102-847: 47, see text Stenophasmidae Benoit, 1949 The Braconidae are a family of parasitoid wasps . After the closely related Ichneumonidae , braconids make up the second-largest family in the order Hymenoptera , with about 17,000 recognized species and many thousands more undescribed. One analysis estimated a total between 30,000 and 50,000, and another provided a narrower estimate between 42,000 and 43,000 species. The Braconidae are currently divided into about 47 subfamilies and over 1000 genera, which include Aerophilus , Aleiodes , Apanteles , Asobara , Bracon , Cenocoelius , Chaenusa , Chorebus , Cotesia , Dacnusa , Diachasma , Dimeris , Microgaster , Opius , Parapanteles , Phaenocarpa , Spathius , and Syntretus . These fall into two major groups, informally called
204-814: A conventional breeding program to provide optimized strains. The program began in the 1980s. Hybrid seeds are distributed in Africa by its Drought Tolerant Maize for Africa project. Tropical landraces remain an important and underused source of resistance alleles – both those for disease and for herbivores . Such alleles can then be introgressed into productive varieties. Rare alleles for this purpose were discovered by Dao and Sood, both in 2014. In 2018, Zerka Rashid of CIMMYT used its association mapping panel, developed for tropical drought tolerance traits. to find new genomic regions providing sorghum downy mildew resistance , and to further characterize known differentially methylated regions . Genetically modified maize
306-403: A corn head (with points and snap rolls instead of a reel) does not cut the stalk; it simply pulls the stalk down. The stalk continues downward and is crumpled into a mangled pile on the ground, where it usually is left to become organic matter for the soil . The ear of maize is too large to pass between slots in a plate as the snap rolls pull the stalk away, leaving only the ear and husk to enter
408-451: A dose of 400 to 1000 rads can kill an average human, a dose of 180,000 rads was required to kill a braconid of genus Habrobracon in an experiment. Parasitoid In evolutionary ecology , a parasitoid is an organism that lives in close association with its host at the host's expense, eventually resulting in the death of the host. Parasitoidism is one of six major evolutionary strategies within parasitism , distinguished by
510-539: A few species are parasitic. The larvae of Epipyropidae feed on Homoptera such as leafhoppers and cicadas, and sometimes on other Lepidoptera. The larvae of Cyclotornidae parasitise first Homoptera and later ant brood. The pyralid moth Chalcoela has been used in biological control of the wasp Polistes in the Galapagos Islands . Parasitism is rare in the Trichoptera (caddisflies), but it
612-401: A host that continues to grow larger and avoid predators. Primary parasitoids have the simplest parasitic relationship, involving two organisms, the host and the parasitoid. Hyperparasitoids are parasitoids of parasitoids; secondary parasitoids have a primary parasitoid as their host, so there are three organisms involved. Hyperparasitoids are either facultative (can be a primary parasitoid or
714-469: A hyperparasitoid depending on the situation) or obligate (always develop as a hyperparasitoid). Levels of parasitoids beyond secondary also occur, especially among facultative parasitoids. In oak gall systems, there can be up to five levels of parasitism. Cases in which two or more species of parasitoids simultaneously attack the same host without parasitizing each other are called multi- or multiple parasitism. In many cases, multiple parasitism still leads to
816-408: A large cob. Yellow maizes derive their color from carotenoids ; red maizes are colored by anthocyanins and phlobaphenes ; and orange and green varieties may contain combinations of these pigments. Maize has short-day photoperiodism , meaning that it requires nights of a certain length to flower. Flowering further requires enough warm days above 10 °C (50 °F). The control of flowering
918-520: A large stalk, growing from the back of the ant's head which subsequently releases ascospores. These spores are too large to be wind dispersed and instead fall directly to the ground where they produce secondary spores that infect ants as they walk over them. O. sinesis , is a parasitoid as well, parasitising ghost moth larvae, killing them within 15-25 days, a similar process to that of O. unilateralis . Host location has been studied in Ormia ochracea ,
1020-804: A lepidopteran moth known for being a pest of maize in East Asia), the African sugarcane borer (a moth commonly found in sub-Saharan Africa), the butterfly Danaus chrysippus in Ghana , and Liriomyza trifolii (the American serpentine leafminer) and Manduca quinquemaculata (the tomato hornworm) in North America. Braconids often will prey on fruit fly larvae like Anastrepha suspensa as well. Endoparasitoid species often display elaborate physiological adaptations to enhance larval survival within
1122-409: A living host which they eventually kill, typically before it can produce offspring, whereas conventional parasites usually do not kill their hosts, and predators typically kill their prey immediately. Parasitoids can be classified as either endo- or ectoparasitoids with idiobiont or koinobiont developmental strategies. Endoparasitoids live within their host's body, while ectoparasitoids feed on
SECTION 10
#17327807387211224-499: A measure of protection against a wide range of pests. Because of its shallow roots, maize is susceptible to droughts, intolerant of nutrient-deficient soils, and prone to being uprooted by severe winds. Maize is diploid with 20 chromosomes . 83% of allelic variation within the genome derives from its teosinte ancestors, primarily due to the freedom of Zea species to outcross . Barbara McClintock used maize to validate her transposon theory of "jumping genes", for which she won
