Pollen is a powdery substance produced by most types of flowers of seed plants for the purpose of sexual reproduction. It consists of pollen grains (highly reduced microgametophytes ), which produce male gametes (sperm cells).
124-663: A pollinator is an animal that moves pollen from the male anther of a flower to the female stigma of a flower. This helps to bring about fertilization of the ovules in the flower by the male gametes from the pollen grains. Insects are the major pollinators of most plants, and insect pollinators include all families of bees and most families of aculeate wasps ; ants ; many families of flies ; many lepidopterans (both butterflies and moths ); and many families of beetles . Vertebrates, mainly bats and birds, but also some non-bat mammals ( monkeys , lemurs , possums , rodents ) and some lizards pollinate certain plants. Among
248-919: A flagellum to assist in hunting for food, and some protozoa travel via infectious spores to act as parasites. Many protists are mixotrophic, having both phototrophic and heterotrophic characteristics. Mixotrophic protists will typically depend on one source of nutrients while using the other as a supplemental source or a temporary alternative when its primary source is unavailable. Prokaryotes , including bacteria and archaea , vary greatly in how they obtain nutrients across nutritional groups. Prokaryotes can only transport soluble compounds across their cell envelopes, but they can break down chemical components around them. Some lithotrophic prokaryotes are extremophiles that can survive in nutrient-deprived environments by breaking down inorganic matter. Phototrophic prokaryotes, such as cyanobacteria and Chloroflexia , can engage in photosynthesis to obtain energy from sunlight. This
372-403: A pollen tube that transfers the sperm to the ovule containing the female gametophyte. Individual pollen grains are small enough to require magnification to see detail. The study of pollen is called palynology and is highly useful in paleoecology , paleontology , archaeology , and forensics . Pollen in plants is used for transferring haploid male genetic material from the anther of
496-466: A sonicating bee (one that vibrates its wing muscles while perched on the flower), such as a bumblebee. Sonicating bees are extremely efficient pollinators of tomatoes, and colonies of bumblebees are quickly replacing humans as the primary pollinators for greenhouse tomatoes. Pollinators require a variety of resources. Most native bees in North America are solitary, ground-nesting species that collect
620-764: A 54% increased chance of asthma attacks when exposed to pollen. The number of people in the United States affected by hay fever is between 20 and 40 million, including around 6.1 million children and such allergy has proven to be the most frequent allergic response in the nation. Hay fever affects about 20% of Canadians and the prevalence is increasing. There are certain evidential suggestions pointing out hay fever and similar allergies to be of hereditary origin . Individuals who suffer from eczema or are asthmatic tend to be more susceptible to developing long-term hay fever. Since 1990, pollen seasons have gotten longer and more pollen-filled, and climate change
744-409: A burglar who brushed against a Hypericum bush during a crime, and has even been proposed as an additive for bullets to enable tracking them. In some Native American religions , pollen was used in prayers and rituals to symbolize life and renewal by sanctifying objects, dancing grounds, trails, and sandpaintings . It may also be sprinkled over heads or in mouths. Many Navajo people believed
868-596: A comprehensive approach to tackling and reducing the impact of multiple stressors on pollinator health, including pests and pathogens, reduced habitat, lack of nutritional resources, and exposure to pesticides. The national strategy laid out federal actions to achieve three goals: Many of the priority projects that the national strategy identified focused on the I-35 corridor, which extends for 1,500 miles (2,400 km) from Texas to Minnesota. The area through which that highway travels provides spring and summer breeding habitats in
992-426: A continuum with intermediate forms, the type of microsporogenesis has systematic significance. The predominant form amongst the monocots is successive, but there are important exceptions. During microgametogenesis, the unicellular microspores undergo mitosis and develop into mature microgametophytes containing the gametes. In some flowering plants, germination of the pollen grain may begin even before it leaves
1116-441: A critical point. This simultaneous collapse occurs, because pollinator species depend on each other when surviving under difficult conditions. Such a community-wide collapse, involving many pollinator species, can occur suddenly when increasingly harsh conditions pass a critical point and recovery from such a collapse might not be easy. The improvement in conditions needed for pollinators to recover, could be substantially larger than
1240-501: A fetid odor . The plants' ecological strategy varies; several species of Stapelia , for example, attract carrion flies that futilely lay their eggs on the flower, where their larvae promptly starve for lack of carrion . Other species do decay rapidly after ripening, and offer the visiting insects large masses of food, as well as pollen and sometimes seed to carry off when they leave. Hoverflies are important pollinators of flowering plants worldwide. Often hoverflies are considered to be
1364-401: A higher requirement of energy in comparison to plants. The macronutrients essential to animal life are carbohydrates, amino acids , and fatty acids . All macronutrients except water are required by the body for energy, however, this is not their sole physiological function. The energy provided by macronutrients in food is measured in kilocalories, usually called Calories, where 1 Calorie is
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#17328512167581488-538: A key ecosystem service vital to the maintenance of both wild and agricultural plant communities. In 1999 the Convention on Biological Diversity issued the São Paulo Declaration on Pollinators, recognizing the critical role that these species play in supporting and maintaining terrestrial productivity as well as the survival challenges they face due to anthropogenic change. Today pollinators are considered to be in
1612-399: A lumen (plural lumina). These reticulations may also be referred to as brochi. The pollen wall protects the sperm while the pollen grain is moving from the anther to the stigma; it protects the vital genetic material from drying out and solar radiation. The pollen grain surface is covered with waxes and proteins, which are held in place by structures called sculpture elements on the surface of
1736-547: A mud chamber prior to oviposition. Also, males of many species of bees and wasps, though they do not gather pollen, rely on flowers as sources of energy (in the form of nectar) and also as territories for meeting fertile females that visit the flowers. Some Diptera (flies) may be the main pollinators at higher elevations of mountains, whereas bumblebee species are typically the only other pollinators in alpine regions at timberline and beyond. Some adult mosquitoes , if they feed on nectar, may act as pollinators; Aedes communis ,
1860-508: A multitude of viruses and eukaryotic parasites are present in the pollen. It is currently unclear if the parasites are introduced by the bee that collected the pollen or if it is from the flower. Though this is not likely to pose a risk to humans, it is a major issue for the bumblebee rearing industry that relies on thousands of tonnes of honey bee collected pollen per year. Several sterilization methods have been employed, though no method has been 100% effective at sterilisation without reducing
