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Which countries do not feature mosquitoes?

Which countries do not feature mosquitoes?


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Please, I am so itchy, I need to know: which countries are free of mosquitoes?


According to India.com, Chris is right and Iceland has been declared mosquito free.

The science behind this is quite interesting and there are various hypotheses regarding as to why Iceland doors are shut to mosquitoes. The most preferred hypothesis by scientists, according to New York Times is >>

When mosquitoes lay eggs in cold weather, the larvae emerge with a thaw, allowing them to breed and multiply. Iceland, however, typically has three major freezes and thaws a year, creating conditions that may be too unstable for the insect's survival.


Biology Chapter 8

A. They are long, thin appendages that allow bacteria to be motile (move).
B. They are stiff fibers that allow bacteria to adhere to surfaces.

A. Plasmids and antibiotic resistance.

B. A peptidoglycan cell wall.

C. An outer membrane composed of lipopolysaccharide.

A. an opportunistic infection.

A. because they do not replicate

B. because they do not possess genetic material

C. because they are not composed of cells

D. because they lack the metabolic machinery to acquire and use nutrients

D. opportunistic infections.

A. helper T cells and macrophages

B. B cells and red marrow cells

C. liver cells and cardiac muscle cells

D. epithelial cells and eosinophils

D. opportunistic infection

A. It can infect any cell it comes in contact with.

B. It can only infect cells on surfaces of the body where the temperature is lower.

C. It can only infect cells that are actively growing and dividing.

A. because there is no HIV in the blood

B. because there are no detectable levels of HIV antibodies in the blood

B. yeast infections of the mouth or vagina

A. the destruction of CD4 T cells by the virus

B. the production of new CD4 T cells

C. the amplification of the virus in the blood

D. the destruction of the virus by the immune system

2. Fusion: HIV fuses with the plasma membrane, and the virus enters the host cell.

3. Entry: The capsid and protein coats are removed, releasing RNA and viral proteins into the host cell's cytoplasm.

4. Reverse transcription: HIV's single-stranded RNA is converted into a double-stranded viral DNA code.

5. Integration: The viral DNA, along with the viral enzyme integrase, migrates into the nucleus of the host cell. The viral DNA is spliced into the host cell's DNA, making it part of the host genome.

6. Biosynthesis and cleavage: The host cell's machinery directs the production of more viral RNA. Some of the viral RNA becomes material for new viruses, while the rest is used to code for viral proteins.

7. Assembly: Capsid proteins, viral enzymes, and RNA are assembled into new viruses.


Genetically Modified Mosquito Sparks a Controversy in Florida

Officials in the Florida Keys are seeking to use a GM mosquito that could help prevent a recurrence of dengue fever there. But fears among some residents — which scientists say are unfounded — are slowing the release of mosquitoes whose offspring are genetically programmed to die.

When people think of genetically modified organisms, food crops like GM corn and soybeans usually come to mind. But engineering more complex living things is now possible, and the controversy surrounding genetic modification has now spread to the lowly mosquito, which is being genetically engineered to control mosquito-borne illnesses.

A U.K.-based company, Oxitec, has altered two genes in the Aedes aegypti mosquito so that when modified males breed with wild females, the offspring inherit a lethal gene and die in the larval stage. The state agency that controls mosquitos in the Florida Keys is awaiting approval from the federal government of a trial release of Oxitec’s genetically modified mosquitos to prevent a recurrence of a dengue fever outbreak. But some people in the Keys and elsewhere are up in arms, with more than 155,000 signing a petition opposing the trial of genetically engineered mosquitoes in a small area of 400 households next to Key West.

Many scientists say, however, that genetically modifying the Aedes mosquito — and possibly other types of mosquitoes carrying diseases such as malaria — is a more effective and environmentally benign way of controlling mosquito-borne illnesses than spraying pesticides and other measures. Oxitec’s genetically engineered Aedes aegypti has proven itself in other countries, successfully reducing populations of the insect by up to 90 percent in field trials in the Cayman Islands, Brazil, Malaysia, and Panama. Overall, the trials were so successful that Brazil approved the use of the GM mosquitoes last year.

“Some people don’t want to see GE (genetically engineered) anything,” says entomologist Raymond St. Leger, distinguished university professor at the University of Maryland. “It’s an emotional response. It’s hard to reason people out of a decision they didn’t reason themselves into.”

St. Leger is now conducting field trials in Burkina Faso to test a method in which a mosquito is exposed to a fungus that prevents it from transmitting malaria. He says that Oxitec’s technology to suppress the Aedes aegypti has relatively little environmental risk and that knocking back the mosquito in the Keys, which experienced a dengue outbreak five years ago, “is a matter of urgency.

“You don’t want to wait until it’s endemic,” he says. “The gun is there and cocked and waiting to spread through their mosquitos. The extensive program and spraying with insecticides isn’t working. You need to do something now and not wait until dengue is there. It’s a very dangerous mosquito doing pretty well for itself in Florida.”

Tom Miller, a retired professor of entomology at the University of California, Riverside, says that the genetically modified mosquitoes Oxitec uses to control dengue should not be regulated at all. “The method only releases males that do not [bite and] take blood meals,” says Miller. “They seek out wild females of the same species and produce offspring with lethal genes, leaving no survivors. In terms of side effects, it is equivalent to dumping dead insects onto the sidewalk.”

The Florida Keys Mosquito Control District first consulted with Oxitec when 28 people in Key West were infected with dengue in 2009 and 2010 — the first outbreak of the disease in Florida in 75 years. Dengue is also known as “breakbone fever” because it causes debilitating bone pain and flu-like symptoms. A severe form of the illness, dengue hemorrhagic fever, can lead to death, although rarely in areas with good medical care.

No dengue cases have been reported in the Keys since 2010. Since the outbreak, local officials have fought the Aedes aegypti — the primary vector for dengue — using every means possible. They spend $1 million of their $10 million annual budget specifically trying to control this one species. It is one of 46 species of mosquitos that live in the Florida Keys, and accounts for 1 percent of the total mosquito population there.

While other mosquitos are nuisances, the problem of the Aedes aegypti is not the itch. The bug contracts diseases like dengue, chikungunya, and yellow fever from humans and then transmits it to people through bites. Only female mosquitos bite, and while other mosquitoes can take their blood meals from animals like dogs and birds, this species relies on humans to survive. It can fly just 100 to 200 yards, so it lays eggs in water that collects near homes, such as in garbage cans, barrels, or in plants. It’s an invasive species in Florida and likely came to the U.S. from Africa on European ships carrying early explorers. The Aedes aegypti was once eliminated through the use of chemicals like DDT, but the species has re-emerged in Florida over time.

“From a health standpoint, we don’t want to wait until we are fighting the disease,” says spokesperson Beth Ranson, of the Florida Keys Mosquito Control District. “We want to prevent it.”