1326-534: A parasitoid tachinid fly that locates their field cricket host acoustically ( phonotaxis ). Preference for the dominant local host species was not explained by DNA analysis. In fact, populations across the southern U.S. were inexplicably closely related, considering rate of range expansion from a presumed Central American origin. A captive population of lab-reared flies were raised on two different host songs ( Gryllus integer or G. lineaticeps ). Responsive adult females overwhelmingly chose their familiar song, indicating
1428-638: A place but a condition, a savage rather than a civilized grain". International groups such as the Centre for Agriculture and Bioscience International consider maize the preferred common name. The word maize is used by the UN's Food and Agriculture Organization , and in the names of the International Maize and Wheat Improvement Center of Mexico, the Indian Institute of Maize Research,
1530-601: A plant that uses C 4 carbon fixation , maize is a considerably more water-efficient crop than plants that use C 3 carbon fixation such as alfalfa and soybeans . Maize is most sensitive to drought at the time of silk emergence, when the flowers are ready for pollination. In the United States, a good harvest was traditionally predicted if the maize was "knee-high by the Fourth of July ", although modern hybrids generally exceed this growth rate. Maize used for silage
1632-399: A range of obstacles to oviposition, including behavioural, morphological, physiological and immunological defences of their hosts. To thwart this, some wasps inundate their host with their eggs so as to overload its immune system's ability to encapsulate foreign bodies; others introduce a virus which interferes with the host's immune system. Some parasitoid wasps locate hosts by detecting
1734-454: A wide range of insects including caterpillars, adult and larval beetles , and true bugs . Commercially, there are two types of rearing systems: short-term seasonal daily output with high production of parasitoids per day, and long-term year-round low daily output with a range in production of 4–1000 million female parasitoids per week, to meet demand for suitable biological control agents for different crops. Maria Sibylla Merian (1647–1717)
1836-477: Is a problem in Asia. Some fungal diseases of maize produce potentially dangerous mycotoxins such as aflatoxin . In the United States, major diseases include tar spot , bacterial leaf streak , gray leaf spot , northern corn leaf blight, and Goss's wilt ; in 2022, the most damaging disease was tar spot, which caused losses of 116.8 million bushels . Maize sustains a billion dollars' worth of losses annually in
1938-408: Is composed of transposons , contains 32,540 genes. Much of it has been duplicated and reshuffled by helitrons , a group of transposable elements within maize's DNA. Maize breeding in prehistory resulted in large plants producing large ears. Modern breeding began with individuals who selected highly productive varieties in their fields and then sold seed to other farmers. James L. Reid was one of
2040-537: Is cultivated throughout the world; a greater weight of maize is produced each year than any other grain. In 2020, world production was 1.1 billion tonnes. It is afflicted by many pests and diseases ; two major insect pests, European corn borer and corn rootworms , have each caused annual losses of a billion dollars in the US. Modern plant breeding has greatly increased output and qualities such as nutrition, drought tolerance, and tolerance of pests and diseases. Much maize
2142-512: Is depicted as an unending combat between humanity and insect-like extraterrestrial species that tend to parasitise human beings in order to reproduce." The Encyclopedia of Science Fiction lists many instances of "parasitism", often causing the host's death. Maize Maize / m eɪ z / ( Zea mays ), also known as corn in North American English , is a tall stout grass that produces cereal grain . It
SECTION 20
#17327807387212244-696: Is found among the Hydroptilidae (purse-case caddisflies), probably including all 10 species in the Orthotrichia aberrans group; they parasitise the pupae of other trichopterans. Mites of the family Acarophenacidae are ectoparasitoids of insect eggs. Unlike the insect parasitoids, it is the adult stage in Acarophenacidae that acts as a parasitoid. Specifically, adult female mites feed on insect eggs and their body swells up with offspring, which eventually emerge as adults. All known fungi in
2346-414: Is harvested while the plant is green and the fruit immature. Sweet corn is harvested in the "milk stage", after pollination but before starch has formed, between late summer and early to mid-autumn. Field maize is left in the field until very late in the autumn to thoroughly dry the grain, and may, in fact, sometimes not be harvested until winter or even early spring. The importance of sufficient soil moisture
2448-492: Is notable. They are often black-brown (sometimes with reddish markings), though some species exhibit striking coloration and patterns, being parts of Müllerian mimicry complexes . They have one or no recurrent veins, unlike other members of the other family in Ichneumonoidea ( Ichneumonidae ), which usually have two. Wing venation patterns are otherwise highly variable. The antennae typically have 16 segments or more;
2550-533: Is now genetically modified . As a food, maize is used to make a wide variety of dishes including Mexican tortillas and tamales , Italian polenta , and American hominy grits . Maize protein is low in some essential amino acids , and the niacin it contains only becomes available if freed by alkali treatment . In Mesoamerica, maize is deified as a maize god and depicted in sculptures. Maize requires human intervention for it to propagate. The kernels of its naturally-propagating teosinte ancestor fall off
