Nomenclature & classification of
insecticides
What is nomenclature?
• The word nomenclature is derived from the Latin word Nomen meaning name and Calare meaning to call
• A name is a label for any noun.
• Thus Names can identify a class or category of things, or a single thing, either individually, or within a given context.
• The word "name" is possibly derived from the Proto-Indo-European language hypothesized word nomn.
• Common names and proper names
• The distinction between proper names and common names is that proper names denote a unique entity e.g.
London Bridge, while common names are used in a more general sense in reference to a class of objects e.g.
bridge.
• Similarly in science, proper names and common names are also assigned to all the objects whether living or none living.
What is Scientific nomenclature?
• In biological science, at least, nomenclature is regarded as a part of taxonomy i.e.
Linnaeus’ system of binomial nomenclature.
• In Chemistry, the IUPAC (
International Union of Pure and Applied Chemistry)
nomenclature is a system of naming chemical compounds and for describing the science of chemistry in general.
• The rules for naming organic and inorganic compounds are printed in two publications: the Blue Book and the Red Book.
• A third publication, Green Book, is also there which contains recommendations for the use of symbols for physical quantities (in association with the IUPAP, (International Union of Pure and Applied physics),
• While a fourth, the Golden Book, defines a large number of technical terms used in chemistry.
• The nomenclature of pesticides is similar to naming a drug.
• In case of drug there are three names:
• (1) A brand or trade or product name: e.g. Motrin
• (2) A generic name (common name or active ingredient): Ibuprofen
• (3) A chemical family: e.g. NSAID (nonsteroidal anti-inflammatory drug.
• Likewise in case of pesticide, three names are also associated with every product i.e.
• (1) A brand or trade or Product Name:
Mortein
• (2) Generic name or Common Name:
Allethrin
• (3) Chemical Name e.g. Pyrethroid
• What is Chemical Name?
• Chemical Name is the systematic name of a chemical compound according to the rules of nomenclature of the IUPAC as adapted for indexing in Chemical Abstracts
• For example: A chemical name of a compound triclopyr is 3,5,6-trichloro-2- pyridinyloxy acetic acid
• What is Generic name or Common Name?
• The common name is the name generally used for describing the characteristic of pesticide like its toxicology, environmental behavior and fate etc.
• It is actually a generic name for a chemical compound.
• For example: The common name for 3,5,6- trichloro-2-pyridinoxyacetic acid is triclopyr
• What is Brand/Trade or Product Name?
• The trade name of a pesticide is the name that appears on the container you purchase.
• It is also the name to which the EPA registration number is applied at the time of registration.
• For example this triclopyr alone is sold as:
Garlon 3A or Garlon 4
OR
• Trade name or Brand name or Product name:
Sevin®
• Generic name or Common name: carbaryl
• Chemical name: 1- naphthyl- N-methyl carbamate
• So Sevin is a Trade name of Carbaryl whose scientific name is 1- naphthyl- N- methyl carbamate
• What is a classification?
• A classification is an ordered set of related categories used to group data according to its similarities.
• It consists of codes and descriptors and allows survey responses to be put into meaningful categories in order to produce useful data.
• A classification is a useful tool for anyone developing statistical surveys.
• It is a framework which both simplifies the topic being studied and makes it easy to categorize all data or responses received.
• Purpose of classifications:
• Classifications have two main purposes:
• They help users understand how the category relates to other categories.
• They help users jump up to higher levels on the hierarchy and we can jump all the way from one category i.e. Organochlorines (insecticides that contain carbon (thus organo-), hydrogen, and chlorine) to other category i.e. Organophosphates (insecticides containing phosphorus) with one click.
• Without the classification it would take difficult.
• What is Pesticides?
• Any substance or mixture of substances intended for preventing, destroying, repelling, or mitigating any pest.
• Insecticide is a substance that kills insects by chemical action.
• Most insecticides are hazardous to human beings. The classification of insecticides is done in several different ways.
• Insecticides can be classified in four different ways:
• 1. Mode of Entry (i.e. stomach, systemic, contact or fumigant)
• 2. Mode of Action (i.e. protoplasmic, nerve poison, respiratory poison)
• 3. Chemical Nature (i.e. inorganic and organic).
• 4. Based on the target that they control (i.e.
Algicides, Avicides, Fungicides, Herbicides, Disinfectants)
• (1) Based on Mode of Entry:
• (i) Stomach poisons: Produce their effect by absorption from digestive tract.
• Such insecticides are effective against insects with chewing type of mouth parts. e.g. arsenic compounds which include Paris green (copper acetoarsenite), lead arsenate, calcium arsenate; fluorine compounds like sodium fluoride and cryolite.
• (ii) Systemic poisons: They are absorbed into the system of plants and bring about their effect on those insects which feed on them either by chewing or piercing. e.g.
Dimethoate, phosphamidon, aldicarb etc.
• (iii) Contact poisons: Kills the insect when they came into contact, enter through cuticle and respiratory centers.
e.g. DDT, BHC etc.