1984-400: A network of interactions between plants and pollinators. Surprising similarities were found in the structure of networks consisting out of the interactions between plants and pollinators. This structure was found to be similar in very different ecosystems on different continents, consisting of entirely different species. The structure of plant-pollinator networks may have large consequences for
2108-553: A nutrient deficiency. Early human nutrition consisted of foraging for nutrients, like other animals, but it diverged at the beginning of the Holocene with the Neolithic Revolution , in which humans developed agriculture to produce food. The Chemical Revolution in the 18th century allowed humans to study the nutrients in foods and develop more advanced methods of food preparation . Major advances in economics and technology during
2232-408: A particular hawk moth , Morgan's sphinx . Yucca species provide other examples, being fertilised in elaborate ecological interactions with particular species of yucca moths . Many bee flies , and some Tabanidae and Nemestrinidae are particularly adapted to pollinating fynbos and Karoo plants with narrow, deep corolla tubes , such as Lapeirousia species. Part of the adaptation takes
2356-505: A pollen allergy is by preventing contact with the material. Individuals carrying the ailment may at first believe that they have a simple summer cold, but hay fever becomes more evident when the apparent cold does not disappear. The confirmation of hay fever can be obtained after examination by a general physician . Antihistamines are effective at treating mild cases of pollinosis; this type of non-prescribed drugs includes loratadine , cetirizine and chlorpheniramine . They do not prevent
2480-871: A preliminary project in Chile, the program has expanded to Colombia, Argentina, and Costa Rica. The ‘Coalition of the Willing on Pollinators' (Promote Pollinators) was initiated in 2016 during the Convention on Biological Diversity's Conference of the Parties (CBD COP13) and is a growing alliance of countries and observers who support the notion that country-led politics can lead to policy measures and innovative action to protect pollinators'. Their supporters are growing steadily, in which 30 countries currently participate. Wild pollinators often visit many plant species and plants are visited by many pollinator species. All these relations together form
2604-481: A significant increase in human intake of fats and oils. Humans have developed advanced methods of food processing that prevent contamination of pathogenic microorganisms and simplify the production of food. These include drying, freezing, heating, milling, pressing, packaging, refrigeration, and irradiation. Most cultures add herbs and spices to foods before eating to add flavor, though most do not significantly affect nutrition. Other additives are also used to improve
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#17328512167582728-473: A single flower to the stigma of another in cross-pollination. In a case of self-pollination, this process takes place from the anther of a flower to the stigma of the same flower. Pollen is infrequently used as food and food supplement . Because of agricultural practices, it is often contaminated by agricultural pesticides. Pollen itself is not the male gamete. It is a gametophyte , something that could be considered an entire organism, which then produces
2852-528: A small number feed on pollen as larvae (including some ant larvae). Spiders are normally considered carnivores but pollen is an important source of food for several species, particularly for spiderlings , which catch pollen on their webs . It is not clear how spiderlings manage to eat pollen however, since their mouths are not large enough to consume pollen grains. Some predatory mites also feed on pollen, with some species being able to subsist solely on pollen, such as Euseius tularensis , which feeds on
2976-698: A species found in North America, is known to pollinate Platanthera obtusata , commonly referred as the blunt-leaved orchid. Beetles of species that specialise in eating pollen, nectar, or flowers themselves, may be important cross-pollinators of some plants such as members of the Araceae and Zamiaceae , that produce prodigious amounts of pollen. Others, for example the Hopliini , specialise on flowers of Asteraceae and Aizoaceae . Minute midges and flower- thrips can occur in vast numbers, moving between flowers and plant individuals, enabling some species to contribute to
3100-507: A state of decline; some species, such as Franklin's bumble bee ( Bombus franklini ) have been red-listed and are in danger of extinction. Although managed bee hives are increasing worldwide, these can not compensate for the loss of wild pollinators in many locations. A 2017 report done for the Center of Biological Diversity utilized data documented in the United States on native bee species and found that nearly 1 in 4 (347 species of 1,437 species)
3224-433: A strain genetically pure. This can involve using a small brush or cotton swab to move pollen, or to simply tap or shake tomato blossoms to release the pollen for the self-pollinating flowers. Tomato blossoms are self-fertile, but (with the exception of potato-leaf varieties) have the pollen inside the anther , and the flower requires shaking to release the pollen through pores . This can be done by wind, by humans, or by
3348-419: A threat to the economic stability of commercial beekeeping and pollination operations in the United States, which could have profound implications for agriculture and food. Severe yearly declines create concern that bee colony losses could reach a point from which the commercial pollination industry would not be able to adequately recover. The loss of native bees, which also play a key role in pollination of crops,
3472-566: A variety of foods. Cultivation of cereals and production of bread has made up a key component of human nutrition since the beginning of agriculture. Early humans hunted animals for meat, and modern humans domesticate animals to consume their meat and eggs. The development of animal husbandry has also allowed humans in some cultures to consume the milk of other animals and process it into foods such as cheese . Other foods eaten by humans include nuts, seeds, fruits, and vegetables. Access to domesticated animals as well as vegetable oils has caused
3596-708: A variety of natural resources including pollen, nectar, leaves, petals and resins to be used as sources of food, supplies for their larva, or nest linings. Floral diet diversity has been seen to increase immunocompetence levels in honeybees (Apis mellifera) where diets that consisted of a wide variety of flowering species induced higher glucose oxidase activity, which honeybees' produce to sterilize their colony. More than 30% of global bee species depend on non-floral resources for nest building, protection, health, pest resistance, and alternative food sources. Non-floral resources include leaves, soil, plant resins and secretions, and are often provided by woody-vegetation. Pollinators provide
3720-797: A widespread anemophilous plant. Arizona was once regarded as a haven for people with pollen allergies, although several ragweed species grow in the desert. However, as suburbs grew and people began establishing irrigated lawns and gardens , more irritating species of ragweed gained a foothold and Arizona lost its claim of freedom from hay fever. Anemophilous spring blooming plants such as oak , birch , hickory , pecan , and early summer grasses may also induce pollen allergies. Most cultivated plants with showy flowers are entomophilous and do not cause pollen allergies. Symptoms of pollen allergy include sneezing , itchy, or runny nose, nasal congestion , red, itchy, and watery eyes. Substances, including pollen, that cause allergies can trigger asthma. A study found
3844-595: Is a collaboration between the Bayer Bee Care Center and the Fraunhofer Chile Research Foundation, that works alongside local researchers at universities and beekeepers' associations. The program focuses on increasing the number of healthy worker bees and their colonies by monitoring honey bee health and the contributing factors. This includes educating beekeepers and research collaborations to jointly work on honey bee health. Founded in 2015 with
