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Trends in Parasitology Aug 2022Disease-transmitting vectors are living organisms that pass infectious agents from one animal/human to another. The epidemiologically important vectors are usually... (Review)
Review
Disease-transmitting vectors are living organisms that pass infectious agents from one animal/human to another. The epidemiologically important vectors are usually hematophagous arthropods, including mosquitoes, ticks, triatome bugs, sand flies, and tsetse flies. All of them harbor an endogenous microbiota that functionally complements their host's biology. Different arthropod vectors are ecologically and behaviorally distinct, and as such, their relationships with symbiotic microbes vary. In this review, we summarize the recent discoveries that reveal how bacterial metabolic activities influence development, nutrition, and pathogen defense in mosquitoes, ticks, triatome bugs, and sand flies. These studies provide a foundation for a systematic understanding of vector-microbiota interactions and for the development of integrated approaches to control vector-borne diseases.
Topics: Animals; Arthropod Vectors; Arthropods; Disease Vectors; Humans; Microbiota; Mosquito Vectors; Ticks
PubMed: 35643853
DOI: 10.1016/j.pt.2022.05.002 -
Parasitology Research Apr 2023Vector-borne parasites may be transmitted by multiple vector species, resulting in an increased risk of transmission, potentially at larger spatial scales compared to...
Vector-borne parasites may be transmitted by multiple vector species, resulting in an increased risk of transmission, potentially at larger spatial scales compared to any single vector species. Additionally, the different abilities of patchily distributed vector species to acquire and transmit parasites will lead to varying degrees of transmission risk. Investigation of how vector community composition and parasite transmission change over space due to variation in environmental conditions may help to explain current patterns in diseases but also informs our understanding of how patterns will change under climate and land-use change. We developed a novel statistical approach using a multi-year, spatially extensive case study involving a vector-borne virus affecting white-tailed deer transmitted by Culicoides midges. We characterized the structure of vector communities, established the ecological gradient controlling change in structure, and related the ecology and structure to the amount of disease reporting observed in host populations. We found that vector species largely occur and replace each other as groups, rather than individual species. Moreover, community structure is primarily controlled by temperature ranges, with certain communities being consistently associated with high levels of disease reporting. These communities are essentially composed of species previously undocumented as potential vectors, whereas communities containing putative vector species were largely associated with low levels, or even absence, of disease reporting. We contend that the application of metacommunity ecology to vector-borne infectious disease ecology can greatly aid the identification of transmission hotspots and an understanding of the ecological drivers of parasite transmission risk both now and in the future.
Topics: Animals; Deer; Insect Vectors; Parasites; Communicable Diseases
PubMed: 36847842
DOI: 10.1007/s00436-023-07799-2 -
Current Opinion in Insect Science Dec 2022Aedes aegypti is the primary vector of dengue, chikungunya, and Zika viruses of medical importance. Behavioral and biological attributes contribute to its vectorial... (Review)
Review
Aedes aegypti is the primary vector of dengue, chikungunya, and Zika viruses of medical importance. Behavioral and biological attributes contribute to its vectorial capacity. The mosquito domestic form, which resides outside Africa (Ae. aegypti aegypti (Aaa)), is considered to breed in artificial containers in and around homes and preferentially feeds on human blood but commonly indulges in a plant diet. Potential divergence in these attributes, in sub-Saharan Africa (SSA) where Aaa coexists with the forest ecotype (Ae. aegypti formosus), should impact the vectoring ability and hence disease epidemiology. A summary of current knowledge on Ae. aegypti blood feeding, oviposition, and plant-feeding habits among SSA populations is provided in comparison with those in different geographies, globally. Emphasis is placed on improved understanding of the connection between changing subspecies adaptation in these traits and arbovirus disease risk in SSA in response to climate change and increasing urbanization, with the ultimate use of this information for effective disease control.
Topics: Female; Humans; Animals; Aedes; Mosquito Vectors; Disease Vectors; Oviposition; Ecology; Zika Virus; Zika Virus Infection
PubMed: 36243315
DOI: 10.1016/j.cois.2022.100986 -
Current Opinion in Insect Science Aug 2019The processing and integration of sensory information are central to the ability of disease vector insects to find their hosts, and eventually transmit diseases.... (Review)
Review
The processing and integration of sensory information are central to the ability of disease vector insects to find their hosts, and eventually transmit diseases. Deciphering the underlying mechanisms and the modulation of their behavioral responses to host cues is likely to reveal molecular pathways and neural processes, which could then be targeted for reducing the transmission rates of pathogens. In addition, the double role of prey and predator played by hosts imposes unique challenges on vectors, making them an underexploited model to study the evolution of sensory neurobiology and of cognitive processes in miniature brains. Here, I review the most recent advances on the cognitive abilities of triatomine bugs and mosquitoes, with a particular emphasis on their ability to learn and remember information.
