Hematophagous Species Research Articles

A brief look at sexual dimorphism in the midgut morphology of lower Diptera and its implications for hematophagy

The insect digestive system is divided into three sections: the foregut, the midgut, and the hindgut. Specific subdivisions and modifications in these regions can characterize distinct insect groups, representing apomorphies. Since only females of hematophagous insects from nematoceran Diptera feed on blood, nearly all studies have focused on specimens of this sex, often neglecting the studies on the males’ internal anatomy. In our studies of Lower Diptera (Nematocera) (Lutzomyia longipalpis Lutz & Neiva, 1912, Aedes aegypti Linnaeus, 1762, and Culex quinquefasciatus Say, 1823), we observed differences in midgut morphology between males and females. In hematophagous species, within both Culicomorpha and Psychodomorpha, females exhibit a prominent dilation in the posterior midgut. In contrast, in Culicomorpha males only a slight dilation in the posterior region of the midgut was observed. For Psychodomorpha males, the midgut remained tubular and narrow throughout its length. Interestingly, in the non-hematophagous insect Clogmia albipunctata Williston, 1893 (Diptera: Psychodidae) both males and females possess a tubular and narrow midgut. Our showed that the observed differences are related to hematophagy, where all hematophagous females have a midgut with prominent posterior dilation, while females from non-hematophagous species have a narrowed midgut. These observations, if further validated, could significantly impact future studies in insect physiology and evolutionary biology, inspiring new research directions and methodologies.

Mosquitoes on a chip-environmental DNA-based detection of invasive mosquito species using high-throughput real-time PCR.

The monitoring of mosquitoes is of great importance due to their vector competence for a variety of pathogens, which have the potential to imperil human and animal health. Until now mosquito occurrence data is mainly obtained with conventional monitoring methods including active and passive approaches, which can be time- and cost-consuming. New monitoring methods based on environmental DNA (eDNA) could serve as a fast and robust complementary detection system for mosquitoes. In this pilot study already existing marker systems targeting the three invasive mosquito species Aedes (Ae.) albopictus, Ae. japonicus and Ae. koreicus were used to detect these species from water samples via microfluidic array technology. We compared the performance of the high-throughput real-time PCR (HT-qPCR) system Biomark HD with real-time PCR (qPCR) and also tested the effect of different filter media (Sterivex® 0.45 µm, Nylon 0.22 µm, PES 1.2 µm) on eDNA detectability. By using a universal qPCR protocol and only 6-FAM-MGB probes we successfully transferred these marker systems on the HT-qPCR platform. All tested marker systems detected the target species at most sites, where their presence was previously confirmed. Filter media properties, the final filtration volume and observed qPCR inhibition did not affect measured Ct values via qPCR or HT-qPCR. The Ct values obtained from HT-qPCR were significantly lower as Ct values measured by qPCR due to the previous preamplification step, still these values were highly correlated. Observed incongruities in eDNA detection probability, as manifested by non-reproducible results and false positive detections, could be the result of methodological aspects, such as sensitivity and specificity issues of the used assays, or ecological factors such as varying eDNA release patterns. In this study, we show the suitability of eDNA-based detection of mosquito species from water samples using a microfluidic HT-qPCR platform. HT-qPCR platforms such as Biomark HD allow for massive upscaling of tested species-specific assays and sampling sites with low time- and cost-effort, thus this methodology could serve as basis for large-scale mosquito monitoring attempts. The main goal in the future is to develop a robust (semi)-quantitative microfluidic-based eDNA mosquito chip targeting all haematophagous culicid species occurring in Western Europe. This chip would enable large-scale eDNA-based screenings to assess mosquito diversity, to monitor species with confirmed or suspected vector competence, to assess the invasion progress of invasive mosquito species and could be used in pathogen surveillance, when disease agents are incorporated.

Presence and infestation waves of hematophagous arthropod species

The invasion of hematophagous arthropod species in human settlements represents a threat, not only to the economy but also to the health system in general. Recent examples of this phenomenon were seen in Paris and Mexico City, evidencing the importance of understanding these dynamics. In this work, we present a reaction–diffusion model to describe the invasion dynamics of hematophagous arthropod species. The proposed model considers a denso-dependent growth rate and parameters related to the control of the invasive species. Our results illustrate the existence of two invasion levels (presence and infestation) within a region, depending on control parameter values. We also prove analytically the existence of the presence and infestation waves and show different theoretical types of invasion waves that result from varying control parameters. In addition, we present a condition threshold that determines whether or not an infestation occurs. Finally, we illustrate some results when considering the case of bedbugs and brown dog ticks as invasion species.

