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What is meant by bionomics of a vector?

What is meant by bionomics of a vector?



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What is supposed to fall under the title Bionomics (The study of an organism and its relation to its environment; ecology.)?

Suppose we are dealing with a vector, Anopheles sp. are the following going to be included in its bionomics:

  1. Life cycle
  2. Interaction with parasite (Plasmodium sp.)
  3. Mode of transmission of parasite by this vector
  4. Control
  5. Diseases caused ?

Bionomics is indeed the 'thorough' study of living organisms and their relationship with the environment/ niche they thrive in.

Aim of Bionomics is mainly to decipher the driving factors for an organism to prefer a given niche. Given this key goal, it is apparent that one needs to focus on all aspects of an organism's life cycle and community dynamics.

So the answer to your question would be: Yes, one will need to focus on all the five points pertaining to Anopheles sp. (the 5th point i.e diseases caused) will more be an information resulting out of the study of its interactions with other living/ non-living forms), than a specific focal point for Bionomics.

References:

A good article on Bionomics

An amazing and detailed report on Bionomics of Entomophagous Coleoptera

Other references:

The dominant Anopheles vectors of human malaria in Africa, Europe and the Middle East: occurrence data, distribution maps and bionomic précis. Sinka et al., 2010

Description and Bionomics of Anopheles (Cellia) ovengensis (Diptera: Culicidae), a New Malaria Vector Species of the Anopheles nili Group from South Cameroon. Awono-ambene et al., 2004


The bionomics of the malaria vector Anopheles farauti in Northern Guadalcanal, Solomon Islands: issues for successful vector control

The north coast of Guadalcanal has some of the most intense malaria transmission in the Solomon Islands. And, there is a push for intensified vector control in Guadalcanal, to improve the livelihood of residents and to minimize the number of cases, which are regularly exported to the rest of the country. Therefore, the bionomics of the target vector, Anopheles farauti, was profiled in 2007–08 which was after 20 years of limited surveillance during which time treated bed nets (ITNs) were distributed in the area.

Methods

In three villages on northern Guadalcanal, blood-seeking female mosquitoes were caught using hourly human landing catches by four collectors, two working indoors and two outdoors, from 18.00-06.00 for at least two nights per month from July 2007 to June 2008. The mosquitoes were counted, identified using morphological and molecular markers and dissected to determine parity.

Results

Seasonality in vector densities was similar in the three villages, with a peak at the end of the drier months (October to December) and a trough at the end of the wetter months (March to May). There was some variability in endophagy (indoor biting) and nocturnal biting (activity during sleeping hours) both spatially and temporally across the longitudinal dataset. The general biting pattern was consistent throughout all sample collections, with the majority of biting occurring outdoors (64%) and outside of sleeping hours (65%). Peak biting was 19.00-20.00. The proportion parous across each village ranged between 0.54-0.58. Parity showed little seasonal trend despite fluctuations in vector densities over the year.

Conclusion

The early, outdoor biting behaviour of An. farauti documented 20 years previously on north Guadalcanal was still exhibited. It is possible that bed net use may have maintained this biting profile though this could not be determined unequivocally. The longevity of these populations has not changed despite long-term ITN use. This early, outdoor biting behaviour led to the failure of the eradication programme and is likely responsible for the continued transmission in Guadalcanal following the introduction of ITNs. Other vector control strategies which do not rely on the vector entering houses are needed if elimination or intensified control is to be achieved.


