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PeerJ 2023In defensive mimicry, resemblance between unequally defended species can be parasitic; this phenomenon has been termed quasi-Batesian mimicry. Few studies have used real...
In defensive mimicry, resemblance between unequally defended species can be parasitic; this phenomenon has been termed quasi-Batesian mimicry. Few studies have used real co-mimics and their predators to test whether the mimetic interactions were parasitic. Here, we investigated the mimetic interaction between two well-defended insect species, the bombardier beetle (Coleoptera: Carabidae) and the assassin bug (Hemiptera: Reduviidae), using their potential predator, the pond frog (Anura: Ranidae), which coexists with these insect species in the same habitat in Japan. We observed behavioural responses of this frog species (adults and juveniles) to adult . and adult . under laboratory conditions. Among the frogs, 100% and 75% rejected . and . , respectively, suggesting that, compared with the assassin bug . , the bombardier beetle . is more well-defended against frogs. An assassin bug or a bombardier beetle was provided to a frog that had encountered the other insect species. Frogs with a history of assassin bug encounter demonstrated a lower rate of attack toward bombardier beetles. Similarly, frogs with a history of bombardier beetle encounter demonstrated a lower rate of attack toward assassin bugs. Therefore, both the bombardier beetle . and the assassin bug . benefit from the mimetic interaction.
Topics: Animals; Insecta; Coleoptera; Triatoma; Biological Mimicry; Anura
PubMed: 37304866
DOI: 10.7717/peerj.15380 -
Parasites & Vectors Dec 2019The identification of Trypanosoma cruzi and blood-meal sources in synanthropic triatomines is important to assess the potential risk of Chagas disease transmission. We...
BACKGROUND
The identification of Trypanosoma cruzi and blood-meal sources in synanthropic triatomines is important to assess the potential risk of Chagas disease transmission. We identified T. cruzi infection and blood-meal sources of triatomines caught in and around houses in the state of Bahia, northeastern Brazil, and mapped the occurrence of infected triatomines that fed on humans and domestic animals.
METHODS
Triatominae bugs were manually captured by trained agents from the Epidemiologic Surveillance team of Bahia State Health Service between 2013 and 2014. We applied conventional PCR to detect T. cruzi and blood-meal sources (dog, cat, human and bird) in a randomized sample of triatomines. We mapped triatomine distribution and analyzed vector hotspots with kernel density spatial analysis.
RESULTS
In total, 5906 triatomines comprising 15 species were collected from 127 out of 417 municipalities in Bahia. The molecular analyses of 695 triatomines revealed a ~10% T. cruzi infection rate, which was highest in the T. brasiliensis species complex. Most bugs were found to have fed on birds (74.2%), and other blood-meal sources included dogs (6%), cats (0.6%) and humans (1%). Trypanosoma cruzi-infected triatomines that fed on humans were detected inside houses. Spatial analysis showed a wide distribution of T. cruzi-infected triatomines throughout Bahia; triatomines that fed on dogs, humans, and cats were observed mainly in the northeast region.
CONCLUSIONS
Synanthropic triatomines have a wide distribution and maintain the potential risk of T. cruzi transmission to humans and domestic animals in Bahia. Ten species were recorded inside houses, mainly Triatoma sordida, T. pseudomaculata, and the T. brasiliensis species complex. Molecular and spatial analysis are useful to reveal T. cruzi infection and blood-meal sources in synanthropic triatomines, identifying areas with ongoing threat for parasite transmission and improving entomological surveillance strategies.
Topics: Animals; Animals, Domestic; Brazil; Cats; Dogs; Feeding Behavior; Humans; Insect Vectors; Triatominae; Trypanosoma cruzi
PubMed: 31878960
DOI: 10.1186/s13071-019-3849-1 -
Mathematical Biosciences and... Jun 2022In this paper, an insect-parasite-host model with logistic growth of triatomine bugs is formulated to study the transmission between hosts and vectors of the Chagas...
