Richness and diversity of sand flies (Diptera, Psychodidae) in an Atlantic rainforest reserve in southeastern Brazil

Authors

  • Israel Souza Pinto,

    1. Laboratório de Parasitologia, Universidade Federal do Espírito Santo, Av. Marechal Campos 1468, 29043–900 Vitória, Espírito Santo, Brazil
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  • Claudiney Biral dos Santos,

    1. Laboratório de Parasitologia, Universidade Federal do Espírito Santo, Av. Marechal Campos 1468, 29043–900 Vitória, Espírito Santo, Brazil
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  • Adelson Luiz Ferreira,

    1. Laboratório de Parasitologia, Universidade Federal do Espírito Santo, Av. Marechal Campos 1468, 29043–900 Vitória, Espírito Santo, Brazil
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  • Aloísio Falqueto

    1. Laboratório de Parasitologia, Universidade Federal do Espírito Santo, Av. Marechal Campos 1468, 29043–900 Vitória, Espírito Santo, Brazil
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ABSTRACT:

Our objective was to study and evaluate the richness and diversity of Phlebotominae fauna in the Duas Bocas Biological Reserve (DBBR) in the state of Espírito Santo, in southeastern Brazil. Sand fly collections were carried out during four consecutive nights each month between August 2007 and July 2008 at DBBR by using CDC automatic light traps and an illuminated Shannon trap. Specific richness (S) and Shannon diversity index (H) was calculated for each trap. We collected 18,868 sand flies belonging to 29 species and 13 genera. Nyssomyia yuilli yuilli was the most abundant species followed by Psychodopygus ayrozai, Ps. hirsutus, Psathyromyia pascalei, and Ps. matosi. We recorded Brumptomyia cardosoi, Br. troglodytes, and Ps. geniculatus for the first time in the state of Espírito Santo. We discuss the differences in diversity and richness of the sand flies in both traps and in relation to other Brazilian localities and biomes. We also discuss the possibility of wild transmission of Leishmania in the DBBR and the influence of the sand fly species in leishmaniasis transmission to the adjacent areas of the reserve.

INTRODUCTION

Phlebotomine sand flies (Diptera, Psychodidae) may carry and transmit etiologic agents of arboviruses, bartonellosis, and leishmaniasis. Studies of the ecology and biology of sand flies may contribute to the elucidation of the transmission cycle of the etiologic agents and support the development of control strategies for these vector-borne diseases (Rangel and Lainson 2003). Approximately 500 sand fly species have been recorded from the Neotropical region, 250 species from Brazil, and 58 species from the state of Espírito Santo (Young and Duncan 1994, Ferreira et al. 2001, Aguiar and Medeiros 2003, Pinto and Santos 2007, Pinto et al. 2008, Pinto et al. 2009).

In Brazil, American cutaneous leishmaniasis (ATL) transmission has been associated with human incursion into wild environments in the first decades of the 20th century, where the natural foci of disease occur with involvement of both reservoirs and wild vectors. In the last three decades of the 20th century, deforestation and an accelerated urbanization process allowed sand flies to adapt to peridomicile environments, and Leishmania parasites to domestic reservoirs such as dogs. Thus, the ATL transmission began to occur in domestic environments in several states of Brazil (Tolezano et al. 1980, Falqueto et al. 1986, Tolezano 1994).

In the state of Espírito Santo in southeastern Brazil, ATL is endemic and is caused by Leishmania (Viannia) braziliensis Vianna. Nyssomyia intermedia (Lutz & Neiva), Nyssomyia whitmani (Antunes & Coutinho), and Migonemyia migonei (França) are identified as the principal vectors, and Canis familiaris (Linnaeus) the putative domestic reservoir. (Barros et al. 1985, Falqueto et al. 1986, Ferreira et al. 2001, Falqueto et al. 2003). In this state, studies about sand flies have been done in both rural and peri-urban areas where most of the human cases of ATL occur. Also, in these areas, sand fly captures have been restricted to domestic environments and small fragments of Atlantic rainforest close to houses (Barros et al. 1985, Ferreira et al. 2001, Falqueto et al. 2003). The only study of the primary Atlantic rainforest reserve in this state was done in an area where the ATL incidence was low (Virgens et al. 2008).

Knowledge about the ecological aspects of sand fly species in primary forest environments, near high incidence areas of ATL, may help in understanding the transmission dynamics of L. (V.) braziliensis to people and pets. Thus, our objective was to study and evaluate the richness and diversity of the Phlebotominae fauna from the Duas Bocas Biological Reserve (DBBR), state of Espírito Santo, southeastern Brazil.