2652-737: Is parasitoidal on cicadas, locating its host by sound. The Strepsiptera (twisted-wing parasites) consist entirely of parasitoids; they usually sterilise their hosts. Two beetle families, Ripiphoridae (450 species ) and Rhipiceridae , are largely parasitoids, as are Aleochara Staphylinidae ; in all, some 400 staphylinids are parasitoidal. Some 1,600 species of the large and mainly freeliving family Carabidae are parasitoids. A few Neuroptera are parasitoidal; they have larvae that actively search for hosts. The larvae of some Mantispidae , subfamily Symphrasinae, are parasitoids of other arthropods including bees and wasps. Although nearly all Lepidoptera (butterflies and moths) are herbivorous,
2754-468: Is set genetically; the physiological mechanism involves the phytochrome system. Tropical cultivars can be problematic if grown in higher latitudes, as the longer days can make the plants grow tall instead of setting seed before winter comes. On the other hand, growing tall rapidly could be convenient for producing biofuel. Immature maize shoots accumulate a powerful antibiotic substance, 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one ( DIMBOA ), which provides
2856-560: Is shown in many parts of Africa, where periodic drought regularly causes maize crop failure and consequent famine . Although it is grown mainly in wet, hot climates, it can thrive in cold, hot, dry or wet conditions, meaning that it is an extremely versatile crop. Maize was planted by the Native Americans in small hills of soil, in the polyculture system called the Three Sisters . Maize provided support for beans ;
2958-411: Is similarly far higher than for screening chemicals: 1:30 against 1:5 respectively, since the search for suitable natural enemies can be guided accurately with ecological knowledge. Natural enemies are more difficult to produce and to distribute than chemicals, as they have a shelf life of weeks at most; and they face a commercial obstacle, namely that they cannot be patented. From the point of view of
3060-557: Is the domesticated variant of the four species of teosintes , which are its crop wild relatives . The teosinte origin theory was proposed by the Russian botanist Nikolai Ivanovich Vavilov in 1931, and the American Nobel Prize -winner George Beadle in 1932. The two plants have dissimilar appearance, maize having a single tall stalk with multiple leaves and teosinte being a short, bushy plant. The difference between
3162-405: Is the leaf most closely associated with a particular developing ear. This leaf and those above it contribute over three quarters of the carbohydrate ( starch ) that fills the grain. The grains are usually yellow or white in modern varieties; other varieties have orange, red, brown, blue , purple , or black grains. They are arranged in 8 to 32 rows around the cob; there can be up to 1200 grains on
Braconidae - Misplaced Pages Continue
3264-612: The Balsas River valley in Mexico's southwestern highlands, as the crop wild relative genetically most similar to modern maize. The middle part of the short Balsas River valley is the likely location of early domestication. Stone milling tools with maize residue have been found in an 8,700 year old layer of deposits in a cave not far from Iguala, Guerrero . Doebley and colleagues showed in 2002 that maize had been domesticated only once, about 9,000 years ago, and then spread throughout
3366-705: The Columbian exchange , it has become a staple food in many parts of the world, with the total production of maize surpassing that of wheat and rice . Much maize is used for animal feed , whether as grain or as the whole plant, which can either be baled or made into the more palatable silage . Sugar-rich varieties called sweet corn are grown for human consumption, while field corn varieties are used for animal feed, for uses such as cornmeal or masa , corn starch , corn syrup , pressing into corn oil , alcoholic beverages like bourbon whiskey , and as chemical feedstocks including ethanol and other biofuels . Maize
3468-540: The Diptera , Coleoptera and other orders of endopterygote insects . Some of these, usually but not only wasps, are used in biological pest control . The 17th-century zoological artist Maria Sibylla Merian closely observed parasitoids and their hosts in her paintings. The biology of parasitoidism influenced Charles Darwin 's beliefs and has inspired science fiction authors and scriptwriters to create numerous parasitoidal aliens that kill their human hosts, such as
3570-604: The alien species in Ridley Scott 's 1979 film Alien . The term "parasitoid" was coined in 1913 by the Swedo-Finnish writer Odo Reuter , and adopted in English by his reviewer, the entomologist William Morton Wheeler . Reuter used it to describe the strategy where the parasite develops in or on the body of a single host individual, eventually killing that host, while the adult is free-living. Since that time,
3672-842: The larval stages of Coleoptera , Diptera , and Lepidoptera , but also some hemimetabolous insects such as aphids , Heteroptera , or Embiidina . Most species kill their hosts, though some cause the hosts to become sterile and less active. Parasitoidy on adult insects (particularly on Hemiptera and Coleoptera) also occurs. Members of two subfamilies, the Mesostoinae and Doryctinae are known to form galls on plants. Braconids are often used as biological pest control agents, especially against aphids. Thousands of species of insects are used as hosts by braconid wasps. A few notable examples are detailed here. Some species of braconids are parasitoids of Ostrinia furnacalis (the Asian corn borer,
3774-1035: The phylogenetic tree ; groups containing parasitoids are shown in boldface, e.g. Coleoptera , with the number of times parasitoidism evolved in the group in parentheses, e.g. (10 clades) . The approximate number (estimates can vary widely) of parasitoid species out of the total is shown in square brackets, e.g. [2,500 of 400,000]. Raphidioptera Megaloptera Neuroptera (net-winged insects) (1 clade) [c. 15 of 6,000] Coleoptera (beetles) (10 clades) [c. 2,500 of 400,000] [REDACTED] Strepsiptera (twisted-wing parasites) [600 of 600] [REDACTED] Symphyta Orussoidea (parasitic wood wasps) [75 of 75] [REDACTED] Apocrita (wasp-waisted insects) [c. 50,000 of 100,000] [REDACTED] Diptera (true flies) (21 clades) [c. 17,000 of 125,000] [REDACTED] Mecoptera Siphonaptera Trichoptera (caddis flies) (1 clade) [c. 10 of 14,500] Lepidoptera (butterflies, moths) (2 clades) [c. 40 of 180,000] [REDACTED] Within
