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Medical and Veterinary Entomology Jun 2024Triatomines are haematophagous insects, some species are vectors of Trypanosoma cruzi, the aetiological agent of Chagas disease. The main strategy for interrupting T....
Triatomines are haematophagous insects, some species are vectors of Trypanosoma cruzi, the aetiological agent of Chagas disease. The main strategy for interrupting T. cruzi transmission is to avoid contact of the vector populations with humans. Volatiles from commercial essential oils are excellent candidates to serve as repellents of kissing bugs. We used an exposure device to assess the repellence effect of eight commercial essential oils on Triatoma pallidipennis. The most effective oils were blended and evaluated against T. infestans, T. pallidipennis and Rhodnius prolixus. The blend was also evaluated on parasitised T. pallidipennis. Data were compared with the commercial repellent NN-diethyl-3-methylbenzamide. We recorded the time the insects spent in the proximity of the host and determined if any of the evaluated oils served as kissing bug repellent. We found commercial essential oils and a blend that significantly reduced the time spent in the proximity of the host. The blend was effective for use by human males and females, repelling infected and non-infected insects. The study of essential oils as repellents of blood-sucking disease-vector insects could shed light on the development of new control strategies.
Topics: Animals; Insect Repellents; Oils, Volatile; Female; Male; Triatoma; Humans; Rhodnius; Insect Vectors; Chagas Disease
PubMed: 38006300
DOI: 10.1111/mve.12702 -
International Journal For Parasitology Mar 2024Vector species richness may drive the prevalence of vector-borne diseases by influencing pathogen transmission rates. The dilution effect hypothesis predicts that higher...
Vector species richness may drive the prevalence of vector-borne diseases by influencing pathogen transmission rates. The dilution effect hypothesis predicts that higher biodiversity reduces disease prevalence, but with inconclusive evidence. In contrast, the amplification effect hypothesis suggests that higher vector diversity may result in greater disease transmission by increasing and diversifying the transmission pathways. The relationship between vector diversity and pathogen transmission remains unclear and requires further study. Chagas disease is a vector-borne disease most prevalent in Brazil and transmitted by multiple species of insect vectors of the subfamily Triatominae, yet the drivers of spatial variation in its impact on human populations remain unresolved. We tested whether triatomine species richness, latitude, bioclimatic variables, human host population density, and socioeconomic variables predict Chagas disease mortality rates across over 5000 spatial grid cells covering all of Brazil. Results show that species richness of triatomine vectors is a good predictor of mortality rates caused by Chagas disease, which supports the amplification effect hypothesis. Vector richness and the impact of Chagas disease may also be driven by latitudinal components of climate and human socioeconomic factors. We provide evidence that vector diversity is a strong predictor of disease prevalence and give support to the amplification effect hypothesis.
Topics: Animals; Humans; Chagas Disease; Triatominae; Biodiversity; Insect Vectors; Climate; Trypanosoma cruzi
PubMed: 37944883
DOI: 10.1016/j.ijpara.2023.10.002 -
Acta Tropica Jan 2024The subfamily Triatominae includes a group of hematophagous insects, vectors of the parasite Trypanosoma cruzi, which is the etiological agent of Chagas disease, also...
The subfamily Triatominae includes a group of hematophagous insects, vectors of the parasite Trypanosoma cruzi, which is the etiological agent of Chagas disease, also known as American trypanosomiasis. Triatomines occur in the Old and New World and occupy diverse habitats including tropical and temperate areas. Some studies suggest the distributions of triatomines group into three or four regions. This study objectively determined bioregions focused specifically on New World Triatominae, using clustering and ordination analysis. We also identified indicator species by bioregion and investigated relationships among bioregions and environmental variables using redundancy analysis and multivariate regression trees. We delineated seven bioregions specific to Triatominae and linked each with indicator species. This result suggests more biogeographical structure exists than was revealed in earlier studies that were more general, subjective, and based on older taxonomic and distributional information. Precipitation, elevation, and vegetation were important variables in the delimitating bioregions. This implies that more detailed study of how these factors influence triatomine distributions could benefit understanding of how Chagas disease is spread.