Background

Malaria still has a devastating impact on public health and welfare on the African continent. In Cameroon, over 30% of the population suffer from yearly malaria attacks resulting in 4000 to 10,000 deaths annually [1]. Long-lasting insecticidal nets (LLINs) are the main tools used across the country for malaria vector control. Over the last decade, up to three important mass distribution campaigns have been conducted [2]. The first, conducted in 2004, saw the free distribution of up to two million nets to children under five years and pregnant women, whereas insecticide treated nets (ITNs) were subsidised for the other age groups [3]. The second campaign conducted in 2011 included the free distribution of over 8 million LLINs to the whole population, and the third campaign conducted in 2015 included free distribution of over 12 million nets countrywide [4]. It is estimated that > 60% of the population currently own treated nets [5, 6], and that 50–70% of the population use nets regularly [7]. Although scale-up of malaria control strategies including mass distribution of treated nets across the continent contributed over the last decade to a significant decrease in malaria morbidity and mortality [1], the effectiveness of these measures is threatened by the rapid expansion of insecticide resistance in vector populations [8,9,10,11,12], change in vector feeding, biting and resting behaviour and the diversity of the vectorial system. Across Africa, several studies have reported different behavioural changes in mosquitoes affecting treated nets efficacy. In Benin, Moiroux et al. [13] reported changes in the biting time of An. funestus from midnight to dawn after LLIN scale-up. In Tanzania and Kenya, An. arabiensis, the main vector in these areas, was reported to be less affected by control measures because of its high zoophagic and exophilic behaviour [14,15,16,17]. Some populations of An. arabiensis were reported to avoid fatal insecticide exposure by entering and rapidly exiting houses containing indoor residual spraying (IRS) and LLINs or limiting the feeding time [18,19,20]. Yet, it is still unknown whether behavioral changes reported so far are true genetic changes resulting from insecticide selection or the expression of pre-existing plastic behavioral traits in response to modified resource availability, also known as resilience [21] or altered taxonomic composition deriving from suppression of the most vulnerable taxa [22]. In addition to these changes, rapid expansion of insecticide resistance in mosquito populations was reported across the continent [23,24,25,26]. A recent review on the status of insecticide resistance in Cameroon indicated that apart from organophosphates, most compounds used in public health are largely affected by insecticide resistance [2]. In addition to target site insensitivity being highly prevalent in An. gambiae, several sets of insecticide detoxification genes have been identified in An. gambiae, An. arabiensis and An. funestus [8, 26]. Another important factor which could affect the performance of vector control tools and has not been scrupulously evaluated is the diversity of the vectorial system. In Cameroon, up to 15 species are permanent or occasional malaria vectors [27]. In the northern part of the country situated in the dry savannah and sahelian region, malaria transmission is seasonal and vectored by species such as An. arabiensis, An. gambiae and An. funestus as the main vectors [28, 29]. Other species such as An. rufipes or An. pharoensis also can be involved in disease transmission [30,31,32], while in the southern part of the country situated in the forest region, malaria transmission is perennial [5] with a high diversity of species responsible for transmission. In addition to the dominant vectors within this area (An. gambiae, An. coluzzii, An. funestus, An. moucheti and An. nili) several secondary vectors such as An. ovengensis, An. paludis, An. ziemanni and An. marshallii contribute either seasonally or occasionally to malaria transmission [27, 33].

In the forested regions of Cameroon, it is estimated that over 80% of households own at least one net [34]. Over a number of years, the area has been affected by increased deforestation following extension of population settlements, construction of roads or dams, and changing agricultural practices with the cutting down of trees, yet the influence of these changes on the vectorial system dynamics and malaria transmission patterns have not been fully examined. The present study was conducted to assess the evolution of mosquito bionomics and malaria transmission patterns in association with the changing use of LLINs and other related changes in the area by comparing samplings undertaken in 2000–2001 and 2016–2017, before and after large scale campaigns of treated net distribution to communities.


Methods

Study site

The study was carried out in Malindi district, which is the tenth largest town in Kenya and a major tourist destination in Kilifi County along the Kenya Coast. Malindi town is approximately 108 km north of Mombasa. Entomological sampling was carried out in Garithe village located 27 kilometres north of Malindi town in Kenya. Garithe has been previously described [8, 11]. The coastal part of Garithe consists of mangrove trees and the area experiences high tides every month leaving pools of water during the low tides. These pools of salty water provide suitable habitats for An. merus breeding. The area also has numerous pockets of man-made ponds.

Entomological sampling

Mosquitoes were collected inside and outside selected homesteads. For indoor collection, mosquitoes were collected weekly in 16 randomly selected houses by use of pyrethrum spray collection method (PSC) [12]. The collections were conducted between 0700 hrs and 1000 hrs from September 2007 to March 2008. Knocked-down mosquitoes were placed in petri-dishes and transported to the KEMRI laboratory for further analysis. Additionally, indoor biting mosquitoes were collected by use of CDC light traps placed inside houses set between 1800 h and 0600 h. Ten traps were set inside 10 selected houses. Outdoor biting mosquitoes were collected by the use of CDC light traps with a lid hung outside five selected houses and cattle sheds.

