scholarly journals Novel repellents for the blood-sucking insects Rhodnius prolixus and Triatoma infestans, vectors of Chagas disease

2019 ◽  
Author(s):  
Melanie Ramírez ◽  
Mario I. Ortiz ◽  
Pablo Guerenstein ◽  
Jorge Molina
Keyword(s):  
Chagas Disease ◽  
Dimethyl Sulfide ◽  
Control Strategies ◽  
Statistical Tests ◽  
Positive Control ◽  
Negative Control ◽  
Rhodnius Prolixus ◽  
Triatoma Infestans ◽  
Host Seeking ◽  
Blood Sucking

AbstractBackgroundStudying the behavioral response of blood-sucking, disease-vector insects to potentially repellent volatile compounds could shed light on the development of new control strategies. Volatiles released by human facial skin microbiota play different roles in the host-seeking behavior of triatomines. We assessed the repellency effect of such compounds of bacterial origin on Triatoma infestans and Rhodnius prolixus, two important vectors of Chagas disease in Latin America.MethodsUsing an exposure device, insects were presented to human odor alone (negative control) and in the presence of three individual tested compounds (2-mercaptoethanol, dimethyl sulfide and 2-phenylethanol, which was only tested in R. prolixus) and the gold-standard repellent NN-diethyl-3-methylbenzamide–DEET (positive control). We quantified the time the insects spent in the proximity of the host and performed nonparametric statistical tests to determine if any of the compounds evaluated affected the behavior of the insect.ResultsWe found volatiles that significantly reduced the time spent in the proximity of the host. These were 2-phenylethanol and 2-mercaptoethanol for R. prolixus, and dimethyl sulfide and 2-mercaptoethanol for T. infestans. Such an effect was also observed in both species when DEET was presented, although only at the higher doses tested.ConclusionsThe new repellents modulated the behavior of two Chagas disease vectors belonging to two different triatomine tribes, and this was achieved using a dose up to three orders of magnitude lower than that needed to evoke the same effect with DEET. Future efforts in understanding deeply the mechanism of action of repellent compounds such as 2-mercaptoethanol, as well as an assessment of their temporal and spatial repellent properties, could lead to the development of novel control strategies for insect vectors refractory to DEET.

UJI AKTIVITAS ANTIBAKTERI EKSTRAK ETANOL DAUN MEKAI (Pycnarrhena cauliflora DIELS.) TERHADAP Staphylococcus aureus

2020 ◽  
Vol 6 (2) ◽  
pp. 246
Author(s):  
Yayuk Bulam Sarifati ◽  
Sjarif Ismail ◽  
Khemasili Kosala
Keyword(s):  
Staphylococcus Aureus ◽  
Antibacterial Activity ◽  
Antimicrobial Agents ◽  
Statistical Tests ◽  
Ethanol Extract ◽  
Inhibition Zone ◽  
Positive Control ◽  
Negative Control ◽  
Control Measurement ◽  
Eye Pain

Mekai leaves (Pycnarrhena cauliflora Diels.) (P. cauliflora). Are known to contain flavonoid compounds, tannins and phenolics that act as antibacterial agents and are used in the treatment of eye pain. Staphylococcus aureus (S. aureus) is one of the examples of bacterial diseases of eye pain and also a major cause of many infections in communities and health facilities with cases of resistance to various antimicrobial agents. The purpose of this study was to prove the antibacterial activity of mekai leaves ethanol extract against S. aureus bacteria. This research is an experimental research. The stages of this research began by extracting mekai leaves using maceration method with 96% ethanol solvent. Antibacterial activity was tested by the disc method (Kirby-Bauer) using ethanol extract concentrations of mekai leaves (EPC) 20%, 30%, 40%, 50%, 60%, 70%, and 80%, positive control using 25 μg amoxicillin and negative control using DMSO 10%. The measurement results of inhibition zones of mekai leaf ethanol extract 20%, 30%, 40%, 50%, 60%, 70% and 80% respectively were 8.32 mm, 8.32 mm, 8.32 mm, 8.67 mm, 9.00 mm, 8.67 mm, and 8.33 mm. While the positive control measurement of 25 μg amoxicillin against S. aureus is 28.67 mm and the measurement of 10% negative DMSO control does not produce inhibitory zones, so it can be concluded that the ethanol extract of mekai leaves has antibacterial activity, but the area of ​​inhibition zone produced is smaller than amoxicillin 25 µg. The results of statistical tests using Mann Whitney between negative controls with all EPC concentrations obtained significant differences with p values ​​<0.05, it can be concluded that there is antibacterial activity produced at all EPC concentrations.

