Chemosterilant

Last updated

A chemosterilant is a chemical compound that causes reproductive sterility in an organism. Chemosterilants are particularly useful in controlling the population of species that are known to cause disease, such as insects, or species that are, in general, economically damaging. The sterility induced by chemosterilants can have temporary or permanent effects. Chemosterilants can be used to target one or both sexes, and it prevents the organism from advancing to be sexually functional. [1] They may be used to control pest populations by sterilizing males. [2] The need for chemosterilants is a direct consequence of the limitations of insecticides. Insecticides are most effective in regions in which there is high vector density in conjunction with endemic transmission, and this may not always be the case. [3] Additionally, the insects themselves will develop a resistance to the insecticide either on the target protein level or through avoidance of the insecticide in what is called a behavioral resistance. [3] If an insect that has been treated with a chemosterilant mates with a fertile insect, no offspring will be produced. [1] The intention is to keep the percent of sterile insects within a population constant, such that with each generation, there will be fewer offspring. [1]

Contents

Early research and concerns

Structure of pyriproxyfen Pyriproxyfen.svg
Structure of pyriproxyfen

Research on chemosterilants began in the 1960s–1970s, but the effort was abandoned due to concerns regarding toxicity. However, with great advancements made in genetics and analysis of vectors, the search for safer chemosterilants has resumed in the 21st century. Initially, there were many concerns with using chemosterilants on an operational scale due to difficulties in finding the ideal small molecule. The molecule used as a chemosterilant must satisfy a certain criteria. Firstly, the molecule must be available at a low cost. The molecule must result in permanent sterility upon exposure through topical application or immersion of larvae into water. Additionally, the survivability of the sterile males must not be affected, and the chemosterilant should not be toxic to humans or the environment. The two promising agents in the beginning were aziridines thiotepa and bisazir, but they were unable to satisfy the criteria of minimal toxicity to humans as well as the vector's predators. Pyriproxyfen was another compound of interest since it is not toxic to humans, but it would not be possible to induce sterility in larvae due to the fact that it exists as a larvicide. Exposure of larvae to pyriproxyfen will essentially kill the larvae. [3]

Examples of chemosterilants

Use of chemosterilants for non-surgical castration (dogs and cats)

There are many regions in which there is a population of cats and dogs that freely roam on the streets. The most conventional approach to controlling reproductive rates in companion animals is through surgical means. However, surgical intervention poses ethical concerns. Through the formulation of a non-surgical castration technique, animals would not have to undergo anesthesia, and would not have to experience post-surgical bleeding or infection of the area that has been operated on. Some examples of chemosterilants include CaCl2 and zinc gluconate. These are specifically known as necrosis-inducing agents, which result in the degeneration of cells in the testes, resulting in infertility. These kinds of chemicals are generally injected into male reproductive organs, such as the testes, vas deferens, or epididymis. When injected, they induce azoospermia, which is the degeneration of the sperm cells normally found in the semen. If no sperm cells are present, reproduction can no longer occur. There is, however, one complication that results from the use of necrosis-inducing agents. Many animals generally exhibit an inflammatory response directly after the injection. To avoid the pain and discomfort associated with necrosis-inducing agents, another form of sterilization, known as apoptosis-inducing agents, has been studied. If cells are signaled to perform apoptosis rather than being eliminated by a foreign substance, this will result in no inflammation in the area. Experiments were tested using mice in vitro and ex vivo that have proved this. Using an apoptosis-inducing agent known as doxorubicin encapsulated in a nanoemulsion, and injecting it into mice, testicular cell death was observed. Inflammation was not observed in this case; however, more research still needs to be conducted with these materials, as the long-term impacts are unknown. [4]

Structure of Zinc Gluconate Zinc gluconate.png
Structure of Zinc Gluconate

Effect of chemosterilants on the behavior of wandering male dogs in Puerto Natales, Chile

Chemosterilants can be useful to developing countries due to the fact that they have less resources and funds that can be allocated towards castration of their free-roaming animals. Additionally, the culture opposes the removal of testes.[ citation needed ] This study, performed in 2015, was unable to conclude the effects of chemical sterilization on dog aggression, as not enough is known about the aggression displayed by free-roaming dogs, and thus, researchers were unable to objectively make a decision on this front. Using GPS technology to track the movement of the free-roaming male dogs, it was found that chemical sterilization in comparison to surgical sterilization did not have a significant impact on the range of their roaming around the city. Much more detailed studies need to be performed in this area, since this study was the first of its kind and had relatively short sample sizes along with the examination of behavior not spanning a long enough time period. [5]