In this paper, an insect-parasite-host model with logistic growth of triatomine bugs is formulated to study the transmission between hosts and vectors of the Chagas disease by using dynamical system approach. We derive the basic reproduction numbers for triatomine bugs and as two thresholds. The local and global stability of the vector-free equilibrium, parasite-free equilibrium and parasite-positive equilibrium is investigated through the derived two thresholds. Forward bifurcation, saddle-node bifurcation and Hopf bifurcation are proved analytically and illustrated numerically. We show that the model can lose the stability of the vector-free equilibrium and exhibit a supercritical Hopf bifurcation, indicating the occurrence of a stable limit cycle. We also find it unlikely to have backward bifurcation and Bogdanov-Takens bifurcation of the parasite-positive equilibrium. However, the sustained oscillations of infected vector population suggest that will persist in all the populations, posing a significant challenge for the prevention and control of Chagas disease.
Topics: Animals; Chagas Disease; Disease Vectors; Rhodnius; Trypanosoma cruzi; Trypanosoma rangeli
PubMed: 35801473
DOI: 10.3934/mbe.2022393 -
Journal of Visualized Experiments : JoVE Apr 2018Heteropteran insects such as assassin bugs (Reduviidae) and giant water bugs (Belostomatidae) descended from a common predaceous and venomous ancestor, and the majority...
Heteropteran insects such as assassin bugs (Reduviidae) and giant water bugs (Belostomatidae) descended from a common predaceous and venomous ancestor, and the majority of extant heteropterans retain this trophic strategy. Some heteropterans have transitioned to feeding on vertebrate blood (such as the kissing bugs, Triatominae; and bed bugs, Cimicidae) while others have reverted to feeding on plants (most Pentatomomorpha). However, with the exception of saliva used by kissing bugs to facilitate blood-feeding, little is known about heteropteran venoms compared to the venoms of spiders, scorpions and snakes. One obstacle to the characterization of heteropteran venom toxins is the structure and function of the venom/labial glands, which are both morphologically complex and perform multiple biological roles (defense, prey capture, and extra-oral digestion). In this article, we describe three methods we have successfully used to collect heteropteran venoms. First, we present electrostimulation as a convenient way to collect venom that is often lethal when injected into prey animals, and which obviates contamination by glandular tissue. Second, we show that gentle harassment of animals is sufficient to produce venom extrusion from the proboscis and/or venom spitting in some groups of heteropterans. Third, we describe methods to harvest venom toxins by dissection of anaesthetized animals to obtain the venom glands. This method is complementary to other methods, as it may allow harvesting of toxins from taxa in which electrostimulation and harassment are ineffective. These protocols will enable researchers to harvest toxins from heteropteran insects for structure-function characterization and possible applications in medicine and agriculture.
Topics: Animals; Insecta; Reduviidae; Toxins, Biological; Venoms
PubMed: 29733320
DOI: 10.3791/57729 -
Biology Letters Apr 2023Tool-use in animals is a complex and rare phenomenon, particularly in insects. Tool-use in assassin bugs has been suggested as several species apply adhesive plant...
Tool-use in animals is a complex and rare phenomenon, particularly in insects. Tool-use in assassin bugs has been suggested as several species apply adhesive plant resins to their body, which has been hypothesized to function in enhancing prey capture. Here, we staged predatory interactions of resin-deprived and resin-equipped assassin bugs ( sp.) and discovered that applying resin as a tool conveys a clear predatory advantage to the assassin bugs. sp. can thus be considered a tool-user, and since this behaviour was present in all individuals, including newly hatched nymphs, tool-use can be considered to be stereotyped. Our study, along with others, suggests that, when compared with other insects, tool-use is disproportionately common within the assassin bugs.
Topics: Animals; Reduviidae; Insecta; Predatory Behavior; Resins, Plant; Nymph
PubMed: 37122198
DOI: 10.1098/rsbl.2022.0608 -
Revista Da Sociedade Brasileira de... 2021Chagas disease is a health problem that affects approximately 7 million people worldwide, according to the World Health Organization. Vector transmission is one of the...
