Biomédica 2017;37:299-302

doi: https://doi.org/10.7705/biomedica.v34i2.3304

IMAGES IN BIOMEDICINE

Blood-feeding of Rhodnius prolixus

Kevin Escandón-Vargas1,2 , Carlos A. Muñoz-Zuluaga1,3, Liliana Salazar3

1 Escuela de Medicina, Facultad de Salud, Universidad del Valle, Cali, Colombia

2 Departamento de Microbiología, Facultad de Salud, Universidad del Valle, Cali, Colombia

3 Departamento de Morfología, Facultad de Salud, Universidad del Valle, Cali, Colombia

Author’s contributions: Kevin Escandón-Vargas conceived the study idea, reviewed the literature and drafted the manuscript.

Carlos A. Muñoz conceived the study idea, reviewed the literature and performed the laboratory experiments.

Liliana Salazar contributed to the analysis of the experiments and to the writing of the manuscript.

All authors reviewed and approved the manuscript.

Received: 01/04/16; accepted: 15/11/16


Triatomines (Hemiptera: Reduviidae) are blood-sucking insect vectors of the protozoan Trypanosoma cruzi which is the causative agent of Chagas’ disease. Rhodnius prolixus is the most epidemiologically important vector of T. cruzi in Colombia. Triatomines are regarded to be vessel-feeders as they obtain their blood meals from vertebrate hosts by directly inserting their mouthparts into vessels. Microscopic techniques are useful for visualizing and describing the morphology of biological structures. Here, we show images of the blood-feeding of R. prolixus, including some histological features by light microscopy and scanning electron microscopy of the mouthparts of R. prolixus when feeding on a laboratory mouse.

Key words: Rhodnius; Triatominae; microscopy; histology.

doi: https://doi.org/10.7705/biomedica.v34i2.3304


Alimentación de Rhodnius prolixus

Los triatominos (Hemiptera: Reduviidae) son insectos hematófagos vectores del protozooTrypanosoma cruzi, el cual causa la enfermedad de Chagas. Rhodnius prolixus es el vector de T. cruzi de mayor importancia epidemiológica en Colombia. Para alimentarse, los triatominos introducen su probóscide directamente en los vasos sanguíneos de los huéspedes vertebrados. La microscopía es una técnica útil para visualizar y describir la morfología de estructuras biológicas. Se presentan imágenes de la hematofagia de R. prolixus, incluidas algunas características histológicas visibles por microscopía de luz y microscopía electrónica de barrido de las partes bucales de R. prolixus al alimentarse de un ratón de laboratorio.

Palabras clave: Rhodnius; Triatominae; microscopía; histología.

doi: https://doi.org/10.7705/biomedica.v34i2.3304


Triatomines (Hemiptera: Reduviidae) are blood - sucking insect vectors of the protozoan Trypanosoma cruzi which is the causative agent of Chagas’ disease (American trypanosomiasis). Vector-borne transmission is the main infection route and occurs in many areas of the Americas (1). Despite significant progress towards the control of domestic vector infestation, Chagas’ disease remains a major public health problem in Latin America due to its epidemiological and economic burden (2-4).

According to the eco-epidemiological studies carried out in Colombia, Rhodnius prolixus is the mo important vector of T. cruzi in the country and has successfully adapted to human domiciles (2,5,6). The preference for feeding on humans, the high susceptibility to infection with T. cruzi, the rapid development cycle and the short defecation time are factors favoring its vector capacity (5).

The first extensive studies on the blood-feeding of triatomine bugs were published in 1952 and 1953 by Barth, who detailed the internal anatomy of the head of Triatoma infestans and its feeding behavior on guinea pigs (7,8). Thereafter, Lavoipierre, et al., observed the mechanism of feeding of three triatomine species (R. prolixus, T. infestans and T. protracta) on a rabbit, a white rat, and a guinea pig, directing particular attention to the structure and function of the mouthparts of R. prolixus (9). An extensive morphological review on R. prolixus was published in 1969 by Ramírez-Pérez (10). Friend, et al., also made observations of mouthpart movements, salivation and ingestion in R. prolixus and correlated them with changes of electrical resistance (11). More recently, the functional anatomy of the hypopharynx and the salivary pump of R. prolixus has been elucidated (12).

The head, mouthparts and the probing process of R. prolixus are shown in figure 1. Triatomines are regarded to be vessel-feeders because they obtain blood from vertebrate hosts by directly inserting their mouthparts into vessels (solenophagy or capillary feeding) (9). Triatomines rely on the sense of CO2 to search for blood meals from sleeping hosts (13). Contact with the host occurs only during feeding, which lasts approximately 20 to 30 min (14). It has been described that these insects feed on a host swinging their proboscis forward and piercing the skin by rapid alternating movements of the resistant mandibles which penetrate only into the superficial tissues. Then, the maxillae (maxillary bundle) penetrate deeply into the dermis with restless twisting movements (9).