Presencia del virus de la rabia en murciélagos no hematófagos en México

The presence of the rabies virus and antibodyes in bats from the Americas is mainly associated with hematophagous species; however, this virus has also been detected with low frequency in bats with other feeding habits. The same thing happens in Mexico, although there is no updated information on the species that have been infected by this virus. Due to the public health implications of the subject, in this study we explore how the presence of the rabies virus is related to eating habits, the family to which they belong, the size of the distribution area and the type of refuge used by bats. Based on a review of the scientific literature published from 1954 to 2015, seven families, 24 genera, and 40 species of non-hematophagous bats that have been detected with rabies virus in Mexico. Most are insectivorous (63%) and belong to the Phyllostomidae and Vespertilionidae families (68%). The presence of rabies is positively and significantly related to the number of species per family (r = 0.9, p < 0.005) and type of feeding habit (r = 0.97, p < 0.002) but is not related to the size of its distribution area (r = 0.2, p = 0.2). Cases of rabies in non-hematophagous species in Mexico are rare, and do not represent a risk of transmission to humans.

Clogmia albipunctata (Williston, 1893) midgut physiology: pH control and functional relationship with Lower Diptera (nematoceran) especially with hematophagous species

Clogmia albipunctata (Williston, 1893) is a non-hematophagous insect belonging to the order Diptera, suborder Nematocera (Lower Diptera) and family Psychodidae. In the present work, we investigated how C. albipunctata control their midgut pH under different physiological conditions, comparing their midgut physiology with some nematoceran hematophagous species. The C. albipunctata midgut pH was measured after ingestion of sugar, protein and under the effect of the alkalinizing hormone released in the hemolymph of the hematophagous sand fly Lutzomyia longipalpis obtained just after a blood meal. The midgut pH of unfed or sugar-fed C. albipunctata is 5.5–6, and its midgut underwent alkalinization after protein ingestion or under treatment with hemolymph collected from blood fed L. longipalpis. These results suggested that in nematocerans, mechanisms for pH control seem shared between hematophagous and non-hematophagous species. This kind of pH control is convenient for successful blood digestion. The independent evolution of many hematophagous groups from the Lower Diptera suggests that characteristics involved in midgut pH control were already present in non-hematophagous species and represent a readiness for adaptation to this feeding mode.

Aedes albopictus salivary adenosine deaminase is an immunomodulatory factor facilitating dengue virus replication

The Asian tiger mosquito, Aedes albopictus, is an important vector for the transmission of arboviruses such as dengue virus (DENV). Adenosine deaminase (ADA) is a well-characterized metabolic enzyme involved in facilitating blood feeding and (or) arbovirus transmission in some hematophagous insect species. We previously reported the immunologic function of ADA by investigating its effect on mast cell activation and the interaction with mast cell tryptase and chymase. The 2-D gel electrophoresis and mass spectrometry analysis in the current study revealed that ADA is present and upregulated following mosquito blood feeding, as confirmed by qRT-PCR and western blot. In addition, the recombinant ADA efficiently converted adenosine to inosine. Challenging the Raw264.7 and THP-1 cells with recombinant ADA resulted in the upregulation of IL-1β, IL-6, TNF-α, CCL2, IFN-β, and ISG15. The current study further identified recombinant ADA as a positive regulator in NF-κB signaling targeting TAK1. It was also found that recombinant Ae. albopictus ADA facilitates the replication of DENV-2. Compared with cells infected by DENV-2 alone, the co-incubation of recombinant ADA with DENV-2 substantially increased IL-1β, IL-6, TNF-α, and CCL2 gene transcripts in Raw264.7 and THP-1 cells. However, the expression of IFN-β and ISG15 were markedly downregulated in Raw264.7 cells but upregulated in THP-1 cells. These findings suggest that the immunomodulatory protein, Ae. albopictus ADA is involved in mosquito blood feeding and may modulate DENV transmission via macrophage or monocyte-driven immune response.

