# Phlebotomines (Diptera: Psychodidae) in a Hydroelectric System Affected Area from Northern Amazonian Brazil: Further Insights into the Effects of Environmental Changes on Vector Ecology

Authors: Nercy Virginia Rabelo Furtado; Allan Kardec Ribeiro Galardo; Clicia Denis Galardo; Viviane Caetano Firmino; Thiago Vasconcelos dos Santos
Journal: Journal of Tropical Medicine
 (2016)

---

## Abstract

During 2012–2015, an entomological survey was conducted as part of a phlebotomine (Diptera: Psychodidae) monitoring program in an area influenced by the Santo Antônio do Jari hydroelectric system (Amapá State, Brazil). The purpose was to study aspects of Amazon/Guianan American cutaneous leishmaniasis (ACL) vectors subjected to stresses by anthropogenic environmental changes. For sampling, CDC light traps were positioned 0.5, 1, and 20 m above ground at five capture locations along the Jari River Basin. Fluctuations in phlebotomine numbers were analyzed to determine any correlation with rainfall, dam waterlogging, and/or ACL cases, from May 2012 to March 2015. We captured 2,800 individuals, and among 45 species identified,Bichromomyia flaviscutellata,Nyssomyia umbratilis, andPsychodopygus squamiventris s.l. were determined to be the main putative vectors, based on current knowledge of the Amazon/Guianan ACL scenario. Rainfall, but not complete flooding, was relatively correlated with phlebotomine fluctuation, mainly observed forPs. squamiventris s.l., as were ACL cases withNy. umbratilis.Behavioral changes were observed in the unexpected high frequency ofBi. flaviscutellata among CDC captures and the noncanopy dominance ofNy. umbratilis, possibly attributable to environmental stress in the sampled ecotopes. Continuous entomological surveillance is necessary to monitor the outcomes of these findings.


---

## Body

## 1. Introduction

Insects of Phlebotominae (Diptera: Psychodidae) species are of great medical interest because of their implications in the transmission of some vector-borne diseases, in particular leishmaniasis [1–3]. American cutaneous leishmaniasis (ACL) is known to be endemic in Amazonian Brazil and is regarded as a serious risk to public health. The high biodiversity of the region induces a complex mosaic of ecological interactions among reservoirs, vectors, and parasites, and consequently a wide spectrum of ACL clinical manifestations, including disfiguring and potentially life-threatening cases [4]. Moreover, this diversity of transmission cycles becomes even more complex to understand in the context of the influence of anthropic effects on natural ecological systems. The consequences of anthropogenic environmental stress on the expansion of the geographical distribution of ACL are, therefore, difficult to predict with any certainty [5].Over the past 30 years, one of the main causes of human influence on the environment in the Brazilian Amazon Basin is its exploitation for generating energy from hydropower. Negative effects of some of the resultant environmental changes have been observed; an example is the disturbance caused by the proliferation ofMansonia (Diptera: Culicidae) in the dammed lake associated with the Tucuruí hydroelectric system [6]. Vector monitoring programs, which are essential to being granted a license to operate, are included in environmental and public health planning, in order to predict and minimize the effects of vector-borne diseases in hydroelectric systems [7]. This monitoring includes spatial/temporal studies of phlebotomines and their potential implications for the transmission dynamics of leishmaniasis agents [8].The geographically closely related Brazilian states of Pará (PA) and Amapá (AP) share a border through the Jari River and cover a region historically associated with the exploitation and processing of cellulose. Early information about leishmaniasis in the region first emerged in the 1970–1980s. In this period, studies conducted in “Monte Dourado” (Almeirim, PA) provided substantial knowledge about ACL ecoepidemiology, with particular reference to the “pian-bois,” a form of cutaneous leishmaniasis caused byLeishmania(Viannia)guyanensis (formerly referred to asLeishmania braziliensis guyanensis), and its respective identity-obscured vector,Nyssomyia umbratilis [9–16].Since those original studies were undertaken, the region also now hosts the Santo Antônio do Jari hydroelectric system. The present study, therefore, aimed to characterize phlebotomine fauna in the area in order to assess the potential impact of the Santo Antônio do Jari hydroelectric system and in particular the spatiotemporal implications of environmental changes on the ecology of ACL vectors in that region.


## 2. Materials and Methods

### 2.1. Study Area

The Santo Antonio do Jari hydroelectric system (0°39′02.4′′S 52°30′56.9′′W) is situated between the municipalities of Almeirim (PA) and Laranjal do Jari (AP), a region within the Guianan Ecoregion Complex. The hydroelectric system comprises 373.4 MW of installed potency and a reservoir area of 31.7 km2. Its construction began in 2011, and the system was totally operative from 2014.The Amazon Region has a “hot-humid” equatorial climate; however, only minor differences are observed in the distinct ecoregions. In this study, four Guianan Ecoregion Complex seasons were characterized as follows: a short rainy (wet) season from mid-November (“novembre humide”) to late January; a short dry season between early February and mid-March; a long rainy season from late March to late July; and a long dry season from late July to mid-November [17].