scholarly journals Identifying Current and Missing Knowledge in the Control of Pyrethroid-Resistant Triatoma infestans, Vector of Chagas Disease

2017 ◽  
Vol 9 (7) ◽  
pp. 47
Author(s):  
Gonzalo Roca Acevedo ◽  
María Inés Picollo
Keyword(s):  
Chagas Disease ◽  
Chemical Control ◽  
Rational Design ◽  
Pyrethroid Resistance ◽  
Triatoma Infestans ◽  
Vector Transmission ◽  
Pyrethroid Insecticides ◽  
Blood Sucking ◽  
Deltamethrin Resistance ◽  
Metabolic Detoxification

Triatomines are blood-sucking bugs that occur mainly in Latin America. They are vectors of Trypanosoma cruzi, the parasite that causes Chagas disease. Chemical control of Chagas disease´s vectors by using pyrethroid insecticides has been highly successful for the elimination of domestic infestation and consequently the reduction of the vector transmission. However, at the beginning of the 2000s a decrease in the effectiveness of the chemical control of triatomines was detected in several areas from Argentina and Bolivia, particularly in the Gran Chaco eco-region.During the last 15 years, several studies demonstrated the evolution of insecticide resistance in Triatoma infestans and established the presence of different toxicological profiles, the autosomal inherence of resistance, the biological costs of deltamethrin resistance, the expression of deltamethrin resistance thorough the embryonic development, and the main mechanisms of resistance (target-site insensitivity and metabolic detoxification of insecticides).The emergence of pyrethroid resistance coupled with the usual difficulties in sustaining adequate rates of insecticide applications emphasize the need of incorporating other tools for integrated vector and disease control, such as the proposal of the organo-phosphorus insecticide fenitrothion as an alternative chemical strategy for the management of the resistance because it was effective against pyrethroid-resistant populations in laboratory and semi-field trials.New studies on the current situation of presence and spread of resistant populations of triatomines and the acceptance of the use of alternative insecticides are critical requirements in the implementation of strategies for the management of resistance and for the rational design of campaigns oriented to reducing the vector transmission of Chagas’ disease.

The Octopamine Receptor Is a Possible Target for Eugenol-Induced Hyperactivity in the Blood-Sucking Bug Triatoma infestans (Hemiptera: Reduviidae)

2019 ◽  
Author(s):  
Mercedes M N Reynoso ◽  
Alejandro Lucia ◽  
Eduardo N Zerba ◽  
Raúl A Alzogaray
Keyword(s):  
Drosophila Melanogaster ◽  
Latin America ◽  
Essential Oils ◽  
Chagas Disease ◽  
American Cockroach ◽  
Triatoma Infestans ◽  
Aromatic Plants ◽  
Blood Sucking ◽  
Site Of Action ◽  
Octopamine Receptor

Abstract Eugenol is a major component of the essential oils in cloves and other aromatic plants. In insects, it produces toxic effects and repellency, and there is evidence that its site of action is the octopamine receptor. The objective of the present study was to explore whether the octopamine receptor is involved in the hyperactivity produced by eugenol in the blood-sucking bug Triatoma infestans (Klug). This insect is the main vector of Chagas disease in Latin America. Four treatments were topically applied on third instar nymphs: 1) octopamine, 2) eugenol, 3) phentolamine hydrochloride (an antagonist of the octopamine receptor) followed by octopamine, and 4) phentolamine hydrochloride followed by eugenol. Both octopamine and eugenol hyperactivated the nymphs. However, pretreatment with phentolamine hydrochloride inhibited the hyperactivating effect of both compounds. These results are in agreement with previous works on Drosophila melanogaster (Meigen) (Diptera: Drosophilidae) and the American cockroach. They suggest that the octopamine receptor is a possible site of action for eugenol.

scholarly journals Elucidating the Mechanism of Trypanosoma cruzi Acquisition by Triatomine Insects: Evidence from a Large Field Survey of Triatoma infestans