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3968-458: Is also associated with asthma exacerbations in some people, a phenomenon termed thunderstorm asthma . In the US, people often mistakenly blame the conspicuous goldenrod flower for allergies. Since this plant is entomophilous (its pollen is dispersed by animals), its heavy, sticky pollen does not become independently airborne. Most late summer and fall pollen allergies are probably caused by ragweed ,
4092-630: Is also present in a wide variety of plants and plant-derived food products. The U.S. Food and Drug Administration (FDA) has not found any harmful effects of bee pollen consumption, except for the usual allergies. However, FDA does not allow bee pollen marketers in the United States to make health claims about their produce, as no scientific basis for these has ever been proven. Furthermore, there are possible dangers not only from allergic reactions but also from contaminants such as pesticides and from fungi and bacteria growth related to poor storage procedures. A manufacturers's claim that pollen collecting helps
4216-468: Is an extensive fossil record of pollen grains, often disassociated from their parent plant. The discipline of palynology is devoted to the study of pollen, which can be used both for biostratigraphy and to gain information about the abundance and variety of plants alive — which can itself yield important information about paleoclimates. Also, pollen analysis has been widely used for reconstructing past changes in vegetation and their associated drivers. Pollen
4340-440: Is an important aspect of the pollination process. Bee pollen for human consumption is marketed as a food ingredient and as a dietary supplement . The largest constituent is carbohydrates , with protein content ranging from 7 to 35 percent depending on the plant species collected by bees. Honey produced by bees from natural sources contains pollen derived p-coumaric acid , an antioxidant and natural bactericide that
4464-482: Is common among bacteria that form in mats atop geothermal springs. Phototrophic prokaryotes typically obtain carbon from assimilating carbon dioxide through the Calvin cycle . Some prokaryotes, such as Bdellovibrio and Ensifer , are predatory and feed on other single-celled organisms. Predatory prokaryotes seek out other organisms through chemotaxis or random collision, merge with the organism, degrade it, and absorb
4588-706: Is described as monosulcate , has two sulci, as bisulcate , or more, as polysulcate . Colpate pollen has furrows other than across the middle of the outer faces, and similarly may be described as polycolpate if more than two. Syncolpate pollen grains have two or more colpi that are fused at the ends. Eudicots have pollen with three colpi ( tricolpate ) or with shapes that are evolutionarily derived from tricolpate pollen. The evolutionary trend in plants has been from monosulcate to polycolpate or polyporate pollen. Additionally, gymnosperm pollen grains often have air bladders, or vesicles, called sacci. The sacci are not actually balloons, but are sponge-like, and increase
4712-548: Is developing strategic plans for conservation that looks to establish partnership between government entities. 11 pollinator-protection agreements have been signed between NAPCC and federal government agencies, responsible for more than 1.5 billion acres of land protections and management. Along with the European Green Deal , which contains initiatives that support pollinator populations, the European Union has implemented
4836-485: Is first found in the fossil record in the late Devonian period, but at that time it is indistinguishable from spores. It increases in abundance until the present day. Nasal allergy to pollen is called pollinosis , and allergy specifically to grass pollen is called hay fever . Generally, pollens that cause allergies are those of anemophilous plants (pollen is dispersed by air currents.) Such plants produce large quantities of lightweight pollen (because wind dispersal
4960-602: Is frequently portrayed as a sequential process that begins with placement on the vector, moves through travel, and ends with deposition. This transfer can be mediated by the wind, in which case the plant is described as anemophilous (literally wind-loving). Anemophilous plants typically produce great quantities of very lightweight pollen grains, sometimes with air-sacs. Non-flowering seed plants (e.g., pine trees) are characteristically anemophilous. Anemophilous flowering plants generally have inconspicuous flowers. Entomophilous (literally insect-loving) plants produce pollen that
5084-490: Is governed by nutrition. Migration patterns and seasonal breeding take place in conjunction with food availability, and courtship displays are used to display an animal's health. Animals develop positive and negative associations with foods that affect their health, and they can instinctively avoid foods that have caused toxic injury or nutritional imbalances through a conditioned food aversion . Some animals, such as rats, do not seek out new types of foods unless they have
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5208-531: Is high protein food, to nurture their young, and transfer some among the flowers as they are working. Euglossine bees pollinate orchids, but these are male bees collecting floral scents rather than females gathering nectar or pollen. Female orchid bees act as pollinators, but of flowers other than orchids. Eusocial bees such as honey bees need an abundant and steady pollen source to multiply. Honey bees travel from flower to flower, collecting nectar (later converted to honey ), and pollen grains. The bee collects
5332-700: Is imperiled and at increasing risk of extinction. More than half of the native bee species is in decline and 40% of global insect pollinators (primarily native bees) are highly threatened. Declines in the health and population of pollinators pose what could be a significant threat to the integrity of biodiversity, to global food webs, and to human health. At least 80% of our world's crop species require pollination to set seed. A 2021 study estimated that without pollinators, fertility would be reduced by 80% in half all wild plant species and one-third of all wild plant species would fail to produce any seeds at all. An estimated one out of every three bites of food comes to us through
5456-554: Is managed by humans through animal feed . Fodder and forage are provided to livestock. Specialized pet food has been manufactured since 1860, and subsequent research and development have addressed the nutritional needs of pets. Dog food and cat food in particular are heavily studied and typically include all essential nutrients for these animals. Cats are sensitive to some common nutrients, such as taurine , and require additional nutrients derived from meat. Large-breed puppies are susceptible to overnutrition, as small-breed dog food
5580-570: Is more energy dense than they can absorb. Most plants obtain nutrients through inorganic substances absorbed from the soil or the atmosphere. Carbon, hydrogen, oxygen, nitrogen, and sulfur are essential nutrients that make up organic material in a plant and allow enzymic processes. These are absorbed ions in the soil, such as bicarbonate , nitrate , ammonium , and sulfate , or they are absorbed as gases, such as carbon dioxide, water, oxygen gas, and sulfur dioxide . Phosphorus, boron, and silicon are used for esterification . They are obtained through
5704-579: Is much less studied, but many native bee species are believed to be in decline. Scientists believe that bee losses are likely caused by a combination of stressors, including poor bee nutrition, loss of forage lands, parasites, pathogens, lack of genetic diversity, and exposure to pesticides. In May 2015, the Pollinator Health Task Force issued a "National Strategy to Promote the Health of Honey Bees and Other Pollinators". The national strategy outlined