### 2.2. Sampled Locations

Five locations, each with the following characteristics, were sampled up- and downstream of the caisson (Figure1):Figure 1
Study area. Maps showing the five surveyed locations for phlebotomine captures (2012–2015) in Santo Antônio do Jari hydroelectric system impacted area, between the states of Pará and Amapá, Brazil.✦: locations.The eastern bank of the Jari River (AP), covered by alluvial dense forest:(I)
Porto Sabão (S 00°37′02.2′′ W 052°30′42.1′′), a forested area with only a few dwelling. A small harbor operates from the opposite side of the river.(II)
Iratapuru Village (S 00°33′50.9′′ W 052°34′48.5′′), a cluster of dwellings, forming a community of approximately 200 inhabitants, which primarily acts as an extractive reserve.(III)
Santo Antônio Village (S 00°38′57.4′′ W 052°30′27.9′′), which is the only site downstream of the caisson, comprising 27 agriculturist families inhabiting riverine wooden buildings.The western bank of the Jari River (PA), covered by submontane (lowland) dense forest.(IV)
Traíra (S 00°37′50.7′′ W 052°31′48.8′′), a location with no dwellings on the Traíra river.(V)
the power Plant (S 00°39′07.7′′ W 052°31′06.4′′), the most affected area, close to the construction site and with very little vegetation.


### 2.3. Sampling

Phlebotomine captures were undertaken during 2012 to 2015 in fourteen quadrimonthly field expeditions, which aimed to sample periods in the short dry (February/March), rainy to dry (June/July), and dry to rainy (October/November) Amazon/Guianan seasons. Eight expeditions were undertaken before and six after dammed lake levels were replenished (in May 2014). In each of the above described five areas, a randomly selected horizontal transect was established in the direction of the primarily forested area, comprising a phlebotomine monitoring station (MS), sited approximately 200 m distance from the forest edge, where human settlements were present. Each MS incorporated three CDC miniature light traps (Sudia and Chamberlain model), installed between 18:00 and 06:00 for two consecutive nights. Each was placed according to the following different verticalstrata: 0.5 m from ground level, 1 m from ground level, and at 20 m, in the tree canopy; they were placed 10 m apart from each other. Trees used for canopy placement of CDC traps were selected based on a minimum height of 20 m, regardless of species. The ground level surface was composed of humid, decomposed organic material, originating from the trees. Phlebotomines were triaged in a stereomicroscope, cleaned with neutral detergent [1% (Extran®)], washed with NaCl 0.9%, and then stored in 70% ethanol. In the laboratory, specimens were processed according to the methodology of Ryan [18], mounted in Berlese fluid (GBI Laboratories, Manchester, England), and identified according to Galati [19].


### 2.4. Data Analysis

Sampling effort was calculated based on number of expeditions, versus the number of installed CDC traps, versus hours of exposition. Phlebotomine frequency was analyzed for correlation with climatic data (monthly average rainfall, temperature, and air relative humidity) sourced from the Jari Meteorological Station (“Jari Energia” database) and with epidemiology (ACL monthly prevalence) obtained after interrogating the database of the “Coordenação de Vigilância em Saúde” (Coordination of Surveillance in Health) of the “Secretaria de Estado da Saúde do Amapá-SESA” (Amapá State Health Secretary). Data were tested by a single linear regression with Pearson’s coefficient (r), using BioEstat 5.0, where ther-value represents a strong correlation if above 0.7, a moderate correlation if between 0.3 and 0.7, a weak correlation if between 0.1 and 0.3, and an insignificant correlation if below 0.1. The index of species abundance (ISA) and the standard index of species abundance (SISA) were calculated using Microsoft Excel for the five ecotopes surveyed, as described by Roberts and Hsi [20]. Species diversity (Shannon’s diversity index,H′) and the coefficient of variation (S′) between monthly records (climatic and epidemiological) were calculated using Past software [21]. All comparisons were performed using at-test to determine significance level (p value ≤ 0.05).


