Ecological interactions of Triatoma sanguisuga (Hemiptera: Reduviidae) and risk for human infection with Trypanosoma cruzi (Kinetoplastida: Trypanosomatidae) in Illinois and Louisiana.

Triatoma sanguisuga (Leconte) is one of the most widely distributed kissing bugs in the United States, associated with an extensive zoonotic circulation of Trypanosoma cruzi, the agent of Chagas disease, in a large part of the country. However, the actual risk for human infection in the United States is poorly understood. Here, we further assessed the ecology of T. sanguisuga bugs collected in residents' houses in Illinois and Louisiana, using a metagenomic approach to identify their blood-feeding sources, T. cruzi parasites and gut microbiota. Blood meal analysis revealed feeding on domestic animals (dogs, cats, pigs, goats, and turkeys), synanthropic species (raccoons, opossums, and squirrels), as well as the more sylvatic white-tail deer. Human blood was identified in 11/14 (78%) of bugs, highlighting a frequent vector-human contact. The infection rate with T. cruzi was 53% (8/15), and most infected bugs (6/8) had fed on humans. A total of 41 bacterial families were identified, with significant differences in microbiota alpha and beta diversity between bugs from Louisiana and Illinois. However, predicted metabolic functions remained highly conserved, suggesting important constraints to fulfill their role in bug biology. These results confirmed a significant risk for vector-borne transmission of T. cruzi to humans in Louisiana and Illinois, which warrants more active screening for human infections. Also, while there is broad plasticity in the bacterial composition of T. sanguisuga microbiota, there are strong constraints to preserve metabolic profile and function, making it a good target for novel vector control strategies.

Dataset of assembly and annotation of the mitogenomes of Triatoma dimidiata and Triatoma huehuetenanguensis captured from Yucatán, México.

Triatoma dimidiata is a species complex, and its members are responsible for the transmission of Trypanosoma cruzi, the causative agent of Chagas disease. We present the assembly and annotation of the mitogenome of the Triatoma dimidiata (Latreille, 1811) and Triatoma huehuetenanguensis Lima-Cordón & Justi, 2019. The mitochondrial genomes were successfully sequenced using the Illumina Nextseq 500 platform, 2×75 cycles, and 5 million reads per sample. Contigs were assembled and annotated using the reference genomes of T. dimidiata and T. huehuetenanguensis available in Genbank (NC_002609 and NC_050325.1, respectively). The mitogenomes of T. dimidiata have lengths of 17,008 bp, while those of T. huehuetenanguensis are 15,910 bp and 15,909 bp. The genome comprises 13 protein-coding genes, 22 transfer RNA genes, two ribosomal RNA genes, and a control region. The mitogenomes will be valuable to scholars and students focused on integrative taxonomy, phylogeography, and evolutionary studies of the Triatoma dimidiata complex and the transmission of Chagas diseases.

Vector species richness predicts local mortality rates from Chagas disease.

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.

What is behind the success of terrestrial bromeliads as microhabitat for the sylvatic triatomine Mepraia spinolai?

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.

Integrated pest management strategies targeting the Florida kissing bug, Triatoma sanguisuga: Preventing this vector of Chagas disease from invading your home.

Triatomines (Hemiptera: Reduviidae: Triatominae), commonly called "kissing bugs", are blood-sucking pests and vectors of the protozoan parasite Trypanosoma cruzi, the causative agent of Chagas disease (CD). Eleven species of kissing bugs occur throughout the southern half of the USA, four of which are well known to invade human dwellings. Certain kissing bugs in the USA are known to transmit T. cruzi to humans and other animals and their bites can also lead to serious allergic reactions, including anaphylaxis. In Florida, the kissing bug Triatoma sanguisuga frequently invades homes, bites residents, and has been found infected with T. cruzi, placing humans and companion animals at risk for CD. This review outlines integrated pest management (IPM) strategies for minimizing human exposure to T. sanguisuga and CD. A comprehensive IPM plan for kissing bugs includes detailed inspections, removal of vertebrate host nesting areas, and kissing bug harborage, home improvements to exclude kissing bugs from entering structures, pest removal, and judicious use of pesticides. This approach can limit or eliminate kissing bug entry into residential structures, thereby preventing kissing bug bites, and CD infections in humans and companion animals.

Corticotropin-releasing factor-like diuretic hormone acts as a gonad-inhibiting hormone in adult female, Rhodnius prolixus.