5828-468: Is produced in the microsporangia in the male cone of a conifer or other gymnosperm or in the anthers of an angiosperm flower . In angiosperms, during flower development the anther is composed of a mass of cells that appear undifferentiated, except for a partially differentiated dermis. As the flower develops, fertile sporogenous cells, the archespore , form within the anther. The sporogenous cells are surrounded by layers of sterile cells that grow into
5952-563: Is random and the likelihood of one pollen grain landing on another flower is small), which can be carried for great distances and are easily inhaled, bringing it into contact with the sensitive nasal passages. Pollen allergies are common in polar and temperate climate zones, where production of pollen is seasonal. In the tropics pollen production varies less by the season, and allergic reactions less. In northern Europe, common pollens for allergies are those of birch and alder , and in late summer wormwood and different forms of hay . Grass pollen
6076-403: Is relatively heavy, sticky and protein -rich, for dispersal by insect pollinators attracted to their flowers. Many insects and some mites are specialized to feed on pollen, and are called palynivores . In non-flowering seed plants, pollen germinates in the pollen chamber, located beneath the micropyle , underneath the integuments of the ovule. A pollen tube is produced, which grows into
6200-409: Is responsible, according to a new study. The researchers attributed roughly half of the lengthening pollen seasons and 8% of the trend in pollen concentrations to climate changes driven by human activity. In Denmark , decades of rising temperatures cause pollen to appear earlier and in greater amounts, exacerbated by the introduction of new species such as ragweed. The most efficient way to handle
6324-796: Is that of sexual deception, where plants, generally orchids, produce remarkably complex combinations of pheromonal attractants and physical mimicry that induce male bees or wasps to attempt to mate with them, conveying pollinia in the process. Examples are known from all continents apart from Antarctica , though Australia appears to be exceptionally rich in examples. Whole groups of plants, such as certain fynbos Moraea and Erica species produce flowers on sticky peduncles or with sticky corolla tubes that only permit access to flying pollinators, whether bird, bat, or insect. Experimental evidence has shown invertebrates (mostly small crustaceans ) acting as pollinators in underwater environments. Beds of seagrass have been shown to reproduce this way in
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#17328512167586448-605: Is the simplest form of carbohydrate. Carbohydrates are broken down to produce glucose and short-chain fatty acids , and they are the most abundant nutrients for herbivorous land animals. Carbohydrates contain 4 calories per gram. Lipids provide animals with fats and oils. They are not soluble in water, and they can store energy for an extended period of time. They can be obtained from many different plant and animal sources. Most dietary lipids are triglycerides , composed of glycerol and fatty acids. Phospholipids and sterols are found in smaller amounts. An animal's body will reduce
6572-580: Is thought to be a severe underestimate as the feeding habits are only known for 1,000 species). Similarly, Ladybird beetles mainly eat insects, but many species also eat pollen, as either part or all of their diet. Hemiptera are mostly herbivores or omnivores but pollen feeding is known (and has only been well studied in the Anthocoridae ). Many adult flies, especially Syrphidae , feed on pollen, and three UK syrphid species feed strictly on pollen (syrphids, like all flies , cannot eat pollen directly due to
6696-479: Is variously sculptured, and the character of the markings is often of value for identifying genus, species, or even cultivar or individual. The spines may be less than a micron in length (spinulus, plural spinuli) referred to as spinulose (scabrate), or longer than a micron (echina, echinae) referred to as echinate . Various terms also describe the sculpturing such as reticulate , a net like appearance consisting of elements (murus, muri) separated from each other by
6820-588: The Environmental Protection Agency to ban neonicotinoids , a type of insecticide. On June 20, 2014, President Barack Obama issued a presidential memorandum entitled "Creating a Federal Strategy to Promote the Health of Honey Bees and Other Pollinators". The President's memorandum established a Pollinator Health Task Force, to be co-chaired by the Secretary of Agriculture and the Administrator of
6944-626: The Great Depression and the Second World War. Due to its importance in human health, the study of nutrition has heavily emphasized human nutrition and agriculture, while ecology is a secondary concern. Nutrients are substances that provide energy and physical components to the organism, allowing it to survive, grow, and reproduce. Nutrients can be basic elements or complex macromolecules . Approximately 30 elements are found in organic matter , with nitrogen , carbon , and phosphorus being
7068-421: The buoyancy of the pollen grain and help keep it aloft in the wind, as most gymnosperms are anemophilous . Pollen can be monosaccate , (containing one saccus) or bisaccate (containing two sacci). Modern pine , spruce , and yellowwood trees all produce saccate pollen. The transfer of pollen grains to the female reproductive structure ( pistil in angiosperms) is called pollination . Pollen transfer
7192-440: The carbon cycle , sulfur cycle , nitrogen cycle , water cycle , phosphorus cycle , and oxygen cycle , among others that continually recycle along with other mineral nutrients into productive ecological nutrition. Biogeochemical cycles that are performed by living organisms and natural processes are water , carbon , nitrogen , phosphorus , and sulfur cycles . Nutrient cycles allow these essential elements to return to
7316-400: The diet of an organism is the sum of the foods it eats. A healthy diet improves the physical and mental health of an organism. This requires ingestion and absorption of vitamins , minerals , essential amino acids from protein and essential fatty acids from fat-containing food. Carbohydrates , protein and fat play major roles in ensuring the quality of life , health and longevity of
7440-444: The innate yellow colour preference of syrphids. Some male dacine fruit flies are exclusive pollinators of some wild Bulbophyllum orchids that lack nectar and have a specific chemical attractant and reward (methyl eugenol, raspberry ketone or zingerone) present in their floral fragrances. Many insects other than bees accomplish pollination by visiting flowers for nectar or pollen, or commonly both. Many do so adventitiously, but
7564-408: The nucellus to provide nutrients for the developing sperm cells. Sperm cells of Pinophyta and Gnetophyta are without flagella , and are carried by the pollen tube, while those of Cycadophyta and Ginkgophyta have many flagella. When placed on the stigma of a flowering plant, under favorable circumstances, a pollen grain puts forth a pollen tube , which grows down the tissue of the style to
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#17328512167587688-511: The ovary , and makes its way along the placenta , guided by projections or hairs, to the micropyle of an ovule . The nucleus of the tube cell has meanwhile passed into the tube, as does also the generative nucleus, which divides (if it has not already) to form two sperm cells. The sperm cells are carried to their destination in the tip of the pollen tube. Double-strand breaks in DNA that arise during pollen tube growth appear to be efficiently repaired in
7812-402: The soil and the atmosphere. Fungi absorb nutrients around them by breaking them down and absorbing them through the mycelium . Scientific analysis of food and nutrients began during the chemical revolution in the late 18th century. Chemists in the 18th and 19th centuries experimented with different elements and food sources to develop theories of nutrition. Modern nutrition science began in
