Triatomines know no boundaries: Triatoma delpontei Romaña & Abalos, 1947 (Heteroptera: Reduviidae) discovered in Mato Grosso do Sul State, Brazil

Abstract

Triatominae are recognized as vectors of Trypanosoma cruzi, a protozoan which is the etiological agent of Chagas disease. A specimen of Triatoma delpontei was found at Porto Murtinho in Mato Grosso do Sul State, Brazil. This is the first report of the occurrence of T. delpontei to the state of Mato Grosso do Sul, Brazil. With the present finding, the total number of triatomines recorded in Mato do Grosso do Sul reaches 17 species, while T. delpontei, previously recorded only from Rio Grande do Sul, is now recorded to a second Brazilian state. Based on the information available in the literature, a meticulous and organized compilation has been crafted, highlighting the cytogenetics differentiations of the species occurring in this state. This work emphasizes the importance of continuous research and surveillance on Triatominae, recognized as vectors of T. cruzi.

Key words
Biogeography; kissing bugs; Triatomini; surveillance; vectors

INTRODUCTION

Since the discovery of the Chagas disease, blood-sucking bugs of the subfamily Triatominae (Hemiptera: Heteroptera: Reduviidae) have been recognized as proved or potential vectors of Chagas disease, caused by the protozoan Trypanosoma cruzi (Chagas, 1909) (Kinetoplastida: Trypanosomatidae), and which is still of major importance in Public Health in Latin America (Lent & Wygodzinsky 1979, Monteiro et al. 2018).

Currently, about 159 species of Triatominae are considered as valid (Oliveira et al. 2023, Alevi et al. 2021, Correia et al. 2022, Gil-Santana et al. 2022, Téllez-Réndon et al. 2023, Zhao et al. 2023, Galvão et al. 2003, Galvão 2014). The two latter works summarized the known distribution of triatomines species to the World and Brazil, respectively. Yet, regional surveys of these insects have increased the knowledge of the species which occur in the Brazilian state of Mato Grosso do Sul (MS) (Almeida et al. 2008, Cominetti & Andreotti 2021, Almeida et al. 2023). As a result, 17 species of Triatominae had been recorded to MS state so far (taken into consideration the first report of T. delpontei presented here) (Galvão et al. 2003, Galvão 2014, Almeida et al. 2023) (Table I).

Table I
Triatominae species currently recorded from Mato Grosso do Sul by Galvão et al. (2003), Galvão (2014), Almeida et al. (2023) and this work.

Tribe	Species	Inaturalist record
Cavernicolini	Cavernicola pilosa Barber, 1937
Rhodniini	Psammolestes coreodes Bergroth, 1911
	Rhodnius neglectus Lent, 1954
	Rhodnius pictipes Stål, 1872
	Rhodnius stali Lent, Jurberg & Galvão, 1993
Triatomini	Panstrongylus diasi Pinto & Lent, 1946	https://www.inaturalist.org/observations/126754495
	Panstrongylus geniculatus (Latreille, 1811)	https://www.inaturalist.org/observations/68920364
	Panstrongylus guentheri Berg, 1879
	Panstrongylus megistus (Burmeister, 1835)	https://www.inaturalist.org/observations/109635127
	Triatoma baratai Carcavallo & Jurberg, 2000
	Triatoma costalimai Verano & Galvão, 1958
	Triatoma delpontei Romaña & Abalos, 1947 (new record)
	Triatoma matogrossensis Leite & Barbosa, 1953
	Triatoma pseudomaculata Côrrea & Spínola, 1964
	Triatoma sordida (Stål, 1859)
	Triatoma vandae Carcavallo et al., 2002
	Triatoma williami Galvão et al., 1965

Triatoma delpontei Romaña & Abalos, 1947 was described from Argentina, based on several male and female specimens (Romaña & Abalos 1947). Besides Argentina, T. delpontei has been recorded from Bolivia, Paraguay, Uruguay (Lent & Wygodzinsky 1979, Galvão et al. 2003), and in Brazil, previously only from the state of Rio Grande do Sul (Agrelo et al. 1993). The species is basically ornitophilic, but has been found naturally infected with T. cruzi (Lent & Wygodzinsky 1979). Triatoma delpontei seems closer to T. platensis Neiva, 1913 from which it is separated by a well-defined set of characters (Romaña & Abalos 1947, Lent & Wygodzinsky 1979, Galvão 2014).