Within insects, corticotropin-releasing factor/diuretic hormones (CRF/DHs) are responsible for the modulation of a range of physiological and behavioural processes such as feeding, diuresis, and reproduction. Rhopr-CRF/DH plays a key role in feeding and diuresis in Rhodnius prolixus, a blood-gorging insect and a vector for human Chagas disease. Here, we extend our understanding on the role of this neurohormone in reproduction in adult female R. prolixus. Double-label immunohistochemistry displays co-localized staining of CRF-like and the glycoprotein hormone (GPA2/GPB5) subunit GPB5-like immunoreactivity in the same neurosecretory cells (NSCs) in the mesothoracic ganglionic mass (MTGM) and in their neurohemal sites in adult female R. prolixus, suggesting these peptides could work together to regulate physiological processes. qPCR analysis reveals that the transcript for Rhopr-CRF/DH receptor 2 (Rhopr-CRF/DH-R2) is expressed in reproductive tissues and fat body (FB) in adult female R. prolixus, and its expression increases post blood meal (PBM), a stimulus that triggers diuresis and reproduction. Using RNA interference, transcript expression of Rhopr-CRF/DH-R2 was knocked down, and egg production monitored by examining the major yolk protein, vitellogenin (Vg), the number and quality of eggs laid, and their hatching ratio. Injection of dsCRFR2 into adult females reduces Rhopr-CRF/DH-R2 transcript expression, accelerates oogenesis, increases the number of eggs produced, and reduces hatching rate in female R. prolixus. Downregulation of Rhopr-CRF/DH-R2 leads to an increase in the transcript expression of RhoprVg1 in the fat body and ovaries, and increases the transcript level for the Vg receptor, RhoprVgR, in the ovaries. A significant increase in Vg content in the fat body and in the hemolymph is also observed. Incubation of isolated tissues with Rhopr-CRF/DH leads to a significant decrease in transcript expression of RhoprVg1 in the fat body and RhoprVg1 in the ovaries. In addition, Rhopr-CRF/DH reduces transcript expression of the ecdysteroid biosynthetic enzymes and reduces ecdysteroid titer in the culture medium containing isolated ovaries. These results suggest the involvement of the CRF-signaling pathway in reproduction, and that Rhopr-CRF/DH acts as a gonad-inhibiting hormone in the adult female R. prolixus, as previously shown for the colocalized glycoprotein, GPA2/GPB5.

Triatominae (Hemiptera: Reduviidae) fauna in bird nests: the case of Morrinhos, Ceará, Brazil.

Triatominae are associated with various Brazilian habitats, including bird nests, animal burrows, and peridomestic structures. Despite extensive studies on triatomines in domiciliary environments in Ceará, Brazil, there has been limited research on their presence in the wild. This study focuses on the municipality of Morrinhos in Ceará, which is characterized by a Caatinga biome and riparian forests along the Acaraú River. During the study, a total of 185 nests of Pseudoseisura cristata were analyzed in rural locations and triatomines were collected in 26 nests from 12 different locations. A total of 117 triatomines was collected, belonging to three species: Psammolestes tertius, Rhodnius nasutus, and Triatoma pseudomaculata. Rhodnius nasutus was the only species found in a nest inhabited by Didelphis albiventris. Nests of P. cristata serve as shelters for various animals, providing an ideal environment for triatomines to establish colonies due to their proximity to food sources and their generalist feeding habits. The incorporation of anthropogenic materials by birds in nest construction can indirectly affect the presence of other animals that may serve as food sources for triatomines. Understanding the interactions between triatomines, birds, and their habitats is essential for assessing the risks associated with triatomine infestation in wild ecosystems.

Detection of Bartonella in kissing bugs Triatoma rubrofasciata collected from Huizhou City, South China.