3876-647: The trochanters have two segments. Females often have long ovipositors , an organ that largely varies interspecifically. This variation is closely related to the host species upon which the wasp deposits its egg. Species that parasitize microlepidopterans , for instance, have longer ovipositors, presumably to reach the caterpillar through layers of plant tissue. Some wasps also have long ovipositors to bypass caterpillar defense mechanisms such as spines or hairs, or to reach deeply-burrowed Coleoptera larvae in tree trunks. The larvae of most braconids are internal or external primary parasitoids of other insects , especially
3978-412: The 'death bite'. This approach is so fine-tuned it causes the ant to bite down on the part of the leaf most optimal for the fungus to fruit; the adaxial leaf midrib. In fact, it has been found that in specific circumstances, the time of the death bite is synchronised to solar noon. As much as 40% of the ant's biomass is fungal hyphae at the moment of the death bite. After the ant dies, the fungus produces
4080-607: The 1983 Nobel Prize in Physiology or Medicine . Maize remains an important model organism for genetics and developmental biology . The MADS-box motif is involved in the development of maize flowers. The Maize Genetics and Genomics Database is funded by the US Department of Agriculture to support maize research. The International Maize and Wheat Improvement Center maintains a large collection of maize accessions tested and cataloged for insect resistance. In 2005,
4182-662: The Americas. Maize pollen dated to 7,300 years ago from San Andres, Tabasco has been found on the Caribbean coast. A primitive corn was being grown in southern Mexico, Central America, and northern South America 7,000 years ago. Archaeological remains of early maize ears, found at Guila Naquitz Cave in the Oaxaca Valley , are roughly 6,250 years old; the oldest ears from caves near Tehuacan , Puebla, are 5,450 years old. Around 4,500 years ago, maize began to spread to
Braconidae - Misplaced Pages Continue
4284-479: The B-vitamin niacin , the lack of which caused pellagra . Once alkali processing and dietary variety were understood and applied, pellagra disappeared in the developed world. The development of high- lysine maize and the promotion of a more balanced diet have contributed to its demise. Pellagra still exists in food-poor areas and refugee camps where people survive on donated maize. The name maize derives from
4386-760: The Hymenoptera, parasitoidism evolved just once, and the many described species of parasitoid wasps represent the great majority of species in the order, barring those like the ants , bees , and Vespidae wasps that have secondarily lost the parasitoid habit. The parasitoid wasps include some 25,000 Ichneumonoidea , 22,000 Chalcidoidea , 5,500 Vespoidea , 4,000 Platygastroidea , 3,000 Chrysidoidea , 2,300 Cynipoidea , and many smaller families. These often have remarkable life cycles. They can be classified as either endoparasitic or ectoparasitic according to where they lay their eggs. Endoparasitic wasps insert their eggs inside their host, usually as koinobionts, allowing
4488-601: The Lepidoptera, 10 times or more in Coleoptera, and no less than 21 times among the Diptera. These are all holometabolous insects ( Endopterygota , which form a single clade ), and it is always the larvae that are parasitoidal. The metamorphosis from active larva to an adult with a different body structure permits the dual lifestyle of parasitic larva, freeliving adult in this group. These relationships are shown on
4590-709: The Maize Association of Australia, the National Maize Association of Nigeria, the National Maize Association of Ghana, the Maize Trust of South Africa, and the Zimbabwe Seed Maize Association. Maize is a tall annual grass with a single stem, ranging in height from 1.2 m (4 ft) to 4 m (13 ft). The long narrow leaves arise from the nodes or joints, alternately on opposite sides on
4692-586: The Spanish form maíz of the Taíno mahis . The Swedish botanist Carl Linnaeus used the common name maize as the species epithet in Zea mays . The name maize is preferred in formal, scientific, and international usage as a common name because it refers specifically to this one grain, unlike corn , which has a complex variety of meanings that vary by context and geographic region. Most countries primarily use
4794-562: The US National Science Foundation , Department of Agriculture, and the Department of Energy formed a consortium to sequence the maize genome . The resulting DNA sequence data was deposited immediately into GenBank , a public repository for genome-sequence data. Sequencing of the maize genome was completed in 2008. In 2009, the consortium published results of its sequencing effort. The genome, 85% of which
4896-534: The US from each of two major insect pests , namely the European corn borer or ECB ( Ostrinia nubilalis ) and corn rootworms ( Diabrotica spp ) western corn rootworm , northern corn rootworm , and southern corn rootworm . Another serious pest is the fall armyworm ( Spodoptera frugiperda ). The maize weevil ( Sitophilus zeamais ) is a serious pest of stored grain. The Northern armyworm, Oriental armyworm or Rice ear-cutting caterpillar ( Mythimna separata )
4998-418: The beans provided nitrogen derived from nitrogen-fixing rhizobia bacteria which live on the roots of beans and other legumes ; and squashes provided ground cover to stop weeds and inhibit evaporation by providing shade over the soil. Sweet corn, harvested earlier than maize grown for grain, grows to maturity in a period of from 60 to 100 days according to variety. An extended sweet corn harvest, picked at