We meticulously compiled cytogenetic data from relevant literature sources, marking the first-ever compilation of such information for the state. This allowed us to propose a table of distinguishing characters.

MATERIALS AND METHODS

The collection was carried out on March 27, 2023, through the retrieval of the specimen in a bedroom inside an intradomiciliary environment. The resident responsible for the collection made the necessary efforts to transport the specimen to the surveillance service. The residence is located at “Fazenda Barranco Branco”, in the municipality of Porto Murtinho, MS, Brazil (Figure 1).

Figure 1
Location of Triatoma delpontei Romaña & Abalos, 1947 collection in the municipality of Porto murtinho, Mato Grosso do Sul, Brazil.

The specimen was studied and identified as T. delpontei, following the dichotomous keys of Lent & Wygodzinsky (1979) and Galvão (2014).

This action reveals a specific interest in scientific investigation, aiming to deepen the knowledge about the species in question. Such an approach provides a valuable context for the analysis and understanding of domestic ecosystems, enabling the identification of possible interactions and impacts that may affect the health and well-being of the population.

Additionally, the collection plays a fundamental role in formulating preventive and control measures aimed at promoting a safe and healthy residential environment through passive surveillance. The records of the Panstrongylus Berg, 1879 species were retrieved from the iNaturalist platform, and the images were graciously provided by the naturalist photographer, Vinicius Rodrigues de Souza.

RESULTS AND DISCUSSION

The specimen (Figure 2) was identified as T. delpontei following the consultation of keys, diagnosis and descriptions available in the literature (Romaña & Abalos 1947, Lent & Wygodzinsky 1979, Carcavallo et al. 71998, Galvão 2014) and showed complete concordance with all these sources of information. In short, the following characteristics allowed the identification of the specimen (Figure 2): a medium sized triatomine (total length of 23.5 mm); general coloration black to brownish black; a pair of lateral orange markings on neck and anterolateral portions of hind lobe of pronotum; corium of hemelytra irregularly marked with pale portions; membrane dark orange mottled with dark, with an irregular central dark marking which includes the median portion of both cells; femora and tibiae dark, without markings; connexivum blackish with subapical (segments II-VI) or submedian (segment VII) whitish pale markings, which are narrower on their middle portion on segments III-VII. Surface of the body, including corium and legs, with numerous adpressed pale to golden setae. Head slightly longer than pronotum; scape relatively short, far from attaining apex of clypeus; first visible labial segment slightly shorter than the last one, the second visible labial segment approximately twice longer than each of the others; scutellum without prominent anterior tubercles; legs stout; fore and middle femora with a pair of small subapical acute prominences, ventrally. The specimen was deposited in the Triatominae Collection of the Oswaldo Cruz Institute (CTIOC) (under No. 14007).

Figure 2
Triatoma delpontei Romaña & Abalos, 1947, male from Mato Grosso do Sul, Brazil, dorsal view, scale bar 5.0 mm.

New record. BRAZIL – Mato Grosso do Sul • Porto Murtinho/Fazenda Fazenda Barranco Branco; 23.III.2023; leg. dweller of the residence.CTIOC 14007, 1 ♂ (Figure 2).

Another important fact is that when checking iNaturalist, we found records of three species already reported for the state of Mato Grosso do Sul: P. diasi Pinto & Lent, 1946 (Figure 3a-b), P. megistus (Burmeister, 1835), and P. geniculatus (Latreille, 1811) (Table I). It is worth noting that the live record of P. diasi is the first reported in the literature. This species had never been reported alive before, and it was documented living in a graveyard in the municipality of Cassilândia, MS. This occurrence reinforces the distribution of triatomines in different habitats, as discussed by Cruz et al. (2023). Triatomines have been previously reported in sylvatic cemeteries (Di Primio 1952, 1963, Buitrago et al. 2010, Paiva et al. 2021). This time we documented their occurrence in an urban graveyard (Figure 3c).

Figure 3
Panstrongylus diasi Pinto & Lent, 1946, a-Dorsal view; b-Lateral view; c-Graveyard where the specimen was photographed.

