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.
Azadirachtin, a chemical compound belonging to the limonoid group, is a secondary metabolite present in neem seeds. It is a highly oxidized tetranortriterpenoid which boasts a plethora of oxygen-bearing functional groups, including an enol ether, acetal, hemiacetal, tetra-substituted epoxide and a variety of carboxylic esters.
Juvenile hormones (JHs) are a group of acyclic sesquiterpenoids that regulate many aspects of insect physiology. The first discovery of a JH was by Vincent Wigglesworth. JHs regulate development, reproduction, diapause, and polyphenisms. The chemical formula for juvenile hormone is .
Cytochromes P450 are a superfamily of enzymes containing heme as a cofactor that mostly, but not exclusively, function as monooxygenases. In mammals, these proteins oxidize steroids, fatty acids, and xenobiotics, and are important for the clearance of various compounds, as well as for hormone synthesis and breakdown. In 1963, Estabrook, Cooper, and Rosenthal described the role of CYP as a catalyst in steroid hormone synthesis and drug metabolism. In plants, these proteins are important for the biosynthesis of defensive compounds, fatty acids, and hormones.
20-Hydroxyecdysone is a naturally occurring ecdysteroid hormone which controls the ecdysis (moulting) and metamorphosis of arthropods. It is therefore one of the most common moulting hormones in insects, crabs, etc. It is also a phytoecdysteroid produced by various plants, including Cyanotis vaga, Ajuga turkestanica and Rhaponticum carthamoides where its purpose is presumably to disrupt the development and reproduction of insect pests. In arthropods, 20-hydroxyecdysone acts through the ecdysone receptor. Although mammals lack this receptor, 20-hydroxyecdysone affects mammalian biological systems. 20-Hydroxyecdysone is an ingredient of some supplements that aim to enhance physical performance. In humans, it is hypothesized to bind to the estrogen receptor beta (ERβ) protein-coding gene.
Rhaponticum carthamoides, synonym Leuzea carthamoides, is a species of herbaceous perennial plant in the family Asteraceae. It is known as maral root or rhaponticum. It inhabits the sub-alpine zone as well as alpine meadows. It can be found growing wild in Southern Siberia, Kazakhstan, the Altay region, and Western Sayan Mountains. Maral root is widely cultivated throughout Russia and Eastern Europe. This plant derives its traditional name maral root (maralu) from the maral deer that fed on it.
Phytotoxins are substances that are poisonous or toxic to the growth of plants. Phytotoxic substances may result from human activity, as with herbicides, or they may be produced by plants, by microorganisms, or by naturally occurring chemical reactions.
Cholesterol 7 alpha-hydroxylase also known as cholesterol 7-alpha-monooxygenase or cytochrome P450 7A1 (CYP7A1) is an enzyme that in humans is encoded by the CYP7A1 gene which has an important role in cholesterol metabolism. It is a cytochrome P450 enzyme, which belongs to the oxidoreductase class, and converts cholesterol to 7-alpha-hydroxycholesterol, the first and rate limiting step in bile acid synthesis.
Ecdysteroids are arthropod steroid hormones that are mainly responsible for molting, development and, to a lesser extent, reproduction; examples of ecdysteroids include ecdysone, ecdysterone, turkesterone and 2-deoxyecdysone. These compounds are synthesized in arthropods from dietary cholesterol upon metabolism by the Halloween family of cytochrome P450s. Phytoecdysteroids also appear in many plants mostly as a protection agents against herbivore insects.
Phytoecdysteroids are plant-derived ecdysteroids. Phytoecdysteroids are a class of chemicals that plants synthesize for defense against phytophagous insects. These compounds are mimics of hormones used by arthropods in the molting process known as ecdysis. When insects eat the plants with these chemicals they may prematurely molt, lose weight, or suffer other metabolic damage and die.
Ecdysone 20-monooxygenase (EC 1.14.99.22) is an enzyme that catalyzes the chemical reaction
Chemosensory proteins (CSPs) are small soluble proteins which mediate olfactory recognition at the periphery of sensory receptors in insects, similarly to odorant-binding proteins. The typical structure of CSPs is made of six or seven α-helical chains of about 110-120 amino acids, including four cysteines that build two small loops, two adjacent disulfide bridges, and a globular "prism-like" functional structure [5]. Three CSP structures have been solved in moths and locusts [5-8].
The enzyme juvenile hormone esterase (EC 3.1.1.59, systematic name methyl-(2E,6E,10R)-10,11-epoxy-3,7,11-trimethyltrideca-2,6-dienoate acylhydrolase, JH esterase) catalyzes the hydrolysis of juvenile hormone:
The ecdysone receptor is a nuclear receptor found in arthropods, where it controls development and contributes to other processes such as reproduction. The receptor is a non-covalent heterodimer of two proteins, the EcR protein and ultraspiracle protein (USP). It binds to and is activated by ecdysteroids. Insect ecdysone receptors are currently better characterized than those from other arthropods, and mimics of ecdysteroids are used commercially as caterpillar-selective insecticides.
The halloween genes are a set of genes identified in Drosophila melanogaster that influence embryonic development. All of the genes code for cytochrome P450 enzymes in the ecdysteroidogenic pathway (biosynthesis of ecdysone from cholesterol). Ecdysteroids such as 20-hydroxyecdysone and ecdysone influence many of the morphological, physiological, biochemical changes that occur during molting in insects.
The prothoracic glands are either of a pair of endocrine glands located in the prothorax of certain insects that regulate molting. They have an ectodermal origin and secrete ecdysteroids, such as ecdysone and 20-hydroxyecdysone. The chemical formula of ecodysin hormone is. They usually disappear in adults.
An insect growth regulator (IGR) is a substance (chemical) that inhibits the life cycle of an insect. IGRs are typically used as insecticides to control populations of harmful insect pests such as cockroaches and fleas.
Tebufenozide is an insecticide that acts as a molting hormone. It is an agonist of the ecdysone receptor that causes premature molting in larvae. It is primarily used against caterpillar pests.
Dibenzoylhydrazine (DBH) is a synthetic chemical compound with the chemical formulation C14H12N2O2. It is sometimes known as a benzoic acid amine, and is related to benzoyl peroxide, tricarban, isocarboxazid, and hydrazine. The substance was patented as an "ecdysone receptor ligand-binding domain structure" on 9 December 2004 by Michael C. Lawrence and nine others at the Australian CSIRO, and since 1991 it had been known to be effective in compound form against insect pests of the orders Lepidoptera, Coleoptera, and Hemiptera.
Cytochrome P450, family 305, also known as CYP305, is an animal cytochrome P450 family found in insect genome. The first gene identified in this family is the CYP305A1 from the Drosophila melanogaster.
