Species Richness and Distribution of Calliphoridae Along an Elevation Gradient in Sicily (Italy) and Ecuador

Abstract

Blow flies (Diptera: Calliphoridae) are among the first insects to arrive on a corpse, and so they are particularly important in forensic entomology. To use blow flies in forensic investigations, there must be information available on their species diversity, abundance, and distribution in the areas where investigations are conducted. Several factors can contribute to species distribution, and elevation is one of those factors. The purpose of this study was to document the distribution of Calliphoridae across four elevational gradients in Sicily and Ecuador, where little information is available. Baited traps were placed at elevations ranging from 20 m to 1552 m in Sicily (a major island and region of Italy and a distinct ecoregion) and 561 m to 3336 m in Ecuador. Species richness, relative abundance, and diversity were calculated, as well as the ratio of female to male blow flies and community assemblage. Twelve species were collected in Sicily, and seventeen species were collected in Ecuador. In Sicily, the most abundant species was Lucilia sericata (Meigen) (68.50% of the total capture), while in Ecuador, it was Compsomyiops verena (Walker) (51.67% of the total capture). In Sicily, significant differences were only observed in the relative abundance of L. sericata across elevations. In Ecuador, significant differences were observed in the relative abundance of Calliphora nigribasis (Macquart), Chrysomya albiceps (Wiedemann), C. verena, Hemilucilia semidiaphana (Rondani), Lucilia ibis (Shannon), L. purpurascens (Walker), and Paralucilia sp. across elevations. These data can help build a checklist of blow fly species in these two regions and can be instrumental in environmental and forensic investigations.

Keywords: Calliphoridae; Diptera; altitude; biodiversity; elevation; entomology; forensic.

Figure 1

Sampling sites at different elevations in Sicily. Orange = 20 m (level 1), blue = 700 m (level 2), yellow = 1153 m (level 3), and red = 1552 m (level 4).

Figure 2

Sampling sites at different elevations in Ecuador. Blue = 561 m (level 1), yellow = 1312 m (level 2), red = 1948 m (level 3), and green = 3336 m (level 4).

Figure 3

Blow fly species diversity across elevations in Sicily using the Shannon (H) diversity index.

Figure 4

Sorenson’s (CC) Similarity Index between elevations in Sicily. a1 = level 1 (20 m), a2 = level 2 (700 m), a3 = level 3 (1153 m), and a4 = level 4 (1552 m).

Figure 5

Rarefaction/Extrapolation curves for the four elevation levels (lvl) in Sicily; the x-axis displays the numbers of specimens and the y-axis the species richness (number of species).

Figure 6

Nonmetric multidimensional scaling ordinations of blow fly communities across elevations in Sicily. This ordination explains 91% of variation (minimum stress = 0.083). MRPP analysis showed significant differences between 700 m and 1153 m (A = 0.3035 p = 0.035). Circles represent elevation 20 m, triangles elevation 700 m, squares elevation 1153 m, and crosses elevation 1552 m.

Figure 7

Blow fly species diversity across elevations in Ecuador using the Shannon (H) diversity index.

Figure 8

Sorenson’s (CC) Similarity Index between elevations in Ecuador. a1 = level 1 (561 m), a2 = level 2 (1312 m), a3 = level 3 (1948 m), and a4 = level 4 (3336 m).

Figure 9

Nonmetric multidimensional scaling ordinations of blow fly communities across elevations in Ecuador. This ordination explains 82% of variation (minimum stress = 0.14). MRPP analysis showed significant differences between all levels (561 m and 1948 m (A = 0.2893 p = 0.027); 561 m and 3336 m (A = 0.2747 p = 0.04); 1312 m and 1948 m (A = 0.31261 p = 0.025); 1312 m and 3336 m (A = 0.2977 p = 0.028)), except between 1948 m and 3336 m (A = 0.1031 p = 0.083). Circles represent elevation 561 m, triangles elevation 1312 m, squares elevation 1948 m, crosses elevation 3336 m.

Figure 10

Rarefaction/Extrapolation curves for the four elevation levels (lvl) in Ecuador; the x-axis displays the numbers of specimens and the y-axis the species richness (number of species).

Figure 11

Blowfly species diversity across elevations in Sicily (orange) and Ecuador (green) using the Shannon (H) diversity index.