In this sense, the use of this information from iNaturalist demonstrates the importance of citizen science. By involving ordinary people in scientific activities, citizen science expands the reach and capacity of research. It allows non-scientists to contribute to data collection, observations, and analyses, playing an active role in the production of scientific knowledge. In the case of conservation science, in particular, the participation of citizens is crucial for addressing complex environmental challenges and gaining a broader understanding of issues related to biodiversity and the biology of a vector species.

Citizen science provides a way to engage society more widely, promoting awareness and public engagement in scientific research. Furthermore, it contributes to a more inclusive and democratic approach to science, allowing different perspectives to be considered and incorporated into decision-making processes. With more diverse participation, citizen science can also help build a more comprehensive and representative knowledge base, addressing gaps and expanding the collective understanding of the environmental challenges we face. In the literature, there are already numerous studies that have highlighted and demonstrated the importance and effectiveness of citizen science, such as Cull (2021), Hamer et al. (2018) and Bonney et al. (2015).

Almeida et al. (2008) highlighted the presence of T. b. brasiliensis Neiva, 1911 in the state of MS. However, after a reevaluation of the identification, 15 years later, the second author (PSA) confirmed that the previous identification was incorrect, and the specimen is actually a specimen of T. matogrossensis Leite & Barbosa, 1953. As a conclusion, with the current report, a total of 17 species of Triatominae are recorded to the state of MS (Table I) and T. delpontei has its occurrence extended to two Brazilian states.

Recently, Nhapulo et al. (2023) and Mello et al. (2023) developed dichotomous keys based on cytogenetic data to assist in the correct identification of triatomines reported in Brazilian states with an outbreak of oral transmission of Chagas disease (Paraíba, Pernambuco and Rio Grande do Norte). The authors highlighted the importance of cytogenetic data for differentiating morphologically related species, such as T. b. brasilensis and T. petrocchiae (Pinto & Barreto, 1925), as well as T. maculata (Erichson, 1848) and T. pseudomaculata Corrêa & Espínola, 1964.

Triatoma b. brasiliensis and T. matogrossensis present cytogenetic differences: presence of 45S rDNA present in a pair of autosomes and in X and Y sex chromosomes, respectively (Pita et al. 2022). This information is important, because if cytogenetic studies were applied by Almeida et al. (2008), the misidentification would not have happened. Thus, we compiled all cytogenetic information from fluorescence in situ hybridization (FISH) of triatomine species from MS (Table II) (Pita et al. 2022), and we emphasize that T. delpontei presents totally different markings from the other taxa (Table II), which can be used for the diagnosis of the species.

Table II
Cytogenetic information from fluorescence in situ hybridization (FISH) of triatomine species from Mato Grosso do Sul. X: X sex chromosome; Y: Y sex chromosome Y; A: autosomes.

Species	X	X and Y	A	X and A
Psammolestes coreodes
Rhodnius neglectus
Rhodnius pictipes
Rhodnius stali
Panstrongylus geniculatus
Panstrongylus megistus
Triatoma baratai
Triatoma costalimai
Triatoma delpontei
Triatoma matogrossensis
Triatoma pseudomaculata
Triatoma sordida
Triatoma vandae
Triatoma williami

It is important to highlight that T. delpontei, previously recorded only in the state of Rio Grande do Sul, has now been identified in a second Brazilian state. These findings are crucial for understanding the diversity and distribution of triatomine in Brazil, providing valuable information for the control and prevention of Chagas disease, especially in states bordering other countries. Additionally, the record of T. delpontei in MS underscores the need for constant monitoring and effective control strategies to address the geographic expansion of these vector insects and the threat they pose to public health.

ACKNOWLEDGMENTS

Jader de Oliveira appreciates the Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), and Kaio Cesar Chaboli Alevi the Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ) for financial support. In addition, the authors are grateful to Dr. Cleber Galvão and Dr. João Paulo Sales Oliveira Correia (CTIOC) for allowing the deposit of the specimen in their institution. We extend our sincere gratitude to the photographer and naturalist, Vinícius Rodrigues de Souza, for kindly providing the images of P. diasi and the photograph depicting the precise location of the recorded specimen, along with valuable information regarding its occurrence.

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Publication Dates

• Publication in this collection
  23 Sept 2024
• Date of issue
  2024

History

• Received
  28 Aug 2023
• Accepted
  07 Apr 2024