Table of nuclides
A table of nuclides or chart of nuclides is a two-dimensional graph in which one axis represents the number of neutrons and the other represents the number of protons in an atomic nucleus. Each point plotted on the graph thus represents the nuclide of a real or hypothetical chemical element; this system of ordering nuclides can offer a greater insight into the characteristics of isotopes than the better-known periodic table, which shows only elements instead of each of their isotopes. A chart or table of nuclides is a simple map to the nuclear, or radioactive, behaviour of nuclides, as it distinguishes the isotopes of an element, it contrasts with a periodic table, which only maps their chemical behavior, since isotopes do not differ chemically to any significant degree, with the exception of hydrogen. Nuclide charts organize nuclides along the X axis by their numbers of neutrons and along the Y axis by their numbers of protons, out to the limits of the neutron and proton drip lines; this representation was first published by Kurt Guggenheimer in 1934 and expanded by Giorgio Fea in 1935, Emilio Segrè in 1945 or G. Seaborg.
In 1958, Walter Seelmann-Eggebert and Gerda Pfennig published the first edition of the Karlsruhe Nuclide Chart. Its 7th edition was made available in 2006. Today, there are several nuclide charts, four of which have a wide distribution: the Karlsruhe Nuclide Chart, the Strasbourg Universal Nuclide Chart, the Chart of the Nuclides from the JAEA and the Nuclide Chart from Knolls Atomic Power Laboratory, it has become a basic tool of the nuclear community. The nuclide table below shows nuclides, including all with half-life of at least one day, they are arranged with increasing atomic numbers from left to right and increasing neutron numbers from top to bottom. Cell color denotes the half-life of each nuclide. In graphical browsers, each nuclide has a tool tip indicating its half-life; each color represents a certain range of length of half-life, the color of the border indicates the half-life of its nuclear isomer state. Some nuclides have multiple nuclear isomers, this table notes the longest one.
Dotted borders mean that a nuclide has a nuclear isomer, their color is represented the same way as for their normal counterparts. Isotopes are nuclides with the same number of protons but differing numbers of neutrons. Isotopes neighbor each other vertically, e.g. carbon-12, carbon-13, carbon-14 or oxygen-15, oxygen-16, oxygen-17. Isotones are nuclides with the same number of neutrons but differing number of protons. Isotones neighbor each other horizontally. Example: carbon-14, nitrogen-15, oxygen-16 in the sample table above. Isobars are nuclides with the same number of nucleons, i.e. mass number, but different numbers of protons and different number of neutrons. Isobars neighbor each other diagonally from lower-left to upper-right. Example: carbon-14, nitrogen-14, oxygen-14 in the sample table above. Isodiaphers are nuclides with the same difference between protons. Like isobars, they at right angles to the isobar lines. Examples: boron-10, carbon-12, nitrogen-14 where N−Z=0. Beyond the neutron drip line along the lower left, nuclides decay by neutron emission.
Beyond the proton drip line along the upper right, nuclides decay by proton emission. Drip lines have only been established for some elements; the island of stability is a hypothetical region of the table of nuclides that contains isotopes far more stable than other transuranic elements. There are no stable nuclides having an equal number of protons and neutrons in their nuclei with atomic number greater than 20 as can be "read" from the chart. Nuclei of greater atomic number require an excess of neutrons for stability; the only stable nuclides having an odd number of protons and an odd number of neutrons are hydrogen-2, lithium-6, boron-10, nitrogen-14 and tantalum-180m. This is because the mass-energy of such atoms is higher than that of their neighbors on the same isobaric chain, so most of them are unstable to beta decay. There are no stable nuclides with mass numbers 5 or 8. There are stable nuclides with all other mass numbers up to 208 with the exceptions of 147 and 151. With the possible exception of the pair tellurium-123 and antimony-123, odd mass numbers are never represented by more than one stable nuclide.