INTRODUCTION
Chagas disease is a health problem that affects approximately 7 million people worldwide, according to the World Health Organization. Vector transmission is one of the most important routes in South and Central American countries. Between 2013 and 2019, municipalities of Sergipe sent 507 triatomines for analysis, unveiling the largest records found in the south in the villages of Poço da Clara, Alagoinhas and Pilões, and the municipality of Tobias Barreto. The high prevalence of infected vectors in these localities motivated this epidemiological study.
METHODS
After educational lectures on the vectors and risks of the disease, a structured questionnaire was administered to identify areas and risk factors for transmission of the parasite. The data guided the collection of vectors and blood samples from domestic reservoirs.
RESULTS
The studied region is considered endemic for triatomines infected by Trypanosoma cruzi with three species of vectors; the highest prevalence was Panstrongylus lutzi (54.83%), followed by Triatoma pseudomaculata (43.54%), and Triatoma tibiamaculata (1.61%). In the villages in this study, 100% of the vectors were found intradomically. The coexistence of residents with domestic animals was reported by 62.04% (255) of those surveyed. Forty-one small animals that were actively living with humans at home in the localities were evaluated serologically. No infection was observed in the domestic animals.
CONCLUSIONS
There are favorable conditions for the domiciliation of triatomines in the evaluated locations, contributing to the risk of vectorial transmission of Chagas disease.
Topics: Animals; Chagas Disease; Humans; Insect Vectors; Panstrongylus; Triatoma; Trypanosoma cruzi
PubMed: 33886818
DOI: 10.1590/0037-8682-0740-2020 -
PLoS Neglected Tropical Diseases Nov 2017Large spatial and temporal fluctuations in the population density of living organisms have profound consequences for biodiversity conservation, food production, pest...
BACKGROUND
Large spatial and temporal fluctuations in the population density of living organisms have profound consequences for biodiversity conservation, food production, pest control and disease control, especially vector-borne disease control. Chagas disease vector control based on insecticide spraying could benefit from improved concepts and methods to deal with spatial variations in vector population density.
METHODOLOGY/PRINCIPAL FINDINGS
We show that Taylor's law (TL) of fluctuation scaling describes accurately the mean and variance over space of relative abundance, by habitat, of four insect vectors of Chagas disease (Triatoma infestans, Triatoma guasayana, Triatoma garciabesi and Triatoma sordida) in 33,908 searches of people's dwellings and associated habitats in 79 field surveys in four districts in the Argentine Chaco region, before and after insecticide spraying. As TL predicts, the logarithm of the sample variance of bug relative abundance closely approximates a linear function of the logarithm of the sample mean of abundance in different habitats. Slopes of TL indicate spatial aggregation or variation in habitat suitability. Predictions of new mathematical models of the effect of vector control measures on TL agree overall with field data before and after community-wide spraying of insecticide.
CONCLUSIONS/SIGNIFICANCE
A spatial Taylor's law identifies key habitats with high average infestation and spatially highly variable infestation, providing a new instrument for the control and elimination of the vectors of a major human disease.
Topics: Animals; Chagas Disease; Ecosystem; Humans; Insect Control; Insect Vectors; Models, Theoretical; Spatio-Temporal Analysis; Triatoma
PubMed: 29190728
DOI: 10.1371/journal.pntd.0006092 -
Genetics May 2022Pigmentation in insects has been linked to mate selection and predator evasion, thus representing an important aspect for natural selection. Insect body color is...