Optimizing tick artificial membrane feeding for Ixodes scapularis

Artificial membrane feeding (AMF) is a powerful and versatile technique with a wide range of applications in the study of disease vectors species. Since its first description, AMF has been under constant optimization and standardization for different tick species and life stages. In the USA, Ixodes scapularis is the main vector of tick-borne zoonoses including the pathogens causing Lyme disease in humans and animals. Seeking to improve the overall fitness of I. scapularis adult females fed artificially, here, we have optimized the AMF technique, considerably enhancing attachment rate, engorgement success, egg laying, and egg hatching compared to those described in previous studies. Parameters such as the membrane thickness and the light/dark cycle to which the ticks were exposed were refined to more closely reflect the tick’s natural behavior and life cycle. Additionally, ticks were fed on blood only, blood + ATP or blood + ATP + gentamicin. The artificial feeding of ticks on blood only was successful and generated a progeny capable of feeding naturally on a host, i.e., mice. Adding ATP as a feeding stimulant did not improve tick attachment or engorgement. Notably, the administration of gentamicin, an antibiotic commonly used in tick AMF to prevent microbial contamination, negatively impacted Rickettsia buchneri endosymbiont levels in the progeny of artificially fed ticks. In addition, gentamicin-fed ticks showed a reduction in oviposition success compared to ticks artificially fed on blood only, discouraging the use of antibiotics in AMF. Overall, our data suggest that the AMF of adult females on blood only, in association with the natural feeding of their progeny on mice, might be used as an integrated approach in tick rearing, eliminating the use of protected species under the Animal Welfare Act (AWA). Of note, although optimized for I. scapularis adult ticks, I. scapularis nymphs, other tick species, and sand flies could also be fed using the membrane described in this study, indicating that it might be a suitable alternative for the artificial feeding of a variety of hematophagous species.

Histamine excretion in common indoor and hematophagous arthropods.

Histamine is a biogenic amine that regulates multiple physiological functions in diverse organisms, specifically playing a central role in the mammalian immune response. The common bed bug, Cimex lectularius L. (Hemiptera: Cimicidae), excretes histamine in large amounts in its feces as a component of its aggregation pheromone, which contaminates homes. The potential health risks associated with the presence of indoor histamine are unclear, but to predict future exposure risks, it is critical that we understand if other arthropods excrete histamine in any discernible phylogenetic pattern. In the present study, we evaluated histamine excretion by various arthropods; specifically those commonly found in large numbers indoors, other hematophagous species, and other species in the order Hemiptera. To evaluate arthropods for histamine excretion, rearing containers for each arthropod were swabbed and/or the harborage substrates were collected. Samples were then analyzed for the presence of histamine using gas chromatography-mass spectrometry. For those arthropods where histamine was present above the method detection limit, total histamine excretion was quantified over a period of 2 wk. Our results indicate that histamine excretion is limited to hematophagous hemipterans (bed bugs, bat bugs, tropical bed bugs, and kissing bugs), suggesting that indoor histamine contamination in the United States can be primarily linked to bed bugs.

School activity on the theme of bats can raise awareness of conservation

Knowing about the basic ecology of less charismatic species helps strengthen conservation measures. In the present study, we evaluated primary high school students' understanding in the southwest of Goias state, a region of Central Brazil, about bats. This paper involved two phases and analysis before and after school intervention, with lectures and practical activities. In the first phase, we recovered the basic knowledge focused on detecting whether the 170 students recognized bats as flying mammals. Then we tried to find out if they were aware of the hematophagous species estimate, and finally, we evaluated the relationship of the use of bats as bioindicators. The results showed confusion in bats' classification, with association with rodents, birds of nocturnal habit. The students believed that there were more than 10 (ten) hematophagous species regarding these animals' diet. And as expected, the concept of bioindicators of environmental quality was unclear to these animals. Finally, after school intervention, there was a significant increase in understanding all the topics covered on bats. These data reveal the importance of academic intervention in schools to reduce the social distance concerning biodiversity. We conclude that the development of school activity with the theme of bats can increase awareness of conservation.

