.