This is because the mass-energy is a convex function of atomic number, so all nuclides on an odd isobaric chain except one have a lower-energy neighbor to which they can decay by beta decay. There are no stable nuclides having atomic number greater than Z=82, although bismuth is stable for all practical human purposes. Elements with atomic numbers from 1 to 82 all have stable isotopes, with the exceptions of technetium and promethium. Interactive Chart of Nuclides app for mobiles: Android or Apple - for PC use The Live Chart of Nuclides - IAEA Another example of a Chart of Nuclides from Korea Data up to Jan 1999 only
The decay scheme of a radioactive substance is a graphical presentation of all the transitions occurring in a decay, of their relationships. Examples are shown below, it is useful to think of the decay scheme as placed in a coordinate system, where the ordinate axis is energy, increasing from bottom to top, the abscissa is the proton number, increasing from left to right. The arrows indicate the emitted particles. For the gamma rays, the gamma energies are given; these relations can be quite complicated. 60Co decays by emitting an electron with a half-life of 5.272 years into an excited state of 60Ni, which decays fast to the ground state of 60Ni, via two gamma decays. All known decay schemes can be found in the Table of Isotopes. Nickel is to the right of cobalt. In beta decay, the proton number increases by one. For a positron decay and for an alpha decay, the oblique arrow would go from right to left since in these cases, the proton number decreases. Since energy is conserved and since the particles emitted carry away energy, arrows can only go downward in a decay scheme.
A somewhat more complicated scheme is shown here: the decay of the nuclide 198Au which can be produced by irradiating natural gold in a nuclear reactor. 198Au decays via beta decay to one of two excited states or to the ground state of the mercury isotope 198Hg. In the figure, mercury is to the right of gold, since the atomic number of gold is 79, that of mercury is 80; the excited states decay after short times to the ground state. While excited nuclear states are very short lived, decaying immediately after a beta decay, the excited state of the technetium isotope shown here to the right is comparatively long lived, it is therefore called "metastable". It decays to the ground state via gamma decay with a half-life of 6 hours. Here, to the left, we now have an alpha decay, it is the decay of the element Polonium discovered by Marie Curie, with mass number 210. The isotope 210Po is the penultimate member of the uranium-radium-decay series. In all cases, the decay is via the emission of an alpha particle of 5.305 MeV.
Only in one case of 100000, an alpha particle of lower energy appears. Alpha- beta- and gamma rays can only be emitted if the conservation laws are obeyed; this leads to so-called selection rules. Applications for gamma decay can be found in Multipolarity of gamma radiation. To discuss such a rule in a particular case, it is necessary to know angular momentum and parity for every state; the figure shows the 60Co decay scheme again, with spins and parities given for every state
The curie is a non-SI unit of radioactivity defined in 1910. According to a notice in Nature at the time, it was named in honour of Pierre Curie, but was considered at least by some to be in honour of Marie Curie as well, it was defined as "the quantity or mass of radium emanation in equilibrium with one gram of radium" but is defined as: 1 Ci = 3.7×1010 decays per second after more accurate measurements of the activity of 226Ra In 1975 the General Conference on Weights and Measures gave the becquerel, defined as one nuclear decay per second, official status as the SI unit of activity. Therefore: 1 Ci = 3.7×1010 Bq = 37 GBqand 1 Bq ≅ 2.703×10−11 Ci ≅ 27 pCiWhile its continued use is discouraged by National Institute of Standards and Technology and other bodies, the curie is still used throughout the government and medicine in the United States and in other countries. At the 1910 meeting which defined the curie, it was proposed to make it equivalent to 10 nanograms of radium, but Marie Curie, after accepting this, changed her mind and insisted on one gram of radium.
According to Bertram Boltwood, Marie Curie thought that'the use of the name "curie" for so infinitesimally small quantity of anything was altogether inappropriate.'The power in milliwatts emitted by one curie of radiation can be calculated by taking the number of MeV for the radiation times 5.93. A radiotherapy machine may have 1000 Ci of a radioisotope such as caesium-137 or cobalt-60; this quantity of radioactivity can produce serious health effects with only a few minutes of close-range, unshielded exposure. Ingesting a millicurie is fatal. For example, the LD-50 for ingested polonium-210 is about 53.5 nanograms. The typical human body contains 0.1 μCi of occurring potassium-40. A human body containing 16 kg of carbon would have about 24 nanograms or 0.1 μCi of carbon-14. Together, these would result in a total of 0.2 μCi or 7400 decays per second inside the person's body. Units of activity refer to a quantity of radioactive atoms; because the probability of decay is a fixed physical quantity, for a known number of atoms of a particular radionuclide, a predictable number will decay in a given time.