Laboratory processing of mosquitoes

In the laboratory, female Anopheles were morphologically identified to species [13]. The legs of each Anopheles gambiae s.l. were detached from the rest of the body and used for sibling species identification using rDNA-PCR [4]. The heads and thorax were used for Plasmodium falciparum sporozoite Enzyme Linked Immunosorbent Assay (ELISA) [14]. The fully blood fed abdomens were tested for host sources of blood by ELISA [15]. Test samples were visually assessed for positivity [16].

Entomological indices

Entomological Inoculation rates (EIR), a standard measure of transmission intensity, is expressed as the number of infective bites per person per unit time (e.g., daily, monthly, yearly). The EIR was obtained by multiplying the human-biting rate by the proportion of sporozoite positive mosquitoes. The human blood index was determined as the proportion of blood-fed mosquitoes that had fed on humans out of the total number tested. The feeding success was determined as the proportion of blood fed and semi-gravid mosquitoes in the total proportion presumed to have been trying to feed (all mosquitoes except gravids) [17]. The sporozoite index for a given species was calculated as the proportion of females carrying infective sporozoites in the head-thorax. The human-biting rates (the number of biting mosquitoes per human-night), was calculated by dividing the total number of blood-fed and half-gravid mosquitoes caught in PSC catches by the number of persons sleeping in the house the night preceding the collection.

Statistical analysis

Fisher’s analysis of variance was used to determine the resting and feeding behaviour of An. merus adults. The data was analysed by the use of SPSS for Windows (version. 15) (CDC Atlanta, USA).

Ethical considerations

This project involves very minimal interaction with human subjects therefore no ethical approval was needed.


Methods

An electronic search of peer-reviewed scientific and medical literature published between January 1954 and September 2016 in Chinese and English was conducted using PubMed (MEDLINE), CNKI (China National Knowledge Infrastructure), VIP (Chongqing VIP Database), and CSPD (China Science Periodical Database, Wan Fang) and Web of Science databases. Gray literature and programmatic documents were also searched using Google, Google Scholar and other search engines using the same search terms.

The following search terms (or their Chinese equivalents) were used: Anopheles sinensis, distribution, biology, bionomics, molecule, ecology and China. The decision tree for the inclusion or exclusion of articles is shown in Figure 1. Only publications reporting biology, bionomics, and molecules of An. sinensis from China were included. Articles submitting a report on morphology, development, reproductive, life cycle, vector competence, larval and adult ecology, vector capacity, molecules involved in physiology and pathology were included. Studies involving insecticides were excluded because it would be the focus of a future review. These data were extracted and processed through a series of rigorous checking procedures before classification into a database. All results were initially reviewed for mosquito bionomics (larval and adult ecology), biology and related molecular studies based on the title and abstract. Relevant publications were further reviewed using the full text to determine whether the data focused on distribution, bionomics, epidemiology, vector competence, or identified molecules.

FIGURE 1. Flow diagram of the selection procedure used for the systematic review of accessible articles.


Culiseta melanura (Coquillett)

GEOGRAPHIC DISTRIBUTION: Culiseta melanura has a distribution that extends from Maine and southern Quebec south to southern Florida, west to eastern Texas and north to the lower Great Lakes region. The mosquito is associated primarily with lowland swamps and is missing from the Appalachian mountain range. Culiseta melanura is most abundant on the coastal plain of southern New Jersey but specimens have been collected from every county in New Jersey except Hudson.

SEASONAL DISTRIBUTION: Culiseta melanura has a life cycle unlike any other mosquito in the northeast. The species is multivoltine, like most Culex, but overwinters as a larva rather than an adult. Egg rafts deposited late in the season, hatch in the underground crypts that are favored as an oviposition site by this species. Larval development is retarded by cold conditions and overwintering takes place in the 2nd, 3rd and 4th instars. The largest larvae pupate in April and adults from this cohort are on the wing by early May. The mosquito exhibits several population peaks during the summer, separated by approximately one month each. The last generation of adults deposits the eggs that produce the overwintering larvae. Eggs that hatch in late summer or early fall, presumably overwinter as 4th instar larvae. Eggs that hatch after water temperatures drop, pass the winter in earlier instars.