Pigmentation in insects has been linked to mate selection and predator evasion, thus representing an important aspect for natural selection. Insect body color is classically associated to the activity of tyrosine pathway enzymes, and eye color to pigment synthesis through the tryptophan and guanine pathways, and their transport by ATP-binding cassette proteins. Among the hemiptera, the genetic basis for pigmentation in kissing bugs such as Rhodnius prolixus, that transmit Chagas disease to humans, has not been addressed. Here, we report the functional analysis of R. prolixus eye and cuticle pigmentation genes. Consistent with data for most insect clades, we show that knockdown for yellow results in a yellow cuticle, while scarlet and cinnabar knockdowns display red eyes as well as cuticle phenotypes. In addition, tyrosine pathway aaNATpreto knockdown resulted in a striking dark cuticle that displays no color pattern or UV reflectance. In contrast, knockdown of ebony and tan, that encode N-beta-alanyl dopamine hydroxylase branch tyrosine pathway enzymes, did not generate the expected dark and light brown phenotypes, respectively, as reported for other insects. We hypothesize that R. prolixus, which requires tyrosine pathway enzymes for detoxification from the blood diet, evolved an unusual strategy for cuticle pigmentation based on the preferential use of a color erasing function of the aaNATpreto tyrosine pathway branch. We also show that genes classically involved in the generation and transport of eye pigments regulate red body color in R. prolixus. This is the first systematic approach to identify the genes responsible for the generation of color in a blood-feeding hemiptera, providing potential visible markers for future transgenesis.
Topics: Animals; Pigmentation; Rhodnius; Tyrosine
PubMed: 35445704
DOI: 10.1093/genetics/iyac064 -
Current Opinion in Insect Science Aug 2018Citizen-collected arthropod vectors are useful for epidemiological studies of vector-borne disease, especially since the vectors encountered by the public are the subset... (Review)
Review
Citizen-collected arthropod vectors are useful for epidemiological studies of vector-borne disease, especially since the vectors encountered by the public are the subset of vectors in nature that have a disproportionate impact on health. Programs integrating educational efforts with collecting efforts may be particularly effective for public health initiatives, resulting in an empowered public with knowledge of vector-borne disease prevention. Citizen science programs have been successfully implemented for the collection of unprecedented sample sets of mosquitos, ticks, and triatomines. Cyber infrastructure employed in digital epidemiology-including websites, email, mobile phone apps, and social media platforms-has facilitated vector citizen science initiatives to assess disease risk over vast spatial and temporal scales, advancing research to mitigate vector-borne disease risk.
Topics: Animals; Arthropod Vectors; Community Participation; Culicidae; Ticks; Triatominae
PubMed: 30551774
DOI: 10.1016/j.cois.2018.05.005 -
Memorias Do Instituto Oswaldo Cruz May 2015This review deals with transmission of Trypanosoma cruzi by the most important domestic vectors, blood transfusion and oral intake. Among the vectors, Triatoma... (Review)
Review
This review deals with transmission of Trypanosoma cruzi by the most important domestic vectors, blood transfusion and oral intake. Among the vectors, Triatoma infestans, Panstrongylus megistus, Rhodnius prolixus, Triatoma dimidiata, Triatoma brasiliensis, Triatoma pseudomaculata, Triatoma sordida, Triatoma maculata, Panstrongylus geniculatus, Rhodnius ecuadoriensis and Rhodnius pallescens can be highlighted. Transmission of Chagas infection, which has been brought under control in some countries in South and Central America, remains a great challenge, particularly considering that many endemic countries do not have control over blood donors. Even more concerning is the case of non-endemic countries that receive thousands of migrants from endemic areas that carry Chagas disease, such as the United States of America, in North America, Spain, in Europe, Japan, in Asia, and Australia, in Oceania. In the Brazilian Amazon Region, since Shaw et al. (1969) described the first acute cases of the disease caused by oral transmission, hundreds of acute cases of the disease due to oral transmission have been described in that region, which is today considered to be endemic for oral transmission. Several other outbreaks of acute Chagas disease by oral transmission have been described in different states of Brazil and in other South American countries.
Topics: Animals; Chagas Disease; Disease Reservoirs; Food Parasitology; Humans; Insect Vectors; Transfusion Reaction; Triatominae
PubMed: 25466622
DOI: 10.1590/0074-0276140362