5100-530: The best-known is the Xenomorph in Ridley Scott 's 1979 film Alien , which runs rapidly through its lifecycle from violently entering a human host's mouth to bursting fatally from the host's chest. The molecular biologist Alex Sercel, writing in Signal to Noise Magazine , compares "the biology of the [ Alien ] Xenomorphs to parasitoid wasps and nematomorph worms from Earth to illustrate how close to reality
5202-519: The biology of these aliens is and to discuss this exceptional instance of science inspiring artists". Sercel notes that the way the Xenomorph grasps a human's face to implant its embryo is comparable to the way a parasitoid wasp lays its eggs in a living host. He further compares the Xenomorph life cycle to that of the nematomorph Paragordius tricuspidatus which grows to fill its host's body cavity before bursting out and killing it. Alistair Dove, on
SECTION 50
#17327807387215304-613: The body of Christ. Maize spread to the rest of the world because of its ability to grow in diverse climates. It was cultivated in Spain just a few decades after Columbus's voyages and then spread to Italy, West Africa and elsewhere. By the 17th century, it was a common peasant food in Southern Europe. By the 18th century, it was the chief food of the southern French and Italian peasantry, especially as polenta in Italy. When maize
5406-776: The chemicals that plants release to defend against insect herbivores. The true flies ( Diptera ) include several families of parasitoids, the largest of which is the Tachinidae (some 9,200 species ), followed by the Bombyliidae (some 4,500 species ), along with the Pipunculidae and the Conopidae , which includes parasitoidal genera such as Stylogaster . Other families of flies include some protelean species. Some Phoridae are parasitoids of ants. Some flesh flies are parasitoids: for instance Emblemasoma auditrix
5508-577: The cob on their own, while those of domesticated maize do not. All maize arose from a single domestication in southern Mexico about 9,000 years ago. The oldest surviving maize types are those of the Mexican highlands. Maize spread from this region to the lowlands and over the Americas along two major paths. The centre of domestication was most likely the Balsas River valley of south-central Mexico. Maize reached highland Ecuador at least 8000 years ago. It reached lower Central America by 7600 years ago, and
5610-440: The concept has been generalised and widely applied. A perspective on the evolutionary options can be gained by considering four questions: the effect on the reproductive fitness of a parasite's hosts; the number of hosts they have per life stage; whether the host is prevented from reproducing; and whether the effect depends on intensity (number of parasites per host). From this analysis, proposed by K. D. Lafferty and A. M. Kunis,
5712-463: The cyclostomes and noncyclostomes. In cyclostome braconids, the labrum and the lower part of the clypeus are concave with respect to the upper clypeus and the dorsal margin of the mandibles. These groups may be clades that diverged early in the evolution of braconids. Cyclostomes are monophyletic whereas noncyclostomes can be divided formally into microgastroids, sigalphoids, helconoids, and euphoroids. The morphological variation among braconids
5814-403: The death of one or more of the parasitoids involved. If multiple parasitoids of the same species coexist in a single host, it is called superparasitism . Gregarious species lay multiple eggs or polyembryonic eggs which lead to multiple larvae in a single host. The end result of gregarious superparasitism can be a single surviving parasitoid individual or multiple surviving individuals, depending on
5916-425: The earliest and most successful, developing Reid's Yellow Dent in the 1860s. These early efforts were based on mass selection (a row of plants is grown from seeds of one parent), and the choosing of plants after pollination (which means that only the female parents are known). Later breeding efforts included ear to row selection (C. G. Hopkins c. 1896), hybrids made from selected inbred lines (G. H. Shull, 1909), and
6018-456: The eggs or larvae of their host, but some attack adults. Oviposition depends on finding the host and on evading host defences; the ovipositor is a tube-like organ used to inject eggs into hosts, sometimes much longer than the wasp's body. Hosts such as ants often behave as if aware of the wasps' presence, making violent movements to prevent oviposition. Wasps may wait for the host to stop moving, and then attack suddenly. Parasitoid wasps face
6120-413: The entire ear is harvested, which requires a separate operation of a maize sheller to remove the kernels from the ear. Whole ears of maize were often stored in corn cribs , sufficient for some livestock feeding uses. Today corn cribs with whole ears, and corn binders, are less common because most modern farms harvest the grain from the field with a combine harvester and store it in bins . The combine with
6222-774: The expansion of the Inca Empire , maize was traded and transported as far south as 40° S in Melinquina, Lácar Department , Argentina, probably brought across the Andes from Chile. After the arrival of Europeans in 1492, Spanish settlers consumed maize, and explorers and traders carried it back to Europe . Spanish settlers much preferred wheat bread to maize. Maize flour could not be substituted for wheat for communion bread, since in Christian belief at that time only wheat could undergo transubstantiation and be transformed into
SECTION 60
#17327807387216324-530: The extraordinarily fast range expansion of O. ochracea, as well as the presence and power of learning in parasitoids. Parasitoids are among the most widely used biological control agents. Classic biological pest control using natural enemies of pests (parasitoids or predators) is extremely cost effective, the cost/benefit ratio for classic control being 1:250, but the technique is more variable in its effects than pesticides; it reduces rather than eliminates pests. The cost/benefit ratio for screening natural enemies