7936-404: The 1910s as individual micronutrients began to be identified. The first vitamin to be chemically identified was thiamine in 1926, and vitamin C was identified as a protection against scurvy in 1932. The role of vitamins in nutrition was studied in the following decades. The first recommended dietary allowances for humans were developed to address fears of disease caused by food deficiencies during
8060-419: The 20th century allowed mass production and food fortification to better meet the nutritional needs of humans. Human behavior is closely related to human nutrition, making it a subject of social science in addition to biology. Nutrition in humans is balanced with eating for pleasure, and optimal diet may vary depending on the demographics and health concerns of each person. Humans are omnivores that eat
8184-746: The Americas and Australia historically has been performed by various native bees. It has also been found that non-native plants may have positive effects on native bee pollinators while also influencing their foraging patterns and bee–plant networks. Lepidoptera ( butterflies and moths ) may also pollinate to various degrees. They are not major pollinators of food crops , but various moths are important pollinators of other commercial crops such as tobacco . Pollination by certain moths may be important, however, or even crucial, for some wildflowers mutually adapted to specialist pollinators. Spectacular examples include orchids such as Angraecum sesquipedale , dependent on
8308-675: The EU Biodiversity Strategy for 2030 which includes the EU Pollinators Initiative that sets long-term objectives to reverse pollinator decline in diversity and numbers by 2030. This initiative includes: (1) improving knowledge of pollinator decline, its causes and consequences; (2) tackling the causes of pollinator decline; and (3) raising awareness, engaging society-at-large and promoting collaboration. The Healthy Hives Latin America 2020 (Salud Apícola 2020 Latinoamérica) program
8432-542: The Environmental Protection Agency . The memorandum stated: Pollinators contribute substantially to the economy of the United States and are vital to keeping fruits, nuts, and vegetables in our diets. Honey bee pollination alone adds more than $ 15 billion in value to agricultural crops each year in the United States. Over the past few decades, there has been a significant loss of pollinators, including honey bees, native bees, birds, bats, and butterflies, from
8556-606: The Task Force issued a "Pollinator Partnership Action Plan". That Plan provided examples of past, ongoing, and possible future collaborations between the federal government and non-federal institutions to support pollinator health under each of the national strategy's goals. The North American Pollinator Protection Campaign (NAPPC) aims to promote pollinator health across the North America and has organized annual conferences since 1997, creates task forces to implement specific objectives that includes public education and policy research, and
8680-438: The United States' key monarch migration corridor. The Pollinator Health Task Force simultaneously issued a "Pollinator Research Action Plan". The Plan outlined five main action areas, covered in ten subject-specific chapters. The action areas were: (1) Setting a Baseline; (2) Assessing Environmental Stressors; (3) Restoring Habitat; (4) Understanding and Supporting Stakeholders; (5) Curating and Sharing Knowledge. In June 2016,
8804-798: The absence of currents. It is not yet known how important invertebrate pollinators might be for other species. Later, Idotea balthica was discovered to help Gracilaria gracilis reproduce – the first known case of an animal helping algae reproduce. Bats are important pollinators of some tropical flowers, visiting to take nectar. Birds, particularly hummingbirds , honeyeaters and sunbirds also accomplish much pollination, especially of deep-throated flowers. Other vertebrates , such as kinkajous , monkeys , lemurs , possums , rodents and lizards have been recorded pollinating some plants. Humans can be pollinators, as many gardeners have discovered that they must hand pollinate garden vegetables , whether because of pollinator decline or simply to keep
8928-476: The amount of energy required to raise 1 kilogram of water by 1 degree Celsius. Carbohydrates are molecules that store significant amounts of energy. Animals digest and metabolize carbohydrates to obtain this energy. Carbohydrates are typically synthesized by plants during metabolism, and animals have to obtain most carbohydrates from nature, as they have only a limited ability to generate them. They include sugars , oligosaccharides , and polysaccharides . Glucose
9052-585: The amount of fatty acids it produces as dietary fat intake increases, while it increases the amount of fatty acids it produces as carbohydrate intake increases. Fats contain 9 calories per gram. Protein consumed by animals is broken down to amino acids, which would be later used to synthesize new proteins. Protein is used to form cellular structures, fluids, and enzymes (biological catalysts ). Enzymes are essential to most metabolic processes, as well as DNA replication , repair , and transcription . Protein contains 4 calories per gram. Much of animal behavior
9176-847: The amount of protein in a food. Humans can also obtain energy from ethanol , which is both a food and a drug, but it provides relatively few essential nutrients and is associated with nutritional deficiencies and other health risks. In humans, poor nutrition can cause deficiency-related diseases, such as blindness , anemia , scurvy , preterm birth , stillbirth and cretinism , or nutrient-excess conditions, such as obesity and metabolic syndrome . Other conditions possibly affected by nutrition disorders include cardiovascular diseases , diabetes , and osteoporosis . Undernutrition can lead to wasting in acute cases, and stunting of marasmus in chronic cases of malnutrition. In domesticated animals , such as pets , livestock , and working animals , as well as other animals in captivity , nutrition
9300-477: The amount of time and energy spent foraging. It was created to analyze the foraging habits of animals, but it can also be extended to other organisms. Some organisms are specialists that are adapted to forage for a single food source, while others are generalists that can consume a variety of food sources. Nutrient deficiencies, known as malnutrition , occur when an organism does not have the nutrients that it needs. This may be caused by suddenly losing nutrients or
9424-609: The authors. Neonicotinoids (Neonics) are a class of synthetic insecticides that are the most widely applied pesticides today due to its water solubility and ability to treat a wide variety of pests. Neonics are highly environmentally persistent, and may contaminate terrestrial and aquatic habitats for as much as six years. Exposed honeybees' (Apis mellifera) have been seen to have lower reproductive output, reduction in nest building or failed to build nests, reduced foraging abilities, and weakened immunity. Researchers are still trying to determine how to scientifically best restore and maintain
9548-464: The bee colonies is also controversial. Pine pollen ( 송화가루 ; Songhwa Garu ) is traditionally consumed in Korea as an ingredient in sweets and beverages. The growing industries in pollen harvesting for human and bee consumption rely on harvesting pollen baskets from honey bees as they return to their hives using a pollen trap . When this pollen has been tested for parasites, it has been found that
9672-474: The body became holy when it traveled over a trail sprinkled with pollen. For agricultural research purposes, assessing the viability of pollen grains can be necessary and illuminating. A very common, efficient method to do so is known as Alexander's stain. This differential stain consists of ethanol , malachite green , distilled water , glycerol , phenol , chloral hydrate , acid fuchsin , orange G , and glacial acetic acid . (A less-toxic variation omits