Technicians now go door-to-door looking for standing water and remove it. They also use bacteria like Bacillus thuringiensis israelensis to kill larvae, spray chemicals into the air to kill adult bugs, and add larvae-hungry fish to eat mosquitoes in abandoned cisterns or fountains. Despite all this effort, they have only reduced the insects by 50 percent over the past several years.

“We can’t go everywhere,” says Ranson. “We can’t get onto rooftops. We don’t have access to some properties. But we hope the Oxitec mosquitoes could get to those hard-to-find females and do the work for us.”

Key West resident Mila de Mier started the petition against Oxitec. She lives two miles from the proposed test site and has been outraged by the possibility of trials. She says the local mosquito control has been more than effective. “We have no local dengue now,” she says. “Why do a clinical trial in an area with no dengue? If it doesn’t work, how do you recall it? I don’t want my kids to be laboratory rats.”

Mier says she wonders what might happen to her three kids and two dogs if a lab-grown mosquito bit them — a concern that scientists say is unfounded. She is also worried that other mosquitoes, such as the Asian Tiger mosquito, would move in and fill the void in the ecosystem. Other opponents worry that the modified insect might have some unknown harmful effects on the environment.

But Oxitec and numerous scientists say fears about genetically modifying the Aedes aegypti mosquito are largely unfounded. Since only male GM mosquitoes would be released and only female mosquitos bite, it is virtually impossible that humans would be bitten by a modified female. Even if they were, the health impacts would be no different than being bitten by a non-modified mosquito, scientists say. And the self-limiting gene in the lab-grown mosquito is only passed on to another organism through sexual reproduction a bird, for instance, cannot acquire the gene by eating the bug.

“The anti-GM mosquito, sterile-insect people have become a lunatic fringe,” says Miller of UC Riverside. “They have no argument that makes any sense.”

The fears expressed by opponents of the GM mosquito initiative in Florida are set against a backdrop of increasing experimentation with genetically modified organisms, says Todd Kuiken, a science and technology expert at the Science, Innovation and Technology Program at the Wilson Center in Washington, D.C. Today 115 different synthetic biology products and applications exist, and they are rapidly advancing.

Some — like a genetically modified, fast-growing salmon — have been languishing in federal regulatory offices for 16 years. Roughly 50 other modified organisms are on the market or close to commercial use. This list includes things like a genetically engineered variety of mustard that is injected with DNA from fireflies the mustard can then be grown to produce “natural” lighting.

“As more products and platforms move onto the market, there will be increased demand for risk research to underpin regulatory decisions,” says Kuiken. “And as more novel species are developed, eco-evolutionary dynamics will need to be evaluated, too.”

Miller says that the main objection to Oxitec’s technology boils down to its newness, rather than scientific merit. He says that the U.S government has approved similar applications for agriculture, noting that the sterile insect technique that Oxitec adapted to dengue control using modern molecular methods was invented by the U.S. Department of Agriculture more than 70 years ago. It has been used successfully to eradicate screwworm flies from North America and most of Central America and now is used to control a large number of crop insects globally, such as the destructive Med fly.

Miller says that using insecticides is only 2 to 5 percent efficient and has far more serious environmental consequences than genetically modifying mosquitoes.

“Insecticides coat the countryside and always leave a subpopulation of mosquitoes to survive, “ says Miller. He says, research suggests that eliminating mosquitos from urban areas has no negative environmental effects.

“We are introducing a new tool to reduce mosquito populations to trace levels that you can do in conjunction with other prevention and control methods,” says Hadyn Parry, chief executive officer of Oxitec. “With insecticide, you are spraying away and you may have insecticide resistance because populations are not going down. You are killing a number of insect species in a targeted area. There’s collateral damage — while reducing the aegypti species, you are also reducing innocent bystanders and beneficial insects. … Ours is controlled and precise. It doesn’t hang around in the environment.”

Two genetic engineering technologies are currently being used to modify mosquitoes, and both are in the trial stage. One is a self-limiting technology, which Oxitec uses, where the modified mosquitoes contain a lethal gene that is passed on to offspring to prevent the larvae from developing into adults. The other is the gene-drive technology, a much more complex modification in which offspring inherit genes that are then passed on to entire populations. This can essentially immunize the pests from getting disease in the first place. The modified mosquito’s lifecycle is about a month, and the company has raised more than 150 generations with no mutations to the mosquitoes.

While the Keys do not currently have locally transmitted dengue or chikungunya, pre-conditions exist for these diseases to become endemic, public health experts say. The mosquito contracts the disease virus from humans, and with travel increasing from the Caribbean — especially Cuba — into Florida, scientists are concerned. Both diseases are severely debilitating. Chikungunya is similar to dengue but causes such severe joint pain that patients are often bent over from it. Chikungunya was not found in the Americas until December 2013 within 12 months, one million cases of chikungunya had spread throughout the Caribbean.

The Wilson Center’s Kuiken, who studies the governance strategies of synthetic biology, says the environmental risks of genetically modifying mosquitoes — which could include the impact of eliminating a mosquito species from an ecosystem — have not been well studied. The regulatory process, he says, for GM products lags far behind technological advancement. The U.S. Food and Drug Administration’s Center for Veterinary Medicine has been reviewing the issue of Oxitec’s GM Aedes aegypti mosquito since 2011. But this is the first time they have reviewed GM pest control, and Kuiken says it’s a decision with far-reaching implications.

“Man has been engineering nature and ecosystems ever since we came out of a cave,” says Kuiken. “What is different now is that we are beginning to engineer species. It is a progression on the scale, and it is a big progression.”

Lisa Palmer is a journalist and senior fellow at the National Socio—Environmental Synthesis Center (SESYNC) in Annapolis, Md. She is the author of "Hot, Hungry Planet" (St. Martin's Press, 2017) and she reports on energy, climate change, the environment, and sustainable business for publications such as Slate, Scientific American, and The Guardian. More about Lisa Palmer →