Triatomines possess a wide variety of bioactive molecules in the saliva which facilitate the blood meal by reducing host physiological responses related to haemostasis, inflammation, and immune activation. In R. prolixus, saliva deposition into the host skin occurs throughout the probing and engorgement phases of the feeding (12,14). Feeding takes place from blood vessels rather than from small hemorrhages which are formed as a result of probing. When the maxillary bundle enters a blood vessel of suitable caliber, probing ceases and the insect gut begins to engorge (9). Blood ingestion through the food canal is aided by the cibarial pump, which is regulated by several strong muscles of the insect head (7). The bug continues to suck up its blood meal until it is full, but the feeding process is not always continuous and may be interrupted and repeated (9).

Microscopic techniques are useful for visualizing and describing the morphology of biological structures. Here, we show images of the blood-feeding of R. prolixus, including some histological features of the mouthpart structures implicated.

Third- and fourth-instar uninfected nymphs of R. prolixus were obtained from the insectary colonies of the Departamento de Microbiología of the Facultad de Salud of Universidad del Valle in Cali, Colombia. In the Laboratorio de Histología of the University, an anesthetized laboratory mouse (Mus musculus) was exposed to the triatomines for blood-feeding (figure 2 and figure 3). Triatomines were decapitated with a curved iris scissor during blood-feeding. We obtained biopsy samples of the skin pierced by the feeding apparatus or proboscis, and of the head of the insect, and processed them accordingly.

Light microscopy (figure 4 and figure 5) was performed in the Laboratorio de Ingeniería de Materiales of Universidad del Valle and scanning electron microscopy procedures (JEOL microscope JSM6490LV) (figure 6, figure 7 and figure 8) were performed in the Laboratorio de Materiales de la Facultad de Ingeniería of Universidad del Valle. Animal experimentation was part of the practical component of the subjects “Basic histochemical techniques” and “Electron microscopy techniques” taken by one of the authors.

Acknowledgments

We thank the Departamento de Microbiología, Facultad de Salud, Universidad del Valle, for providing us the triatomines, as well as Nhora Holguín and Martha Lucía Ceballos from the Departamento de Morfología, Facultad de Salud, Universidad del Valle, for their assistance in the Laboratorio de Ingeniería de Materiales, and Gustavo A. Bolaños, from the Laboratorio de Materiales, Facultad de Ingeniería, Universidad del Valle, for his help during scanning electron microscopy experiments.

Conflicts of interest

The authors declare no conflict of interest.

Funding

None.

Corresponding author: Kevin Escandón-Vargas, Escuela de Medicina, Facultad de Salud, Universidad del Valle, Calle 4B N° 36-00, Cali, Colombia Telephone number: (572) 518 5652 ariasmurillo@hotmail.com

References

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3. World Health Organization. Chagas disease in Latin America: An epidemiological update based on 2010 estimates. Wkly Epidemiol Rec. 2015;90:33-43.

4. Moncayo á, Silveira AC. Current epidemiological trends for Chagas disease in Latin America and future challenges in epidemiology, surveillance and health policy. Mem Inst Oswaldo Cruz. 2009;104(Suppl.1):17-30. https://doi.org/10.1590/S0074-02762009000900005

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7. Barth R. Estudos anatômicos e histológicos sôbre a subfamília Triatominae (Heteroptera, Reduviidae). I: A cabeça do Triatoma infestans. Mem Inst Oswaldo Cruz. 1952;50:69196. https://doi.org/10.1590/S0074-02761952000100004

8. Barth R. Estudos anatômicos e histológicos sôbre a subfamília Triatominae (Heteroptera, Reduviidae). III: Pesquisas sôbre o mecanismo da picada dos Triatominae. Mem Inst Oswaldo Cruz. 1953;51:11-68. https://doi.org/10.1590/S007402761953000100002

9. Lavoipierre MM, Dickerson G, Gordon RM. Studies on the methods of feeding of blood-sucking arthropods. I. The manner in which triatomine bugs obtain their blood-meal, as observed in the tissues of the living rodent, with some remarks on the effects of the bite on human volunteers. Ann Trop Med Parasitol. 1959;53:235-50. https://doi.org/10.1080/00034983.1959.11685921

10. Ramírez-Pérez J. Estudio sobre la anatomía de Rhodnius prolixus. Rev Venez Sanid Asist Soc. 1969;34:9-98.

11. Friend WG, Smith JJ. Feeding in Rhodnius prolixus: Mouthpart activity and salivation, and their correlation with changes of electrical resistance. J Insect Physiol. 1971;17: 233-43. https://doi.org/10.1016/0022-1910(71)90207-1

12. Wenk P, Lucic S, Betz O. Functional anatomy of the hypopharynx and the salivary pump in the feeding apparatus of the assassin bug Rhodnius prolixus (Reduviidae, Heteroptera). Zoomorphology. 2010;129:225-34. https://doi.org/10.1007/s00435-010-0115-7

13. Guerenstein PG, Lazzari CR. Host-seeking: How triatomines acquire and make use of information to find blood. Acta Trop. 2009;110:148-58. https://doi.org/10.1016/j.actatropica.2008.09.019

14. Soares AC, Carvalho-Tavares J, Gontijo N de F, dos Santos VC, Teixeira MM, Pereira MH. Salivation pattern of Rhodnius prolixus (Reduviidae; Triatominae) in mouse skin. J Insect Physiol. 2006;52:468-72. https://doi.org/10.1016/j.jinsphys.2006.01.003

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Revista Biomédica -  https://doi.org/10.7705/issn.0120-4157
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