Topics: Animals; Triatominae; Insect Vectors; Chagas Disease; Trypanosoma cruzi; Ecosystem
PubMed: 37944838
DOI: 10.1016/j.actatropica.2023.107063 -
Epidemics Dec 2023Infection with Trypanosoma cruzi, etiological agent of Chagas disease, is common in US government working dogs along the US-Mexico border. This 3145 km long border...
Infection with Trypanosoma cruzi, etiological agent of Chagas disease, is common in US government working dogs along the US-Mexico border. This 3145 km long border comprises four states: Texas (TX), New Mexico (NM), Arizona (AZ) and California (CA) with diverse ecosystems and several triatomine (a.k.a., kissing bug) species, primary vectors of T. cruzi in this region. The kissing bug (Heteroptera: Reduviidae) community ranging from CA to TX includes Triatoma protracta (Uhler), Triatoma recurva (Stål) and Triatoma rubida (Uhler) and becomes dominated by Triatoma gerstaeckeri Stål in TX. Here, we ask if T. cruzi infection dynamics in dogs varies along this border region, potentially reflecting changes in vector species and their vectorial capacity. Using reversible catalytic models of infection, where seropositivity can be lost, we estimated an R (Estimate ± S.E.) of 1.192 ± 0.084 for TX and NM. In contrast, seropositivity decayed to zero as dogs aged in AZ and CA. These results suggest that dogs are likely infected by T. cruzi during their training in western TX, with a force of infection large enough for keeping R above 1, i.e., the disease endemically established, in TX and NM. In AZ and CA, a lower force of infection, probably associated with different vector species communities and associated vectorial capacity and/or different lineages of T. cruzi, results in dogs decreasing their seropositivity with age.
Topics: Animals; Dogs; Mexico; Ecosystem; Insect Vectors; Chagas Disease; Triatoma
PubMed: 37935075
DOI: 10.1016/j.epidem.2023.100723 -
The American Journal of Tropical... Dec 2023Vector-borne diseases continue to impose a major health burden on Peru and neighboring countries. The challenge of addressing vector-borne disease is compounded by...
Vector-borne diseases continue to impose a major health burden on Peru and neighboring countries. The challenge of addressing vector-borne disease is compounded by changing social, economic, and climatic conditions. Peri-urban Arequipa is an important region to study insect infestations because of ongoing challenges with disease vectors such as triatomines and a variety of other insects. We conducted surveys (N = 1,182) and seven focus groups (average seven participants) in peri-urban Arequipa to explore knowledge of and perception toward various insects that infest the region. Focus group participants reported the presence of a wide variety of insects in and around the home, including disease vectors such as triatomines (also identified by 27.2% of survey households), mosquitoes, spiders, and bed bugs, as well as nuisance insects. Health concerns related to insects included vector-borne diseases, spider bites, allergies, and sequelae from bed bug bites, and hygiene concerns. A majority of participants in the quantitative surveys identified triatomines as the insect they were most worried about (69.9%) and could identify Chagas disease as a health risk associated with triatomines (54.9%). Insect infestations in peri-urban Arequipa present multiple burdens to residents, including injury and illness from triatomines and other insects, as well as potential mental and economic concerns related to insects such as bed bugs. Future initiatives should continue to address triatomine infestations through educational outreach and implement a more holistic approach to address the burden of both disease and nuisance insects.
Topics: Animals; Humans; Peru; Mosquito Vectors; Chagas Disease; Triatoma; Insecta; Trypanosoma cruzi
PubMed: 37931314
DOI: 10.4269/ajtmh.23-0266 -
ZooKeys 2023and its type species (Hemiptera: Heteroptera: Reduviidae: Harpactorinae) from Yunnan, China, are described and illustrated. A key to separate the new genus and its...
and its type species (Hemiptera: Heteroptera: Reduviidae: Harpactorinae) from Yunnan, China, are described and illustrated. A key to separate the new genus and its closely related genera is provided.