LARVAL HABITAT: Culiseta melanura favors acid water and is normally found in acid bogs with a pH of 5.0 or lower. Two primary habitats for this species are found in New Jersey. In coastal areas, the mosquito reaches greatest numbers in Atlantic White Cedar swamps. At inland foci, the mosquito is associated with swamps comprised mainly of Red Maple. In either case, the adults seek out passageways through the root mat of trees where the water table is highest and lay their eggs in underground crypts. The larvae develop in the dark confines of the subterranean breeding sites and frequently have no contact with standing water that is visible from the surface. In swamps where mature trees have fallen, larvae can be found in the darkest recesses up, under the canopy provided by the root ball. When rotted out stumps occur in the swamp, larvae may be present in the deepest hollows.

COMMON ASSOCIATE SPECIES: Ae. thibaulti, Cs. morsitans

LARVAL COLLECTION: Culiseta melanura larvae are most numerous in large Atlantic White Cedar swamps along the Atlantic coast and Delaware Bay shores of southern New Jersey. Alternate habitats include mature stands of Red Maple that remain flooded well into the summer. This species may be found anywhere that acid water conditions provide larval habitat. There is a cedar swamp behind the lookout tower at High Point, on the NY-NJ-PA line that produces sizable populations of Cs. melanura every year. Areas where beaver have created habitat may be productive in any area of the state if the forest has been flooded for more than 3 years. Dipping for Cs. melanura larvae is often time consuming and non-productive. The mosquito prefers the deepest recesses and most are not accessible with a standard pint dipper. Dipping as far back into the recess of a fallen tree may produce a few specimens. The water, however, is usually deep close to the upended root mat and the first dips cause enough disturbance to make the larvae sound. Similar habitat is usually hard to find, thus, much of the time spent collecting this species involves waiting for larvae to re-surface in the limited habitat available. Collecting in cedar swamps involves traversing small clumps of land that support young trees and open water that has a treacherous bottom. The larvae of Cs. melanura are not in the open water they are located beneath the hummocks where the trees are growing. Most cedar swamp hummocks have holes through the root mat that provide access to the water beneath. The openings to these "crypts" may only be 1-3" in diameter. A dipper is too large to fit into the hole and a turkey baster is not long enough to reach the water. We have had success using a bilge pump which is normally used to bail water out of boats. By removing the valve and using the pump as a syringe, it is possible to suck up water, larvae and debris from the crypts. If you use the pump without removing the valve, the larvae will be filtered out of the sample. Sorting the sample can be extremely tedious in the interior of the swamp but the bilge pump will reach habitat where larvae occur.

LARVAL IDENTIFICATION: Culiseta melanura is one of the easiest mosquitoes to recognize in the larval stage. The long air tube and prominent antennae are recognizable in the dipper. Under the microscope, the unique barlike comb scales are diagnostic. No other larva has a comb that is even remotely similar. Most of the difficulty identifying this species involves keying it out to genus. Culiseta melanura lacks the prominent basal hair tufts on the siphon that are used as the final generic character for Culiseta. Close examination reveals 2-3 tiny hairs but individuals who are not familiar with the species miss the character and place the larva in the genus Culex where species identification is not possible. The first couplet of every Culex key should describe barlike comb scales to catch any Cs. melanura that were mistakenly identified as Culex.

REPRESENTATIVE COLLECTION RECORDS

Northern New Jersey

Location: High Point State Park, Sussex Co.

Habitat: Base of uprooted tree in cedar swamp

Central New Jersey

Location: Helmetta, Middlesex Co.

Habitat : Rotted out stump in Sphagnum Bog

Southern New Jersey

Location: Villas, Cape May Co.

Habitat : Base of fallen tree in Red Maple Swamp

IMPORTANCE: Culiseta melanura is a mosquito species that is not attracted to mammals. It does its host seeking in the canopy and feeds almost entirely on birds. The mosquito is responsible for maintaining eastern equine encephalitis virus in bird populations and plays a significant vector role in that regard.Culiseta melanura initiates the infection in bird populations other mosquito vectors are responsible for equine and human cases.