Background: The blood-feeding behavior of kissing bugs (subfamily Triatominae, family Reduviidae, order Hemiptera) means they are potential vectors of multiple humans pathogens. However, investigations of vector-borne pathogens harbored by kissing bugs are rare. Methods: In the current study, 22 adult kissing bugs (Triatoma rubrofasciata) were captured in Huizhou City, Guangdong Province, south China. The presence of vector-borne pathogens in the kissing bugs was tested, and the genetic diversity of these potential pathogens was investigated. Results: All the kissing bugs were negative for Anaplasmataceae bacteria, Rickettsia, and Coxiella. Bartonella DNA was detected in 36.4% (8/22) of the kissing bugs. The sequences of the Bartonella gltA genes divided into two clades in a phylogenetic tree, with close relationships to B. tribocorum and uncultured Bartonella sp. clone MYR-283, respectively. All the groEL sequences were closely related to those of B. kosoyi (identity 98.75%-100%). The ftsZ and rpoB sequences were most closely related to those of B. elizabethae, a recognized human pathogen, with nucleotide similarities of 98.70%-100% and 99.45%-100%, respectively. Conclusions: We report the detection of Bartonella DNA in Triatoma kissing bugs in southern China. Although the sample size is limited, the high positive rate of detection of Bartonella DNA, the close relationship of the gene sequences to those of zoonotic Bartonella species, and the distribution of the kissing bugs near human residences, hint at a risk to public health.

Eugenol and menthol synergize the toxicity of permethrin in the blood-sucking bug, Triatoma infestans.

The blood-sucking bug, Triatoma infestans, is one of the main vectors of Chagas disease in America. It is usually controlled with pyrethroids, but the emergence of resistance to these insecticides creates the need to look for alternative products. Eugenol, menthol and menthyl acetate are botanical monoterpenes, which produce lethal and sublethal effects on insects. The purpose of this work was to determine what type of toxicological interactions occur when binary mixtures, formed by the pyrethroid permethrin and sublehtal doses of eugenol, menthol or menthyl acetate, are applied to T. infestans. First instar nymphs were exposed to filter papers impregnated with the insecticides. The number of knocked down insects was registered at different times and Knock Down Time 50% (KT50) values were calculated. The following KT50 values with their corresponding 95% Confidence Intervals were obtained: permethrin, 47.29 (39.92 - 56.32) min; permethrin + eugenol, 34.08 (29.60 - 39.01) min; permethrin + menthol, 27.54 (23.28 - 32.55) min; permethrin + menthyl acetate, 43.62 (39.99 - 47.59) min. Eugenol and menthol increased the speed of action of permethrin (synergism), but menthyl acetate had no effect on it (additivity). These results provide the basis to further explore interactions between conventional insecticides and plant monoterpenes as potential tools for controlling T. infestans.

Natural Trypanosoma cruzi Infection and Climatic Season Influence the Developmental Capacity in Field-Caught Mepraia spinolai Nymphs.

In this study, we evaluated the effect of the climatic season and infection by Trypanosoma cruzi, etiological agent of Chagas disease, on the molting capacity of the triatomine vector Mepraia spinolai endemic to Chile. We used wild-caught first-to-fourth instar nymphs during cooling (fall and winter) and warming (spring) periods. After capturing, nymphs were fed at the laboratory, and maintained under optimal rearing conditions. Feeding was repeated 40 days later. We followed-up the molting events on 709 nymphs, recording one, two or the absence of molts after two feeding opportunities. Within the same climatic period, only infected second- and fourth-instar nymphs from the warming period showed a larger proportion of double molting compared to uninfected nymphs. Regarding the climatic period, infected and uninfected first- and fourth-instar nymphs exhibited a larger proportion of double molting in the warming and cooling periods, respectively. The pattern of non-molting nymph occurrence suggests they probably reach diapause by environmental stochasticity. The effect of the climatic period and T. cruzi infection on the development of M. spinolai is an instar-dependent phenomenon, highlighting the occurrence of finely synchronized processes at different moments of the life cycle of such an hemimetabolous insect as triatomines.

Phenology and environmental predictors of Triatoma sanguisuga dispersal in east-central Texas, United States.

Of 11 triatomine species in the United States (US), Triatoma sanguisuga has the widest distribution across a 23-state region encompassing the southeastern US. This species consistently feeds on humans and dogs and has a high infection prevalence with the Chagas parasite Trypanosoma cruzi, with over 30-60% of adults infected. Little is known about the phenology and environmental predictors of dispersal activity of Triatoma sanguisuga. Using manual searches standardized by effort, we sampled kissing bugs in east central Texas, US every other night from June to November 2020 to determine their phenology and environmental predictors of activity. We found 176 triatomines alive, all of which were T. sanguisuga, with peak collections in early August and cessation of activity by late October; the phenology as determined by this active surveillance matched what has been reported using a passive community science approach. Using a negative binomial regression, we found temperature to have a positive correlation with T. sanguisuga dispersal activity, while wind speed had a significant negative correlation. We identified increased collections during sampling sessions with precipitation during the preceding 22 h. Further, wind from the southwest - the direction of most of the sylvatic habitat in the study area - was correlated with an increased dispersal activity, suggesting wind-facilitated dispersal. Given concerns for human and animal Chagas disease within the distribution of T. sanguisuga, vector control strategies can be adapted based on the factors influencing dispersal behavior.