## 2.1. Study Area

The Santo Antonio do Jari hydroelectric system (0°39′02.4′′S 52°30′56.9′′W) is situated between the municipalities of Almeirim (PA) and Laranjal do Jari (AP), a region within the Guianan Ecoregion Complex. The hydroelectric system comprises 373.4 MW of installed potency and a reservoir area of 31.7 km2. Its construction began in 2011, and the system was totally operative from 2014.The Amazon Region has a “hot-humid” equatorial climate; however, only minor differences are observed in the distinct ecoregions. In this study, four Guianan Ecoregion Complex seasons were characterized as follows: a short rainy (wet) season from mid-November (“novembre humide”) to late January; a short dry season between early February and mid-March; a long rainy season from late March to late July; and a long dry season from late July to mid-November [17].


## 2.2. Sampled Locations

Five locations, each with the following characteristics, were sampled up- and downstream of the caisson (Figure1):Figure 1
Study area. Maps showing the five surveyed locations for phlebotomine captures (2012–2015) in Santo Antônio do Jari hydroelectric system impacted area, between the states of Pará and Amapá, Brazil.✦: locations.The eastern bank of the Jari River (AP), covered by alluvial dense forest:(I)
Porto Sabão (S 00°37′02.2′′ W 052°30′42.1′′), a forested area with only a few dwelling. A small harbor operates from the opposite side of the river.(II)
Iratapuru Village (S 00°33′50.9′′ W 052°34′48.5′′), a cluster of dwellings, forming a community of approximately 200 inhabitants, which primarily acts as an extractive reserve.(III)
Santo Antônio Village (S 00°38′57.4′′ W 052°30′27.9′′), which is the only site downstream of the caisson, comprising 27 agriculturist families inhabiting riverine wooden buildings.The western bank of the Jari River (PA), covered by submontane (lowland) dense forest.(IV)
Traíra (S 00°37′50.7′′ W 052°31′48.8′′), a location with no dwellings on the Traíra river.(V)
the power Plant (S 00°39′07.7′′ W 052°31′06.4′′), the most affected area, close to the construction site and with very little vegetation.


## 2.3. Sampling

Phlebotomine captures were undertaken during 2012 to 2015 in fourteen quadrimonthly field expeditions, which aimed to sample periods in the short dry (February/March), rainy to dry (June/July), and dry to rainy (October/November) Amazon/Guianan seasons. Eight expeditions were undertaken before and six after dammed lake levels were replenished (in May 2014). In each of the above described five areas, a randomly selected horizontal transect was established in the direction of the primarily forested area, comprising a phlebotomine monitoring station (MS), sited approximately 200 m distance from the forest edge, where human settlements were present. Each MS incorporated three CDC miniature light traps (Sudia and Chamberlain model), installed between 18:00 and 06:00 for two consecutive nights. Each was placed according to the following different verticalstrata: 0.5 m from ground level, 1 m from ground level, and at 20 m, in the tree canopy; they were placed 10 m apart from each other. Trees used for canopy placement of CDC traps were selected based on a minimum height of 20 m, regardless of species. The ground level surface was composed of humid, decomposed organic material, originating from the trees. Phlebotomines were triaged in a stereomicroscope, cleaned with neutral detergent [1% (Extran®)], washed with NaCl 0.9%, and then stored in 70% ethanol. In the laboratory, specimens were processed according to the methodology of Ryan [18], mounted in Berlese fluid (GBI Laboratories, Manchester, England), and identified according to Galati [19].


## 2.4. Data Analysis

Sampling effort was calculated based on number of expeditions, versus the number of installed CDC traps, versus hours of exposition. Phlebotomine frequency was analyzed for correlation with climatic data (monthly average rainfall, temperature, and air relative humidity) sourced from the Jari Meteorological Station (“Jari Energia” database) and with epidemiology (ACL monthly prevalence) obtained after interrogating the database of the “Coordenação de Vigilância em Saúde” (Coordination of Surveillance in Health) of the “Secretaria de Estado da Saúde do Amapá-SESA” (Amapá State Health Secretary). Data were tested by a single linear regression with Pearson’s coefficient (r), using BioEstat 5.0, where ther-value represents a strong correlation if above 0.7, a moderate correlation if between 0.3 and 0.7, a weak correlation if between 0.1 and 0.3, and an insignificant correlation if below 0.1. The index of species abundance (ISA) and the standard index of species abundance (SISA) were calculated using Microsoft Excel for the five ecotopes surveyed, as described by Roberts and Hsi [20]. Species diversity (Shannon’s diversity index,H′) and the coefficient of variation (S′) between monthly records (climatic and epidemiological) were calculated using Past software [21]. All comparisons were performed using at-test to determine significance level (p value ≤ 0.05).