School activity on the theme of bats can raise awareness of conservation

Knowing about the basic ecology of less charismatic species helps strengthen conservation measures. In the present study, we evaluated primary high school students' understanding in the southwest of Goias state, a region of Central Brazil, about bats. This paper involved two phases and analysis before and after school intervention, with lectures and practical activities. In the first phase, we recovered the basic knowledge focused on detecting whether the 170 students recognized bats as flying mammals. Then we tried to find out if they were aware of the hematophagous species estimate, and finally, we evaluated the relationship of the use of bats as bioindicators. The results showed confusion in bats' classification, with association with rodents, birds of nocturnal habit. The students believed that there were more than 10 (ten) hematophagous species regarding these animals' diet. And as expected, the concept of bioindicators of environmental quality was unclear to these animals. Finally, after school intervention, there was a significant increase in understanding all the topics covered on bats. These data reveal the importance of academic intervention in schools to reduce the social distance concerning biodiversity. We conclude that the development of school activity with the theme of bats can increase awareness of conservation.

An Overview of D7 Protein Structure and Physiological Roles in Blood-Feeding Nematocera.

Each time an insect bites a vertebrate host, skin and vascular injury caused by piercing triggers a series of responses including hemostasis, inflammation and immunity. In place, this set of redundant and interconnected responses would ultimately cause blood coagulation, itching and pain leading to host awareness, resulting in feeding interruption in the best-case scenario. Nevertheless, hematophagous arthropod saliva contains a complex cocktail of molecules that are crucial to the success of blood-feeding. Among important protein families described so far in the saliva of blood sucking arthropods, is the D7, abundantly expressed in blood feeding Nematocera. D7 proteins are distantly related to insect Odorant-Binding Proteins (OBP), and despite low sequence identity, observation of structural similarity led to the suggestion that like OBPs, they should bind/sequester small hydrophobic compounds. Members belonging to this family are divided in short forms and long forms, containing one or two OBP-like domains, respectively. Here, we provide a review of D7 proteins structure and function, discussing how gene duplication and some modifications in their OBP-like domains during the course of evolution lead to gain and loss of function among different hematophagous Diptera species.

Histamine Excretion by the Common Bed Bug (Hemiptera: Cimicidae).

The common bed bug (Cimex lectularius L.) is a hematophagous pest species that lives in close proximity to humans. Following a blood meal, bed bugs deposit fecal material indoors. The feces contain a variety of compounds, including histamine, which serves as a component of their aggregation pheromone. Histamine is a pivotal mammalian immune modulator, and recently it was shown to be present in high concentrations in household dust from homes infested with bed bugs. To better understand the dynamics of histamine excretion, we analyzed bed bug fecal material from different life stages and populations, along with fecal material collected at different post-feeding times and from bed bugs fed on different diets. Our analysis showed significant variation in histamine excretion among life stages, with mated females excreting the most histamine and first instar nymphs excreting the least histamine. However, when histamine excretion was normalized for blood consumption, males were found to excrete more histamine than the other life stages. There was no difference in histamine excretion among laboratory and recently home-collected bed bug populations. Further, we found histamine excretion continued for at least 14 d post-feeding, with the highest amount of histamine excreted 3-4 d after a bloodmeal. Overall, this work demonstrates that bed bugs excrete histamine across all feeding life stages, populations, and at various times after feeding, and that histamine excretion is directly related to blood feeding. These results will be used to better understand the health risks associated with histamine excretion and potential mitigation strategies of environmental histamine.

Diversity and distribution of blackflies (Diptera: Simuliidae) of the Tormes river basin (western Spain)

To enhance the partial knowledge on blackfly (Diptera: Simuliidae) fauna in Spain it is crucial to collect all the available data on this group to better understand their ecology and distribution over the years. This study presents data from samples collected along the Tormes river basin (western Spain) during the years 1988, 1989 and 1996 and then stored at the University of Salamanca. As a result of a research stay, a total of 19 species belonging to 3 genera (Prosimulium, Metacnephia and Simulium) and 5 Simulium subgenera (Boophthora, Eusimulium, Nevermannia, Simulium and Wilhelmia) were identified after examining 64% of the stored material, representing 35% of the species known from Spain. In addition, 14 species are reported for the first time in 3 provinces in the study area. Further sampling of blackflies is foreseen in the near future in order to check if the blackfly fauna composition determined in samples collected during the last two decades of the 20th century has changed. This aim gains in importance as a consequence of haematophagous species having been found, relevant for both public health and animal welfare, not only because of the discomfort caused by their bites but also because of their potential as vectors of disease-causing agents in animals and humans.