Use of CaCl2 and zinc gluconate in cattle

The method of administration of CaCl2 and zinc gluconate is through a transvaginal injection of the chemical into the ovaries, and visualization is achieved through the use of an ultrasound. One group of cattle was only treated with CaCl2, one group was only treated with zinc gluconate, and one group was treated with both CaCl2 and zinc gluconate. Treatment with CaCl2 seems to be most promising, as the ovarian mass of the female cattle upon slaughter was less than cattle treated with zinc gluconate or the combination. The goal of treatment with CaCl2 is to cause ovarian atrophy with a minimal amount of pain. [6]

Ornitrol in controlling the sparrow population

Another chemosterilant found to be effective is known as ornitrol. This chemosterilant was provided to sparrows by impregnating canary seeds, and this was used as a food source for a group of sparrows. There was a control group that was fed canary seeds without the ornitrol, and these birds laid almost twice as many eggs as group that was given ornitrol. It was deemed an effective chemosterilant in the study; however, after the removal of the chemosterilant from the diet, the birds were able to lay viable eggs as soon as 1–2 weeks later. [7]

Commonly used chemosterilants

Two types of chemosterilants are commonly used:

See also

Related Research Articles

<span class="mw-page-title-main">Necrosis</span> Unprogrammed cell death caused by external cell injury

Necrosis is a form of cell injury which results in the premature death of cells in living tissue by autolysis. The term "necrosis" came about in the mid-19th century and is commonly attributed to German pathologist Rudolf Virchow in, who is often regarded as one of the founders of modern pathology. Necrosis is caused by factors external to the cell or tissue, such as infection, or trauma which result in the unregulated digestion of cell components. In contrast, apoptosis is a naturally occurring programmed and targeted cause of cellular death. While apoptosis often provides beneficial effects to the organism, necrosis is almost always detrimental and can be fatal.

<span class="mw-page-title-main">Insecticide</span> Pesticide used against insects

Insecticides are pesticides used to kill insects. They include ovicides and larvicides used against insect eggs and larvae, respectively. Insecticides are used in agriculture, medicine, industry and by consumers. Insecticides are claimed to be a major factor behind the increase in the 20th-century's agricultural productivity. Nearly all insecticides have the potential to significantly alter ecosystems; many are toxic to humans and/or animals; some become concentrated as they spread along the food chain.

<span class="mw-page-title-main">Cypermethrin</span> Chemical compound

Cypermethrin (CP) is a synthetic pyrethroid used as an insecticide in large-scale commercial agricultural applications as well as in consumer products for domestic purposes. It behaves as a fast-acting neurotoxin in insects. It is easily degraded on soil and plants but can be effective for weeks when applied to indoor inert surfaces. Exposure to sunlight, water and oxygen will accelerate its decomposition. Cypermethrin is highly toxic to fish, bees and aquatic insects, according to the National Pesticides Telecommunications Network (NPTN). It is found in many household ant and cockroach killers, including Raid, Ortho, Combat, ant chalk, and some products of Baygon in Southeast Asia.

<span class="mw-page-title-main">Calcium chloride</span> Chemical compound

Calcium chloride is an inorganic compound, a salt with the chemical formula CaCl2. It is a white crystalline solid at room temperature, and it is highly soluble in water. It can be created by neutralising hydrochloric acid with calcium hydroxide.

In the field of genetics, a suicide gene is a gene that will cause a cell to kill itself through the process of apoptosis. Activation of a suicide gene can cause death through a variety of pathways, but one important cellular "switch" to induce apoptosis is the p53 protein. Stimulation or introduction of suicide genes is a potential way of treating cancer or other proliferative diseases.

<span class="mw-page-title-main">Permethrin</span> Medication and insecticide

Permethrin is a medication and an insecticide. As a medication, it is used to treat scabies and lice. It is applied to the skin as a cream or lotion. As an insecticide, it can be sprayed onto outer clothing or mosquito nets to kill the insects that touch them.

<span class="mw-page-title-main">Sterile insect technique</span> Method of biological control for insect populations

The sterile insect technique (SIT) 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 fertile 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, therefore, 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.