Topics: Animals; Cognition; Culicidae; Insect Vectors; Memory; Triatoma
PubMed: 31247420
DOI: 10.1016/j.cois.2019.04.002 -
Parasites, Hosts and Diseases Aug 2023Chigger mites are the vector of scrub typhus. This study estimates the infestation status and ecological characteristics of chiggers on the chestnut white-bellied rat...
Chigger mites are the vector of scrub typhus. This study estimates the infestation status and ecological characteristics of chiggers on the chestnut white-bellied rat Niviventer fulvescens in Southwest China between 2001 and 2019. Chiggers were identified under the microscope, and infestation indices were calculated. The Preston's log-normal model was used to fit the curve of species abundance distribution. A total of 6,557 chiggers were collected in 136 of 342 N. fulvescens rats, showing high overall infestation indices (prevalence=39.8%, mean abundance=19.2, mean intensity=48.2) and high species diversity (S=100, H'=3.0). Leptotrombidium cangjiangense, Neotrombicula japonica, and Ascoschoengastia sifanga were the three dominant chigger species (constituent ratio=42.9%; 2,736/6,384) and exhibited an aggregated distribution among different rat individuals. We identified 100 chigger species, with 3 of them (Leptotrombidium scutellare, Leptotrombidium wenense, and Leptotrombidium deliense) as the main vectors of scrub typhus in China and nine species as potential vectors of this disease. Disease vector occurrence on N. fulvescens may increase the risk of spreading scrub typhus from rats to humans. Chigger infestation on N. fulvescens varied significantly in different environments. The species abundance distribution showed a log-normal distribution pattern. The estimated number of chigger species on N. fulvescens was 126 species.
Topics: Humans; Animals; Rats; Trombiculidae; Scrub Typhus; Mite Infestations; Murinae; Asteraceae; China; Disease Vectors
PubMed: 37648232
DOI: 10.3347/PHD.22044 -
Phytopathology Jan 2022Citrus greening, or huanglongbing (HLB), currently is the most destructive disease of citrus. HLB disease is putatively caused by the phloem-restricted... (Review)
Review
Citrus greening, or huanglongbing (HLB), currently is the most destructive disease of citrus. HLB disease is putatively caused by the phloem-restricted α-proteobacterium ' Liberibacter asiaticus'. This bacterium is transmitted primarily by the Asian citrus psyllid (Hemiptera: Liviidae). Most animal pathogens are considered pathogenic to their insect vectors, whereas the relationships between plant pathogens and their insect vectors are variable. Lately, the relationship of '. L. asiaticus' with its insect vector, , has been well investigated at the molecular, biochemical, and biological levels in many studies. Herein, the findings concerning this relationship are discussed and molecular features of the acquisition of ' L. asiaticus' from the plant host and its growth and circulation within , as well as its transmission to plants, are presented. In addition, the effects of ' L. asiaticus' on the energy metabolism (respiration, tricarboxylic acid cycle, and adenosine triphosphate production), metabolic pathways, immune system, endosymbionts, and detoxification enzymes of are discussed together with other impacts such as shorter lifespan, altered feeding behavior, and higher fecundity. Overall, although '. L. asiaticus' has significant negative effects on its insect vector, it increases its vector fitness, indicating that it develops a mutualistic relationship with its vector. This review will help in understanding the specific interactions between ' L. asiaticus' and its psyllid vector in order to design innovative management strategies.
Topics: Animals; Citrus; Hemiptera; Insect Vectors; Plant Diseases; Rhizobiaceae
PubMed: 34096774
DOI: 10.1094/PHYTO-05-21-0182-FI -
Philosophical Transactions of the Royal... Jun 2023Individuals from multiple species often aggregate at resources, group to facilitate defense and foraging, or are brought together by human activity. While it is...
Individuals from multiple species often aggregate at resources, group to facilitate defense and foraging, or are brought together by human activity. While it is well-documented that host-seeking disease vectors and parasites show biases in their responses to cues from different hosts, the influence of mixed-species assemblages on disease dynamics has received limited attention. Here, we synthesize relevant research in host-specific vector and parasite bias. To better understand how vector and parasite biases influence infection, we provide a conceptual framework describing cue-oriented vector and parasite host-seeking behaviour as a two-stage process that encompasses attraction of these enemies to the assemblage and their choice of hosts once at the assemblage. We illustrate this framework, developing a case study of mixed-species frog assemblages, where frog-biting midges transmit trypanosomes. Finally, we present a mathematical model that investigates how host species composition and asymmetries in vector attraction modulate transmission dynamics in mixed-species assemblages. We argue that differential attraction of vectors by hosts can have important consequences for disease transmission within mixed-species assemblages, with implications for wildlife conservation and zoonotic disease. This article is part of the theme issue 'Mixed-species groups and aggregations: shaping ecological and behavioural patterns and processes'.