Background

In the recent past, with the development of aided tools of molecular systematics, there have been significant advances in our understanding of malaria vector species and disease relationships [1, 2]. With the global efforts for malaria elimination, in-depth study of malaria vectors is regaining its significance for effective vector management. In this drive, India has recently joined the Asia Pacific Malaria Elimination Network (APMEN) with mission to decrease malaria transmission and move into pre-elimination phase by 2017 (www.apmen.org). There are several Anopheles species transmitting malaria agents in India and disease epidemiology is complex due to varied ecology and contextual determinants [3, 4]. Among seven main malaria vector taxa in southeast Asia, such as Anopheles dirus (sensu lato) (s.l.), An. maculatus (s.l.), An. fluviatilis (s.l.), An. culicifacies (s.l.), An. minimus (s.l.), An. stephensi and An. sundaicus (s.l.), An. minimus is the major species in the northeastern states of India [5]. During the 1940s, An. minimus was widely prevalent and studied for bionomical characteristics and disease transmission relationships in geographical range of its distribution extending from sub-Himalayan foothills of Uttar Pradesh to eastern and northeastern region of India [6–11]. With the advent of DDT and large-scale application for residual spraying during National Malaria Eradication Programme in the 1960s, An. minimus was believed to have disappeared from its range [12–15]. Extensive fauna surveys in the Himalayan foothills region did not report An. minimus and consequently other prevalent mosquito species were implicated in the continuing disease transmission [16–18]. However, epidemic malaria and emerging drug-resistance, for which northeast India is considered the epicenter, warranted additional investigations to target disease vectors for formulating appropriate containment strategies [19]. In this context, extensive entomological investigations revealed the prevalence of An. minimus in northeast India and re-incriminated it by records of sporozoite infections [20–25]. However, there are no records of its return in Terai area of Uttar Pradesh [26], but it has recently resurfaced in eastern state of Odisha (formerly Orissa) after lapse of nearly 45 years of disappearance [27–30]. It has once again been proven unequivocally as the major vector species in the foothill valley areas of eastern and northeast India requiring renewed efforts for its effective control. Given the behavioral characteristics of An. minimus, including its plasticity [31], associated to rapid ecological changes owing to human population explosion, development projects, deforestation and human migration affecting mosquito ecology, it was mandated to review its bionomical characteristics and disease relationships. This information is considered important in view of the disappearing malaria and elimination efforts globally. We report the available and most recent information on the systematic position of An. minimus, its bionomical characteristics and distribution in India to help formulate species-specific control strategies to reduce transmission in space and time.

Taxonomy and molecular systematics

Anopheles minimus Theobald 1901 (s.l.) belongs to the Minimus Subgroup of the Funestus Group, in the Myzomyia Series within the subgenus Cellia [32]. It has now been recognized as a species complex comprising three formally named sibling species, including An. minimus (sensu stricto) (s.s.) (former An. minimus species A), An. harrisoni Harbach & Manguin (former An. minimus species C) and An. yaeyamaensis Somboon & Harbach (former An. minimus species E), with distinct bionomical characteristics and distribution records [33–35]. These three designated species are difficult to distinguish due to overlapping morphological characters, yet these can only be identified reliably by a number of molecular assays [36–38]. Among these, restriction fragment length polymorphism polymerase chain reaction (RFLP-PCR) assay is useful to distinguish in large-scale screening of anopheline fauna, but is more expensive and time consuming [39, 40]. Instead, the allele-specific polymerase chain reaction (AS-PCR) is more convenient, quite reliable and therefore more commonly used for distinguishing An. minimus and An. harrisoni and closely related sympatric species such as An. aconitus, An. pampanai and An. varuna unequivocally [41, 42].

Adult morphological distinguishing features

Anopheles minimus (s.l.) is a small-sized mosquito and can possibly be distinguished from other members of the Funestus Group such as An. aconitus and An. varuna by a combination of morphological characteristics, such as apical and sub-apical pale bands equal, separated by a dark band tarsomeres without bands fringe spot absent on vein-6 wing (anal vein) presence of a presector pale spot and a humeral pale spot on the costa [10, 38]. However, the formal identification of these closely related species cannot rely on morphology only and must be accompanied by the use of an appropriate PCR assay for precise and definite species identification [36].

Sibling species composition and distribution

Anopheles minimus (s.l.) is reported to occur in the Oriental region of countries including India, Myanmar, Thailand, Laos, Cambodia, Vietnam, Southern China comprising Hong Kong, Taiwan and the Ryukyu Islands of Japan [11, 31, 35, 37, 43–45] (Figs. 1 and 2). With molecular identification of the sibling species of the Minimus Complex, the geographical range of each species has now been more detailed [2, 35, 36, 46, 47]. In India, An. minimus has a distribution extending from eastern to northeastern regions down to Orissa State and further eastwards to China including Taiwan (Figs. 1 and 2). It occurs in sympatry with An. harrisoni over areas in Myanmar, Thailand, Laos, Cambodia, Vietnam and southern China (up to 32.5°N latitude for An. harrisoni and up to 24.5°N latitude for An. minimus) [31, 36, 40, 43, 46, 48, 49] (Fig. 2). Instead, An. yaeyamaensis is exclusively restricted to Ishigaki Island of the Ryukyu Archipelago of Japan (Fig. 2).

The predicted distribution of Anopheles (Cellia) minimus (s.l.) in the world. Red and blue color depicts respectively the high and low probability of occurrence of this complex. Black dots display the sites of data collected. Copyright: Licensed to the Malaria Atlas Project [92] under a Creative Attribution 3.0 License. Citation: Sinka et al. (2011) The dominant Anopheles vectors of human malaria in the Asia Pacific region: occurrence data, distribution maps and bionomic précis, Parasites & Vectors 2011, 4:89 [2]

Updated distribution map of sibling species of the Anopheles minimus complex in Southeast Asia based on molecular identification. Anopheles minimus has wide distribution extending from East India to northeast and eastwards to China including Taiwan, and occurs in sympatry with An. harrisoni over a large area in southern China, northern and central Vietnam, northern Laos, and northern and western Thailand. Anopheles yaeyamaensis is restricted to Ishigaki Island of the Ryukyu Archipelago in Japan (S. Manguin, original map)

In northeast India, An. minimus is reported to occur in Assam, Arunachal Pradesh, Meghalaya, Nagaland and Tripura [50, 51] and in eastern State of Odisha [28]. All these populations morphologically identified as An. minimus (s.l.) were confirmed to be An. minimus (s.s.) by routinely applied molecular assays including sequencing of the internal transcribed spacer 2 (ITS2) and the D3 domain of 28S rDNA (28S-D3). The prevalence of An. harrisoni and An. yaeyamaensis could not be established in India. Given the molecular diagnostic assays, An. minimus, can now be easily distinguished from other closely related, namely An. varuna and An. fluviatilis (s.l.) having similar geographical range and ecology. In fact, formerly identified populations of An. fluviatilis (s.l.) from Assam are now genetically characterized to be a hyper-melanic form of An. minimus that is prevalent during cooler months [52].

Historically, in India, besides present records of distribution in the eastern and northeastern regions, An. minimus was also reported to be prevalent with scattered records of its occurrence in the States of Andhra Pradesh, Tamil Nadu, Kerala and Karnataka [11]. Although these records are dating (1984), there still exists a possibility of its occurrence especially in northern Andhra Pradesh (south of Odisha), given the similar ecology and corridors for transmission in its earlier domains of distribution [53] (Figs. 1 and 2).