MATERIALS AND METHODS

Study area

The Duas Bocas Biological Reserve (DBBR) is located in the municipality of Cariacica, state of Espírito Santo, southeastern Brazil (20°18’05’ S; 40°28’06’ W). The municipality of Cariacica is endemic for ATL and has the highest occurrence index of the disease in the state with approximately 50 new human cases reported every year. Most of these cases occur in the localities surrounding the DBBR, such as Duas Bocas district and Roda D'água district (SESA/ES 2004).

The DBBR covers an area of about 29.1 Km² and is characterized by broadleaf evergreen forest and sloping relief with an elevation between 450–850 m above sea level (Feitoza 1986, IPEMA 2005). The Köppen-Geiger climate classification for the region is tropical monsoon (Peel et al. 2007), with average annual temperatures ranging between 17 and 32° C and approximately 1,200 mm of annual rainfall (Hijmans et al. 2005).

Sand fly captures

We collected sand flies during four consecutive nights each month between August 2007 and July 2008 at DBBR. Each night, we used an illuminated Shannon trap and two CDC automatic light traps. The traps were placed randomly inside the forest with a distance of 30 m of each other and at least 50 m from the forest edge. The traps were tied to trees; the CDC traps were suspended to one meter above the ground while the Shannon trap was stretched so that the base touched the ground. In the illuminated Shannon trap, one of us captured the sand flies using an aspirator during the first three hours of the night (18:00 to 21:00), while the CDC automatic light traps remained in operation during all 12 h of the night (18:00 to 06:00). In total, we spent 144 collection hours using the Shannon trap and 1,152 hours using CDC automatic light traps. The specimens were separated and mounted on glass slides using the technique proposed by Barreto and Coutinho (1940). We used the classification of Galati (1995, 2003) and the abbreviation of generic names of Marcondes (2007). We identified all the species according to morphological characters with the taxonomic key of Galati (2003). Sand fly vouchers were deposited in the Phlebotomine Collection of the Instituto de Pesquisas René Rachou – Fundação Oswaldo Cruz, Belo Horizonte municipality, state of Minas Gerais, Brazil.

Statistical analyses

We evaluated the specific richness (S), equitability (J), and Shannon's diversity indexes for each month and kind of trap. The statistical analyses were performed in PAST (Hammer et al. 2001).

We calculated the constancy of species occurrence for each kind of trap using the index C of Dajoz (1973), where C = P × 100/N (P is the number of samples in which the species was present and N is the total number of individuals collected). The species collected were grouped as constant, accessory, or occasional when presented in more than 50%, from 25 to 50%, or less than 25% of the samples, respectively. We also calculated the male to female ratios for each type of trap for the most frequently collected species.

RESULTS

We collected 18,868 sand flies belonging to 13 genera and 29 species. These included 14,425 specimens belonging to 11 genera and 22 species captured in the Shannon trap (Table 1), while 4,443 specimens belonging to 13 genera and 28 species were captured in the CDC trap (Table 2). The success of capture in the Shannon trap was 100.17 sand flies/h/trap, while in the CDC trap it was 3.85 sand flies/h/trap.

Table 1.  Number and sex of species sand flies collected monthly in Shannon traps and constancy (CT) of species occurrence between August 2007 to July 2008 at Duas Bocas Biological Reserve, municipality of Cariacica, state of Espírito Santo, southeastern Brazil. (C=constant; A=accessory; O=occasional). Thumbnail image of
Table 2.  Number and sex of species sand flies collected monthly in Shannon traps and constancy (CT) of species occurrence between August 2007 to July 2008 at Duas Bocas Biological Reserve, municipality of Cariacica, state of Espírito Santo, southeastern Brazil. (C=constant; A=accessory; O=occasional). Thumbnail image of

Evandromyia edwardsi (Mangabeira) was collected only in the Shannon trap (Table 1). The genera Migonemyia (Galati) and Pressatia (Mangabeira), and the species Brumptomyia cardosoi (Barreto & Coutinho), Brumptomyia nitzulescui (Costa Lima), Evandromyia sericea (Floch & Abonnenc), Migonemyia migonei (França), Ny. intermedia, Pressatia equatorialis (Mangabeira), and Psathyromyia pestanai (Barretto & Coutinho) were collected only in the CDC trap (Table 2). The specific richness (S), equitability (J), and Shannon's diversity indexes calculated for each month and kind of trap, are shown in Tables 1 and 2.

The genera with the highest number of species captured were Evandromyia (Mangabeira) and Psathyromyia (Barreto), with five species each. The species with the highest number of specimens captured (n) were respectively, Nyssomyia yuilli yuilli (Young & Porter) (n=12,759), Psychodopygus ayrozai (Barreto & Coutinho) (n=2,492), Psychodopygus hirsutus (Mangabeira) (n=1,210), Psathy-romyia pascalei (Coutinho & Barreto) (n=1,024), and Psychodopygus matosi (Barreto & Zago) (n=228).