The number of decays that will occur in one second in one gram of atoms of a particular radionuclide is known as the specific activity of that radionuclide. The activity of a sample decreases with time because of decay; the rules of radioactive decay may be used to convert activity to an actual number of atoms. They state that 1 Ci of radioactive atoms would follow the expression: N × λ = 1 Ci = 3.7 × 1010 Bqand so, N = 3.7 × 1010 Bq / λ,where λ is the decay constant in s−1. We can express activity in moles: 1 Ci = 3.7 × 10 10 N A moles × t 1 / 2 in seconds ≈ 8.8639 × 10 − 14 moles × t 1 / 2 in seconds ≈ 5.3183 × 10 − 12 moles × t 1 / 2 in minutes ≈ 3.1910 × 10 − 10 moles × t 1 / 2 in hours ≈ 7.6584 × 10 − 9 moles × t 1 / 2 in days ≈ 2.7972 × 10 − 6 moles × t 1 / 2 in years where NA is Avogadro's number and t1/2 is the half life. The number of moles may be converted to grams by multiplying by the atomic mass. Here are some examples, ordered by half-life: The following table shows radiation quantities in SI and non-SI units: Geiger counter Ionizing radiat
A gamma ray or gamma radiation, is a penetrating electromagnetic radiation arising from the radioactive decay of atomic nuclei. It consists of the shortest wavelength electromagnetic waves and so imparts the highest photon energy. Paul Villard, a French chemist and physicist, discovered gamma radiation in 1900 while studying radiation emitted by radium. In 1903, Ernest Rutherford named this radiation gamma rays based on their strong penetration of matter. Gamma rays from radioactive decay are in the energy range from a few keV to ~8 MeV, corresponding to the typical energy levels in nuclei with reasonably long lifetimes; the energy spectrum of gamma rays can be used to identify the decaying radionuclides using gamma spectroscopy. Very-high-energy gamma rays in the 100–1000 TeV range have been observed from sources such as the Cygnus X-3 microquasar. Natural sources of gamma rays originating on Earth are as a result of radioactive decay and secondary radiation from atmospheric interactions with cosmic ray particles.
However there are other rare natural sources, such as terrestrial gamma-ray flashes, that produce gamma rays from electron action upon the nucleus. Notable artificial sources of gamma rays include fission, such as occurs in nuclear reactors, as well as high energy physics experiments, such as neutral pion decay and nuclear fusion. Gamma rays and X-rays are both electromagnetic radiation and they overlap in the electromagnetic spectrum, the terminology varies between scientific disciplines. In some fields of physics, they are distinguished by their origin: Gamma rays are created by nuclear decay, while in the case of X-rays, the origin is outside the nucleus. In astrophysics, gamma rays are conventionally defined as having photon energies above 100 keV and are the subject of gamma ray astronomy, while radiation below 100 keV is classified as X-rays and is the subject of X-ray astronomy; this convention stems from the early man-made X-rays, which had energies only up to 100 keV, whereas many gamma rays could go to higher energies.
A large fraction of astronomical gamma rays are screened by Earth's atmosphere. Gamma rays are thus biologically hazardous. Due to their high penetration power, they can damage internal organs. Unlike alpha and beta rays, they pass through the body and thus pose a formidable radiation protection challenge, requiring shielding made from dense materials such as lead or concrete; the first gamma ray source to be discovered was the radioactive decay process called gamma decay. In this type of decay, an excited nucleus emits a gamma ray immediately upon formation. Paul Villard, a French chemist and physicist, discovered gamma radiation in 1900, while studying radiation emitted from radium. Villard knew that his described radiation was more powerful than described types of rays from radium, which included beta rays, first noted as "radioactivity" by Henri Becquerel in 1896, alpha rays, discovered as a less penetrating form of radiation by Rutherford, in 1899. However, Villard did not consider naming them as a different fundamental type.
In 1903, Villard's radiation was recognized as being of a type fundamentally different from named rays by Ernest Rutherford, who named Villard's rays "gamma rays" by analogy with the beta and alpha rays that Rutherford had differentiated in 1899. The "rays" emitted by radioactive elements were named in order of their power to penetrate various materials, using the first three letters of the Greek alphabet: alpha rays as the least penetrating, followed by beta rays, followed by gamma rays as the most penetrating. Rutherford noted that gamma rays were not deflected by a magnetic field, another property making them unlike alpha and beta rays. Gamma rays were first thought to be particles like alpha and beta rays. Rutherford believed that they might be fast beta particles, but their failure to be deflected by a magnetic field indicated that they had no charge. In 1914, gamma rays were observed to be reflected from crystal surfaces, proving that they were electromagnetic radiation. Rutherford and his co-worker Edward Andrade measured the wavelengths of gamma rays from radium, found that they were similar to X-rays, but with shorter wavelengths and higher frequency.