Bionomical characteristics

Seasonal prevalence and resting habitat

Anopheles minimus is characteristically a species of the forested hills and foothill valley areas in most areas of Southeast Asia and India [20, 30, 36, 54]. It is recorded to be prevalent throughout the year at elevations ranging from 100 to 2000 ft above mean sea level (amsl) but its occurrence at higher altitudes up to

1000 m) has also been reported [11]. Its relative abundance, however, varied across seasons in different geographical locations [22, 30]. In Assam (Northeast India), its population density appeared rising with increasing temperatures beginning in March (spring season) and peak density was reported in April till August varying from 9.87 to 17.13 specimens per person hour. These were also the months of heavy rainfall (monsoon season) during which maximum and minimum temperatures ranged from 27–32 °C to 19–25 °C, respectively (Fig. 3). For the rest of the year (post-monsoon season), mosquito density remained low and varied from 0.97 to 6.06 per person hour. Instead, in east-central India (Odisha State), peak density was observed during July till October/November coinciding with the wet season and was comparatively low for the rest of the year [30]. In northeast India, An. minimus is primarily an endophilic mosquito evidenced by collections of nearly equal proportions of fully fed, semi-gravid/gravid mosquitoes in human dwellings [20]. In contrast, there was indication of exophilic behavior in east-central India marked by lesser proportions of semi-gravid and gravid than fully fed mosquito adults resting indoors [30]. Nevertheless, this species invariably constituted good proportion of indoor resting mosquito collections in non-intervention (unsprayed) human dwellings both in Assam and Odisha [20, 30, 55]. Typically, it is found resting in mud houses/huts made of split bamboo with thatched roofing often adjacent to rice fields/seepage water streams (Fig. 4a and b). Its spatial distribution, however, is highly uneven with houses in closer proximity to breeding habitat (< 1 km) yielding more adults than beyond [56]. In Assam, adult mosquitoes were invariably seen resting on walls in darker corners of the house, hanging clothes, umbrellas and other articles, underneath cots and furniture, etc. (Fig. 4b). In the State of Odisha, however, most adults were observed resting on walls at height of 3–4 ft (1 m) and none on the hanging objects [30]. The species exhibited great degree of behavioral plasticity in response to residual insecticide spray operations and/or introduction of insecticide-treated nets/long-lasting insecticidal nets by changing resting habitat from indoors to outdoors avoiding contact with sprayed/treated surfaces. The mosquito density was reduced to virtually nil in intervention villages [57, 58]. Similar behavioral responses have also been reported in other countries such as Vietnam [48].

Density of Anopheles minimus (number of mosquitoes caught per person hour) and seasonal variations based on meteorological data collected monthly in the Dimoria block of Kamrup district of Assam, northeast India (1989–1991). Abbreviations: Cms, centimeters °C, degree Celsius RH (%), relative humidity in percent


How our Wolbachia method works

Our Wolbachia method is simple.

We discovered that when Aedes aegypti mosquitoes carry Wolbachia, the bacteria compete with viruses like dengue, Zika, chikungunya and yellow fever.

This makes it harder for viruses to reproduce inside the mosquitoes. And the mosquitoes are much less likely to spread viruses from person to person.

This means that when Aedes aegypti mosquitoes carry natural Wolbachia bacteria, the transmission of viruses like dengue, Zika, chikungunya and yellow fever is reduced.

So, at the World Mosquito Program, we breed Wolbachia-carrying mosquitoes. Then, in partnership with local communities, we release them into areas affected by mosquito-borne diseases.

Which means less risk of disease in communities where we work.


Structure and Life Cycle of Mosquito (With Diagram)

Mosquito IS a common insect found almost everywhere. In some species of mosquito, the females feed on humans, and are therefore vectors for a number of infectious diseases affecting millions of people every year.

The body of mosquito is differentiated into head, thorax and abdomen with a short and mobile neck joining the head with the thorax.

The head is small and spherical in shape. It bears two large compound eyes and a pair of long, many-segmented antennae.

The thorax has three segments prothorax, mesothorax and metathorax (fig. 8.5, 8.6). Each thoracic segment bears a pair of legs. Mesothorax bears a pair of wings and prothorax a pair of spiracles near the legs.

The abdomen is long, slender and made up of 10 segments. Second to eighth abdominal segment are normal and bear a pair of spiracles, 8th segment bears the terminal anus and 9th bears the terminal gonopore. In females the 10th segment bears a pair of anal cerci, sandwiching a small post-genital plate. In males 9th segment bears a pair of clawed claspers and 10th modified into a copulatory organ aedigus.

The abdomen is specialized for food digestion and egg development. This segmented body part expands considerably when a female takes a blood meal. The blood is digested over time serving as a source of protein for the production of eggs, which gradually fill the abdomen.

The mouthparts of male mosquitoes are ‘sucking type’ to suck the nectar of flowers while those of females are of ‘piercing and sucking type’ to pierce the skin of warm-blooded vertebrate hosts and suck their blood for feeding.

Life cycle of mosquitoes:

Mosquitoes copulate while flying during the night. It is believed that the pitch of sound produced during flight is higher in females, and this helps the male mosquitoes to locate the female mosquitoes and copulate.

After copulation the female Anopheles lays about 40 to 100 and female culex about 150 to 300 eggs after midnight in standing water of some pond, ditch, pool, puddle, lake, well, water-storage tanks etc., or even in water containers in our houses. A blood-meal by the female is necessary before oviposition.

While laying its eggs one-by-one, the female culex holds these upright upon water surface with the help of its hind legs and plasters these with each other. Hence, its eggs occur in boat-shaped floating clusters called “rafts”. Female anopheles lays its eggs singly.

Eggs of culex are somewhat elongated and cigar shaped with their narrower end directed upwards in the floating rafts. The lower, broader end bears a micropyle cap. In the beginning, the eggs are white, but gradually these acquire a grey colour.

The eggs of Anopheles are smaller, spindle-shaped and black. On each side of its middle, thicker part, the egg bears an umbrella-like membranous structure filled with air and called “air float”. These floats give buoyancy to the egg.

Within one to three days, the embryonic development is completed in an egg and a larva, called wriggler, hatches out in water from it. The larva of Culex hatches out by breaking open the micropyle cap. In the beginning, it is about 1 mm. long and transparent. It actively swims in water by wriggling, feeds upon aquatic micro-organisms at bottom, and grows by undergoing four moults. The larva of Anopheles, however, feeds upon the water surface.

The body of larva is distinguished into head, thorax and abdomen. The head is relatively large and somewhat flattened. On each lateral side, it bears a large compound eye and a small simple eye or ocellus. Just in front of each compound eye is a shot antenna.

The tip of the head is marked by larval mouth. The mouth is ventrally bounded by a lower lip or labium and laterally by a mandible and a bristle-bearing maxilla on each side. Dorsally, a pair of plate-like lobes, bearing hard setae, project infront from upper part of the mouth. The larval mouthparts are of chewing type. Food particles, coming in contact with mouthparts, are caught and chewed before swallowing.

Soon after the fourth moult, the larva becomes inactive, sinks down to the bottom and metamorphosis into a comma-shaped stage called pupa. Unlike the pupa of housefly, the pupa of mosquitoes is without a tough covering and it is as active as the larva. The pupa of Culex is grayish, while that of Anopheles is greenish grey. Its body is differentiated into two regions—a cephalothorax in the front region and abdomen in the back region.

The abdomen is narrow, 9-segmented and curved towards the ventral side. A pair of small, trumpet-shaped ‘respiratory horns’ helps in respiration. It has terminal spiracles and remain connected with tracheal system of body. Most of the time, the pupa remains at water surface with its respiratory horns protruding out in air for breathing.