## 3. Results

A total of 2,800 individuals were captured (1,894 females and 906 males), belonging to 45 species, in approximately 2,520 h of sampling effort. Females ofTrichophoromyia(exceptionallyTh. ubiquitalis) andPressatia(not identifiable at species level), and some unidentifiedEvandromyia,Nyssomyia, andPsychodopygus species were allocated at generic level (Table 1).Table 1
Phebotomine species composition of Santo Antônio do Jari hydroelectric system impacted area (Amapá State, Amazonian Brazil) on the basis of five surveyed locations (2012–2015).
Species Porto Sabão Traíra River Iratapuru Santo Power Plant ISA SISA Rank Total % Village Antônio Village ♀ ♂ ♀ ♂ ♀ ♂ ♀ ♂ ♀ ♂ 1 Sciopemyia sordellii 149 66 13 10 15 4 42 16 — 1 3,6 0,87 2nd 316 11,29 2 Psychodopygus davisi 46 37 95 56 15 10 38 17 — — 6,4 0,74 3rd 314 11,21 — Trichophoromyiaspp. 177 — 34 — 40 — 17 — — — — — — 268 9,57 3 Bichromomyia flaviscutellata 76 32 24 14 22 11 52 31 1 2 2 0,95 1st 265 9,46 4 Evandromyia infraspinosa 44 10 25 18 3 2 30 18 — — 9,2 0,6 6th 150 5,36 5 Nyssomyia umbratilis 26 12 31 30 19 6 13 9 — — 8,6 0,63 5th 146 5,21 6 Trichophoromyia castanheirai — 104 — 6 — 14 — 11 — — 11,2 0,51 9th 135 4,82 — Pressatiaspp. 43 — 1 — 9 — 78 — — — — — — 131 4,68 — Evandromyiaspp. 52 10 4 — 39 11 12 — — — — — — 128 4,57 7 Viannamyia furcata 44 4 11 5 11 1 30 5 — — 10,4 0,55 7th 111 3,96 8 Psychodopygus squamiventris sensu lato 36 14 15 5 10 — 9 — — — 11 0,52 8th 89 3,18 9 Trichopygomyia trichopyga 11 16 9 8 9 — 21 12 — — 7,2 0,7 4th 86 3,07 10 Trichophoromyia ubiquitalis 21 6 5 8 14 8 13 9 2 — 11,4 0,5 10th 86 3,07 11 Evandromyia saulensis 40 9 5 — 4 4 12 1 — — 12,8 0,43 11th 75 2,68 12 Psychodopygus hirsutus hirsutus 13 — 20 4 14 4 — — — — 13,6 0,4 12th 55 1,96 13 Trichophoromyia brachypyga — 36 — 12 — 2 — 2 — — 15,2 0,32 14th 52 1,86 14 Pressatia choti — 17 — 3 — 5 — 25 — — 14,2 0,37 13th 50 1,79 15 Nyssomyia anduzei 6 5 24 10 — — — — — — 17 0,23 16th 45 1,61 16 Lutzomyia gomezi 27 11 — — — — — — — — 19,4 0,12 22th 38 1,36 — Nyssomyiaspp. — — — 1 1 — 11 25 — — — — — 38 1,36 17 Nyssomyia antunesi — 2 9 — 5 2 — — 1 — 14,2 0,37 13th 19 0,68 18 Sciopemyia fluviatilis 2 1 3 — 9 1 — — — — 18 0,19 18th 16 0,57 19 Micropygomyia rorotaensis 4 — — — 8 — 2 1 — — 17,8 0,2 17th 15 0,54 20 Psychodopygus paraensis — — — — 6 3 5 1 — — 17,6 0,2 17th 15 0,54 21 Psychodopygus claustrei 7 1 — — — — 2 — 3 1 15,4 0,31 15th 14 0,50 — Psychodopygusspp. 4 — 2 — 6 — 2 — — — — — — 14 0,50 22 Trichophoromyia eurypyga — 8 — — — 3 — 1 — — 18,2 0,18 19th 12 0,43 23 Psathyromyia aragaoi — — 5 2 — — 4 — — — 18,8 0,15 20th 11 0,39 24 Evandromyia brachyphalla 4 3 2 1 1 — — — — — 19 0,14 21th 11 0,39 25 Psychodopygus carrerai carrerai 1 1 — 7 — — — — — — 20,2 0,08 26th 9 0,32 26 Evandromyia begonae 2 2 — — 4 — — — — — 19,6 0,11 23th 8 0,29 27 Nyssomyia whitmani — — — — — — 8 — — — 20 0,09 25th 8 0,29 28 Psathyromyia scaffi 3 2 — — 2 — — — — — 19,8 0,1 24th 7 0,25 29 Pressatia trispinosa — — — 7 — — — — — — 20,4 0,07 27th 7 0,25 30 Micropygomyia trinidadensis 7 — — — — — — — — — 20,8 0,05 29th 7 0,25 31 Viannamyia tuberculata 6 — — — — — — — — — 21 0,04 30th 6 0,21 32 Pintomyia damascenoi — — — — — — 