Horizontal Stratification of the Sand Fly Fauna (Diptera: Psychodidae) in a Transitional Vegetation between Caatinga and Tropical Rain Forest, State of Bahia, Brazil

Vol. 98(6): 733-737, September 2003

Artur Gomes Dias-Lima/⁺, Maria Lenise Silva Guedes*, Italo A Sherlock

Laboratório de Parasitologia e Entomologia, Centro de Pesquisas Gonçalo Moniz-Fiocruz, Rua Valdemar Falcão 121, 40295-001 Salvador, BA, Brasil *Departamento de Botânica, Instituto de Biologia, Universidade Federal da Bahia, Salvador, BA, Brasil

A study about the horizontal stratification of the sand fly fauna in two distinct ecosystems, caatinga area, endemic for visceral leishmaniasis, and the tropical rain forest area, endemic for cutaneous leishmaniasis, was performed in the state of Bahia, Brazil. Lutzomyia longipalpis was predominant in the caatinga, and following it came the species L. capixaba and L. oswaldoi. In the tropical rain forest other species were found, such as L. intermedia, L. migonei, L. whitmani, L. yuilli, L.fischeri, L. damascenoi, L. evandroi, L. monticola, and L. lenti. It was found that the geographical limits of the vector species of visceral and cutaneous leishmaniasis are clearly defined by the biological and phytogeographic characteristics.

Key words: sand fly fauna - horizontal stratification - phytogeography - leishmaniasis - Lutzomyia longipalpis -
Lutzomyia whitmani

The leishmaniases in Brazil are included among the main parasitic diseases that affect humans. Bahia is presently the Brazilian state with the higher incidence of reported cases of American visceral leishmaniasis (AVL), also being one of the first in number of cases of American cutaneous leishmaniasis (ACL) (Funasa 2002a, b). In this state, Jequié and Jitaúna, important districts of AVL and ACL are respectively in areas of caatinga and Atlantic Forest, occupying, in part, transition areas of both types of vegetation. Therefore, despite being geographically close, the area of the city of Jequié basically has a caatinga vegetation, whilst in Jitaúna, the vegetation characteristics are distinct, being of mainly tropical rain forest, included in the domains of the Atlantic Forest.

According to Sherlock et al. (1996) two species of leishmanias were found in these municipal districts: the Leishmania chagasi Cunha & Chagas, 1937 transmitted by Lutzomyia longipalpis (Lutz & Neiva, 1912), and the Leishmania braziliensis Vianna, 1911, probably transmitted by the species Lutzomyia whitmani (Antunes & Coutinho, 1939), Lutzomyia intermedia (Lutz & Neiva, 1912), and Lutzomyia migonei (França, 1920).

Despite the existence of various studies about the sand fly fauna in many states of Brazil, these are generally restricted, involving only a single type of phytogeo-graphic zone. Few are the studies relating the species of sand flies and phytogeographic succession.

However, in the state of Maranhão, that comprises areas of transition between the humid Amazon Forest and the caatinga, Rebelo et al. (1999) realized surveys about the sand flies in areas of ACL and AVL, respectively. Ribeiro and Missawa (2002) researched in the state of Mato Grosso the spatial distribution of the sand flies in an area of Amazon Forest, savanna and Marsh Land. In the last two ecosystems, the presence of L. longipalpis and Lutzomyia cruzi (Mangabeira, 1938) was strong. In Normandia, state of Roraima, in a caatinga area known in the region as Lavrados, Cabanillas (1999) found an abundant quantity of L. longipalpis, while studying the eco-epidemiological aspects of the visceral leishmaniasis. In the south of the state, in areas of Amazon Forest, this species was not found.

In Santarém, in the state of Pará, a high density of L. longipalpis was found in the savanna, despite being surrounded by the Amazon Forest (Senra et al. 1986).

The L. longipalpis has been associated with the dry and semi-dry zones in rural and urban areas, more frequently found in domestic animal shelters, although it is also numerous inside the houses (Deane & Deane 1962, Sherlock & Guitton 1969, Galati et al. 1997). The specie is common in not too humid and mountainous places, with an abundance of superficial rocks. It is absent in areas of humid forests (Deane & Deane 1962, Forattini 1992).

The beginning of the devastation of the Atlantic Forest probably dates from 1500, at the start of the Brazilian colonization by the Portuguese. The agricultural ex-pansion, the urban occupation and the industrial development in the state of Bahia, until the 20th century, caused the diminution of the vegetation resources (Instituto Socioambiental 2001).

The human intervention in natural environments, both for the extraction of wood and/or for the cultivation of cocoa plant Theobroma cacao L. and pastures, was intensified in the last few decades, radically modifying the vegetation cover. In the same way, the caatinga has also suffered an accentuated degradation. These environmental alterations caused modifications in the vegetation patterns and composition of the sand fly fauna.

Therefore, an entomological investigation on the leishmaniases vectors could provide valuable information about the spatial distribution of the important sand flies species and define the risk areas of transmission of the disease, safely guiding the control programs.

The study of the horizontal stratification of the sand fly fauna in a transition area between caatinga and tropical rain forest is of great importance for the understanding of the ecoepidemiology of leishmaniases.

MATERIALS AND METHODS

RESULTS

DISCUSSION

ACNOWLEDGMENTS

To the botanists Denise Maria Loureiro and Denise Lima Santana for the collections of the plants and to Antonio Carlos dos Santos and Carlos Gustavo Silva Santos, for the help with the sand flies' collections.

REFERENCES

Fig.1 | Fig. 2 | Fig. 3 | Table

This work was supported by Fiocruz, CNPq and Capes.

⁺Corresponding author. Fax: +55-71-356.2155. E-mail: alima@cpqgm.fiocruz.br.

Received 20 December 2002

Accepted 9 July 2003