6426-414: The farmer or horticulturalist, the most important groups are the ichneumonid wasps , which prey mainly on caterpillars of butterflies and moths ; braconid wasps , which attack caterpillars and a wide range of other insects including greenfly ; chalcidoid wasps , which parasitise eggs and larvae of greenfly, whitefly , cabbage caterpillars , and scale insects ; and tachinid flies , which parasitise
6528-511: The fatal prognosis for the host, which makes the strategy close to predation . Among parasitoids, strategies range from living inside the host ( endoparasitism ), allowing it to continue growing before emerging as an adult, to paralysing the host and living outside it ( ectoparasitism ). Hosts can include other parasitoids, resulting in hyperparasitism ; in the case of oak galls , up to five levels of parasitism are possible. Some parasitoids influence their host's behaviour in ways that favour
6630-428: The genera Cordyceps and Ophiocordyceps are endoparasitic. One of the most notable fungal parasitoids is O. unilateralis which infects carpenter ants by breaching the ant's exoskeletons via their spores and growing in the ant's hemocoel as free living yeast cells. Eventually the yeast cells progress to producing nerve toxins to alter the behaviour of the ant causing it to climb and bite onto vegetation, known as
6732-532: The highly successful double cross hybrids using four inbred lines ( D. F. Jones c. 1918, 1922). University-supported breeding programs were especially important in developing and introducing modern hybrids. Since the 1940s, the best strains of maize have been first-generation hybrids made from inbred strains that have been optimized for specific traits, such as yield, nutrition, drought, pest and disease tolerance. Both conventional cross-breeding and genetic engineering have succeeded in increasing output and reducing
6834-625: The hind wing is in 95% of Braconidae basal to the separation of R1 and Rs (it is opposite or apical in Ichneumonidae). In Braconidae, metasomal tergum 2 is fused with tergum 3, (secondarily flexible in Aphidiinae) – 90% of Ichneumonidae have a flexible suture. The species Microplitis croceipes possesses an extremely accurate sense of smell and can be trained for use in narcotics and explosives detection . At least some braconids appear to be very resistant to ionizing radiation . While
6936-487: The history of the word corn in North America that "[t]o say the word corn is to plunge into the tragi-farcical mistranslations of language and history". Similar to the British usage, the Spanish referred to maize as panizo , a generic term for cereal grains, as did Italians with the term polenta . The British later referred to maize as Turkey wheat, Turkey corn, or Indian corn; Fussell comments that "they meant not
7038-399: The hive. About 10% of described insects are parasitoids, in the orders Hymenoptera , Diptera , Coleoptera , Neuroptera , Lepidoptera , Strepsiptera , and Trichoptera . The majority are wasps within the Hymenoptera; most of the others are Dipteran flies. Parasitoidism has evolved independently many times: once each in Hymenoptera, Strepsiptera, Neuroptera, and Trichoptera, twice in
7140-537: The host caterpillar. Through the evolutionary history of being used by the wasps, these viruses apparently have become so modified, they appear unlike any other known viruses today. Because of this highly modified system of host immunosuppression , a high level of parasitoid-host specificity is not surprising. The family seems to date from early Cretaceous (provided that Eobracon is properly assigned to this family). It underwent extensive diversification from mid or late Cretaceous to early Cenozoic , correlating with
7242-410: The host from outside. Idiobiont parasitoids prevent further development of the host after initially immobilising it, whereas koinobiont parasitoids allow the host to continue its development while feeding upon it. Most ectoparasitoids are idiobiont, as the host could damage or dislodge the external parasitoid if allowed to move and moult . Most endoparasitoids are koinobionts, giving them the advantage of
7344-406: The host to continue to grow (thus providing more food to the wasp larvae), moult, and evade predators. Ectoparasitic wasps deposit theirs outside the host's body, usually as idiobionts, immediately paralysing the host to prevent it from escaping or throwing off the parasite. They often carry the host to a nest where it will remain undisturbed for the wasp larva to feed on. Most species of wasps attack
7446-435: The host's behaviour. Among the parasitic wasps, Glyptapanteles modifies the behaviour of its host caterpillar to defend the pupae of the wasps after they emerge from the caterpillar's body. The phorid fly Apocephalus borealis oviposits into the abdomen of its hosts, including honey bees , causing them to abandon their nest, flying from it at night and soon dying, allowing the next generation of flies to emerge outside
7548-412: The host, such as the co-option of endosymbiotic viruses for compromising host immune defenses . These bracoviruses are often used by the wasps instead of, or in addition to, a venom cocktail. The DNA of the wasp actually contains portions that are the templates for the components of the viral particles and they are assembled in an organ in the female's abdomen known as the calyx. A 2009 study has traced
7650-480: The living bodies of Caterpillars." The palaeontologist Donald Prothero notes that religiously minded people of the Victorian era , including Darwin, were horrified by this instance of evident cruelty in nature, particularly noticeable in the ichneumonid wasps. Parasitoids have inspired science fiction authors and screenwriters to create terrifying parasitic alien species that kill their human hosts. One of
7752-419: The machinery. The combine separates the husk and the cob, keeping only the kernels. Drying is vital to prevent or at least reduce damage by mould fungi, which contaminate the grain with mycotoxins . Aspergillus and Fusarium spp. are the most common mycotoxin sources, and accordingly important in agriculture. If the moisture content of the harvested grain is too high, grain dryers are used to reduce