5 — — — 20 0,09 25th 5 0,18 33 Evandromyia evandroi — — — — 4 1 — — — — 20,4 0,07 27th 5 0,18 34 Psathyromyia lutziana 5 — — — — — — — — — 21,2 0,03 31th 5 0,18 35 Brumptomia travassosi — — — — — — 3 1 — — 19,6 0,11 23th 4 0,14 36 Evandromyia bacula — — — — 1 — 3 — — — 20,2 0,08 26th 4 0,14 37 Evandromyia monstruosa — — 4 — — — — — — — 20,6 0,06 28th 4 0,14 38 Psychodopygus amazonensis — — — — 2 2 — — — — 21 0,04 30th 4 0,14 39 Psychodopygus corossoniensis — — — — — 2 — — — — 20,6 0,06 28th 2 0,07 40 Pressatia equatorialis — 2 — — — — — — — — 21 0,04 30th 2 0,07 41 Psathyromyia inflata — — — — — — 2 — — — 21 0,04 30th 2 0,07 42 Micropygomyia micropyga — — — — — — 1 1 — — 21,4 0,02 32th 2 0,07 43 Psychodopygus geniculatus — — — 2 — — — — — — 21,8 0 33th 2 0,07 44 Lutzomyia carvalhoi — — 1 — — — — — — — 20,8 0,05 29th 1 0,04 45 Psathyromyia punctigeniculata — — — — 1 — — — — — 21,6 0,01 32th 1 0,04 Total 856 411 342 209 274 96 415 186 7 4    2800 100,0 1267 551 370 601 11 Each location comprised a monitoring station (MS) sampled with 0.5, 1, and 20 m CDC traps, providing approximately 504 h/MS. ♀: female; ♂: male; ISA: index of species abundance; SISA: standard index of species abundance. “the bold italic font” Proven and/or putative ACL vectors in the Amazon Region, based in Young and Duncan [1], Rangel and Lainson [4], Ready [2], and Lainson and Shaw [16].New AP records includedTh. castanheirai,Th. eurypyga,Evandromyia begonae,Ev. bacula,Pressatia equatorialis, andPsathyromyia punctigeniculata.The five most frequent species captured wereSciopemyia sordellii (n=316; SISA = 0.87),Ps. davisi(n=314; SISA = 0.74), Bichromomyia flaviscutellata (n=265; SISA = 0.95), Ev. infraspinosa(n=150; SISA = 0.6), andNy. umbratilis(n=146; SISA = 0.63). Less frequently captured but nonetheless epidemiologically relevant species includedPs. squamiventris s.l. (n=89; SISA = 0.52),Th. ubiquitalis (n=86; SISA=0.5),Ps. hirsutus hirsutus (n=55; SISA = 0.4),Ny. anduzei (n=45; SISA = 0.23),Lutzomyia gomezi (n=38; SISA = 0.12),Ny. antunesi (n=19; SISA = 0.37),Ps. paraensis (n=15; SISA = 0.2), andNy. whitmani (n=8; SISA = 0.09).Sampling effort for each area comprised approximately 504 h of CDC trapping (14 expeditions, 3 CDC traps, and 12-hour CDC exposition). Porto Sabão was the site of the most captured specimens (1,267), followed by Santo Antônio Village (601). The highest diversity was observed in captures from Iratapuru Village (H′=3.027). All H′ value comparisons between the different environments were significant (p≤0.05), except when comparing Traíra River and the Power Plant (p≤0.099) (Figure 2).Figure 2
Comparison of Shannon diversity indexes for CDC-captured phlebotomines from the five surveyed locations in Santo Antônio do Jari hydroelectric system impacted area, between the states of Pará and Amapá, Brazil (2012–2015).Regarding vertical distribution, sampling of the same captures described above accounted for approximately 840 h of CDC trapping bystratum (14 expeditions, 5 ecotopes, and 12-hour CDC exposition). CDC traps placed 0.5 m above ground level accounted for a greater number of individuals (1,225) than those placed 1 m above ground level (1,021) and 20 m above ground level in the canopy (554) (Table 2). WhilePs. davisi was most likely to be found at canopy level (75 individuals at 0.5 m, 83 at 1 m, and 156 at 20 m) andBi. flaviscutellata closer to ground level (130 at 0.5 m, 120 at 1 m, and 15 at 20 m), there was little difference in numbers ofNy. umbratilis individuals captured at the different levels ofstrata (58 at 0.5 m, 39 at 1 m, and 49 at 20 m).Table 2