Opportunistic or selective? Stage-dependent feeding behavior in a wild vector of Chagas disease.

The composition and contribution of different host species in the dynamics of vector-borne zoonotic parasites are particularly relevant for public health. Hence, the study of host selection by vectors is fundamental. Developmental stage and infection status are factors that may modulate vector feeding behavior. In the semi-arid Mediterranean ecosystem of South America, the transmission of Trypanosoma cruzi, the protozoan causing Chagas disease, includes the triatomine vector Mepraia spinolai and several vertebrate species. In this field study, we examined whether M. spinolai exhibits an opportunistic feeding behavior dependent upon developmental stage and/or infection status. We found that M. spinolai does not feed according to the relative availability of vertebrate species. In addition, early stage nymphs (first/second instars) fed on twice as many different species as middle (third/fourth instars) and late (fifth instars and adults) M. spinolai, with the former feeding on native rodents and lizards and the latter mostly on rabbits. Infected and uninfected M. spinolai showed similar feeding profiles. Wild triatomine species might be described as stage-dependent selective blood feeders, as a consequence of the temporal and spatial scale at which host-vector interactions occur, highlighting that all developmental stages might be infected and capable of transmitting T. cruzi.

Veterinary Chagas Disease (American Trypanosomiasis) in the United States.

Veterinary Chagas disease is a persistent threat to humans, dogs, and other wild or domestic mammals that live where infected triatomine "kissing bug" insect vectors occur across the Americas, including 28 states in the Southern United States. Animals infected with the Trypanosoma cruzi parasite may be asymptomatic or may develop myocarditis, heart failure, and sudden death. It is difficult to prevent animal contact with vectors because they are endemic in sylvatic environments and often disperse to domestic habitats. Challenges for disease management include imperfect diagnostic tests and limited antiparasitic treatment options.

New Cell Lines Derived from Laboratory Colony Triatoma infestans and Rhodnius prolixus, Vectors of Trypanosoma cruzi, Do Not Harbour Triatoma Virus.

Triatomine bugs of the genera Triatoma and Rhodnius are vectors of Chagas disease, a neglected tropical disease of humans in South America caused by Trypanosoma cruzi. Triatoma virus (TrV), a natural pathogen of Triatoma infestans, has been proposed as a possible tool for the bio-control of triatomine bugs, but research into this virus has been hampered by a lack of suitable host cells for in vitro propagation. Here we report establishment and partial characterisation of continuous cell lines from embryos of T. infestans (TIE/LULS54) and Rhodnius prolixus (RPE/LULS53 and RPE/LULS57). RNAseq screening by a sequence-independent, single primer amplification approach confirmed the absence of TrV and other RNA viruses known to infect R. prolixus, indicating that these new cell lines could be used for propagation of TrV.

Trypanosoma cruzi infection in the wild Chagas disease vector, Mepraia spinolai: Parasitic load, discrete typing units, and blood meal sources.

BACKGROUND: Mepraia spinolai, a wild vector of Trypanosoma cruzi in Chile, is an abundant triatomine species that is frequently infected by the parasite that causes Chagas disease. The aim of this study was to determine if the parasitic load of T. cruzi in M. spinolai is related to its blood meal source and the infecting DTUs of T. cruzi. METHODS: The vector was captured in rural areas. In the laboratory, DNA was extracted from its abdomen and T. cruzi was quantified using qPCR. Real time PCR assays for four T. cruzi DTUs were performed. Blood meal sources were identified by real-time PCR amplification of vertebrate cytochrome b gene sequences coupled with high resolution melting (HRM). RESULTS: Trypanosoma cruzi was detected in 735 M. spinolai; in 484 we identified one blood meal source, corresponding to human, sylvatic, and domestic species. From these, in 224 we were able to discriminate the infecting DTU. When comparing the parasitic loads between the unique blood meal sources, no significant differences were found, but infections with more than one DTU showed higher parasitic loads than single infections. DTU TcI was detected in a high proportion of the samples. CONCLUSIONS: Higher parasitic loads are related to a greater number of T. cruzi DTUs infecting M. spinolai, and this triatomine seems to have a wide span of vertebrate species in its diet.