For the constancy index in both kinds of traps, Bichromomyia flaviscutellata (Mangabeira), Ny. yuilli yuilli, Pintomyia fischeri (Pinto), Ps. ayrozai, Ps. matosi, and Ps. hirsutus were grouped as constant; Evandromyia tupinambai (Mangabeira), Martinsmyia gasparviannai (Martins, Godoy & Silva), and Psathyromyia pelloni (Sherlock & Alencar) were grouped as accessory; and Micropygomyia schreiberi (Martins, Falcão & Silva) was grouped as occasional. The male/female ratio was 0.33 in the Shannon trap and 0.81 in the CDC trap. For the species with the highest number of specimens captured, the male/female ratios in the Shannon trap and CDC trap were, respectively, 0.26 and 0.09 for Ny. yuilli yuilli; 0.95 and 1.59 for Ps. ayrozai; 0.35 and 0.92 for Ps. hirsutus; 0.8 and 2.37 for Pa. pascalei; and 1.02 and 1.34 for Ps. matosi. The species Brumptomyia cardosoi (Barretto & Coutinho), Brumptomyia troglodytes (Lutz), and Psychodopygus geniculatus (Mangabeira) were recorded for the first time in the state of Espírito Santo.

DISCUSSION

The reported specific richness and diversity of sand flies were higher in the DBBR when compared to other localities of the Atlantic rainforest (Aguiar et al. 1996, Ferreira et al. 2001, Souza et al. 2001, Marcondes et al. 2001, Afonso et al. 2007, Virgens et al. 2008) and some localities of Cerrado (Brazilian Savannah) (Andrade-Filho et al. 1998, Souza et al. 2004, Galati et al. 2006), but they were lower or equivalent to what was reported in some localities from the Amazon Forest (Freitas et al. 2002). Yet, the specific richness of sand flies in the DBBR was higher than the specific richness of sand flies reported in all of the state of Piauí (Andrade-Filho et al. 2001). These high values of both specific richness and diversity of sand flies in the DBBR may be related to the degree of conservation in the region and the availability of food sources influenced by a large diversity of vertebrates (Carão 2008, Tonini 2008, Tonini et al. 2010).

The highest specific richness and diversity found in the CDC trap may be attributed to the fact that the capture of species using this trap lasted an entire night, while capture using the Shannon trap occurred during the first three hours of the night. Thereby, species with higher activity after the first three hours of the night may have been captured only in small numbers using the Shannon trap. This was also observed by Teodoro et al. (1993).

A higher rate of success in the capture of the species using the Shannon trap compared to the CDC trap may be due to the presence of the collector, which attracted the anthropophilic sand flies. This is corroborated by the absence or the small number of the non-anthropophilic sand fly species such as Br. nitzulescui, Br. cardosoi, Ev. sericea, Pa. pascalei, and Pr. equatorialis collected in the Shannon trap compared to that in the CDC trap.

The predominant species at the DBBR, Ny. yuilli yuilli, is often found in the states of the Amazon region, north of Brazil (Azevedo et al. 1993, Castellón et al. 1994, Azevedo et al. 2008) and bordering countries like Colombia, where this species has been associated with Leishmania transmission (Alexander et al. 2001). This is the first record from a Brazilian locality where Ny. yuilli yuilli was the most abundant species found. In the Atlantic rainforest areas, the species was recorded in the Sooretama Biological Reserve (Virgens et al. 2008); in the municipality of Santa Teresa (Pinto et al. 2008), state of Espírito Santo; and in the municipalities of Ilhéus (Azevedo et al. 1996), Jitaúna (Dias-Lima et al. 2003), and Três Braços (Vexenat et al. 1986), state of Bahia. Also, the density of Ny. yuilli yuilli was observed to be higher in the DBBR compared to the states of the Amazon region and the Atlantic rainforest region. Vexenat et al. (1986) highlighted the anthropophilic behavior of Ny. yuilli yuilli, which was also indirectly observed at the DBBR.

High abundances of Ps. ayrozai and Ps. hirsutus, as recorded from the DBBR, were observed by Aguiar and Soucasaux (1984) in the Serra dos Órgãos National Park, state of Rio de Janeiro, Brazil. This park shows geoclimatic characteristics similar to the DBBR, with mild temperatures, high rainfall, sloping reliefs, and elevations higher than 500 m above sea level (Feitoza 1986). These characteristics may contribute to the breeding of both Ps. ayrozai and Ps. hirsutus. These species were collected in small numbers at the Sooretama Biological Reserve, state of Espírito Santo (Virgens et al. 2008) that is closer to the DBBR than to the Serra dos Órgãos National Park. However, the geoclimatic characteristics of the Sooretama Biological Reserve, such as hot temperatures, plan relief, and elevations smaller than 200 m above sea level (Feitoza 1986), are very different compared to those of the DBBR and the Serra dos Órgãos National Park.