Vertical stratification of Phebotomine species composition of Santo Antônio do Jari hydroelectric system impacted area (Amapá State, Amazonian Brazil) on the basis of five surveyed locations (2012–2015).
Species 0.5 m ground 1 m ground 20 m canopy Total ♀ ♂ ♀ ♂ ♀ ♂ 1 Sciopemyia sordellii 117 71 91 23 11 3 316 2 Psychodopygus davisi 48 27 44 39 102 54 314 — Trichophoromyiaspp. 117 — 127 — 24 — 268 3 Bichromomyia flaviscutellata 85 45 79 41 11 4 265 4 Evandromyia infraspinosa 38 18 48 27 16 3 150 5 Nyssomyia umbratilis 35 23 26 13 28 21 146 6 Trichophoromyia castanheirai — 50 — 59 — 26 135 — Pressatiaspp. 66 — 39 — 26 — 131 — Evandromyiaspp. 55 12 41 9 11 — 128 7 Vianamyia furcata 42 8 46 6 8 1 111 8 Psychodopygus squamiventris s.l. 27 11 20 1 23 7 89 9 Trichopygomyia trichopyga 18 20 10 5 22 11 86 10 Trichophoromyia ubiquitalis 28 15 16 13 9 5 86 — Other species (11–45) 137 112 129 69 71 57 575 Total 813 412 716 305 362 192 2800  Total (♀ + ♂) 1225 1021 554 — Eachstratum was sampled with approximately 840 h of CDC trap. ♀: female; ♂: male.The monthly average rainfall was the only climatic data with a representative coefficient of variance (S′=70.81) when tested against ACL occurrence and phlebotomine frequency (S′=65.95), in contrast to temperature (S′=5.96), and relative air humidity (S′=9.56). The available data enabled correlations to be determined between the periods of May 2012 to April 2015, a period within which nine of the fourteen capture efforts were undertaken. Rainfall presented a moderate correlation with overall phlebotomine frequency (r=0.65; p=0.00001), as also individually compared withPs. squamiventris s.l. (r=0.65; p=0.00001), and a similarly moderate, but lower correlation withBi. flaviscutellata (r=0.48; p=0.0021) andNy. umbratilis (r=0.48; p=0.002). A decrease in the overall phlebotomine population was observed after March until November 2014, coinciding with the transition between the rainy and dry periods and with flooding (Figure 3).Figure 3
Correlation between rainfall and phlebotomine putative vector species captured in Santo Antônio do Jari hydroelectric system impacted area, between the states of Pará and Amapá, Brazil (2012–2015).The number of ACL cases presented a moderate correlation with overall phlebotomine frequency (r=0.44; p=0.0063) and also withPs. squamiventris(r=0.32; p=0.0003) and an insignificant negative correlation withBi. flaviscutellata (r=-0.02; p=0.0001). A similarly moderate, but higher correlation was however found withNy. umbratilis (r=0.48; p=0.002) (Figure 4).Figure 4
Correlation between ACL cases and phlebotomine putative vector species captured in Santo Antônio do Jari hydroelectric system impacted area, between the states of Pará and Amapá, Brazil (2012–2015).