PubMed: 37900705
DOI: 10.3897/zookeys.1182.108219 -
Acta Tropica Jan 2024Puya alpestris, P. berteroniana and P. chilensis (Bromeliaceae) are terrestrial plants present in north-central Chile, considered important part of the shrub flora due...
Puya alpestris, P. berteroniana and P. chilensis (Bromeliaceae) are terrestrial plants present in north-central Chile, considered important part of the shrub flora due to their abundance and close interaction with animals. A previous study showed that bromeliad cover positively correlates with the abundance of the sylvatic triatomine vector Mepraia spinolai, only when infected by the protozoan Trypanosoma cruzi, the etiological agent of Chagas disease. Here, we assessed the biological interactions and abiotic conditions provided by these Puya species to M. spinolai. During the austral summers of 2015 and 2016, we sampled 17 sites with presence of M. spinolai colonies. In each site, we estimated the presence of bromeliad and its cover proportion, and placed a camera trap for three months near a M. spinolai colony to record the vertebrates potentially interacting with this triatomine. Three of the camera traps were placed right in front of M. spinolai-colonized bromeliads. At the same time, triatomines present under these bromeliads were collected to assess their blood meal by Next Generation Sequencing. Between July 2017 and January 2018, we examined the abiotic conditions (temperature and humidity) under bromeliad, under rocks and at ground level. We detected 40 vertebrate species associated to Puya spp. (18 birds, 16 mammals, and 6 reptiles). Puya spp. are a resource for keystone species in T. cruzi sylvatic transmission, including small mammals (Octodon degus, Phyllotis darwini) and lizard species (Liolaemus spp.), detecting a positive association between bromeliad presence and availability of reptiles and non-domestic mammals. Native rodents and humans were the most represented vertebrates in the diet of M. spinolai collected under bromeliads. Temperatures were more stable under bromeliad, showing lower amplitude (up to 14.3 °C) compared to under rocks (23.7 °C) or at ground level (49.6 °C). Bromeliads present in the semiarid-Mediterranean ecosystem provide feeding opportunities for triatomines, and act as buffer of abiotic conditions reducing daily thermal amplitude. The presence of bromeliads near human settlements should be carefully monitored, especially because their leaves are consumed by people and browsed by livestock present in endemic areas of Chagas disease.
Topics: Animals; Humans; Ecosystem; Triatominae; Chagas Disease; Trypanosoma cruzi; Rodentia; Mammals; Octodon; Lizards
PubMed: 37898478
DOI: 10.1016/j.actatropica.2023.107053 -
Parasites & Vectors Oct 2023Hybridization events between Triatoma spp. have been observed under both natural and laboratory conditions. The ability to produce hybrids can influence different...
First evidence of gonadal hybrid dysgenesis in Chagas disease vectors (Hemiptera, Triatominae): gonad atrophy prevents events of interspecific gene flow and introgression.
BACKGROUND
Hybridization events between Triatoma spp. have been observed under both natural and laboratory conditions. The ability to produce hybrids can influence different aspects of the parent species, and may even result in events of introgression, speciation and extinction. Hybrid sterility is caused by unviable gametes (due to errors in chromosomal pairing [meiosis]) or by gonadal dysgenesis (GD). All of the triatomine hybrids analyzed so far have not presented GD. We describe here for the first time GD events in triatomine hybrids and highlight these taxonomic and evolutionary implications of these events.
METHODS
Reciprocal experimental crosses were performed between Triatoma longipennis and Triatoma mopan. Intercrosses were also performed between the hybrids, and backcrosses were performed between the hybrids and the parent species. In addition, morphological and cytological analyzes were performed on the atrophied gonads of the hybrids.
RESULTS
Hybrids were obtained only for the crosses T. mopan♀ × T. longipennis♂. Intercrosses and backcrosses did not result in offspring. Morphological analyses of the male gonads of the hybrids confirmed that the phenomenon that resulted in sterility of the hybrid was bilateral GD (the gonads of the hybrids were completely atrophied). Cytological analyses of the testes of the hybrids also confirmed GD, with no germ cells observed (only somatic cells, which make up the peritoneal sheath).