Culex quinquefasciatus Holobiont: A Fungal Metagenomic Approach.

Microorganisms associated with mosquitoes have fundamental roles, not only in their nutrition, but also in physiological and immunological processes, and in their adaptation to the environment as well. Studies on mosquito hologenomes have increased significantly during the last years, achieving important advances in the characterization of the "core bacteriome" of some species of health importance. However, the fungal mycobiome has not been exhaustively researched, especially throughout the life cycle of some hematophagous mosquito species. In this work, the diversity and composition of fungal communities in different developmental stages, sexes, and adult nutrition of Culex quinquefasciatus reared on laboratory conditions were characterized, using internal transcribed spacer high throughput amplicon sequencing. Larvae presented a higher fungal richness, while sucrose-fed males and females showed a similar diversity between them. Blood-fed females presented few operational taxonomic units with an even distribution. Results are consistent with the reduction of larval microbiota after molting, observed for the bacterial microbiome in other mosquito species. The filamentous Ascomycota Penicillium polonicum and Cladosporium sp. were present in all stages of the mosquitoes; in addition, the presence of yeasts in the insects or their subsequent colonization associated with their diet is also discussed. These results suggest that some species of fungi could be essential for the nutrition and development of mosquitoes throughout their life cycle.

Contributions of CO2-Baited Malaise-Type Traps to the Knowledge of Hematophagous and Oestrid Flies (Diptera: Oestridae) Parasitizing Cervid Hosts.

This review describes an innovative and efficient modification of a type of Malaise trap meme overlooked in a recent review of such insect traps. It further identifies the large variety of dipteran parasites of vertebrates caught in the traps when CO2 was added as an attractant that otherwise rarely were caught in unbaited traps. Baited trap catches of parasitic flies mimicked those caught attacking cervid hosts. This review particularly focuses on comprehensive studies of: 1) several hematophagous species of largely unknown snipe flies (Diptera: Rhagionidae: Symphoromyia [Artiodactyla: Cervidae]) found host specific for Columbian black-tailed deer (Odocoileus hemionus columbianus Richardson), and 2) the biology of oestrid fly (Diptera: Oestridae) parasites of black-tailed deer and caribou/reindeer [Rangifer tarandus (L.) (Artiodactyla: Cervidae)], after it was discovered that the non-hematophagous females are guided to their vertebrate hosts by tracking a source of CO2, as done by many hematophagous flies.

Гамазовые клещи (Mesostigmata: Gamasina), обнаруженные в нежилых подснежных гнездах обыкновенной полевки Microtus arvalis s. l. (Rodentia: Cricetidae) на территории Духовницкого района Саратовской области

The results of a parasitological study of uninhabited nests of the common vole Microtus arvalis s.l., collected on territory of the Dukhovnitsky district of the Saratov Region in April 2019 are presented. We identified nine species of gamasid mites associated with nests of the common vole. For the first time, Laelaps algericus Hirst., 1925, was recorded for the fauna of the Dukhovnitsky district of the Saratov Region. We found two new to Saratov region genera of free-living mites (without species identification): Laelaspis A. Berlese, 1903 (Laelapidae) and Neoseiulus A. M. Hughes, 1948 (Phytoseiidae). The study has shown that facultative hematophages dominate numerically, and free-living forms predominate in terms of species composition. All hematophagous species found belong to the typical ectoparasites of the common vole, they have wide distribution and are common species for the fauna of the Saratov region.