## 4. Discussion

It is important to consider current investigations of phlebotomine fauna in the Jari River Basin in the context of the historical findings from the 1970s and 1980s. These earlier studies represent comprehensive research conducted in Monte Dourado (northern PA), a region close to the area investigated in the present study and on which the present epidemiological background to ACL transmission in the associated region is based. In brief, the previous research includes a description ofNy. umbratilis (formerly “obscured” asNy. anduzei) [13] and its incrimination as the main vector ofL.(V.)guyanensis [9–11], confirmed by strong ecological associations [15]. Just as important, a parasite, more recently described asL.(V.)naiffi, was isolated from the armadillo,Dasypus novemcinctus,for which transmission was locally driven and attributed toPs. squamiventris s.l., and otherPsychodopygus species [22]; this comprised a primarily enzootic ACL, occasionally infecting humans [23]. Finally, the isolation ofL.(L.)amazonensis from rodents in an area affected by occurrence of the main vectorBi. flaviscutellata [11] comprised the third known Jari ACL transmission cycle.These facts described above suggest thatNy. umbratilis,Ps. squamiventris s.l., andBi. flaviscutellataare implicated in the transmission scenario of the area covered by the present study and thus merit particular attention.The present study incorporated a representative composition of the known AP fauna. Considering the substantial sampling effort (2,520 h), the determined diversity showed agreement with the findings of other inventories from the Brazilian Amazon basin [1, 24]. Moreover, all new records for AP have already been recorded for PA [25].Apart fromNy. umbratilis,Ps. squamiventris s.l., andBi. flaviscutellata,other species captured were noted as being epidemiologically relevant to ACL in the Brazilian Amazon Region:Ps. paraensis,Ps. davisi, andPs. hirsutus hirsutus, which are putative vectors ofL.(V.)naiffi [26, 27];Th. ubiquitalis, a proven vector ofL.(V.)lainsoni [28];Ny. anduzei,a secondary vector ofL.(V.)guyanensis[4];Ny. whitmaniandLu. gomezi, proven and putative vectors ofL.(V.)shawi, respectively [4, 26]; and lastly,Ny. antunesi,a suspected vector ofL.(V.)lindenbergi [4].Among the above species,Ps. davisi is notable as the third highest ranking according to SISA (0.74) and as having the highest presence in all verticalstrata, in particular, at the canopy level. This species is generally anthropophilic, is widely distributed in the Amazon Basin [1, 24], and is related toLeishmania (Viannia) infections in the States of Rondônia (RO) [29] and PA [27, 30]. Interestingly, this species remains frequent in recently surveyed areas affected by hydroelectric schemes in RO [8] and PA (TVS, unpublished). These observations add weight to the need for further investigation into the putative epidemiological role ofPs. davisi in Jari.The species most frequently captured,Sc. sordellii, would appear not to be of epidemiological concern. Firstly, the apparent abundance of a given phlebotomine species is not sufficient of itself to incriminate it as a vector [31], particularly when it does not demonstrate high levels of anthropophilic behavior. Secondly, flagellate infections isolated from this species (formerly referred to asLutzomyia nordestina) are historically recognized as distinct fromLeishmania [22] or remain undetermined, [32] and are more likely to be other trypanosomatids [22]. Furthermore, despite recent reports of molecularLeishmania ascribed to this fly [33, 34], currently, polymerase chain reaction-based techniques do not allow “true infection” to be distinguished from a “simple and occasionally ingested” DNA fragment [3]. Thus, there remains insufficient evidence for a potential vector role ofS. sordelliiinLeishmaniatransmission.High frequencies of light-trappedBi. flaviscutellata have been documented [8, 35], despite rodent-baited trapping being better recognized as a method for attracting the species. Additionally, the first SISA Rank (0.95) was indicative of this high presence in all five surveyed ecotopes; this has been observed in the Belém metropolitan area (PA), whereBi. flaviscutellata was the only omnipresent species in seven urban and ecologically isolated forest fragments surveyed [36]. Furthermore, this species has been reported as being able to adapt to plantations of introduced tree species and in other nonclimax forests in Jari [14], suggesting it is capable of responding positively to environmental change, such as the vegetal suppression and flooding caused by hydroelectric operations. Nonetheless, ecological niche model projections predict no change in spatial distribution forBi. flaviscutellata in the Jari area, which is an environment that remains suitable for the species [37].In an area in Regina, French Guiana, ecologically disturbed due to agricultural practices, flagellates infecting aBi. flaviscutellata specimen have been determined to beL.(V.)guyanensis [38], in similar circumstances to the observed low presence ofNy. umbratilis. Although this possibly changing pattern in ACL transmission should be interpreted with caution, it raises an intriguing possibility about the permissiveness ofBi. flaviscutellata toL.(V.)guyanensis in the Amazon/Guianan ACL scenario.In the present study, a higher number ofBi. flaviscutellata individuals was captured compared toNy. umbratilis(265 versus 146, resp.). A lack of available evidence for natural infection in this unnatural vector/parasite system, however, precludes speculation about the possible involvement ofBi. flaviscutellata, even in the context of occasional transmission of parasites distinct fromL.