Imidacloprid
Encyclopedia
Imidacloprid is a nicotine
Nicotine
Nicotine is an alkaloid found in the nightshade family of plants that constitutes approximately 0.6–3.0% of the dry weight of tobacco, with biosynthesis taking place in the roots and accumulation occurring in the leaves...

-based, systemic insecticide
Insecticide
An insecticide is a pesticide used against insects. They include ovicides and larvicides used against the eggs and larvae of insects respectively. Insecticides are used in agriculture, medicine, industry and the household. The use of insecticides is believed to be one of the major factors behind...

, which acts as a neurotoxin
Neurotoxin
A neurotoxin is a toxin that acts specifically on nerve cells , usually by interacting with membrane proteins such as ion channels. Some sources are more general, and define the effect of neurotoxins as occurring at nerve tissue...

 and belongs to a class of chemicals called the neonicotinoids
Neonicotinoids
Neonicotinoids are a class of insecticides which act on the central nervous system of insects with lower toxicity to mammals. Neonicotinoids are among the most widely used insecticides worldwide, but recently the uses of some members of this class have been restricted in some countries due to a...

. Although it is now off patent, the primary manufacturer of this chemical is Bayer CropScience, (part of Bayer AG
Bayer
Bayer AG is a chemical and pharmaceutical company founded in Barmen , Germany in 1863. It is headquartered in Leverkusen, North Rhine-Westphalia, Germany and well known for its original brand of aspirin.-History:...

). It is sold under the trade name
Trade name
A trade name, also known as a trading name or a business name, is the name which a business trades under for commercial purposes, although its registered, legal name, used for contracts and other formal situations, may be another....

s Kohinor, Admire, Advantage (Advocate) (flea killer for pets), Gaucho, Mallet, Merit, Nuprid, Prothor, Turfthor, Confidor, Conguard, Dominion 2L, Hachikusan, Premise, Prothor, Provado, Intercept, and Winner. Imidacloprid is one of the most widely used insecticides and can be applied by soil injection, tree injection, application to the skin, or broadcast foliar or ground application as a granular or liquid formulation or as a pesticide-coated seed treatment
Seed treatment
In agriculture, a seed treatment or seed dressing is a chemical, typically antimicrobial or fungidal, with which seeds are treated prior to planting...

.

In France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

, beekeepers reported a significant loss of honeybees in the 1990s, which they attributed to the use of imidacloprid (Gaucho). See Imidacloprid effects on bee population
Imidacloprid effects on bee population
Imidacloprid is a systemic neonicotinoid insecticide produced by the German chemical firm Bayer CropScience and sold under such trade names as Gaucho, Admire, Merit, Advantage, Confidor, Provado, and Winner. It acts as a neurotoxin and interferes with the transmission of nerve impulses in insects...

. In response to this loss of bees called "mad bee disease," the French Minister of Agriculture convened a panel of expert scientists (Comite Scientifique et Technique) to examine the impact of imidacloprid on bees. After reviewing dozens of laboratory and field studies conducted by Bayer CropScience and by independent scientists, the panel concluded that there was a significant risk to bees from exposure to imidacloprid on sunflowers and maize (corn), the only crops for which they had exposure data. Following the release of this report, the French Agricultural Ministry suspended the use of imidacloprid on maize and sunflowers. Italy
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...

, Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

, and Slovenia
Slovenia
Slovenia , officially the Republic of Slovenia , is a country in Central and Southeastern Europe touching the Alps and bordering the Mediterranean. Slovenia borders Italy to the west, Croatia to the south and east, Hungary to the northeast, and Austria to the north, and also has a small portion of...

 have also suspended certain uses of the neonicotinoids based on concerns for bees.

History

On January 21, 1986 a patent was filed, and granted on May 3, 1988, for imidacloprid in the United States (U.S. Pat. No. 4,742,060) by Nihon Tokushu Noyaku Seizo K.K. of Tokyo, Japan.

On March 25, 1992, Miles, Inc. (later Bayer CropScience) applied for registration of imidacloprid for turfgrass and ornamentals in the United States. On March 10, 1994, the U.S. Environmental Protection Agency approved the registration of imidacloprid.