Detection of Trypansoma cruzi in Kissing Bugs (Hemiptera: Reduviidae: Triatominae) Collected Across Oklahoma.

Trypanosoma cruzi is the causative agent of Chagas disease in humans and dogs in the Americas. Transmission predominantly occurs via the feces of infected kissing bugs (Hemiptera: family Reduviidae; subfamily Triatominae) contaminating bite site wounds or mucous membranes. To better understand Chagas disease entomologic risk in Oklahoma, kissing bugs collected from within the state were tested for T. cruzi DNA. Data including county of insect collection, species and instar, and specific locations where specimens were found were collated. Triatomines were also tested by PCR to potentially identify DNA of vertebrate species on which specimens had recently fed. In total, 110 kissing bugs from 22 counties were tested. All triatomines were identified as Triatoma sanguisuga nymphs or adults, with the exception of one possible T. lecticularia adult. Trypanosoma cruzi DNA was detected in 22 (20%) triatomines from 12 counties spanning the state. The majority of T. cruzi PCR positive kissing bugs were found inside homes or associated structures (i.e., garages, porches). Vertebrate DNA was identified in 27 (24.5%) triatomines, with human DNA detected in 25 (92.6%) of these specimens, and canine and raccoon DNA detected in one specimen each (3.7%). Two specimens tested positive for both T. cruzi and human DNA and one specimen tested positive for both T. cruzi and raccoon DNA. Results from this study indicate that kissing bugs carrying T. cruzi are widespread in Oklahoma, that positive kissing bugs infest homes and associated structures, and that human-vector, canine-vector, and wildlife-vector contact all occur within the state.

Exploring the role of glycoprotein hormone GPA2/GPB5 in the medically important insect, Rhodnius prolixus.

Glycoprotein hormones are formed by the heterodimerization of alpha and beta subunits. In vertebrates, there are five glycoprotein hormones, four of which have a common alpha subunit (GPA1) bound to a specific beta subunit (GPB1, GPB2, GPB3, or GPB4), and the fifth, thyrostimulin, is formed by the dimerization of GPA2 and GPB5 subunits. These hormones mediate physiological events such as development, metabolism, and reproduction, although the functional role of thyrostimulin in vertebrates has not been fully elucidated. Recent reports in invertebrates, specifically in holometabolous insects, suggest that GPA2/GPB5 plays a critical role in development, diuresis, and reproduction. In this study, we clone and characterize the transcripts for the glycoprotein hormone GPA2/GPB5 and its receptor (LGR1) in fifth instar Rhodnius prolixus, a hemimetabolous insect vector of Chagas disease. Sequence analyses reveals considerable identity and similarity between GPA2/GPB5 and LGR1 and those reported in other arthropod species. Quantitative PCR (qPCR) shows that both subunit transcripts, GPA2 and GPB5, and LGR1 transcripts are present in a variety of tissues, with greatest expression of the subunits in the central nervous system (CNS) and highest LGR1 expression in the Malpighian tubules (MT). Results from temporal qPCR analyses reveal a decrease in transcript expression 24 h after feeding, followed by an increase as the days post-feeding advance. Using immunohistochemistry, we show that GPB5 is expressed throughout the CNS, and importantly is present in neurosecretory cells in the brain and abdominal neuromeres and their neurohemal organs, indicating a neurohormonal role for this signaling pathway. A reduction in LGR1 transcript expression (via RNA interference) led to a greater weight loss and mortality rate in unfed insects. In addition, when a blood meal is offered, the insects with reduced LGR1 consume a significantly smaller blood meal and have higher mortality rates as the days post-feeding advance. Overall, the results suggest that the GPA2/GPB5 signaling pathway may play roles during a prolonged unfed state and in feeding-related events.

Panstrongylusnoireaui, a remarkable new species of Triatominae (Hemiptera, Reduviidae) from Bolivia.

Panstrongylusnoireaui sp. nov. from Bolivia is described based on male and female specimens. Although morphologically almost indistinguishable from Panstrongylusrufotuberculatus (Champion, 1899), the new species shows remarkable chromosome and molecular features, which are very distinctive among all others Panstrongylus species. The new species is also separated by some characteristics of the processes of the endosoma of the male genitalia. An updated key for species of Panstrongylus is provided.