9796-745: The carbon of other organisms, while autotrophs are organisms that produce their own nutrients from the carbon of inorganic substances like carbon dioxide . Mixotrophs are organisms that can be heterotrophs and autotrophs, including some plankton and carnivorous plants . Phototrophs obtain energy from light, while chemotrophs obtain energy by consuming chemical energy from matter. Organotrophs consume other organisms to obtain electrons, while lithotrophs obtain electrons from inorganic substances, such as water , hydrogen sulfide , dihydrogen , iron(II) , sulfur , or ammonium . Prototrophs can create essential nutrients from other compounds, while auxotrophs must consume preexisting nutrients. In nutrition,
9920-770: The depth and width of the corolla, the color (including patterns called nectar guides that are visible only in ultraviolet light), the scent , amount of nectar, composition of nectar, etc. For example, birds visit red flowers with long, narrow tubes and much nectar, but are not as strongly attracted to wide flowers with little nectar and copious pollen, which are more attractive to beetles. When these characteristics are experimentally modified (altering colour, size, orientation), pollinator visitation may decline. Although non-bee pollinators have been seen to be less effective at depositing pollen than bee pollinators one study showed that non-bees made more visits than bees resulting in non-bees performing 38% of visits to crop flowers, outweighing
10044-557: The discharge of histamine , but it has been proven that they do prevent a part of the chain reaction activated by this biogenic amine , which considerably lowers hay fever symptoms. Decongestants can be administered in different ways such as tablets and nasal sprays . Allergy immunotherapy (AIT) treatment involves administering doses of allergens to accustom the body to pollen, thereby inducing specific long-term tolerance. Allergy immunotherapy can be administered orally (as sublingual tablets or sublingual drops), or by injections under
10168-692: The diverse pollinator habitats found around the world. Many studies conclude that restoration and conservation are key to maintaining biodiversity and pollinator populations. According to the Kansas National Park Service, native tallgrass prairie was widespread through North America and home to over 300 species of flowering plants. This habitat is crucial to wild pollinators and now only covers 4% of its original 170-million acre range. By restoring wild pollinators natural habitat and maintaining Earth's biodiversity, populations are assumed to increase. In recent times, environmental groups have put pressure on
10292-492: The environment after being absorbed or consumed. Without proper nutrient cycling, there would be risk of change in oxygen levels, climate, and ecosystem function. Foraging is the process of seeking out nutrients in the environment. It may also be defined to include the subsequent use of the resources. Some organisms, such as animals and bacteria, can navigate to find nutrients, while others, such as plants and fungi, extend outward to find nutrients. Foraging may be random, in which
10416-489: The environment. The problem is serious and requires immediate attention to ensure the sustainability of our food production systems, avoid additional economic impact on the agricultural sector, and protect the health of the environment. Pollinator losses have been severe. The number of migrating Monarch butterflies sank to the lowest recorded population level in 2013-14, and there is an imminent risk of failed migration. The continued loss of commercial honey bee colonies poses
10540-425: The form of a structure known as the scopa , which is on the hind legs of most bees, and/or the lower abdomen (e.g., of megachilid bees), made up of thick, plumose setae . Honey bees , bumblebees , and their relatives do not have a scopa, but the hind leg is modified into a structure called the corbicula (also known as the " pollen basket "). Most bees gather nectar , a concentrated energy source, and pollen, which
10664-404: The form of remarkably long probosces. This also applies to empidine dance flies ( Empidinae ) that visit a wide range of flowering plants, some species of which can pollinate the woodland geranium ( Geranium sylvaticum L. ) as effectively as bees . Carrion flies and flesh flies in families such as Calliphoridae and Sarcophagidae are important for some species of plants whose flowers exude
10788-665: The formation of the four microspores, which are contained by callose walls, the development of the pollen grain walls begins. The callose wall is broken down by an enzyme called callase and the freed pollen grains grow in size and develop their characteristic shape and form a resistant outer wall called the exine and an inner wall called the intine. The exine is what is preserved in the fossil record. Two basic types of microsporogenesis are recognised, simultaneous and successive. In simultaneous microsporogenesis meiotic steps I and II are completed before cytokinesis , whereas in successive microsporogenesis cytokinesis follows. While there may be
10912-427: The generative cell that carries the male genomic information to be passed on to the next plant generation. However, the vegetative cell that is responsible for tube elongation appears to lack this DNA repair capability. The sporopollenin outer sheath of pollen grains affords them some resistance to the rigours of the fossilisation process that destroy weaker objects; it is also produced in huge quantities. There
11036-475: The grain. The outer pollen wall, which prevents the pollen grain from shrinking and crushing the genetic material during desiccation, is composed of two layers. These two layers are the tectum and the foot layer, which is just above the intine. The tectum and foot layer are separated by a region called the columella, which is composed of strengthening rods. The outer wall is constructed with a resistant biopolymer called sporopollenin. Pollen apertures are regions of
11160-544: The identification of classes of pollen. Pollen may be referred to as inaperturate (apertures absent) or aperturate (apertures present). The aperture may have a lid ( operculum ), hence is described as operculate . However the term inaperturate covers a wide range of morphological types, such as functionally inaperturate (cryptoaperturate) and omniaperturate. Inaperaturate pollen grains often have thin walls, which facilitates pollen tube germination at any position. Terms such as uniaperturate and triaperturate refer to
11284-432: The improvement needed to return to conditions at which the pollinator community collapsed. Pollen Pollen grains have a hard coat made of sporopollenin that protects the gametophytes during the process of their movement from the stamens to the pistil of flowering plants, or from the male cone to the female cone of gymnosperms . If pollen lands on a compatible pistil or female cone, it germinates , producing
11408-743: The inability to absorb proper nutrients. Not only is malnutrition the result of a lack of necessary nutrients, but it can also be a result of other illnesses and health conditions. When this occurs, an organism will adapt by reducing energy consumption and expenditure to prolong the use of stored nutrients. It will use stored energy reserves until they are depleted, and it will then break down its own body mass for additional energy. A balanced diet includes appropriate amounts of all essential and non-essential nutrients. These can vary by age, weight, sex, physical activity levels, and more. A lack of just one essential nutrient can cause bodily harm, just as an overabundance can cause toxicity. The Daily Reference Values keep