<span class="mw-page-title-main">Chlorhexidine</span> Disinfectant and antiseptic

Chlorhexidine is a disinfectant and antiseptic with the molecular formula C22H30Cl2N10, which is used for skin disinfection before surgery and to sterilize surgical instruments. It is also used for cleaning wounds, preventing dental plaque, treating yeast infections of the mouth, and to keep urinary catheters from blocking. It is used as a liquid or a powder. It is commonly used in salt form, either the gluconate or the acetate.

<span class="mw-page-title-main">Gluconic acid</span> Chemical compound

Gluconic acid is an organic compound with molecular formula C6H12O7 and condensed structural formula HOCH2(CHOH)4CO2H. A white solid, it is forms the gluconate anion in neutral aqueous solution. The salts of gluconic acid are known as "gluconates". Gluconic acid, gluconate salts, and gluconate esters occur widely in nature because such species arise from the oxidation of glucose. Some drugs are injected in the form of gluconates.

Sterilization may refer to:

<span class="mw-page-title-main">Asepsis</span> Absence of disease-causing microorganisms

Asepsis is the state of being free from disease-causing micro-organisms. There are two categories of asepsis: medical and surgical. The modern day notion of asepsis is derived from the older antiseptic techniques, a shift initiated by different individuals in the 19th century who introduced practices such as the sterilizing of surgical tools and the wearing of surgical gloves during operations. The goal of asepsis is to eliminate infection, not to achieve sterility. Ideally, a surgical field is sterile, meaning it is free of all biological contaminants, not just those that can cause disease, putrefaction, or fermentation. Even in an aseptic state, a condition of sterile inflammation may develop. The term often refers to those practices used to promote or induce asepsis in an operative field of surgery or medicine to prevent infection.

<span class="mw-page-title-main">Zinc gluconate</span> Chemical compound

Zinc gluconate is the zinc salt of gluconic acid. It is an ionic compound consisting of two anions of gluconate for each zinc(II) cation. Zinc gluconate is a popular form for the delivery of zinc as a dietary supplement providing 14.35% elemental zinc by weight.

<i>Delia</i> (fly) Genus of flies

Delia flies are members of the Anthomyiidae family within the superfamily Muscoidae. The identification of different species of Delia can be very difficult for non-specialists as the diagnostic characteristics used for immature and/or female specimens may be inconsistent between species. Past taxonomic keys were not as comprehensive in their identification of Delia specimens; they were either too reliant on genetic characteristics, focused solely on a specific life stage, or were focused only on certain species. However current taxonomic keys aim to be more thorough by not only including morphological diagnostics for males, females, and immature specimens of various species, but also their genetic make-up or molecular barcode.

<span class="mw-page-title-main">PAC-1</span>

PAC-1 is a synthesized chemical compound that selectively induces apoptosis, in cancerous cells. It was granted orphan drug status by the FDA in 2016.

<i>Chrysomya bezziana</i> Species of fly

Chrysomya bezziana, also known as the Old World screwworm fly or screwworm, is an obligate parasite of mammals. Obligate parasitic flies require a host to complete their development. Named to honor the Italian entomologist Mario Bezzi, this fly is widely distributed in Asia, tropical Africa, India, and Papua New Guinea. The adult can be identified as metallic green or blue with a yellow face and the larvae are smooth, lacking any obvious body processes except on the last segment.

<i>Chloridea virescens</i> Species of moth

Chloridea virescens, commonly known as the tobacco budworm, is a moth of the family Noctuidae found throughout the eastern and southwestern United States along with parts of Central America and South America.

Inherited sterility in insects is induced by substerilizing doses of ionizing radiation. When partially sterile males mate with wild females, the radiation-induced deleterious effects are inherited by the F1 generation. As a result, egg hatch is reduced and the resulting offspring are both highly sterile and predominately male. Compared with the high radiation required to achieve full sterility in Lepidoptera, the lower dose of radiation used to induce F1 sterility increases the quality and competitiveness of the released insects as measured by improved dispersal after release, increased mating ability, and superior sperm competition.