In the pupa of Anopheles, the respiratory horns are relatively shorter, but the spiracles are broader (fig. 8.7, 8.8).

The 8th abdominal segment of pupa bears a pair of large, backwardly directed, leaf-like fins or paddles which help it in darting. Each paddle terminally bears a single, slender spine in the pupa of culex and two in case of anopheles. Around the spiracle at the tip of each respiratory horn, there is a crown of fine bristles which prevent entrance of water into the horn. Besides these structures, all abdominal segments bear tufts of long bristles.

Metamorphosis of pupa:

Pupa has no mouth or anus. Hence, it is non-feeding. It depends only upon stored food. That is why, its life is very short (2 to 7 days). During this period, active histolysis and histogenesis occur inside its body as described in case of housefly. These processes of metamorphosis in the pupa can be observed from outside through the semitransparent pupal skin.

Metamorphosis in the pupa results into the formation of young mosquito. Eventually, the pupal spin splits in mid-dorsal line of cephalothoraxes, between the respiratory horns, and the young mosquito, called imago, hatches out from it. The pupa at this time essentially keeps floating at water surface. After hatching, the imago keeps sitting upon the dead pupal skin for a while to dry its wings and then flies away.

From egg to imago, the life cycle of mosquito is completed in about a month. The imago becomes sexually mature after about a week of hatching. The life span of male mosquito is hardly of three weeks. It generally dies soon after copulation. The female mosquitoes remain alive for one to several months.

Mosquitoes are a vector agent that carries disease-causing viruses and parasites from person to person without catching the disease themselves. The principal mosquito borne diseases are the viral diseases yellow fever, dengue fever and Chikungunya, transmitted mostly by the Aedes aegypti, and malaria carried by the genus Anopheles. There are many methods used for mosquito control.

Depending on the situation, source reduction, bio-control, larviciding (control of larvae), or adulticiding (control of adults) may be used to manage mosquito populations. These techniques are accomplished using habitat modification, such as removing stagnant water and other breeding areas, spraying pesticide like DDT, natural predators. The dragonfly nymph eats mosquitoes at all stages of development and is quite effective in controlling its populations.


Malaria: Obstacles and Opportunities (1991)

WHERE WE WANT TO BE IN THE YEAR 2010

Vector biology will play a major role in the battle against malaria. Improved vector surveillance networks will allow most countries, particularly those in Africa, to mount effective control efforts and to predict outbreaks of disease. Researchers will be able to conduct epidemiologic surveys and track drug resistance simply by analyzing mosquito populations. Simple techniques will be used in the field to identify morphologically indistinguishable mosquitoes that have different capabilities to transmit malaria parasites, leading to more effective application of vector control measures. The entomological risk factors for severe disease and death will be identified, and interventions will be implemented. The development of environmentally safe antimosquito compounds will complement traditional residual insecticide spraying, and genetically engineered microbial agents will be used to kill mosquito larvae. An antimosquito vaccine will add to the growing arsenal of malaria control weapons. Feasibility studies will be carried out to replace populations of malaria vectors with natural or genetically altered forms that cannot transmit human malaria.

WHERE WE ARE TODAY

Vector biology, broadly defined, is the science devoted to studying insects that transmit pathogens, their contact with humans, and their interaction with the disease-causing organisms. In the case of malaria, the vector is the anopheline mosquito and the disease-causing organism is the malaria parasite. Humans and anopheline mosquitoes are both considered to be the parasite's hosts.

One of the primary goals of vector biology in malaria research is to promote a better understanding of the disease cycle that will facilitate more effectively targeted control strategies. The vast majority of successful antimalaria campaigns have relied heavily on vector control.

The distribution of malaria within human populations is linked closely to site-specific characteristics of vector populations. Within any given area, there are usually fewer than five vector species, although the biology of each species is unique in many respects, including the sites where larvae develop, adult mosquito behavior (especially human-biting behavior), susceptibility to Plasmodium parasites, and the ability to transmit these parasites.

Not all mosquitoes can transmit human malarial parasites. Of the thousands of described mosquito species, only a fraction of those in the genus Anopheles serve as vectors. Some anopheline species do not feed on humans, others are not susceptible to human malaria parasites, and a number have life spans too short to allow the parasite to fully mature. Vector species that pose the greatest threat are abundant, long-lived, commonly feed on humans, and typically dwell in proximity to people. Their role in malaria transmission depends largely on the presence of a favorable environment for larval development and adult survival, and the ability to feed on humans. Transmission also depends significantly on human habits that promote host-vector contact.

Perhaps the least understood process in malaria transmission is the development of the parasite in the vector. To transmit malaria, vectors must be able to support parasite development through several key stages over 8 to 15 days. Only then are the sporozoite-stage parasites present and ready for transmission to new human hosts. Thus, from the standpoint of vector biology, there are three main points of attack for controlling malaria: the environment, human habits, and parasite development in the vector.

In cases in which the impact and feasibility of vector control are questioned, the result is often an overwhelming reliance on chemotherapy-based measures for reducing malaria-related mortality and morbidity. In countries with the most severe malaria problems, there are seldom funds for anything but antimalarial drugs and, in some cases, for limited vector control activities (mostly in urban areas). Such approaches usually do little

to prevent malaria transmission, however. The continuous need for adequate drug supplies to treat clinically ill residents of endemic areas severely limits progress toward malaria prevention. In most malarious regions of the world, there is little baseline information on vector populations and variation in the intensity of malaria transmission. Thus, it is exceedingly difficult, and often unrealistic, for developing countries to formulate malaria control strategies aimed at prevention.

As in other areas of tropical health, distinctions between field and laboratory research in vector biology are sometimes blurred, since basic research problems often require use of field-collected specimens to explore natural phenomena. Similarly, even the least sophisticated laboratories are now using modern techniques. The distinction between basic and applied research in vector biology is difficult to make, because most research topics have long-term applied or operational applications.

Throughout the world, vector biology field studies generally use a common set of techniques for collecting vectors and processing field-collected specimens. The same general methods used to study malaria transmission and vector behavior are used to evaluate new vector control strategies. As new vector-related techniques are developed for investigating the biology of anopheline mosquitoes, they are quickly adopted by field-based malaria control programs. Thus, developments in malaria vector control are highly dependent on basic research.

Vector-Parasite Interactions
Sporogonic Development in Anopheles Mosquitoes

The four human malarial parasites&mdashPlasmodium falciparum, P. vivax, P. malariae, and P. ovale&mdashall undergo a similar process of sporogonic development in the mosquito host (Garnham, 1966). Development begins when a susceptible female mosquito ingests microgametocytes (male forms) and macrogametocytes (female forms) during blood feeding on an infected human. Sexual reproduction (and, importantly, genetic recombination) occurs in the mosquito host as microgametocytes quickly exflagellate, producing microgametes that fuse with macrogametes to form zygotes. Zygotes develop into ookinetes, which penetrate the midgut epithelial cells and mature into oocysts. These in turn mature and release thousands of sporozoites into the mosquito hemolymph system. A mosquito is considered infective as soon as sporozoites invade the salivary glands. Transmission to humans occurs when sporozoites are injected with salivary fluids during a blood meal.