The Neglected Virome of Triatomine Insects

The Triatominae subfamily (Reduviidae) harbors some hematophagous insect species that have been firmly connected to the transmission of Trypanosoma cruzi, the causative agent of Chagas disease. Triatomines not only host and transmit trypanosomatids, but also coexist with a variety of symbiotic microorganisms that generally reside in the insect’s intestinal flora. The microbiome has profound effects on the physiology, immunity, fitness and survival of animals and plants. The interaction between triatomines and bacteria has been investigated to some extent and has revealed important bacteria symbionts. In contrast, the range of viral species that can infect triatomine insects is almost completely unknown. In some cases, genomic and metatranscriptomic approaches have uncovered sequences related to possible viral genomes, but, to date, only eight positive single-strand RNA viruses, namely Triatoma virus and Rhodnius prolixus viruses 1 - 7 have been investigated in more detail. Here, we review the literature available on triatomine viruses and the viruses-insect host relationship. The lack of broader metagenomic and metatranscriptomic studies in these medically relevant insects underscores the importance of expanding our knowledge of the triatomine virome both for surveillance purposes as well as to possibly harness their potential for insect vector population control strategies.

A New Species of Hershkovitzia (Diptera: Nycteribiidae) from Maranhão, Brazil

Hershkovitzia Guimarães & D'Andretta, 1956 belongs to Nycteribiidae, composed of hematophagous species exclusively ectoparasites of bats. The new species was collected from the bat Thyroptera devivoi Gregorin, Gonçalves, Lim & Engstrom, 2006 (Chiroptera: Thyropteridae) from Barreirinhas in Maranhão State, Brazil. Herein, we proposed schematic drawings of the abdomen, legs and head. We also proposed an identification key to species of Hershkovitzia.

Trophic interactions of vampire catfishes (Siluriformes: Vandelliinae) revealed by metabarcoding analysis of stomach contents

Abstract The trichomycterid catfishes of the subfamily Vandelliinae, the candirus, are parasite fishes that feed on blood. Therefore, the trophic interactions and dynamics of food webs in aquatic systems involving these catfishes cannot be determined through visual analysis of stomach contents, and the parasite–host interactions in this group of fishes are mostly unknown, except for a few anecdotal or experimental observations. We used DNA analysis of stomach contents of these fluid‐feeding fishes to identify hosts and study the ecological interactions of the haematophagous species Paravandellia oxyptera. Specifically, we used sequences of the cytochrome oxidase I gene collected from the gut contents of the catfish and compared them to data from GenBank to identify the host species. Our analysis indicated that examined specimens of Paravandellia oxyptera were exclusively fish parasites, and we identified genetic markers from eight host species from five families and three orders based on stomach contents. Paravandellia oxyptera does not exhibit host specificity. Unlike mucophagous trichomycterids, host species of haematophagous P. oxyptera belong to different trophic levels, showing a wide spectrum of interactions in the food web. A comparison of the host species with the accompanying fauna collected during sampling allowed an association between host preference and host size. Barcode analysis of stomach contents further produced a secondary source of information on the diversity of fish in the study area. This is the first study to identify host species of haematophagous parasitic fishes through the analysis of gut contents, demonstrating that specimens obtained in natural environments show much larger spectra of ecological interactions than previously reported from anecdotal or laboratory observations. This research is of broad interest, and exemplifies how DNA barcoding analysis of stomach contents provides new and relevant information on parasite/host interactions, with results not obtained by traditional methods of stomach content analysis.

Trypanosoma cruzi DNA in Desmodus rotundus (common vampire bat) and Histiotus montanus (small big-eared brown bat) from Chile

The protozoan Trypanosoma cruzi, the causative agent of Chagas disease, is transmitted by infected feces or consumption of blood-sucking triatomine insects to several mammalian orders including Chiroptera. In Chile, the distribution of several insectivorous and one hematophagous bat species overlaps with those of triatomine vectors, but the T. cruzi infection status of local chiropterans is unknown. In 2018, we live-captured bats from two protected areas in Chile to collect plagiopatagium tissue, feces and perianal swab samples, in search for T. cruzi-DNA by real time PCR assays using species-specific primers. In Pan de Azúcar island (∼26°S), we examined a roost of Desmodus rotundus (common vampire bat) and sampled tissue from 17 individuals, detecting T. cruzi-DNA in five of them. In Las Chinchillas National Reserve (∼31°S), we examined two roosts of Histiotus montanus (small big-eared brown bat), collecting feces or perianal swab samples from eight individuals, detecting T. cruzi-DNA in four of them. This is the first report of T. cruzi-DNA evidence in bat species from Chile. Both vector-borne and oral transmission are potential infection routes that can explain our results. Further investigation is needed for a better understanding of the role of bats in the T. cruzi transmission cycle.