7854-543: The major evolutionary strategies of parasitism emerge, alongside predation. Parasitoidism, in the view of R. Poulin and H. S. Randhawa, is one of six main evolutionary strategies within parasitism , the others being parasitic castrator , directly transmitted parasite, trophically transmitted parasite, vector -transmitted parasite, and micropredator. These are adaptive peaks , with many possible intermediate strategies, but organisms in many different groups have consistently converged on these six. Parasitoids feed on
7956-413: The milk stage, can be arranged either by planting a selection of varieties which ripen earlier and later, or by planting different areas at fortnightly intervals. Maize harvested as a grain crop can be kept in the field a relatively long time, even months, after the crop is ready to harvest; it can be harvested and stored in the husk leaves if kept dry. Before World War II , most maize in North America
8058-427: The moisture content by blowing heated air through the grain. This can require large amounts of energy in the form of combustible gases ( propane or natural gas ) and electricity to power the blowers. Maize is widely cultivated throughout the world, and a greater weight of maize is produced each year than any other grain. In 2020, total world production was 1.16 billion tonnes , led by the United States with 31.0% of
8160-501: The need for cropland, pesticides, water and fertilizer. There is conflicting evidence to support the hypothesis that maize yield potential has increased over the past few decades. This suggests that changes in yield potential are associated with leaf angle, lodging resistance, tolerance of high plant density, disease/pest tolerance, and other agronomic traits rather than increase of yield potential per individual plant. Certain varieties of maize have been bred to produce many ears; these are
8262-400: The new crop. The rise in maize cultivation 500 to 1,000 years ago in what is now the southeastern United States corresponded with a decline of freshwater mussels , which are very sensitive to environmental changes. Because it is cold-intolerant, in the temperate zones maize must be planted in the spring. Its root system is generally shallow, so the plant is dependent on soil moisture. As
8364-465: The north. In the United States, maize was first cultivated at several sites in New Mexico and Arizona about 4,100 years ago. During the first millennium AD, maize cultivation spread more widely in the areas north. In particular, the large-scale adoption of maize agriculture and consumption in eastern North America took place about A.D. 900. Native Americans cleared large forest and grassland areas for
8466-446: The origins of these templates to a 100-million-year-old viral infection whose alterations to its host DNA provided the necessary basis for these virus-like "templates". These viruses suppress the immune system and allow the parasitoid to grow inside the host undetected. The exact function and evolutionary history of these viruses are unknown. Sequences of polydnavirus genes show the possibility that venom-like proteins are expressed inside
8568-419: The parasitoidal fluke's life cycle in its definitive host . Similarly, as strepsipteran parasitoids of ants mature, they cause the hosts to climb high on grass stalks, positions that are risky, but favour the emergence of the strepsipterans. Among pathogens of mammals, the rabies virus affects the host's central nervous system , eventually killing it, but perhaps helping to disseminate the virus by modifying
8670-760: The presence of Starlink genetically modified corn, which had been approved only for animal consumption. The maize genus Zea is relatively closely related to sorghum , both being in the PACMAD clade of Old World grasses, and much more distantly to rice and wheat , which are in the other major group of grasses, the BOP clade . It is closely related to Tripsacum , gamagrass. various grasses e.g. fescue , ryegrass Hordeum (barley) Triticum (wheat) Oryza (rice) Pennisetum (fountaingrasses) Sorghum (sorghum) Tripsacum (gamagrass) Zea mays (maize) other Zea species ( teosintes ) Maize
8772-493: The propagation of the parasitoid. Parasitoids are found in a variety of taxa across the insect superorder Endopterygota , whose complete metamorphosis may have pre-adapted them for a split lifestyle, with parasitoid larvae and free-living adults. Most are in the Hymenoptera , where the ichneumons and many other parasitoid wasps are highly specialised for a parasitoidal way of life. There are parasitoids, too, in
8874-569: The radiation of flowering plants and associated insect herbivores , the main hosts of braconids. Braconids are distinguished from their sister group Ichneumonidae by these character combinations. In Braconidae, vein 2m-cu of the forewing is absent except in the Chilean species Apozyx penyai – this vein is present in 95% of Ichneumonidae. Vein 1/Rs+M of the forewing is 85% present in Braconidae, but absent in all Ichneumonidae. Vein 1r-m of
8976-701: The science website Deep Sea News , writes that there are multiple parallels with parasitoids, though there are in his view more disturbing life cycles in real biology. In his view, the parallels include the placing of an embryo in the host; its growth in the host; the resulting death of the host; and alternating generations , as in the Digenea (trematodes). The social anthropologist Marika Moisseeff argues that "The parasitical and swarming aspects of insect reproduction make these animals favoured villains in Hollywood science fiction. The battle of culture against nature
9078-491: The source of the " baby corn " used as a vegetable in Asian cuisine . A fast-flowering variety named mini-maize was developed to aid scientific research, as multiple generations can be obtained in a single year. One strain called olotón has evolved a symbiotic relationship with nitrogen-fixing microbes, which provides the plant with 29%–82% of its nitrogen. The International Maize and Wheat Improvement Center (CIMMYT) operates