The time needed for sporozoites to reach the salivary glands of the mosquito depends on both the species of parasite and the ambient temperature. For example, P. falciparum takes 9 days at 30°C, 10 days at 25°C,

11 days at 24°C, and 23 days at 20°C, a difference of 14 days over a range of 10°C. At 25°C, the process is completed in 9 days for P. vivax, compared with 15 to 20 days for P. malariae and 16 days for P. ovale. The relatively short extrinsic incubation periods of P. falciparum and P. vivax are among the several reasons why these parasite species are more common than either P. malariae or P. ovale.

Once a female mosquito is infective, she remains so for life. Generally, mosquitoes are capable of transmitting sporozoites during each blood-feeding episode, sometimes to multiple individuals during each feeding cycle. Boyd and Stratman-Thomas (1934) demonstrated that P. vivax-infected mosquitoes could infect 90 percent of patients during the first three weeks, 66 percent by the fifth week, and only 20 percent by the seventh week. Although old infective mosquitoes that have fed 5 to 10 times can still transmit malaria sporozoites, over time these sporozoites tend to lose infectivity.

Factors Affecting Susceptibility

Factors that affect the susceptibility of anopheline mosquitoes to human malaria parasites are poorly understood. Mosquitoes of the genera Culex and Aedes contain numerous species that feed on humans and transmit a number of infectious diseases. However, none of these species transmit human malarias. The physiological and genetic basis of this insusceptibility to the human malaria parasite is unknown, just as are the differences in susceptibility among various Anopheles species.

The inability of malaria parasites to develop in some mosquito species may be due to the absence of some critical factor in the mosquito required for normal parasite development, or it could be due to the presence of a toxin that actively inhibits or aborts parasite development (Weathersby, 1952). One mechanism that may make mosquitoes susceptible to parasites is species-specific stimulation of exflagellation (Micks, 1949 Nijhout, 1979), while encapsulation of ookinetes and oocysts (Collins et al., 1986) and the failure of sporozoites to penetrate salivary glands (Rosenberg, 1985) may help explain mosquito resistance to malaria parasites.

The genetic basis for mosquito susceptibility or refractoriness to malaria is extremely complex (Curtis and Graves, 1983). Using laboratory-reared vectors and malaria parasites from animals, it is possible to select for highly susceptible and highly refractory strains of mosquitoes. In most cases, several genes and often complicated modes of inheritance appear to be involved.

Factors Affecting Transmission

The basic process of sporogonic development in susceptible vector species is poorly understood. The numbers of gametocytes ingested, ookinetes

and oocysts that develop, sporozoites in the hemolymph and in the salivary glands, and sporozoites transmitted during a blood meal have not been well quantified. Most studies of vector competence count only oocysts on the midgut wall and crudely estimate salivary gland sporozoites. Thus, there is little information on this very important process for any vector species, and there is no basis for comparison among vector species.

Studies of sporogonic development in the vector and vector-parasite relationships for human malaria parasites are largely restricted to P. falciparum, the only species that can be grown in vitro. The extent to which similar vector-related studies, using animal model systems (Mons and Sinden, 1990), are relevant to human malaria is unknown.

Malaria Transmission

Most vector biology field studies focus on determining human-vector contact, feeding and resting habits, survival, and other life history parameters of vector populations. Usually, the vector status of populations is defined by determining sporozoite and oocyst rates (the proportion of infective mosquitoes in a vector population and the proportion of mosquitoes with oocysts, respectively). This approach provides essential but not sufficient information about vectorial systems (all anopheline species in a given area that transmit malaria).

Field studies of malaria transmission need to be reoriented toward quantifying other important epidemiologic parameters of anopheline populations. For example, little is known about the variation in the number of sporozoites in mosquito salivary glands (sporozoite loads), nor is there much information on the numbers of sporozoites transmitted per feeding and whether this parameter is affected by sporozoite loads. Globally, the diversity of vectorial systems should allow for great heterogeneity in the ability of vectors to transmit sporozoites this has significant implications for malaria control. For example, a sporozoite vaccine may be effective in one country where a certain Anopheles species transmits an average of 5 sporozoites per bite, but not in another country where a different Anopheles species transmits 500 sporozoites per bite.

Factors influencing variation in sporozoite rates and in sporozoite loads, within geographic zones, are equally important. Life stages of Plasmodium in the vector, other than oocysts and sporozoites, have never been studied in nature. Lack of information about the early stages of sporogonic development, from the point of ingestion of gametocytes to ookinetes to the appearance of oocysts, is critical because these stages influence the development of sporozoites. It is also likely that the life history parameters of vector populations, such as vector size, feeding habits, frequency of feeding, age, and reproductive state, can influence the mosquito's susceptibil-

ity to parasites and the probability it will survive long enough for the parasite to fully develop.

Vector biologists know very little about vector-related factors that affect sporozoite viability in nature. Epidemiologic studies indicate that, at most, between 1 and 20 percent of sporozoite inoculations produce infections in nature (Pull and Grab, 1974). Effective, direct assays for determining sporozoite viability for individual, field-collected mosquitoes do not exist. Human antibodies ingested by mosquitoes may play some role in regulating sporozoite infectivity. In one study, human immunoglobulin G antibody was found on sporozoites in over 80 percent of infected mosquitoes sampled in Kenya (Beier et al., 1989) the significance in terms of sporozoite infectivity is unknown.

Regulation of Vector Populations&mdashLarval Ecology

The mechanisms that regulate vector populations are poorly understood but are of great importance for malaria control (Molineaux, 1988). For example, there is limited information on the biology of aquatic stages of malaria vectors. The factors affecting larval survival and the mechanisms controlling adult production are largely unknown for even the most important vector species. The basic concept of density-dependent regulation has never been studied for populations in nature. It is extremely important to know whether populations are regulated through competition (intra-and/or interspecific) and predation in the aquatic habitat. Furthermore, there is no baseline information on the foraging habits and strategies of larval-stage vector populations. The study of larval biology is complicated further by inadequate techniques for the identification of larvae belonging to species complexes. Consequently, few entomologists seek to tackle this important area of anopheline biology.

A basic understanding of the aquatic stages of vectors is extremely relevant to malaria control. Source reduction through the modification of larval habitats was the key to malaria eradication efforts in the United States, Israel, and Italy (Kitron and Spielman, 1989). In these countries, a variety of measures directed against the aquatic stages of important vectors reduced cases of malaria and eliminated parasite transmission.