(L.)amazonensis. Nevertheless, the current high occurrence ofBi. flaviscutellatain the Amazon/Guianan ACL scenario may be of future concern; unnatural parasite/vector/reservoir systems, when closely related in an ecological context, can, on a century-level scale, undergo stress adaptation (evolutionary fitness) and form new ecological systems driven by coevolution [39].There is no doubt thatNy. umbratilis is the main vector of ACL in the Jari River Basin [15]. Surprisingly, the well-documented tree-dwelling behavior of this species [15, 40] was not observed in CDC canopy captures in the present study; very little difference was found between the number of individuals captured in the three sampledstrata (58 at 0.5 m, 39 at 1 m, and 49 at 20 m). AlthoughNy. umbratilis is known to climb into the canopy at night to feed on edentates (mainly sloths) [12, 41], it is possible that an alternative terrestrial source of blood, such as rodents, may be attracting females toward ground level. Sloths are very slow moving and are therefore commonly rescued for relocation during environmental monitoring operations; their resulting rareness meansNy. umbratilis has had to find other food sources. Conversely, blood meal analysis conducted during studies in a forest fragment of the Western Amazon has shown rodent blood to be the predominant feeding source forNy. umbratilis[42]. Wild and synanthropic rodents have been shown to survive environmental disturbance in Jari and to proliferate in areas of introduced tree species [14]; this indicated a plausible reason not only for the putative adaptation ofNy. umbratilis, but also for the increasing population levels of the rodent blood-feederBi. flaviscutellata, as already discussed.Given the clear importance ofPsychodopygusof the Chagasi series (formerly referred to as the Squamiventris series) in the context of ACL transmission [22], taxonomic studies on identifying the cryptic females have been undertaken previously [43] and more recently, with interesting results (Rodrigo E. Godoy, unpublished). These techniques, however, could not be employed in the field at the time. Early consideration of the assumed geographic distribution of the complexPs. squamiventris s.l. [1, 44] shows that individuals from AP are likely to be predominantlyPs. s. maripaensis. Determining males of the species present could clarify these taxonomic uncertainties in the area covered by the present study; however, doubts about identification of some male specimens meant they were grouped asPs. squamiventris s.l.Ryan et al. [22] did not findPs. squamiventris s.l. to be naturally infected in the Jari area but proposed a link toL. (V.)naiffi along the same northern bank of the Amazon River through studies in Cachoeira Porteira (PA); Fouque et al. [38] came to the same conclusions in French Guiana. Interestingly, this fly species complex was found alongsideL.(V.)braziliensisDNA in Suriname [45], an area where the known Amazonian vectors of this parasite,Ps. complexusandPs. wellcomei, are unlikely to occur. As previously discussed in the context ofBi. flaviscutellata, the changing transmission patterns of unnatural vector/parasite systems must be carefully interpreted and only after strong ecological associations have been determined. Thus, the putative vector importance ofPs. squamiventris s.l. in Jari can only be assumed in respect ofL.(V.)naiffi.The five surveyed areas presented, in general, different diversity indexes, showing variations in the phlebotomine composition along the affected area. This finding can be attributed not only to the distance between capture sites, but also to forest composition, fragmentation, geographic barriers, and migration of mammal fauna between sites; this latter can occur naturally or be induced by rescue operations involved in hydroelectric planning, whereby animals are moved to suitable “dry land” environments safe from potential flooding.A decrease in the phlebotomine population in 2014, in the period after filling the reservoir, could not be attributed exclusively either to flooding or to the transition from the rainy to the dry season. Both eventualities, although opposite in effect, are likely to lead to unsuitable conditions for phlebotomine reproduction. However, they did coincide in May 2014, when rainfall decreased and the lake was formed.Conversely, rainfall was a valid determinant of overall phlebotomine fluctuation;Ps. squamiventris s.l. was the main putative vector directly correlated with this. Other variables, such as forest composition and altitudinal variation, are known to influence seasonal dynamics of species from the complexPs. squamiventris s.l. For example, the dry period from October to November in Serra dos Carajás (southern PA) can be unsuitable forPs. wellcomei, which is adapted to high altitudes, in contrast toPs. complexus, which flourishes in lowland areas during the same months [46].An insignificant negative to a moderate positive correlation was observed between cases of ACL and phlebotomine fluctuations. In the case ofNy. umbratilis,however, the apparently higher correlation when compared with other species is in agreement with its known vector importance in Amazon/Guianan ACL. A strong spatiotemporal association between a given vector and ACL cases is considered essential to maintenance of theLeishmania life cycle [2, 14].In summary, the present study filled a temporal gap on phlebotomine data relating to the Jari area. It provides a meaningful update on species composition and further insights into seasonal dynamics of species under pressures caused by environmental change. The presence of ACL vectors, in particularNy. umbratilis,Bi. flaviscutellata, andPs. squamiventris s.l., is noteworthy, due to their direct association with Amazon/Guianan-ACL transmission. ForNy. umbratilis, the lower frequency associated with the unpredicted lack of tree-dwelling behavior may be attributable to a reduction in numbers of canopy-dwelling mammals, due to the environmental disturbance and relocation efforts; this could consequently have led to seeking for alternative terrestrial blood sources at ground level. The possible association ofPs. davisi withLeishmaniatransmission cycles in other Amazon ecoregions draws attention to its high rank position in Jari. Rainfall can be partly associated with local seasonal fluctuations in fly numbers, mainly with respect toPs. squamiventris s.l. Cases of ACL were also more highly correlated withNy. umbratilis dynamics. Further attention was also given to results forBi. flaviscutellata, which has been apparently tolerant of anthropic activity: continued phlebotomine monitoring is proposed in order to evaluate the implication for social welfare and health in the future.



---

*Source: 9819723-2016-11-29.xml*