The sampling yielded 374 specimens (N) distributed across 34 species (S) belonging to six different tribes (Table 1), with 298 males and 76 females. The Shannon diversity and uniformity indices were (H’= 2.59), and (U= 0.733), respectively, and the Berger- Parker dominance index was (BP= 0.235) (Table 2).

Table 1.
Richness (S), abundance (N), and dominance (E= eudominant; D= dominant; S= sub-dominant; EV= occasional; and R= rare) of Sphingidae species collected in two seasons (dry and wet) using Pennsylvania light traps in areas of savannah in the Alter do Chão Environmental Protection Area, June 2014 to May 2015.

With respect to dominance, four were eudominant (12%), three dominant (8%), four subdominant (12%), five occassional (14%), and 19 rare (54%). The eudominant species were: Isognathus caricae (Linnaeus, 1758) (N= 88), Enyo lugubris lugubris (Linnaeus, 1771) (N= 58), Isognathus menechus (Boisduval, [1875]) (N= 46) and Cocytius duponchel (Poey, 1832) (N= 44).

The richness estimate showed that this sampling collected between 63% and 87% of expected species. The Bootstrap estimated 39 species and Chao1 estimated 54 (Table 2), and this result supports those from the species accumulation curve which did not reach an asymptote (Figure 2a).

Table 2.
Richness (S), Abundance (N), Shannon diversity (H’), and uniformity (U) indices, and Berger-Parker dominance (BP), and Sphingidae richness estimates collected in two seasons (dry and wet) using Pennsylvania light trap, in areas of savannah in the Alter do Chão Environmental Protection Area, June 2014 to May 2015

Figure 2
Accumulation curve for collected Sphingidae species, in function of sample size, using Pennsylvania light traps in areas of savannah in the Alter do Chão Environmental Protection Area, Santarém, Pará, Brazil. from June 2014 to May 2015, (2a) total sampling period, (2b) dry season, and (2c) wet season. Samples (solid line) and upper and lower 95% confidence intervals (dotted lines).

With respect to abundance, the correlations were moderate, positive and significant for temperature (r= 0.5768; p < 0.049599); moderate, negative and significant for relative air humidity (r= -0.63301; p < 0.027146); moderate, negative and not significant for precipitation (r= -0.53502; p > 0.07307) (Figures 3, 4, and 5, respectively). For the correlation of climate with species richness, there was no significant correlation, and the results were: temperature, positive and weak (r= 0.34068; p > 0.27853); relative air humidity, negative and moderate (r= -0.45113; p > 0.14101); and for precipitation, negative and moderate (r= -0.40011; p > 0.19749) (Figures 3, 4, and 5, respectively).

Figure 3.
Richness (S), and Abundance (N) of Sphingidae species with total monthly precipitation, in mm, collected in the dry season (June to November) and wet season (December to May) using Pennsylvania light traps, in areas of savannah in the Alter do Chão Environmental Protection Area, June 2014 to May 2015

Figure 4.
Richness (S), and Abundance (N) of Sphingidae species with average monthly temperature (°C), collected in the dry season (June to November) and wet season (December to May) using Pennsylvania light traps, in areas of savannah in the Alter do Chão Environmental Protection Area, June 2014 to May 2015

Figure 5
Richness (S), and Abundance (N) of Sphingidae species with percent relative humidity of the air (RH), collected in the dry season (June to November) and wet season (December to May) using Pennsylvania light traps, in areas of savannah in the Alter do Chão Environmental Protection Area, June 2014 to May 2015.

In the dry season there were 222 specimens (N) distributed across 26 species (S), with 11 being exclusive to this period, with 174 males and 48 females. The month of September had the greatest abundance (N= 61), and the months of September and October had the greatest richness (S= 13), with June being the month with the lowest N (11) and S (4) (Table 1 and Figure 3).

The Shannon diversity and uniformity indices were (H’= 2.40), and (U= 0.726), respectively, and the Berger- Parker dominance index was (BP= 0.238) (Table 2).

Four species were eudominant: Isognathus caricae (N= 53), Cocytius duponchel (N= 36), Enyo lugubris lugubris (N= 34), and Isognathus menechus (N= 34). There were 11 rare species encountered (42% of the total collection in this period).