2020 ◽  
Vol 5 (2) ◽  
pp. 87
Author(s):  
Aaron W. Tustin ◽  
Ricardo Castillo-Neyra ◽  
Laura D. Tamayo ◽  
Renzo Salazar ◽  
Katty Borini-Mayorí ◽  
...  
Keyword(s):  
Trypanosoma Cruzi ◽  
Regression Models ◽  
Control Strategies ◽  
Protozoan Parasite ◽  
Etiologic Agent ◽  
Triatoma Infestans ◽  
Large Field ◽  
Blood Sucking ◽  
Triatomine Bugs ◽  
Cruzi Infection

Blood-sucking triatomine bugs transmit the protozoan parasite Trypanosoma cruzi, the etiologic agent of Chagas disease. We measured the prevalence of T. cruzi infection in 58,519 Triatoma infestans captured in residences in and near Arequipa, Peru. Among bugs from infected colonies, T. cruzi prevalence increased with stage from 12% in second instars to 36% in adults. Regression models demonstrated that the probability of parasite acquisition was roughly the same for each developmental stage. Prevalence increased by 5.9% with each additional stage. We postulate that the probability of acquiring the parasite may be related to the number of feeding events. Transmission of the parasite does not appear to be correlated with the amount of blood ingested during feeding. Similarly, other hypothesized transmission routes such as coprophagy fail to explain the observed pattern of prevalence. Our results could have implications for the feasibility of late-acting control strategies that preferentially kill older insects.

scholarly journals High-Throughput Identification of the Rhodnius prolixus Midgut Proteome Unravels a Sophisticated Hematophagic Machinery

Proteomes ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 16 ◽  
Author(s):  
Radouane Ouali ◽  
Karen Caroline Valentim de Brito ◽  
Didier Salmon ◽  
Sabrina Bousbata
Keyword(s):  
Digestive Tract ◽  
Chagas Disease ◽  
High Throughput ◽  
Control Strategies ◽  
Anterior Part ◽  
Rhodnius Prolixus ◽  
Etiologic Agent ◽  
Parasitic Infections ◽  
Developmental Cycle ◽  
Starting Point

Chagas disease is one of the most common parasitic infections in Latin America, which is transmitted by hematophagous triatomine bugs, of which Rhodnius prolixus is the vector prototype for the study of this disease. The protozoan parasite Trypanosoma cruzi, the etiologic agent of this disease, is transmitted by the vector to humans through the bite wound or mucosa. The passage of the parasite through the digestive tract of its vector constitutes a key step in its developmental cycle. Herewith, by a using high-throughput proteomic tool in order to characterize the midgut proteome of R. prolixus, we describe a set of functional groups of proteins, as well as the biological processes in which they are involved. This is the first proteomic analysis showing an elaborated hematophagy machinery involved in the digestion of blood, among which, several families of proteases have been characterized. The evaluation of the activity of cathepsin D proteases in the anterior part of the digestive tract of the insect suggested the existence of a proteolytic activity within this compartment, suggesting that digestion occurs early in this compartment. Moreover, several heat shock proteins, blood clotting inhibitors, and a powerful antioxidant enzyme machinery against reactive oxygen species (ROS) and cell detoxification have been identified. Highlighting the complexity and importance of the digestive physiology of insects could be a starting point for the selection of new targets for innovative control strategies of Chagas disease.

scholarly journals Structure Determination of Juvenile Hormone from Chagas Disease Vectors, Rhodnius prolixus and Triatoma infestans

2020 ◽  
Vol 49 (5) ◽  
pp. 538-541
Author(s):  
Keiji Matsumoto ◽  
Yoko Yasuno ◽  
Kohei Yasuda ◽  
Tsuyoshi Hayashi ◽  
Shin G. Goto ◽  
...  
Keyword(s):  
Juvenile Hormone ◽  
Chagas Disease ◽  
Structure Determination ◽  
Rhodnius Prolixus ◽  
Triatoma Infestans ◽  
Disease Vectors ◽  
Chagas Disease Vectors

scholarly journals Host-Seeking Behavior and Dispersal of Triatoma infestans, a Vector of Chagas Disease, under Semi-field Conditions

2015 ◽  
Vol 9 (1) ◽  
pp. e3433 ◽  
Author(s):  
Ricardo Castillo-Neyra ◽  
Corentin M. Barbu ◽  
Renzo Salazar ◽  
Katty Borrini ◽  
Cesar Naquira ◽  
...  
Keyword(s):  
Chagas Disease ◽  
Field Conditions ◽  
Triatoma Infestans ◽  
Host Seeking ◽  
Seeking Behavior

scholarly journals Comparative dissection of the peripheral olfactory system of the Chagas disease vectors Rhodnius prolixus and Rhodnius brethesi