Conclusion

The current study describes the bionomics of the primary malaria vector in the Solomon Islands, An. farauti. Recently, the NVBDCP of the Solomon Islands refocused to implement intensified countrywide control and regional elimination. The key to a successful programme will be understanding, and responding to, the behaviours of the target vector. It was observed that An. farauti has a distinct seasonal profile, with peak activity from October to December, indicating that annual vector control activities should be completed before this period. Importantly, it was observed that the early outdoor biting habit of An. farauti, first observed in the study area in 1988 still persists 20 years later. With this feeding behaviour, the target mosquitoes are able to minimize exposure to ITNs and IRS. Therefore, there is a need to implement complementary tools that provide personal protection or target other bionomics’ vulnerabilities that may exist outside of houses, such as in the larval stages, during mating, sugar feeding or any other aspect of the life cycle. This will not only improve the success of vector control in Guadalcanal, but will reduce the number of cases that are exported to the control provinces.


Key Features

Current - each chapter represents the present state of knowledge in the subject area
Authoritative - authors include leading researchers in the field
Complete - provides both independent investigator and the student with a single reference volume which adopts an explicitly evolutionary viewpoint throuoghout all chapters.
Useful - conceptual frameworks for all subject areas include crucial information needed for application to difficult problems of controlling vector-borne diseases


What is a Viral Vector? (with pictures)

A viral vector is a virus which has been modified in a laboratory environment for the purpose of introducing genetic material into a cell. There are a number of uses for viral vectors, including therapeutic treatments for disease, gene therapy, and pure research. Labs all over the world make viral vectors for their own research and produce vectors for use by other labs, and some companies specialize in the production and sale of viral vectors which can be customized by request.

The development of the viral vector dates to the 1960s, when a number of researchers recognized that since viruses operate by inserting genetic material into cells, surely researchers could harness this trait by modifying viruses to change the genetic material they are inserting. A viral vector is made by taking a virus, removing the harmful genetic material it uses to gain control of cells, and replacing it with desirable genetic material. The process of delivering genetic material with the use of a virus is known as transduction, with the first successful attempt occurring in 1968 with plant cells.

Adenoviruses, retroviruses, herpesviruses, and lentiviruses are popular choices for viral vectors. Modification of a virus to act as a viral vector is not as simple as removing some genes and splicing in new ones. The virus must be altered so that it is safe, with minimal toxicity, so that the cells it transducts are not inadvertently damaged or killed, and it must also be highly stable. Viral vectors can also be modified to target specific types of cells, which is of special interest to cancer researchers who want to created targeted therapies which go after tumor cells and nothing else.

The process of developing viral vectors can be painstaking and challenging, and an individual viral vector can take some time to create. Researchers may opt to insert genetic markers into the organisms they modify so that they can be easily identified, with the markers acting like a fingerprint which allows a vector to be traced to a particular project, researcher, or lab. This allows researchers to track their vectors when they share them, and in the event that they are released.

Viral vectors can be used for a wide variety of purposes in the medical community. They are also used to vaccinate plants against disease, and to conduct laboratory research which is designed to advance the sciences as a whole. There are also some unsavory potential uses for vectors if they can be modified to introduce good genetic material, they can also be modified to introduce bad genetic material, which means that they could be applied in bioterrorism which is designed to hurt human, animal, or plant populations.

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a InfoBloom researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a InfoBloom researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.


What is meant by bionomics of a vector? - Biology

China has set a goal to eliminate all malaria in the country by 2020, but it is unclear if current understanding of malaria vectors and transmission is sufficient to achieve this objective. Anopheles sinensis is the most widespread malaria vector specie in China, which is also responsible for vivax malaria outbreak in central China. We reviewed literature from 1954 to 2016 on An. sinensis with emphasis on biology, bionomics, and molecular biology. A total of 538 references were relevant and included. An. sienesis occurs in 29 Chinese provinces. Temperature can affect most life-history parameters. Most An. sinensis are zoophilic, but sometimes they are facultatively anthropophilic. Sporozoite analysis demonstrated An. sinensis efficacy on Plasmodium vivax transmission. An. sinensis was not stringently refractory to P. falciparum under experimental conditions, however, sporozoite was not found in salivary glands of field collected An. sinensis. The literature on An. sienesis biology and bionomics was abundant, but molecular studies, such as gene functions and mechanisms, were limited. Only 12 molecules (genes, proteins or enzymes) have been studied. In addition, there were considerable untapped omics resources for potential vector control tools. Existing information on An. sienesis could serve as a baseline for advanced research on biology, bionomics and genetics relevant to vector control strategies