The richness estimate for this season showed that this sampling collected between 76% and 90% of expected species. The ACE estimator yielded 39 species and Jackknife 2 estimated 34 (Table 2), and this result supports those from the species accumulation curve which continued rising (Figure 2b).

In the wet season 152 specimens (N) distributed across 24 species (S), with 8 being exclusive to this period, with 124 males and 28 females. The month of January had the greatest richness and abundance (S= 16, N= 48), and the month of February was the month with the lowest N (12) and S (6) (Table 1 and Figure 3).

The Shannon diversity and uniformity indices were (H’= 2.55), and (U= 0.801), respectively, and the Berger- Parker dominance index was (BP= 0.230) (Table 2), and the t-test for the comparison of the Shannon diversity indices between the two seasons was insignificant (t= -1.368).

The eudominant species were Isognathus caricae (N= 35), Enyo lugubris lugubris (N= 24), Callionima parce (Fabricius, 1775), Erinnyis ello ello (Linnaeus, 1758) and Isognathus menechus (N= 14). There were 8 rare species encountered (33% of the total collection in this period).

The richness estimates for this season showed that this sampling collected between 53% and 83% of expected species. The Bootstrap estimator yielded 29 species and Jackknife 2 estimated 45 (Table 2), and these results support those from the species accumulation curve which continued rising (Figure 2c).

The abundance of Sphingidae in the ACEPA (N= 374) was greater than in Amazon savannah in Roraima (Motta et al., 1991), open forest savannah in the Tabuleiro Paraibano (Darrault & Schlindwein, 2002), the semi-arid Caatinga biome and swamplands in Paraíba (Gusmão & Duarte, 2004), in the Atlantic Forest (Duarte JR & Schlindwein, 2008) and also in a few areas of forest in the Amazon (Motta & Xavier Filho, 2005; Hawes et al., 2009). However, the results for abundance in this study were inferior to those for forest in the Amazon (Motta et al., 1991; Motta et al., 1998; Motta & Andreazze, 2001, 2002; Camargo et al., 2016; Lourido, Motta, Graça, & Rafael, 2018), in the Atlantic Forest by Marinoni, Dutra, and Mielke (1999), and in Caatinga by Duarte JR and Schlindwein (2005b). Compared to areas of savannah, the results from the current study are greater than those from Amorim, Ávila, Camargo, Vieira, and Oliveira (2009) in the region of the Mineiro Triangle on the border of the State of Minas Gerais in the southeast of Brazil (Table 3).

Table 3.
Inventories that were used to compare Sphingidae fauna collected in two seasons (dry and wet) using Pennsylvania light traps, in areas of savannah in the Alter do Chão Environmental Protection Area, Pará, Brazil.

The richness (S= 34) sampled in the ACEPA corresponds to 31% of that found in the State of Pará (Moss, 1920; Motta & Soares, 1997; Hawes et al., 2009; Camargo et al., 2016). When compared to results from studies done in other regions of the Brazilian Amazon, the richness in the ACEPA is superior to that in a savannah in the Pacaraima Mountains studied by Motta et al. (1991), and inferior to the richness found in Amazonian forests (Motta et al., 1991; Motta et al., 1998; Motta & Andreazze, 2001, 2002; Motta & Xavier Filho, 2005; Hawes et al., 2009; Camargo et al., 2016; Lourido, et al., 2018) (Table 3). In comparison with other biomes, the richness of Sphingidae in the ACEPA was superior to that found by Darrault and Schlindwein (2002) in an open forest savannah, and to that reported by Duarte JR and Schlindwein (2005b) in the caatinga. The richness found in the current study was also greater than that reported by Gusmão and Duarte (2004) in an area of the semi-arid Caatinga biome and swampland, and inferior to that found in a savannah (Amorim et al., 2009) (Table 3).

The striking differences between the values for diversity and richness between the study sites mentioned above could be related to the collection technique as influenced by the geographical characteristics of the region studied. For example, the savannah studied in the current study is made up of patches of savannah inserted in the tropical forest, and due to this fact low-power light traps were used in order to reduce the radius of the sampled area, but in the studies mentioned above light traps with a larger radius of luminosity, and therefore of capture potential, were used (Table 3). It was also observed in this study that sample size is a key factor for the determination of greater richness and abundance.

The occurrence of a larger number of males in our samples is a common pattern for hawkmoths as found in other studies (Motta et al., 1991; Motta et al., 1998; Motta & Andreazze, 2001, 2002; Duarte JR & Schlindwen, 2005a; Primo et al., 2013; Lourido et al., 2018).