2021 ◽  
Vol 15 (4) ◽  
pp. e0009098
Author(s):  
Florencia Campetella ◽  
Rickard Ignell ◽  
Rolf Beutel ◽  
Bill S. Hansson ◽  
Silke Sachse
Keyword(s):  
Chagas Disease ◽  
Olfactory System ◽  
Control Strategies ◽  
Natural Habitat ◽  
Rhodnius Prolixus ◽  
Functional Study ◽  
Olfactory Responses ◽  
Efficient Vector ◽  
Vertebrate Hosts ◽  
Morphological Differences

American trypanosomiasis, or Chagas disease, is transmitted by both domestic and sylvatic species of Triatominae which use sensory cues to locate their vertebrate hosts. Among them, odorants have been shown to play a key role. Previous work revealed morphological differences in the sensory apparatus of different species of Triatomines, but to date a comparative functional study of the olfactory system is lacking. After examining the antennal sensilla with scanning electronic microscopy (SEM), we compared olfactory responses of Rhodnius prolixus and the sylvatic Rhodnius brethesi using an electrophysiological approach. In electroantennogram (EAG) recordings, we first showed that the antenna of R. prolixus is highly responsive to carboxylic acids, compounds found in their habitat and the headspace of their vertebrate hosts. We then compared responses from olfactory sensory neurons (OSNs) housed in the grooved peg sensilla of both species, as these are tuned to these compounds using single-sensillum recordings (SSRs). In R. prolixus, the SSR responses revealed a narrower tuning breath than its sylvatic sibling, with the latter showing responses to a broader range of chemical classes. Additionally, we observed significant differences between these two species in their response to particular volatiles, such as amyl acetate and butyryl chloride. In summary, the closely related, but ecologically differentiated R. prolixus and R. brethesi display distinct differences in their olfactory functions. Considering the ongoing rapid destruction of the natural habitat of sylvatic species and the likely shift towards environments shaped by humans, we expect that our results will contribute to the design of efficient vector control strategies in the future.

scholarly journals Comparative dissection of the peripheral olfactory system of the Chagas disease vectors Rhodnius prolixus and Rhodnius brethesi

2021 ◽  
Author(s):  
Florencia Campetella ◽  
Rickard Ignell ◽  
Rolf Beutel ◽  
Bill S. Hansson ◽  
Silke Sachse
Keyword(s):  
Chagas Disease ◽  
Olfactory System ◽  
Control Strategies ◽  
Natural Habitat ◽  
Rhodnius Prolixus ◽  
Functional Study ◽  
Domestic Species ◽  
Olfactory Responses ◽  
Efficient Vector ◽  
Morphological Differences

American trypanosomiasis or Chagas disease is thought to be transmitted by both domestic and sylvatic species of Triatominae. These haematophagous insects use sensory cues to find their vertebrate hosts. Among them, odorants have been shown to play a key role. Previous work revealed morphological differences in the sensory apparatus of sylvatic and domestic species of Triatomines, but to date a functional study of the olfactory system is not available. After examining the antennal sensilla with scanning electronic microscopy (SEM), we compared olfactory responses of the domestic Rhodnius prolixus and the sylvatic Rhodnius brethesi with an electrophysiological approach. In electroantennogram (EAG) recordings, we first show that the antenna of R. prolixus shows high responses to carboxylic acids, compounds found in their habitat and headspace of hosts. We then compared responses from olfactory sensory neurons (OSNs) housed in the grooved peg sensilla of both species as these are tuned to these compounds using single-sensillum recordings (SSR). In R. prolixus , the SSR responses revealed a narrower tuning breath than its sylvatic counterpart, with the latter showing responses to a broader range of chemical classes. Additionally, we observed significant differences between these two species in their response to particular volatiles, such as amyl acetate and butyryl chloride. In summary, the closely related, but ecologically differentiated R. prolixus and R. brethesi display distinct differences in their olfactory functions. Considering the ongoing rapid destruction of the natural habitat of sylvatic species and likely shifts towards environments shaped by humans, we expect that our results will contribute to the design of efficient vector control strategies in the future.

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