Vector Incrimination

The identification of anopheline mosquitoes responsible for malaria transmission is known as vector incrimination, and the approach is the same for any given area. Mosquitoes, preferably those coming to feed on humans, are collected, identified, and dissected to determine the presence of sporozoites in the salivary glands. Immunological techniques can be used to


Universal features of music around the world

Is music really a "universal language"? Two articles in the most recent issue of Science support the idea that music all around the globe shares important commonalities, despite many differences. Researchers led by Samuel Mehr at Harvard University have undertaken a large-scale analysis of music from cultures around the world. Cognitive biologists Tecumseh Fitch and Tudor Popescu of the University of Vienna suggest that human musicality unites all cultures across the planet.

The many musical styles of the world are so different, at least superficially, that music scholars are often sceptical that they have any important shared features. "Universality is a big word -- and a dangerous one," the great Leonard Bernstein once said. Indeed, in ethnomusicology, universality became something of a dirty word. But new research promises to once again revive the search for deep universal aspects of human musicality.

Samuel Mehr at Harvard University found that all cultures studied make music, and use similar kinds of music in similar contexts, with consistent features in each case. For example, dance music is fast and rhythmic, and lullabies soft and slow -- all around the world. Furthermore, all cultures showed tonality: building up a small subset of notes from some base note, just as in the Western diatonic scale. Healing songs tend to use fewer notes, and more closely spaced, than love songs. These and other findings indicate that there are indeed universal properties of music that likely reflect deeper commonalities of human cognition -- a fundamental "human musicality."

In a Science perspective piece in the same issue, University of Vienna researchers Tecumseh Fitch and Tudor Popescu comment on the implications. "Human musicality fundamentally rests on a small number of fixed pillars: hard-coded predispositions, afforded to us by the ancient physiological infrastructure of our shared biology. These 'musical pillars' are then 'seasoned' with the specifics of every individual culture, giving rise to the beautiful kaleidoscopic assortment that we find in world music," Tudor Popescu explains.

"This new research revives a fascinating field of study, pioneered by Carl Stumpf in Berlin at the beginning of the 20th century, but that was tragically terminated by the Nazis in the 1930s," Fitch adds.

As humanity comes closer together, so does our wish to understand what it is that we all have in common -- in all aspects of behaviour and culture. The new research suggests that human musicality is one of these shared aspects of human cognition. "Just as European countries are said to be 'United In Diversity', so too the medley of human musicality unites all cultures across the planet," concludes Tudor Popescu.


Countries with the Highest Rates of Malaria

Transmission And Diagnosis Of Malaria

Malaria is transmitted via the female Anopheles mosquito which thrives in tropical and subtropical regions. It is very rarely, if ever, found at high altitudes, in deserts, or during cold seasons. In 2015, 214 million new cases of malaria were reported with approximately 438 thousand deaths. These numbers are from diagnosed cases, and many infections go undiagnosed. Malaria is preventable and treatable. The majority if these new cases and 90% of the resulting deaths occur in Africa. Uganda, for example, reported the highest number of new infections with 10.3 million. This figure is followed by Ghana with 8.8 million and another 6.3 million in the Democratic Republic of Congo.

Factors Leading To The Spread Of The Disease

Why do healthcare professionals diagnose so many new malaria infections throughout Africa every year? In addition to previously mentioned countries, there have also been 6.1 million new cases in Burkina Faso, 5.8 million in Kenya, and 4.7 million in Zambia. The overwhelming response to the spread of malaria is poverty. In countries where the majority of people live in poverty, infections like malaria are far more likely to occur. The construction of homes in the rural areas of developing countries does little to protect against mosquitoes entering and the families cannot afford mosquito nets to hang over beds. These individuals are unable to pay for transportation and healthcare facilities and even if they manage to get a formal diagnosis, are often unable to pay for medicines. Lack of education about malaria prevention, like covering water stores to prevent mosquito breeding, also contributes to why these countries face high rates of malaria. Malnutrition is rampant in these areas as well which makes immune systems weaker.

Effects On Newborns and Children

Malaria infections cause a tremendous burden on the health systems in these countries and primarily affects children who are infected in 1 of 3 ways. When the mother is infected during pregnancy, the parasite is passed along to the fetus. This event results in premature birth and low birth weight which decreases the chance of survival. A rapid and severe case of malaria can also cause seizures, coma, or respiratory infection, all of which lead to death. Finally, children who become infected repeatedly are more likely to suffer from anemia which, in turn, weakens their immune system.

Other countries with high numbers of new malaria infections are Pakistan (4.3 million), Ethiopia (3.9 million), Malawi (3.7 million), and Niger (3.5 million).


Why Study Mosquitoes?

In the early 1900s, mosquito-transmitted malaria was prevalent throughout the southern and central United States. Improved infrastructure, housing, and increased mosquito control efforts interrupted the disease transmission cycle and extirpated the pathogen by 1951 (Centers for Disease Control and Prevention [CDC], 2010) (for definitions of three main terms, see Table 1). Although human malaria transmission was eliminated from the United States, other mosquito-transmitted pathogens still circulate, such as the encephalitis viruses (West Nile, eastern equine, western equine, La Crosse, and St. Louis encephalitis viruses U.S. Geological Survey, 2015) and pose a risk to humans, their animals (mainly horses and birds), and wildlife (Figure 1). Also of major concern are mosquitoes that transmit canine heart worm or filarial worms to animals. Three mosquito-transmitted viruses recently introduced to North America – West Nile, chikungunya, and Zika – have highlighted the importance of mosquito control programs and public health education to detect introduced pathogens and reduce disease transmission. One large knowledge gap this project targets is mapping the ever changing and expanding geographic distribution of mosquito species in the United States.

Distribution of positive West Nile cases in 2014. Counties shaded in gray reported at least one case, and counties in white had none (source: http://diseasemaps.usgs.gov/).

Distribution of positive West Nile cases in 2014. Counties shaded in gray reported at least one case, and counties in white had none (source: http://diseasemaps.usgs.gov/).

PathogenCausative agent of disease. May be a virus or parasite.
DiseasePossible results of infection by a pathogen.
VectorInsect species capable of transmitting a pathogen that may cause disease.
PathogenCausative agent of disease. May be a virus or parasite.
DiseasePossible results of infection by a pathogen.
VectorInsect species capable of transmitting a pathogen that may cause disease.

Mosquito monitoring generally consists of trapping mosquitoes and determining the types of species present (species composition). Only a few mosquito species are able to transmit specific pathogens therefore, transmission is possible only if a vector-competent mosquito species is present. Using mosquito monitoring, scientists can identify the species composition and determine the risk of disease transmission in an area. The more mosquitoes trapped and counted, the better the chance of detecting a vector-competent species. This offers the perfect opportunity for student participation in a citizen science project.