11532-597: The ineffectiveness of their ability to pollinate. It has recently been discovered that cycads , which are not flowering plants , are also pollinated by insects. In 2016, researchers showed evidence of pollination occurring underwater, which was previously thought not to happen. The most recognized pollinators are the various species of bees , which are plainly adapted to pollination. Bees typically are fuzzy and carry an electrostatic charge. Both features help pollen grains adhere to their bodies, but they also have specialized pollen-carrying structures; in most bees, this takes
11656-856: The majority of people from nutrient deficiencies. DRVs are not recommendations but a combination of nutrient references to educate professionals and policymakers on what the maximum and minimum nutrient intakes are for the average person. Food labels also use DRVs as a reference to create safe nutritional guidelines for the average healthy person. Animals are heterotrophs that consume other organisms to obtain nutrients. Herbivores are animals that eat plants, carnivores are animals that eat other animals, and omnivores are animals that eat both plants and other animals. Many herbivores rely on bacterial fermentation to create digestible nutrients from indigestible plant cellulose, while obligate carnivores must eat animal meats to obtain certain vitamins or nutrients their bodies cannot otherwise synthesize. Animals generally have
11780-427: The male gamete. Each pollen grain contains vegetative (non-reproductive) cells (only a single cell in most flowering plants but several in other seed plants) and a generative (reproductive) cell. In flowering plants the vegetative tube cell produces the pollen tube , and the generative cell divides to form the two sperm nuclei. Pollen grains come in a wide variety of shapes, sizes, and surface markings characteristic of
11904-467: The microsporangium, with the generative cell forming the two sperm cells. Except in the case of some submerged aquatic plants, the mature pollen grain has a double wall. The vegetative and generative cells are surrounded by a thin delicate wall of unaltered cellulose called the endospore or intine , and a tough resistant outer cuticularized wall composed largely of sporopollenin called the exospore or exine . The exine often bears spines or warts, or
12028-471: The most important commercial pollinating agents, but many other kinds of pollinators, from blue bottle flies, to bumblebees, orchard mason bees , and leaf cutter bees are cultured and sold for managed pollination . Other species of bees differ in various details of their behavior and pollen-gathering habits, and honey bees are not native to the Western Hemisphere ; all pollination of native plants in
12152-630: The most important pollinators are specialists for at least parts of their life cycles for at least certain functions. Prominent among Hymenoptera other than bees are predatory aculeate wasps (especially Crabronidae , Sphecidae , Vespidae , and Pompilidae ). The term " pollen wasps ", in particular, is widely applied to the Masarinae, a subfamily of the Vespidae; they are remarkable among solitary wasps in that they specialise in gathering pollen for feeding their larvae, carried internally and regurgitated into
12276-824: The most important. Macronutrients are the primary substances required by an organism, and micronutrients are substances required by an organism in trace amounts. Organic micronutrients are classified as vitamins , and inorganic micronutrients are classified as minerals . Nutrients are absorbed by the cells and used in metabolic biochemical reactions. These include fueling reactions that create precursor metabolites and energy, biosynthetic reactions that convert precursor metabolites into building block molecules, polymerizations that combine these molecules into macromolecule polymers , and assembly reactions that use these polymers to construct cellular structures. Organisms can be classified by how they obtain carbon and energy. Heterotrophs are organisms that obtain nutrients by consuming
12400-416: The number of apertures present (one and three respectively). Spiraperturate refers to one or more apertures being spirally shaped. The orientation of furrows (relative to the original tetrad of microspores) classifies the pollen as sulcate or colpate . Sulcate pollen has a furrow across the middle of what was the outer face when the pollen grain was in its tetrad. If the pollen has only a single sulcus, it
12524-527: The nutritional needs of the brood. Good pollination management seeks to have bees in a "building" state during the bloom period of the crop, thus requiring them to gather pollen, and making them more efficient pollinators. Thus, the management techniques of a beekeeper providing pollination services are different from, and to some extent in tension with, those of a beekeeper who is trying to produce honey. Millions of hives of honey bees are contracted out as pollinators by beekeepers , and honey bees are by far
12648-491: The nutritional value of the pollen In forensic biology , pollen can tell a lot about where a person or object has been, because regions of the world, or even more particular locations such a certain set of bushes, will have a distinctive collection of pollen species. Pollen evidence can also reveal the season in which a particular object picked up the pollen. Pollen has been used to trace activity at mass graves in Bosnia , catch
12772-433: The organism seeks nutrients without method, or it may be systematic, in which the organism can go directly to a food source. Organisms are able to detect nutrients through taste or other forms of nutrient sensing , allowing them to regulate nutrient intake. Optimal foraging theory is a model that explains foraging behavior as a cost–benefit analysis in which an animal must maximize the gain of nutrients while minimizing
12896-425: The organism. Some cultures and religions have restrictions on what is acceptable for their diet. A nutrient cycle is a biogeochemical cycle involving the movement of inorganic matter through a combination of soil, organisms, air or water, where they are exchanged in organic matter. Energy flow is a unidirectional and noncyclic pathway, whereas the movement of mineral nutrients is cyclic. Mineral cycles include
13020-448: The phenol and chloral hydrate .) In angiosperms and gymnosperms non-aborted pollen grain will appear red or pink, and aborted pollen grains will appear blue or slightly green. Nutrition Nutrition is the biochemical and physiological process by which an organism uses food to support its life . It provides organisms with nutrients , which can be metabolized to create energy and chemical structures. Failure to obtain
13144-453: The pollen by rubbing against the anthers. The pollen collects on the hind legs, in a structure referred to as a "pollen basket". As the bee flies from flower to flower, some of the pollen grains are transferred onto the stigma of other flowers. Nectar provides the energy for bee nutrition ; pollen provides the protein . When bees are rearing large quantities of brood (beekeepers say hives are "building"), bees deliberately gather pollen to meet
13268-474: The pollen of dozens of plant species. Members of some beetle families such as Mordellidae and Melyridae feed almost exclusively on pollen as adults, while various lineages within larger families such as Curculionidae , Chrysomelidae , Cerambycidae , and Scarabaeidae are pollen specialists even though most members of their families are not (e.g., only 36 of 40,000 species of ground beetles , which are typically predatory, have been shown to eat pollen—but this
13392-455: The pollen wall that may involve exine thinning or a significant reduction in exine thickness. They allow shrinking and swelling of the grain caused by changes in moisture content. The process of shrinking the grain is called harmomegathy. Elongated apertures or furrows in the pollen grain are called colpi (singular: colpus) or sulci (singular: sulcus ). Apertures that are more circular are called pores. Colpi, sulci and pores are major features in