9180-483: The species. If superparasitism occurs accidentally in normally solitary species the larvae often fight among themselves until only one is left. In another strategy, some parasitoids influence the host's behaviour in ways that favour the propagation of the parasitoid, often at the cost of the host's life. A spectacular example is the lancet liver fluke , which causes host ants to die clinging to grass stalks, where grazers or birds may be expected to eat them and complete
9282-415: The stalk. Maize is monoecious , with separate male and female flowers on the same plant. At the top of the stem is the tassel, an inflorescence of male flowers; their anthers release pollen, which is dispersed by wind . Like other pollen, it is an allergen , but most of it falls within a few meters of the tassel and the risk is largely restricted to farm workers. The female inflorescence, some way down
9384-425: The stem from the tassel, is first seen as a silk, a bundle of soft tubular hairs , one for the carpel in each female flower, which develops into a kernel (often called a seed. Botanically, as in all grasses, it is a fruit, fused with the seed coat to form a caryopsis ) when it is pollinated. A whole female inflorescence develops into an ear or corncob , enveloped by multiple leafy layers or husks. The ear leaf
9486-608: The term maize , and the name corn is used mainly in the United States and a handful of other English-speaking countries. In countries that primarily use the term maize , the word corn may denote any cereal crop, varying geographically with the local staple , such as wheat in England and oats in Scotland or Ireland. The usage of corn for maize started as a shortening of " Indian corn " in 18th-century North America. The historian of food Betty Fussell writes in an article on
9588-472: The total (table). China produced 22.4% of the global total. Many pests can affect maize growth and development, including invertebrates, weeds, and pathogens. Maize is susceptible to a large number of fungal, bacterial, and viral plant diseases . Those of economic importance include diseases of the leaf, smuts such as corn smut , ear rots and stalk rots. Northern corn leaf blight damages maize throughout its range, whereas banded leaf and sheath blight
9690-500: The two is largely controlled by differences in just two genes, called grassy tillers-1 ( gt1 , A0A317YEZ1 ) and teosinte branched-1 ( tb1 , Q93WI2 ). In the late 1930s, Paul Mangelsdorf suggested that domesticated maize was the result of a hybridization event between an unknown wild maize and a species of Tripsacum , a related genus; this has been refuted by modern genetic testing . In 2004, John Doebley identified Balsas teosinte, Zea mays subsp. parviglumis , native to
9792-468: The use of a learned, auditory search image. This phenotypic plasticity allows such a highly specialized parasitoid to avoid overspecialization disasters. Interestingly, when receptive females only heard silence the night before testing for preference, they chose the host songs equally, 50/50. This capacity for learning and use of search images paired with a highly specialized morphology and lifestyle (eg. tympana tuned to host sound cues, larviparous) supports
9894-589: The valleys of the Colombian Andes between 7000 and 6000 years ago. The earliest maize plants grew a single, small ear per plant. The Olmec and Maya cultivated maize in numerous varieties throughout Mesoamerica ; they cooked, ground and processed it through nixtamalization . By 3000 years ago, maize was central to Olmec culture, including their calendar, language, and myths. The Mapuche people of south-central Chile cultivated maize along with quinoa and potatoes in pre-Hispanic times. Before
9996-555: Was domesticated by indigenous peoples in southern Mexico about 9,000 years ago from wild teosinte . Native Americans planted it alongside beans and squashes in the Three Sisters polyculture . The leafy stalk of the plant gives rise to male inflorescences or tassels which produce pollen , and female inflorescences called ears . The ears yield grain, known as kernels or seeds. In modern commercial varieties, these are usually yellow or white; other varieties can be of many colors. Maize relies on humans for its propagation. Since
10098-458: Was harvested by hand. This involved a large number of workers and associated social events (husking or shucking bees ). From the 1890s onward, some machinery became available to partially mechanize the processes, such as one- and two-row mechanical pickers (picking the ear, leaving the stover ) and corn binders, which are reaper-binders designed specifically for maize. The latter produce sheaves that can be shocked . By hand or mechanical picker,
10200-425: Was introduced into Western farming systems, it was welcomed for its productivity. However, a widespread problem of malnutrition soon arose wherever it had become a staple food . Indigenous Americans had learned to soak maize in alkali -water — made with ashes and lime — since at least 1200–1500 BC, creating the process of nixtamalization. They did this to liberate the corn hulls, but coincidentally it also liberated
10302-466: Was one of the 26 genetically engineered food crops grown commercially in 2016. The vast majority of this is Bt maize . Genetically modified maize has been grown since 1997 in the United States and Canada; by 2016, 92% of the US maize crop was genetically modified. As of 2011, herbicide-tolerant maize and insect-resistant maize varieties were each grown in over 20 countries. In September 2000, up to $ 50 million worth of food products were recalled due to
10404-420: Was one of the first naturalists to study and depict parasitoids and their insect hosts in her closely-observed paintings. Parasitoids influenced the religious thinking of Charles Darwin , who wrote in an 1860 letter to the American naturalist Asa Gray : "I cannot persuade myself that a beneficent and omnipotent God would have designedly created parasitic wasps with the express intention of their feeding within
#720279