In the Serra dos Órgãos National Park, Aguiar et al. (1986) highlighted the anthropophilic behavior of Ps. ayrozai and Ps. hirsutus and the same was shown by Vexenat et al. (1986) in the state of Bahia. Anthropophilic behavior of these two species is also manifested in the DBBR evidenced by the large number of females collected in the Shannon trap due to the presence of a human. We were not able to evaluate the seasonality of sand flies in the DBBR, but Ps. ayrozai and Ps. hirsutus were constant throughout the year at the Serra dos Órgãos National Park corroborating the findings of Aguiar et al. (1985). In the Amazon region, Ps. ayrozai was found naturally infected by Leishmania (Viannia) naiffi Lainson & Shaw (Arias et al. 1985), while in the state of Minas Gerais Ps. hirsutus was found naturally infected by Leishmania parasites of L. braziliensis complex (Rangel et al. 1985). The occurrence of a wild cycle of transmission of these parasites at the DBBR is possible due to the capture of a large number of sand flies belonging to the species Ps. ayrozai and Ps. hirsutus.

Bichromomyia flaviscutellata is a known vector of Leishmania (Leishmania) amazonensis Lainson & Shaw in Brazil owing to its attraction to rodent reservoirs (Shaw and Lainson 1968) and findings of natural infection by the parasite (Lainson and Shaw 1968). In the laboratory, this sand fly may be experimentally infected (Lainson et al. 1987) and the parasite transmitted by biting from hamster to hamster (Ward et al. 1977). At the DBBR, the presence and constancy of Bi. flaviscutellata in both Shannon and CDC traps may be associated with the higher specific richness of rodents (Carão 2008). However, studies of natural infection by Leishmania in both rodents and sand flies in the DBBR are required, whereas L. (L.) amazonensis was not recorded in the state of Espírito Santo.

Studies carried out on sand fly fauna in domiciliary and forest fragments from the localities of the municipalities of Cariacica and Viana, near the DBBR, have shown that Ny. intermedia, Mg. migonei, and Pi. fischeri were the predominant species, representing more than 98% of the sand flies collected (Barros et al. 1985). However, at the DBBR, these species accounted for less than 1% of the total sand flies. While Ny. intermedia and Mg. migonei are recognized as vectors of L. (V.) braziliensis in the state of Espírito Santo (Ferreira et al. 2001), leishmaniasis human cases could have occurred in areas adjacent to the DBBR, which might not have had any influence on the sand fly fauna found in the reserve. In the Vale do Ribeira, state of São Paulo, Brazil, the frequency of Ny. intermedia, Mg. migonei, and Pi. fischeri in a forest environment was low, suggesting that these species had no influence in the transmission of tegumentary leishmaniasis in this ecotype (Gomes and Galati 1989).

Although the sand fly fauna in the DBBR is not related to the human leishmaniasis cases in adjacent areas, the occurrence of a wild transmission cycle in the reserve involving mammals and sylvatic vectors is possible. In a locality close to the DBBR were isolated Leishmania parasites identified as Leishmania (Leishmania) forattinii Yoshida et al. from the rodent Trinomys paratus (Moojen) (hereafter called Proechimys iheringi) (Falqueto et al. 1998). Based on food preferences, in the state of Espírito Santo, Mt. gasparviannai was recognized as the possible vector of L. (L.) forattinii (Falqueto et al. 1985). The same parasite was isolated from the rodent Proechimys iheringi denigratus (Moojen) in the municipality of Três Braços, state of Bahia, Brazil (Barreto et al. 1985). In the state of Bahia, based on the large numbers of specimens collected, experimental infection, and parasite development in the midgut of sand flies, Ny. yuilli yuilli and Ps. ayrozai were recognized as possible vectors of L. (L.) forattinii (Barretto et al. 1985, 1986). However, no sand fly species were found naturally infected by L. (L.) forattinii. Therefore, the presence of all possible sand fly vectors and a high frequency of the principal reservoirs of L. (L.) forattinii increase the need for studies regarding the natural infection of sand flies in the DBBR in order to elucidate the transmission cycle of this Leishmania species.

Acknowledgments

Rafaela Duda provided help in the field work. Cristiani C. Saguinette and Gustavo M. L. Carvalho helped in the identification of Ps. geniculatus. Luiz G. S. R. Bauzer provided crucial suggestions that contributed to improve the quality of this article. Fellowship support was provided by Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) to Israel S. Pinto. Instituto Estadual de Recursos Hídricos e Meio Ambiente (IEMA) provided lodging and logistic support in the field. Instituto Brasileiro do Meio Ambiente e dos Recursos Naturais Renováveis (IBAMA) provided collecting permissions.

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