BACKGROUND The state of Rondônia (RO) is a hot spot for human cases of cutaneous leishmaniasis. Many sandfly species in RO are putative vectors of leishmaniasis. OBJECTIVES This study examines the diversity patterns and the presence of Leishmania DNA and blood meal sources of sandflies in RO. METHODS A sandfly survey was performed between 2016 and 2018 in 10 municipalities categorised into three different environment types: (i) Conservation Unit (CUN)-comprised of preserved ombrophilous forests; (ii) Forest Edge (FE)-small forest fragments; and (iii) Peridomicile (PE)-areas around dwellings. FINDINGS A total of 73 species were identified from 9,535 sandflies. The most abundant species were Psychodopygus davisi (1,741 individuals), Nyssomyia antunesi (1,397), Trichophoromyia auraensis (1,295) and Trichophoromyia ubiquitalis (1,043). Diversity was the highest in CUN, followed by the FE and PE environments. One pool of Ps. davisi tested positive for Leishmania braziliensis, reinforcing the possibility that Ps. davisi acts as a vector. The cytochrome b (cytb) sequences were used to identify three blood meal sources: Bos taurus, Homo sapiens and Tamandua tetradactyla. MAIN CONCLUSIONS Our results demonstrated that sandflies can switch between blood meal sources in differing environments. This study enhances the knowledge of the vector life cycle in RO and provides information relevant to leishmaniasis surveillance.
Background
Almost 1000 cases of American cutaneous leishmaniasis have been registered yearly in Rondônia State, Brazil. Little is known about the
Leishmania
transmission cycle (vectors and reservoirs) in the state. This study aimed to evaluate sand fly fauna from two vertical stratification layers in order to identify potential vectors and their blood-meal sources.
Methods
The study was conducted in Jamari National Forest. Sand flies were collected in the canopy (15 m) and at ground level (1 m) using HP light traps during four months, February, April, August and October, 2018. Insects were identified to the species level, and females were subjected to DNA extraction and PCR targeting minicircle
k
DNA and
hsp
70 (for
Leishmania
detection and species identification), and
cytb
(to identify blood-meal sources). Exploratory data analysis was used to determine mean of abundance and species richness between stratifications. The
hsp
70 and
cytb
sequences were analyzed and compared with sequences from GenBank.
Results
Overall, 68 species were identified from 15,457 individuals. On the Potosi trail, 7531 individuals of 49 species were collected; canopy captures totaled 6463 individuals of 46 species, while ground captures totaled 1068 individuals of 38 species. On the Santa Maria trail, 7926 individuals of 61 species were collected; canopy captures totaled 6136 individuals of 51 species, while ground captures totaled 1790 individuals of 53 species. A total of 23 pools were positive for
k
DNA (canopy
n
= 21, ground
n
= 2). Only two samples were sequenced for
hsp
70 (both in canopy); one sequence exhibited similarity with
Leishmania braziliensis
(
Lutzomyia davisi
pool) and another with
L. naiffi
(
Lu. antunesi
pool). The
cytb
fragment was amplified in 11 of 86 samples. Sample sequencing identified
cytb
DNA from 5 blood-meal sources:
Micrastur gilvicollis
,
Psophia viridis
,
Tamandua tetradactyla
,
Homo sapiens
and
Choloepus didactylus
.
Conclusions
Sand fly fauna is more diverse in the canopy than at ground level. Factors such as blood-meal sources, resting sites, and abiotic components probably contribute to high abundance in the canopy. Our results reinforce the possibility that
Lu. antunesi
and
Lu
.
davisi
participate in
Leishmania
...
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