This was recognized as giving them more energy per photon, as soon as the latter term became accepted. A gamma decay was understood to emit a gamma photon. Natural sources of gamma rays on Earth include gamma decay from occurring radioisotopes such as potassium-40, as a secondary radiation from various atmospheric interactions with cosmic ray particles; some rare terrestrial natural sources that produce gamma rays that are not of a nuclear origin, are lightning strikes and terrestrial gamma-ray flashes, which produce high energy emissions from natural high-energy voltages. Gamma rays are produced by a number of astronomical processes in which high-energy electrons are produced; such electrons produce secondary gamma rays by the mechanisms of bremsstrahlung, inverse Compton scattering and synchrotron radiation. A large fraction of such astronomical gamma rays are screened by Earth's atmosphere. Notable artificial sources of gamma rays include fission, such as occurs in nuclear reactors, as well as high energy physics experiments, such as neutral pion decay and nuclear fusion.
A sample of gamma ray-emitting material, used for irradiating or imaging is known as a gamma source. It is called a radioactive sou
A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission or from a combination of fission and fusion reactions. Both bomb types release large quantities of energy from small amounts of matter; the first test of a fission bomb released an amount of energy equal to 20,000 tons of TNT. The first thermonuclear bomb test released energy equal to 10 million tons of TNT. A thermonuclear weapon weighing little more than 2,400 pounds can release energy equal to more than 1.2 million tons of TNT. A nuclear device no larger than traditional bombs can devastate an entire city by blast and radiation. Since they are weapons of mass destruction, the proliferation of nuclear weapons is a focus of international relations policy. Nuclear weapons have been used twice in war, both times by the United States against Japan near the end of World War II. On August 6, 1945, the U. S. Army Air Forces detonated a uranium gun-type fission bomb nicknamed "Little Boy" over the Japanese city of Hiroshima.
S. Army Air Forces detonated a plutonium implosion-type fission bomb nicknamed "Fat Man" over the Japanese city of Nagasaki; these bombings caused injuries that resulted in the deaths of 200,000 civilians and military personnel. The ethics of these bombings and their role in Japan's surrender are subjects of debate. Since the atomic bombings of Hiroshima and Nagasaki, nuclear weapons have been detonated over two thousand times for testing and demonstration. Only a few nations are suspected of seeking them; the only countries known to have detonated nuclear weapons—and acknowledge possessing them—are the United States, the Soviet Union, the United Kingdom, China, India and North Korea. Israel is believed to possess nuclear weapons, though, in a policy of deliberate ambiguity, it does not acknowledge having them. Germany, Turkey and the Netherlands are nuclear weapons sharing states. South Africa is the only country to have independently developed and renounced and dismantled its nuclear weapons.
The Treaty on the Non-Proliferation of Nuclear Weapons aims to reduce the spread of nuclear weapons, but its effectiveness has been questioned, political tensions remained high in the 1970s and 1980s. Modernisation of weapons continues to this day. There are two basic types of nuclear weapons: those that derive the majority of their energy from nuclear fission reactions alone, those that use fission reactions to begin nuclear fusion reactions that produce a large amount of the total energy output. All existing nuclear weapons derive some of their explosive energy from nuclear fission reactions. Weapons whose explosive output is from fission reactions are referred to as atomic bombs or atom bombs; this has long been noted as something of a misnomer, as their energy comes from the nucleus of the atom, just as it does with fusion weapons. In fission weapons, a mass of fissile material is forced into supercriticality—allowing an exponential growth of nuclear chain reactions—either by shooting one piece of sub-critical material into another or by compression of a sub-critical sphere or cylinder of fissile material using chemically-fueled explosive lenses.
The latter approach, the "implosion" method, is more sophisticated than the former. A major challenge in all nuclear weapon designs is to ensure that a significant fraction of the fuel is consumed before the weapon destroys itself; the amount of energy released by fission bombs can range from the equivalent of just under a ton to upwards of 500,000 tons of TNT. All fission reactions generate the remains of the split atomic nuclei. Many fission products are either radioactive or moderately radioactive, as such, they are a serious form of radioactive contamination. Fission products are the principal radioactive component of nuclear fallout. Another source of radioactivity is the burst of free neutrons produced by the weapon; when they collide with other nuclei in surrounding material, the neutrons transmute those nuclei into other isotopes, altering their stability and making them radioactive. The most used fissile materials for nuclear weapons applications have been uranium-235 and plutonium-239.