This lesson is designed to target two invasive, container-breeding mosquito species (Aedes aegypti and Ae. albopictus) associated with the dengue, chikungunya, and Zika viruses. Dengue virus (DENV) is a major public health problem in tropical and subtropical countries throughout the world. The disease causes fever, severe pain, and internal bleeding (hemorrhaging). Although DENV is generally not endemic in the United States, there has been virus circulation in the Florida Keys, where Ae. aegypti is present, and in Hawaii, where Ae. albopictus is the most common container mosquito species. Chikungunya virus (CHIKV) is a virus recently introduced to the Western Hemisphere, and in the summer of 2014 there was transmission in Florida. Furthermore, CHIKV has a high symptomatic frequency, which means that a large percentage of individuals have clinical symptoms if they are infected (CDC, 2015a). Zika virus (ZIKAV) causes mild symptoms (fever and rash) but has been linked to microcephaly in newborns and in 2016 has resulted in several travel warnings to South and Central American countries. The human population at risk of DENV, CHIKV, and ZIKAV transmission in the United States remains unknown because the distribution of the two main mosquito vector species is unknown. The last complete survey of Ae. aegypti was by Morlan and Tinker (1965), and a list of reports of Ae. albopictus was compiled by Eisen and Moore (2013). More information on their distributions can be found on the CDC website (CDC, 2015b).

Participating in this lesson's mosquito survey will update the distribution data for both species, as well as for other mosquito species that lay their eggs in containers. The lesson emphasizes critical-thinking skills as students use the data collected to assess personal risks from mosquito-borne diseases. Mosquito control and abatement districts funded by local, state, and federal taxes help reduce the risk and burden of these diseases by killing larval and adult mosquitoes. Without these essential services, the number of illnesses would be much higher. However, the best methods to prevent mosquito-transmitted pathogens remain individual actions such as wearing long sleeves, using repellents, and putting screens on windows and doors.

Interpreting data and connecting it to the “real world” is occasionally a hard concept for students to grasp. This inexpensive learning activity introduces students to national datasets and long-term data. The experiment can be run each year to see the year-to-year changes in mosquito abundance and distribution. Furthermore, the lesson covers a variety of branches of biological study and how they all connect in a real-life issue that is pertinent to students’ lives (Table 2). Students have individual responsibility for planning and carrying out their own mosquito egg collection, and collaborative work occurs in the classroom during discussions of the collected and supplied data. This lesson allows students to experience obtaining, evaluating, and communicating valuable information as part of a national invasive-mosquito-project study. Students benefit from the fact that this lesson takes place as part of a national program in a number of ways: they have access to the national datasets to compare with their local data answers to various questions posed by the data collected cannot be found by simply searching on the Internet and must be logically thought out and the data collected will be visible results of their efforts – an often gratifying reward. Students are not only informed of the global problems in this lesson, but are also educated and participate in a solution to the issue.

Create or revise a simulation of a phenomenon, designed device, process, or system. (HS-LS4-6)

Design, evaluate, and refine a solution to a complex real-world problem, based on scientific knowledge, student-generated sources of evidence, prioritized criteria, and tradeoff considerations. (HS-LS2-7)

Evaluate the claims, evidence, and reasoning behind currently accepted explanations or solutions to determine the merits of arguments. (HS-LS2-6)

Evaluate the evidence behind currently accepted explanations or solutions to determine the merits of arguments. (HS-LS2-8)

Asking questions (for science) and defining problems (for engineering)

Developing and using models

Planning and carrying out investigations

Analyzing and interpreting data

Using mathematics and computational thinking

Constructing explanations (for science) and designing solutions (for engineering)

Engaging in argument from evidence

Obtaining, evaluating, and communicating information

Cause and Effect: The significance of a phenomenon is dependent on the scale, proportion, and quantity at which it occurs. (HS-LS2-1)

Using the concept of orders of magnitude allows one to understand how a model at one scale relates to a model at another scale. (HS-LS2-2)

Stability and Change: Much of science deals with constructing explanations of how things change and how they remain stable. (HS-LS2-6)

Cause and effect: Mechanism and explanation

Scale, proportion, and quantity

Systems and system models

Changes in the physical environment, whether naturally occurring or human induced, have thus contributed to the expansion of some species, the emergence of new distinct species as populations diverge under different conditions, and the decline – and sometimes the extinction – of some species. (HS-LS4-6)

HS-LS2-1. Use mathematical and/or computational representations to support explanations of factors that affect carrying capacity of ecosystems at different scales.

HS-LS2-2. Use mathematical representations to support and revise explanations based on evidence about factors affecting biodiversity and populations in ecosystems of different scales.

HS-LS2-6. Evaluate the claims, evidence, and reasoning that the complex interactions in ecosystems maintain relatively consistent numbers and types of organisms in stable conditions, but changing conditions may result in a new ecosystem.

HS-LS2-7. Design, evaluate, and refine a solution for reducing the impacts of human activities on the environment and biodiversity.

HS-LS2-8. Evaluate the evidence for the role of group behavior on individual and species’ chances to survive and reproduce. HS-LS2-1. Use mathematical and/or computational representations to support explanations of factors that affect carrying capacity of ecosystems at different scales.

Create or revise a simulation of a phenomenon, designed device, process, or system. (HS-LS4-6)

Design, evaluate, and refine a solution to a complex real-world problem, based on scientific knowledge, student-generated sources of evidence, prioritized criteria, and tradeoff considerations. (HS-LS2-7)

Evaluate the claims, evidence, and reasoning behind currently accepted explanations or solutions to determine the merits of arguments. (HS-LS2-6)

Evaluate the evidence behind currently accepted explanations or solutions to determine the merits of arguments. (HS-LS2-8)

Asking questions (for science) and defining problems (for engineering)

Developing and using models

Planning and carrying out investigations

Analyzing and interpreting data

Using mathematics and computational thinking

Constructing explanations (for science) and designing solutions (for engineering)

Engaging in argument from evidence

Obtaining, evaluating, and communicating information

Cause and Effect: The significance of a phenomenon is dependent on the scale, proportion, and quantity at which it occurs. (HS-LS2-1)

Using the concept of orders of magnitude allows one to understand how a model at one scale relates to a model at another scale. (HS-LS2-2)

Stability and Change: Much of science deals with constructing explanations of how things change and how they remain stable. (HS-LS2-6)

Cause and effect: Mechanism and explanation

Scale, proportion, and quantity

Systems and system models

Changes in the physical environment, whether naturally occurring or human induced, have thus contributed to the expansion of some species, the emergence of new distinct species as populations diverge under different conditions, and the decline – and sometimes the extinction – of some species. (HS-LS4-6)

HS-LS2-1. Use mathematical and/or computational representations to support explanations of factors that affect carrying capacity of ecosystems at different scales.

HS-LS2-2. Use mathematical representations to support and revise explanations based on evidence about factors affecting biodiversity and populations in ecosystems of different scales.

HS-LS2-6. Evaluate the claims, evidence, and reasoning that the complex interactions in ecosystems maintain relatively consistent numbers and types of organisms in stable conditions, but changing conditions may result in a new ecosystem.

HS-LS2-7. Design, evaluate, and refine a solution for reducing the impacts of human activities on the environment and biodiversity.

HS-LS2-8. Evaluate the evidence for the role of group behavior on individual and species’ chances to survive and reproduce. HS-LS2-1. Use mathematical and/or computational representations to support explanations of factors that affect carrying capacity of ecosystems at different scales.