Investigating the role of glycoprotein hormone GPA2/GPB5 signaling in reproduction in adult female Rhodnius prolixus.

Glycoprotein hormones are essential for regulating various physiological activities in vertebrates and invertebrates. In vertebrates, the classical glycoprotein hormones include follicle-stimulating hormone (FSH), luteinizing hormone (LH), thyroid-stimulating hormone (TSH) and chorionic gonadotropin (CG), which have crucial roles in growth, development, metabolism, and reproduction. In female mammals, FSH stimulates egg production in the ovaries, whereas LH and CG act as the triggers for follicular ovulation. The more recently discovered heterodimeric glycoprotein hormone GPA2/GPB5 (called thyrostimulin in vertebrates) is suggested to be involved in reproductive processes in arthropods. Here, we focus on understanding the role of GPA2/GPB5 and its receptor, LGR1, in the reproductive success of adult female Rhodnius prolixus, a vector of Chagas disease. qPCR was used to monitor the expression of GPA2 and GPB5 transcripts and their receptor in different tissues. Immunohistochemistry was used to show the distribution of GPB5 in the nervous system and reproductive system, and RNA interference was used to disrupt the glycoprotein hormone signaling pathway. Both subunit transcripts, GPA2 and GPB5, are present in a variety of tissues, with the greatest expression in the central nervous system; whereas the LGR1 transcript is present in peripheral tissues, including the fat body and the reproductive system of adult females. In the adult female, GPB5-like immunoreactive axonal projections are present in the trunk nerves extending onto the reproductive tissues, with processes overlaying the ovaries, oviducts, spermatheca, and bursa, indicating the possibility of neural control by neurons containing GPA2/GPB5. In addition, GPB5-like immunostaining is present in muscles encircling the ovarioles, and in the cytoplasm of trophocytes (nurse cells) located in the tropharium. GPB5-like immunoreactive processes and blebs are also localized to the previtellogenic follicles, suggesting an involvement of this glycoprotein hormone signaling in oocyte development. LGR1 transcript expression increases in the adult female reproductive system post-feeding, a stimulus that initiates reproductive development, adding further support to an involvement in reproduction. We have investigated the effect of LGR1 downregulation on reproductive processes, monitoring the number and the quality of eggs laid, hatching ratio, and production of vitellogenin (Vg), the major yolk protein for developing eggs. Downregulation of LGR1 leads to increases in transcript expression of vitellogenin, RhoprVg1, in the fat body and the vitellogenin receptor, RhoprVgR, in the ovaries. Total protein in the fat body and hemolymph of dsLGR1-injected insects increased compared to controls and associated with this effect was a significant increase in vitellogenin in these tissues. dsLGR1-injection leads to accelerated oogenesis, an increase in the number of eggs produced and laid, an increase in egg size and a reduction in hatching rate. Our results indicate that GPA2/GPB5 signaling acts to delay egg production in adult female R. prolixus.

Anaphylactic Reactions Due to Triatoma protracta (Hemiptera, Reduviidae, Triatominae) and Invasion into a Home in Northern California, USA.

BACKGROUND: Triatoma protracta is a triatomine found naturally throughout many regions of California and has been shown to invade human dwellings and bite residents. A man living in Mendocino County, California, reported developing anaphylactic reactions due to the bite of an "unusual bug", which he had found in his home for several years. METHODS: We conducted environmental, entomological, and clinical investigations to examine the risk for kissing bug invasion, presence of Trypanosoma cruzi, and concerns for Chagas disease at this human dwelling with triatomine invasion. RESULTS: Home assessment revealed several risk factors for triatomine invasion, which includes pack rat infestation, above-ground wooden plank floor without a concrete foundation, canine living in the home, and lack of residual insecticide use. Triatomines were all identified as Triatoma protracta. Midgut molecular analysis of the collected triatomines revealed the detection of T. cruzi discrete typing unit I among one of the kissing bugs. Blood meal PCR-based analysis showed these triatomines had bitten humans, canine and unidentified snake species. The patient was tested for chronic Chagas disease utilizing rapid diagnostic testing and laboratory serological testing, and all were negative. CONCLUSIONS: Triatoma protracta is known to invade human dwellings in the western portions of the United States. This is the first report of T. cruzi-infected triatomines invading homes in Mendocino County, California. Triatoma protracta is a known vector responsible for autochthonous Chagas disease within the United States, and their bites can also trigger serious systemic allergic reactions, such as anaphylaxis.