Less used has been uranium-233. Neptunium-237 and some isotopes of americium may be usable for nuclear explosives as well, but it is not clear that this has been implemented, their plausible use in nuclear weapons is a matter of dispute; the other basic type of nuclear weapon produces a large proportion of its energy in nuclear fusion reactions. Such fusion weapons are referred to as thermonuclear weapons or more colloquially as hydrogen bombs, as they rely on fusion reactions between isotopes of hydrogen. All such weapons derive a significant portion of their energy from fission reactions used to "trigger" fusion reactions, fusion reactions can themselves trigger additional fission reactions. Only six countries—United States, United Kingdom, China and India—have conducted thermonuclear weapon tests. North Korea claims to have tested a fusion weapon as of January 2016. Thermonuclear weapons a
Isotopes are variants of a particular chemical element which differ in neutron number, in nucleon number. All isotopes of a given element have the same number of protons but different numbers of neutrons in each atom; the term isotope is formed from the Greek roots isos and topos, meaning "the same place". It was coined by a Scottish doctor and writer Margaret Todd in 1913 in a suggestion to chemist Frederick Soddy; the number of protons within the atom's nucleus is called atomic number and is equal to the number of electrons in the neutral atom. Each atomic number identifies a specific element, but not the isotope; the number of nucleons in the nucleus is the atom's mass number, each isotope of a given element has a different mass number. For example, carbon-12, carbon-13, carbon-14 are three isotopes of the element carbon with mass numbers 12, 13, 14, respectively; the atomic number of carbon is 6, which means that every carbon atom has 6 protons, so that the neutron numbers of these isotopes are 6, 7, 8 respectively.
A nuclide is a species of an atom with a specific number of protons and neutrons in the nucleus, for example carbon-13 with 6 protons and 7 neutrons. The nuclide concept emphasizes nuclear properties over chemical properties, whereas the isotope concept emphasizes chemical over nuclear; the neutron number has large effects on nuclear properties, but its effect on chemical properties is negligible for most elements. In the case of the lightest elements where the ratio of neutron number to atomic number varies the most between isotopes it has only a small effect, although it does matter in some circumstances; the term isotopes is intended to imply comparison, for example: the nuclides 126C, 136C, 146C are isotopes, but 4018Ar, 4019K, 4020Ca are isobars. However, because isotope is the older term, it is better known than nuclide, is still sometimes used in contexts where nuclide might be more appropriate, such as nuclear technology and nuclear medicine. An isotope and/or nuclide is specified by the name of the particular element followed by a hyphen and the mass number.
When a chemical symbol is used, e.g. "C" for carbon, standard notation is to indicate the mass number with a superscript at the upper left of the chemical symbol and to indicate the atomic number with a subscript at the lower left. Because the atomic number is given by the element symbol, it is common to state only the mass number in the superscript and leave out the atomic number subscript; the letter m is sometimes appended after the mass number to indicate a nuclear isomer, a metastable or energetically-excited nuclear state, for example 180m73Ta. The common pronunciation of the AZE notation is different from how it is written: 42He is pronounced as helium-four instead of four-two-helium, 23592U as uranium two-thirty-five or uranium-two-three-five instead of 235-92-uranium; some isotopes/nuclides are radioactive, are therefore referred to as radioisotopes or radionuclides, whereas others have never been observed to decay radioactively and are referred to as stable isotopes or stable nuclides.
For example, 14C is a radioactive form of carbon, whereas 12C and 13C are stable isotopes. There are about 339 occurring nuclides on Earth, of which 286 are primordial nuclides, meaning that they have existed since the Solar System's formation. Primordial nuclides include 32 nuclides with long half-lives and 253 that are formally considered as "stable nuclides", because they have not been observed to decay. In most cases, for obvious reasons, if an element has stable isotopes, those isotopes predominate in the elemental abundance found on Earth and in the Solar System. However, in the cases of three elements the most abundant isotope found in nature is one long-lived radioisotope of the element, despite these elements having one or more stable isotopes. Theory predicts that many "stable" isotopes/nuclides are radioactive, with long half-lives; some stable nuclides are in theory energetically susceptible to other known forms of decay, such as alpha decay or double beta decay, but no decay products have yet been observed, so these isotopes are said to be "observationally stable".