13516-456: The pollinating birds are hummingbirds , honeyeaters and sunbirds with long beaks; they pollinate a number of deep-throated flowers. Humans may also carry out artificial pollination . A pollinator is different from a pollenizer , a plant that is a source of pollen for the pollination process. Plants fall into pollination syndromes that reflect the type of pollinator being attracted. These are characteristics such as: overall flower size,
13640-485: The pollination of tree-crops such as cacao, Theobroma cacao L. (Malvaceae) and elderflower Sambucus nigra L. (Adoxaceae). Ants also pollinate some kinds of flowers, but for the most part they are parasites, consuming nectar and/or pollen without conveying useful amounts of pollen to a stigma. Other insect orders are rarely pollinators, and then typically only incidentally (e.g., Hemiptera such as Anthocoridae and Miridae ). A strategy of great biological interest
13764-871: The required amount of nutrients causes malnutrition . Nutritional science is the study of nutrition, though it typically emphasizes human nutrition . The type of organism determines what nutrients it needs and how it obtains them. Organisms obtain nutrients by consuming organic matter , consuming inorganic matter, absorbing light, or some combination of these. Some can produce nutrients internally by consuming basic elements, while some must consume other organisms to obtain pre-existing nutrients. All forms of life require carbon , energy , and water as well as various other molecules . Animals require complex nutrients such as carbohydrates , lipids , and proteins , obtaining them by consuming other organisms. Humans have developed agriculture and cooking to replace foraging and advance human nutrition. Plants acquire nutrients through
13888-897: The root-like mycelium, which grows through the organism's source of nutrients and can extend indefinitely. The fungus excretes extracellular enzymes to break down surrounding matter and then absorbs the nutrients through the cell wall. Fungi can be parasitic, saprophytic, or symbiotic. Parasitic fungi attach and feed on living hosts, such as animals, plants, or other fungi. Saprophytic fungi feed on dead and decomposing organisms. Symbiotic fungi grow around other organisms and exchange nutrients with them. Protists include all eukaryotes that are not animals, plants, or fungi, resulting in great diversity between them. Algae are photosynthetic protists that can produce energy from light. Several types of protists use mycelium similar to those of fungi. Protozoa are heterotrophic protists, and different protozoa seek nutrients in different ways. Flagellate protozoa use
14012-433: The safety, quality, flavor, and nutritional content of food. Humans obtain most carbohydrates as starch from cereals, though sugar has grown in importance. Lipids can be found in animal fat , butterfat , vegetable oil, and leaf vegetables , and they are also used to increase flavor in foods. Protein can be found in virtually all foods, as it makes up cellular material, though certain methods of food processing may reduce
14136-419: The second most important pollinators after wild bees. Although hoverflies as a whole are generally considered to be nonselective pollinators, some species have more specialized relationships. The orchid species Epipactis veratrifolia mimics alarm pheromones of aphids to attract hover flies for pollination. Another plant, the slipper orchid in southwest China, also achieves pollination by deceit by exploiting
14260-429: The skin (subcutaneous). Discovered by Leonard Noon and John Freeman in 1911, allergy immunotherapy represents the only causative treatment for respiratory allergies. Most major classes of predatory and parasitic arthropods contain species that eat pollen, despite the common perception that bees are the primary pollen-consuming arthropod group. Many Hymenoptera other than bees consume pollen as adults, though only
14384-474: The soil as phosphates , boric acid , and silicic acid , respectively. Other nutrients used by plants are potassium, sodium, calcium, magnesium, manganese, chlorine, iron, copper, zinc, and molybdenum. Plants uptake essential elements from the soil through their roots and from the air (consisting of mainly nitrogen and oxygen) through their leaves . Nutrient uptake in the soil is achieved by cation exchange , wherein root hairs pump hydrogen ions (H ) into
14508-528: The soil in which they grow. This is made possible by the fact that largely inert atmospheric nitrogen is changed in a nitrogen fixation process to biologically usable forms in the soil by bacteria. As these nutrients do not provide the plant with energy, they must obtain energy by other means. Green plants absorb energy from sunlight with chloroplasts and convert it to usable energy through photosynthesis . Fungi are chemoheterotrophs that consume external matter for energy. Most fungi absorb matter through
14632-467: The soil through proton pumps . These hydrogen ions displace cations attached to negatively charged soil particles so that the cations are available for uptake by the root. In the leaves, stomata open to take in carbon dioxide and expel oxygen . Although nitrogen is plentiful in the Earth's atmosphere, very few plants can use this directly. Most plants, therefore, require nitrogen compounds to be present in
14756-413: The species (see electron micrograph , right). Pollen grains of pines , firs , and spruces are winged. The smallest pollen grain, that of the forget-me-not ( Myosotis spp.), is 2.5–5 μm (0.005 mm) in diameter. Corn pollen grains are large, about 90–100 μm. Most grass pollen is around 20–25 μm. Some pollen grains are based on geodesic polyhedra like a soccer ball . Pollen
14880-408: The structure of their mouthparts, but can consume pollen contents that are dissolved in a fluid). Some species of fungus, including Fomes fomentarius , are able to break down grains of pollen as a secondary nutrition source that is particularly high in nitrogen. Pollen may be valuable diet supplement for detritivores , providing them with nutrients needed for growth, development and maturation. It
15004-441: The wall of the pollen sac. Some of the cells grow into nutritive cells that supply nutrition for the microspores that form by meiotic division from the sporogenous cells. The archespore cells divide by mitosis and differentiate to form pollen mother cells (microsporocyte, meiocyte ). In a process called microsporogenesis , four haploid microspores are produced from each diploid pollen mother cell, after meiotic division . After
15128-579: The way in which pollinator communities respond to increasingly harsh conditions. Mathematical models, examining the consequences of this network structure for the stability of pollinator communities suggest that the specific way in which plant-pollinator networks are organized minimizes competition between pollinators and may even lead to strong indirect facilitation between pollinators when conditions are harsh. This allows pollinator species to survive together under harsh conditions. But it also means that pollinator species collapse simultaneously when conditions pass
15252-514: The work of animal pollinators. The quality of pollinator service has declined over time and this had led to concerns that pollination will be less resistant to extinction in the future. A 2022 study concludes that the decline of pollinator populations is responsible for 500,000 early human deaths per year by reducing the supply of healthy foods. A decline of pollinators has caused 3-5% loss of fruits, vegetables and nuts. Lower consumption of these healthy foods translates to 1% of all deaths, according to
15376-508: Was suggested that obtaining nutrients from pollen, deposited on the forest floor during periods of pollen rains, allows fungi to decompose nutritionally scarce litter. Some species of Heliconius butterflies consume pollen as adults, which appears to be a valuable nutrient source, and these species are more distasteful to predators than the non-pollen consuming species. Although bats , butterflies and hummingbirds are not pollen eaters per se , their consumption of nectar in flowers
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