CONCLUSIONS
The observations made during this study allowed us to characterize, for the first time, GD in triatomines and demonstrated that gametogenesis does not occur in atrophied gonads. The characterization of GD in male hybrids resulting from the crossing of T. mopan♀ × T. longipennis♂ highlights the importance of evaluating both the morphology and the cytology of the gonads to confirm which event resulted in the sterility of the hybrid: GD (which results in no gamete production) or meiotic errors (which results in non-viable gametes).
Topics: Male; Animals; Triatominae; Gene Flow; Chagas Disease; Triatoma; Gonads; Hybridization, Genetic; Infertility; Gonadal Dysgenesis; Disease Vectors
PubMed: 37891624
DOI: 10.1186/s13071-023-06006-6 -
Biology Sep 2023Species in Ectrichodiinae are known for their prey specialization on millipedes. However, knowledge of the morphological adaptations to this unique feeding habit was...
Species in Ectrichodiinae are known for their prey specialization on millipedes. However, knowledge of the morphological adaptations to this unique feeding habit was limited. In the current study, we examined the microstructures of the antennae, mouthparts, and legs of four millipede feeding ectrichodiines, (Thunberg, 1888), Miller, 1953, (Stål, 1863), and (Taueber, 1930), and compared them with those of three species of tribelocephalines, a group closely related to Ectrichodiinae. On the antennae, we found four types of antennal sensilla. On the mouthparts, we recognized four types of labial sensilla. Sampled ectrichodiines have distinctly more and denser slightly transverse ridges on the external side of mandibles than tribelocephalines. and possess numerous small papillae fringed with densely arranged finger-print-like grains on the trochanter and femur; these probably facilitate the immobilization of prey. Overall, our study illustrates, at a microstructural level, the remarkable morphological adaption of prey manipulation in ectrichodiine, and has enhanced our understanding about stenophagy in the family Reduviidae.
PubMed: 37887009
DOI: 10.3390/biology12101299 -
Medical and Veterinary Entomology Mar 2024The hematophagous insect Mepraia spinolai (Hemiptera: Reduviidae: Triatominae) is naturally infected with the protozoan parasite Trypanosoma cruzi, the agent of Chagas...
The hematophagous insect Mepraia spinolai (Hemiptera: Reduviidae: Triatominae) is naturally infected with the protozoan parasite Trypanosoma cruzi, the agent of Chagas disease in humans. In this study, we compared the demographic parameters of M. spinolai with and without T. cruzi infection. We collected the immature life table data of 479 M. spinolai individuals of control cohort (reared on mice without T. cruzi infection) and 563 M. spinolai individuals of treatment cohort (reared on mice with T. cruzi infection). Nymphs were maintained in individual compartments inside a growth chamber (26°C; 65-75%) until adult emergence; moulting and survival were recorded daily. For the adult life table study of the control, we used 24 pairs of adults from the control cohort. For the adult life table study of T. cruzi-infected cohort, 25 infected females were paired with 25 males from the control cohort. Life table data were analysed using bootstrap-match technique based on the age-stage, two-sex life table. The preadult survival rate (0.5282) of the control cohort was significantly higher than that of the infected cohort (0.2913). However, the mean fecundity of reproductive females (F = 22.29 eggs/♀) and net reproductive rate of population (R = 5.07 offspring/individual) of the 0.5th percentile bootstrap-match control cohort were not significantly different from those of the infected cohort (F = 23.35 eggs/♀, R = 3.77 offspring/individual). Due to the shorter total preoviposition period and higher proportion of reproductive female, the intrinsic rate of increase (r = 0.0053 d ) and finite rate of increase (λ = 1.0053 d ) of control cohort of M. spinolai were significantly higher than those of the T. cruzi-infected cohort (r = 0.0035 d , λ = 1.0035 d ). These results suggest that T. cruzi infection reduces the population fitness of the Chagas disease vector M. spinolai.
Topics: Humans; Male; Female; Animals; Mice; Genetic Fitness; Insect Vectors; Chagas Disease; Triatominae; Trypanosoma cruzi; Rodent Diseases
PubMed: 37877753
DOI: 10.1111/mve.12700