Topics: Animals; Humans; Parasites; Animals, Wild; Zoonoses; Disease Vectors; Host-Parasite Interactions
PubMed: 37066659
DOI: 10.1098/rstb.2022.0109 -
Ecology Letters Apr 2021Vector-borne diseases (VBDs) are embedded within complex socio-ecological systems. While research has traditionally focused on the direct effects of VBDs on human... (Review)
Review
Vector-borne diseases (VBDs) are embedded within complex socio-ecological systems. While research has traditionally focused on the direct effects of VBDs on human morbidity and mortality, it is increasingly clear that their impacts are much more pervasive. VBDs are dynamically linked to feedbacks between environmental conditions, vector ecology, disease burden, and societal responses that drive transmission. As a result, VBDs have had profound influence on human history. Mechanisms include: (1) killing or debilitating large numbers of people, with demographic and population-level impacts; (2) differentially affecting populations based on prior history of disease exposure, immunity, and resistance; (3) being weaponised to promote or justify hierarchies of power, colonialism, racism, classism and sexism; (4) catalysing changes in ideas, institutions, infrastructure, technologies and social practices in efforts to control disease outbreaks; and (5) changing human relationships with the land and environment. We use historical and archaeological evidence interpreted through an ecological lens to illustrate how VBDs have shaped society and culture, focusing on case studies from four pertinent VBDs: plague, malaria, yellow fever and trypanosomiasis. By comparing across diseases, time periods and geographies, we highlight the enormous scope and variety of mechanisms by which VBDs have influenced human history.
Topics: Disease Vectors; Humans; Malaria; Vector Borne Diseases
PubMed: 33501751
DOI: 10.1111/ele.13675 -
Current Opinion in Insect Science Aug 2020Mosquito vectors in the genera Anopheles, Aedes, and Culex transmit a variety of medically important pathogens. Current vector control tools are reaching the limits of... (Review)
Review
Mosquito vectors in the genera Anopheles, Aedes, and Culex transmit a variety of medically important pathogens. Current vector control tools are reaching the limits of their effectiveness, necessitating the introduction of innovative vector control technologies. RNAi, which facilitates functional characterization of mosquito genes in the laboratory, could one day be applied as a new method of vector control. Recent advances in the oral administration of microbial-based systems for delivery of species-specific interfering RNA pesticides to mosquitoes may facilitate translation of this technology to the field. Oral RNAi-based pesticides represent a new class of biorational pesticides that could combat increased global incidence of insecticide resistance and which could one day become critical components of integrated human disease vector mosquito control programs.
Topics: Animals; Culicidae; Mosquito Control; Mosquito Vectors; RNA Interference
PubMed: 32516723
DOI: 10.1016/j.cois.2020.05.002 -
Journal of the American Mosquito... Sep 2023Insects' daily rhythms occur in response to their surrounding environment. Recognizing the daily rhythms of pathogen vectors can be helpful in developing effective,...
Insects' daily rhythms occur in response to their surrounding environment. Recognizing the daily rhythms of pathogen vectors can be helpful in developing effective, safe, and sustainable management strategies to control vector insects and reduce the spread of pathogens. However, studying the daily rhythm of insects often requires costly or labor-intensive trapping, and few tools are available to quantify daily rhythms in the field. We developed a simple collection system to study the flight activity of mosquitoes and biting midges using a contained, programmable, rotating, automatic pet feeder. A diverse assemblage of nuisance and vector species were collected with our system, including mosquitoes of the genera Aedes, Anopheles, Culex, and Deinocerites and biting midges (Ceratopogonidae) such as the coastal pest Culicoides furens. Surprisingly, mosquitoes and biting midges were less active during crepuscular periods (1800-2100h; 0600-0900h) than during dark periods (2100h-2400h; 0300h-0600h). A number of urban and agricultural pest insects were captured, including Coleoptera, Hymenoptera, Isoptera and Lepidoptera. This study shows that relatively inexpensive products can be adapted to study the daily rhythms of flying vectors and nuisance arthropods, with implications for vector-borne disease transmission and control. The collection system could also be used with flight intercept or pitfall traps, permitting study of the circadian activity patterns of a diverse array of arthropods.
Topics: Animals; Mosquito Vectors; Aedes; Culex; Anopheles
PubMed: 37796732
DOI: 10.2987/23-7137