The diversity indices compared to those from Gusmão and Duarte (2004) are higher for the Shannon index in the swampland (H’= 2.32) and the Caatinga (H’= 1.65). The Shannon uniformity index in this study was inferior to that of the swampland (U= 0.86) and superior to that of the semi-arid Caatinga (U= 0.63), demonstrating that the species in the Alter do Chão savannah have greater similarity in abundance compared to that of the Caatinga and less than that of the swampland. The Berger-Parker dominance index was inferior to that of the Caatinga (BP= 0.53) and similar to that of the swampland (BP= 0.22), demonstrating that the occurrence of dominant species was more constant in the Caatinga and similar to that of the savannah and the swampland. The results for the swampland and the Caatinga were found using similar sampling techniques to those used in the savannah; however, the fact that the results found in the current study are similar to those of the swampland could be explained due to the proximity of the sampling area to the forest.

The estimator Chao1 was the one that was the least representative of the samples, and the results from this estimator were less representative than those from the study by Amorim et al. (2009). When compared to estimates from other studies done in the Amazon, cited by Camargo et al. (2016), our estimate is 99% equal to the estimate made by Motta et al. (1991) (Maracá Island), and less representative compared to Camargo et al. (2016), Motta et al. (1998), Motta and Andreazze (2001, 2002), Motta and Xavier Filho (2005), but superior to the estimates of Motta et al. (1991) from the Pacaraima Mountains, and Hawes et al. (2009).

Isognathus caricae was the most abundant species in our study, different than the results from other studies in the Amazon (Motta et al., 1991; Motta et al., 1998; Motta & Andreazze, 2001, 2002; Hawes et al., 2009; Lourido et al., 2018), demonstrating that the occurrence of species differs according to habitat type.

In general, the composition of the fauna of Sphingidae in the ACEPA is similar to that found in forest areas (Camargo et al., 2016). When species composition is compared to that found in other Amazonian savannahs (Motta et al., 1991) there are just 10 species in common. When compared to the savannah as a whole, the species Eumorpha phorbas (Cramer, 1775) and Xylophanes loelia (Druce, 1878) occur only in the Amazon region (Amorim et al., 2009; Darrault & Schlindwein, 2002; Camargo, Camargo, Corrêa, Vilela, & Amorim, 2018), a result that is justified by the fact that these species also occur in Amazon tropical forests.

The results for the correlations with climatic variables were similar to those from Amorim et al. (2009) with respect to temperature and abundance, and were different than those from Primo et al. (2013), who studied in forest fragments wherein they obtained a positive correlation between annual precipitation and richness and abundance of species.

The greater indices of abundance and richness that occurred in the wet season are contrary to the results reported by Primo et al. (2013), Amorim et al. (2009), Duarte JR and Schlindwein (2005a) and Duarte JR and Schlindwein (2005b), studies that reported that the wet season has greater richness and abundance. These authors cite three probable factors that justify this greater richness and abundance of Sphingidae: first, this seasonality could be influenced by the availability of food sources for caterpillars; second, the flowering of plants that could be potentially pollinated coincides with hawkmoth population increases; third, that there is migration between areas within the mosaic of vegetation formations between biomes or adjacent areas.

In both the wet and dry seasons there was a greater occurrence of males, with a value of 4.4:1 for the ratio wet : dry seasons, and in the dry season this ratio was 3.6:1 in spite of the fact that the absolute number of males and females was greater during the dry season.

The Shannon diversity and uniformity indices were higher in the wet season, and the Berger-Parker dominance index was more representative of the sampled population in the dry season. The t-test for the comparison of the Shannon diversity indices between the two seasons was insignificant.

The dry season had a greater number of rare species, different than the result reported by Amorim et al. (2009), wherein a larger number of rare species was found in the wet season. Three species were eudominant during both seasons (Isognathus caricae, Enyo lugubris lugubris and Isognathus menechus). Cocytius duponchel was eudominant only in the dry season, and Callionima parce and Erinnyis ello ello were eudominant only in the wet season. The wet season also showed greater estimates for species richness with estimators showing that the number of species sampled in this season was much closer to the expected richness, with the Jackknife 2 estimator being the only one that yielded a greater number of species for the dry season.