The predicted half-lives for these nuclides greatly exceed the estimated age of the universe, in fact there are 27 known radionuclides with half-lives longer than the age of the universe. Adding in the radioactive nuclides that have been created artificially, there are 3,339 known nuclides; these include 905 nuclides that are either stable or have half-lives
Sterile insect technique
The sterile insect technique is a method of biological insect control, whereby overwhelming numbers of sterile insects are released into the wild. The released insects are preferably male, as this is more cost-effective and the females may in some situations cause damage by laying eggs in the crop, or, in the case of mosquitoes, taking blood from humans; the sterile males compete with wild males to mate with the females. Females that mate with a sterile male produce no offspring, thus reducing the next generation's population. Sterile insects are not self-replicating and, cannot become established in the environment. Repeated release of sterile males over low population densities can further reduce and in cases of isolation eliminate pest populations, although cost-effective control with dense target populations is subjected to population suppression prior to the release of the sterile males; the technique has been used to eradicate the screw-worm fly from North and Central America. Many successes have been achieved for control of fruit fly pests, most the Mediterranean fruit fly and the Mexican fruit fly.
Sterilization is induced through the effects of irradiation on the reproductive cells of the insects. SIT does not involve the release of insects modified through transgenic processes. Moreover, SIT does not introduce non-native species into an ecosystem. Raymond Bushland and Edward Knipling developed the SIT to eliminate screw-worms preying on warm-blooded animals cattle, they exploited the fact to attack screw-worm reproduction. The larvae of these flies invade open wounds and eat into animal flesh, killing infected cattle within 10 days. In the 1950s, screw-worms caused annual losses to American meat and dairy supplies that were projected at above $200 million. Screw-worm maggots can parasitize human flesh. Bushland and Knipling began searching for an alternative to chemical pesticides in the late 1930s when they were working at the United States Department of Agriculture Laboratory in Menard, Texas. At that time, the screw-worm was devastating livestock herds across the American South. Red meat and dairy supplies were affected across Mexico, Central America, South America.
Knipling developed the theory of autocidal control – breaking the pest's reproductive cycle. Bushland's enthusiasm for Knipling's theory sparked the pair to search for a way to rear flies in a "factory" setting, to find an effective way to sterilize flies, their work was interrupted by World War II, but they resumed their efforts in the early 1950s with successful tests on the screw-worm population of Sanibel Island, Florida. The sterile insect technique worked. In 1954, the technique was used to eradicate screw-worms from the 176-square-mile island of Curaçao, off the coast of Venezuela. Screw-worms were eliminated in seven weeks, saving the domestic goat herds that were a source of meat and milk. During the late 1950s to the 1970s, SIT was used to control the screw-worm population in the US. In the 1980s, Mexico and Belize eliminated their screw-worm problems with SIT. Eradication programs progressed across Central America in the 1990s, followed by the establishment of a biological barrier in Panama to prevent reinfestation from the south.
The map shows the current and former distribution area and the approximate seasonal spread of the screw-worm fly. In 1991, Knipling and Bushland's technique halted a serious outbreak of New World screw-worm in northern Africa. Programs against the Mediterranean fruit fly in Mexico and California use the SIT to maintain their fly-free status; the technique was used to eradicate the melon fly from Okinawa and in the fight against the tsetse fly in Africa. The technique has suppressed insects threatening livestock, fruit and fiber crops; the technique was lauded for its environmental attributes: it leaves no residues and has no negative effect on nontarget species. The technique has been a boon in protecting the agricultural products to feed the world's human population. Both Bushland and Knipling received worldwide recognition for their leadership and scientific achievements, including the 1992 World Food Prize; the technique were hailed by former U. S. Secretary of Agriculture Orville Freeman as "the greatest entomological achievement of the 20th century."
Sleeping sickness or African trypanosomiasis is a parasitic disease in humans. Caused by protozoa of genus Trypanosoma and transmitted by the tsetse fly, the disease is endemic in regions of sub-Saharan Africa, covering about 36 countries and 60 million people. An estimated 50,000 – 70,000 people are infected and about 40,000 die every year; the three most recent epidemics occurred in 1896 -1906, 1920, 1970. Studies of the tsetse fly show that females mate only once. Studies found this process to be effective in preventing the scourge; the screw-worm fly was eradicated from the United States, Central America, Puerto Rico and Libya. The Mexican fruit fly was eradicated from most of northern Mexico; the tsetse fly was eradicated from Zanzibar. The Mediterranean fruit fly was eradicated from the northern part of Chile and southern parts of Argentina and Mexico, it is being suppressed by SIT in fruit-producing areas of Croatia, South Africa and Spain. The codling moth is being suppressed in parts of British Columbia, The pink bollworm eradicated from southwestern USA and northwestern Mexico.
The false codling moth (Thaumatotibia