Zeuterin (zū-tur-in) is the trade name of an injectable product containing zinc gluconate and the amino acid arginine, which is used for sterilizing young male dogs without the removal of the testicles. The product is injected directly into the testicle, where the zinc gluconate destroys the sperm and causes inflammation, which leads to fibrosis and causes sterility. Sperm production continues for up to 60 days after product administration, and in some dogs does not stop completely, although the product is 99.6% effective when given to dogs aged 3-10 months of age. Following administration, the testicles atrophy; the degree of atrophy may vary noticeably between testicles. The male hormone, testosterone, is produced in limited quantities following treatment with Zeuterin, but after two years, testosterone production is similar to that in untreated dogs. The continuing presence of testosterone means that, unlike surgical castration, chemical castration does not remove the risk of testosterone-associated disease, such as prostatic disease.

<span class="mw-page-title-main">Cry6Aa</span>

Cry6Aa is a toxic crystal protein generated by the bacterial family Bacillus thuringiensis during sporulation. This protein is a member of the alpha pore forming toxins family, which gives it insecticidal qualities advantageous in agricultural pest control. Each Cry protein has some level of target specificity; Cry6Aa has specific toxic action against coleopteran insects and nematodes. The corresponding B. thuringiensis gene, cry6aa, is located on bacterial plasmids. Along with several other Cry protein genes, cry6aa can be genetically recombined in Bt corn and Bt cotton so the plants produce specific toxins. Insects are developing resistance to the most commonly inserted proteins like Cry1Ac. Since Cry6Aa proteins function differently than other Cry proteins, they are combined with other proteins to decrease the development of pest resistance. Recent studies suggest this protein functions better in combination with other virulence factors such as other Cry proteins and metalloproteinases.>

Non-surgical fertility control is the prevention of reproduction without the use of surgery. The most common form of sterilization in dogs and cats is surgical, spaying in females and castration in males. Non-surgical fertility control can either result in sterilization or temporary contraception and could offer a cheaper way to keep wild dog and cat populations under control. As of 2019, only contraceptives are commercially available. Research is ongoing into methods that could result in permanent suppression of fertility.

References

  1. 1 2 3 "chemosterilant | pesticide | Britannica". www.britannica.com. Retrieved 2022-04-22.
  2. Hayes, Wayland J. Jr; Laws, Edward R. (1991). Handbook of pesticide toxicology. Elsevier. ISBN   978-1-4832-8863-5. OCLC   899003092.
  3. 1 2 3 Baxter, Richard H. G. (2016-10-26). "Chemosterilants for Control of Insects and Insect Vectors of Disease". CHIMIA. 70 (10): 715–720. doi:10.2533/chimia.2016.715. ISSN   2673-2424. PMC   5108522 . PMID   27779930.
  4. Pagseesing, S.; Yostawonkul, J.; Surassmo, S.; Boonrungsiman, S.; Namdee, K.; Khongkow, M.; Boonthum, C.; Iempridee, T.; Ruktanonchai, U. R.; Saengkrit, N.; Chatdarong, K.; Ponglowhapan, S.; Yata, T. (28 April 2021). "Formulation, physical, in vitro and ex vivo evaluation of nanomedicine-based chemosterilant for non-surgical castration of male animals". Theriogenology. 108: 167–175. doi:10.1016/j.theriogenology.2017.12.014. PMID   29223654 via ScienceDirect.
  5. Garde, E.; Pérez, G.E.; Vanderstichel, R; Dalla Villa, P.F.; Serpell, J.A. (2016). "Effects of surgical and chemical sterilization on the behavior of free-roaming male dogs in Puerto Natales, Chile". Preventive Veterinary Medicine. 123: 106–120. doi:10.1016/j.prevetmed.2015.11.011. ISSN   0167-5877. PMID   26657528.
  6. Cavalieri, J; Hayes, L (2017). "Examination of the use of intraovarian administration of CaCl 2 and zinc gluconate as potential chemosterilants in Bos indicus heifers". Australian Veterinary Journal. 95 (11): 403–415. doi:10.1111/avj.12644. PMID   29076219. S2CID   20622517.
  7. Mitchell, Carl J.; Hayes, Richard O.; Hughes, T. B. (28 April 2021). "Effects of the Chemosterilant Ornitrol on House Sparrow Reproduction". The American Midland Naturalist. 101 (2): 443–446. doi:10.2307/2424610. JSTOR   2424610 via JSTOR.
  8. Carson, Rachel (2002) [1st. Pub. Houghton Mifflin, 1962]. Silent Spring. Mariner Books. ISBN   0-618-24906-0