• (iv) Fumigants: Chemicals employed in gaseous forms for killing the insects.
Such insecticides are use in enclosed space. e.g. HCN, So2, Phosphine etc.
• (2) Based on Mode of Action:
• (i) Protoplasmic: which bring about their
effect on protoplasm of the cell e.g. Heavy metals like Hg etc
• (ii) Nerve poison: Affect the nervous system e.g. DDT and Nicotines etc
• (iii)Respiratory poison: Affect the respiratory system e.g. Arsenates, Flourides etc.
• (3) Based on Chemical Nature:
• Based on chemical nature, insecticides are of two types:
• Inorganic
• Organic.
• Inorganic pesticides are simpler compounds.
• They do not contain carbon in their molecular structure.
• They have a crystalline, salt-like appearance, are environmentally stable, and usually dissolve readily in water.
• The earliest chemical pesticides were inorganic, and included substance such as Arsenicals, Fluorides, Sulphure, Flurosilicates etc.
• Organic pesticides are based on chemicals having carbon as the basis of their molecular structure.
• The chemicals are more complex than those of inorganic pesticides, and usually do not dissolve easily in water.
• The vast majority of modern pesticides contain an organic chemical.
• There have been hundreds of pesticides developed based on organic chemicals, often with oxygen, phosphorus, or sulfur in their molecules, in addition to their basic carbon structure.
• Organic pesticides can be subdivided into two additional groups:
• the Natural Organics and the Synthetic Organics.
• Natural Organics:
• The natural organic pesticides (sometimes just called "organics“ or Botanicals) are derived from naturally occurring sources such as plants or products from petroleum and coal tar e.g. Nicotine sulphate, Pyrethrins, Rotenone etc.
• Synthetic organic pesticides (usually just called "synthetics") are produced artificially by chemical synthesis.
• This group comprises most "modern"
pesticides (i.e., discovered or used as insecticides post-World War II), and includes DDT, permethrin, malathion, 2, 4- D, glyphosphate, and many, many others.
• The Synthetic Organic Insecticides are further divided into:
• Organochlorine compounds (OC) such as Lindane, Chlordane DDT etc.
• Organophosphorous compounds (OP) like Chlorpyrifos, Chlorpyrifos-methyl, Diazinon, Dichlorvos, Pirimphos-methyl, Fenitrothion, Malathion etc.
• Carbamates(C) e.g. Carbaryl, Isolan, Carbofuran Bendiocarbamate.
• Pyrethrum is a natural insecticide obtained from the flower heads of chrysanthemum.
• Pyrethrins/Synthetic Pyrethroids(SP)
• Insect Growth Regulators (IGRs) e.g. Methoprene, Hydramethylnon, Pyriproxyfen, Flufenoxuron.
• Fumigants e.g. Methyl Bromide (CH3Br), Aluminium Phosphide, Magnesium Phosphide, Calcium Cyanide, Hydrogen Cyanide.
• (4) Based on the target or that they control
• Algicides - Chemicals used to manage algae in areas such as swimming pools.
• Avicides- Chemicals used to manage birds.
• Disinfectants- Chemicals used to destroy harmful microorganisms.
• Fungicides- Chemicals used to manage fungi.
• Herbicides- Chemicals used to manage unwanted plants or weeds.
• Insecticides- Chemicals used to manage insects and other related creatures, such as ticks, spiders, and centipedes.
• Microbial Insecticides- Naturally occurring insect-disease microorganisms that are lethal to a specific group of insects.
• Molluscicides- Chemicals used to control snails or slugs.
• Pheromones- Chemicals used to attract insects.
• Repellents- Chemicals used to repel insects or other pests.
• Rodenticides- Chemicals used to manage rats, mice, and other rodents.
• Problems and Benefits.
• An insecticide is a substance which is used to kill the disease carrying insects or those insects that damage crops and property, but at the same time the use of insecticides may create problems for example:
• (1) Most species of insects have become resistant or immune if exposed for a
longer period.
• (2) Inappropriate or excessive use of insecticides also destroys many beneficial insects, birds, and small mammals.
• (3) Some insecticides, e.g. DDT, tend to stay in soil and water and degrade very slowly and eventually accumulate in the body tissue of fish, wildanimals or human beings (Biomagnification).
• (4) In some case these compounds, e.g. DDT also tends to combine with other chemicals in the soil, producing new toxic compounds that are more harmful than DDT alone (Secondary compounds).
• Such problems can be prevented or minimized by using selective chemicals or synthetic sterilants or pheromones, or growth-regulating hormones etc.
• Sterilants are a substance that does not kill an insect but does prevent it from reproducing. Selective use of sterilants may in time succeed in removing harmful species, including insecticides-tolerant ones, without injuring beneficial species.
• Pheromone is a substance that resembles the sexual secretion of a particular species of insect. The substance is used to attract an insect of that species to a trap, where it can be destroyed with an insecticide. This method may replace the wholesale spraying and dusting that endanger other creatures.
• Growth-regulating Hormone is a substance that prevents juvenile insects from maturing into adults