On January 26, 2005, the Federal Register notes the establishment of the '(Pesticide Tolerances for) Emergency Exemptions' for imidacloprid. It use was granted to Hawaii (for the) use (of) this pesticide on bananas and the States of Minnesota, Nebraska, and North Dakota to use (of) this pesticide on sunflower(s).

Biochemistry

Imidacloprid is a systemic
Systemic
Systemic refers to something that is spread throughout, system-wide, affecting a group or system such as a body, economy, market or society as a whole. Systemic may also refer to:-In medicine:...

 chloronicotinyl pesticide
Pesticide
Pesticides are substances or mixture of substances intended for preventing, destroying, repelling or mitigating any pest.A pesticide may be a chemical unicycle, biological agent , antimicrobial, disinfectant or device used against any pest...

, belonging to the class of neonicotinoid insecticides. It is very widely used on a wide array of plants including many major crops. In the landscape the largest use by far is on lawns or sports turfgrass as a treatment for Japanese beetle larvae. A much smaller use is on trees, but this is growing, because imidacloprid is one of the most effective products used to save Hemlocks from the Hemlock woolly adelgid
Hemlock Woolly Adelgid
Hemlock woolly adelgid , commonly abbreviated as HWA, is a true bug native to East Asia that feeds by sucking sap from hemlock trees . In eastern North America, it is a destructive pest that poses a major threat to the eastern hemlock and the Carolina hemlock...

 - a killer of the giant Hemlocks throughout Appalachia. Recently it was found to be highly effective against the Emerald ash borer and other boring insects of Oaks and Birch. It is also used as a de-wormer and a flea treatment for dogs and cats because of its very low toxicity to mammals.

A two-year feeding study in rats fed up to 1,800 ppm resulted in a No Observable Effect Level (NOEL) of 100 ppm (5.7 mg/kg body weight in males and 7.6 mg/kg in females). A one-year feeding study in dogs fed up to 2,500 ppm resulted in a NOEL of 1,250 ppm (41 mg/kg). If a dog were to ingest more than this concentration (which is very unlikely), adverse effects would include increased cholesterol levels in the blood and some stress to the liver (measured by elevated liver cytochrome p-450 levels) (6).

Imidacloprid acts as a neurotoxin
Neurotoxin
A neurotoxin is a toxin that acts specifically on nerve cells , usually by interacting with membrane proteins such as ion channels. Some sources are more general, and define the effect of neurotoxins as occurring at nerve tissue...

 and interferes with the transmission of nerve impulses in insects by binding to specific nicotinic acetylcholine receptors. Not all insects are affected, however. For example, Lepidoptera (butterflies and moths) are typically unaffected by imidacloprid. Spiders and spider mites are also unaffected. As a systemic pesticide, imidacloprid translocates or moves from the soil into the leaves, pollen, and nectar of a plant. Since imidacloprid is efficacious at very low levels (nanogram and picogram), it can be applied at low concentrations (e.g., 0.05–0.125 lb/acre or 55–140 g/ha) to be effective.

The main routes of dissipation of imidacloprid in the environment are aqueousphotolysis (half-life = 1–4 hours) and plant uptake. The major photo-metabolites include imidacloprid desnitro, imidacloprid olefine, imidacloprid urea, and five minor metabolites. The end product of photodegradation is chloronicotinic acid (CNA). Since imidacloprid has a low vapor pressure
Vapor pressure
Vapor pressure or equilibrium vapor pressure is the pressure of a vapor in thermodynamic equilibrium with its condensed phases in a closed system. All liquids have a tendency to evaporate, and some solids can sublimate into a gaseous form...

, it normally does not volatilize readily.

Imidacloprid is moderately soluble in water. When it is exposed to sunlight, it breaks down very rapidly (with a half-life of about 3 hours). Imidacloprid is very unstable in high pH water and breaks down rapidly. In acidic water, and in the absence of sunlight, it has a half-life of about 70–110 days, depending on other conditions. In soil under aerobic
Aerobic
Aerobic is a word that means "requiring air", where "air" usually means oxygen.Aerobic may also refer to:* Aerobic exercise, prolonged exercise of moderate intensity* Aerobics, a form of aerobic exercise...

 conditions, imidacloprid is relatively persistent – with a half-life that can be as long as 6 months. It has a low mobility in most soils and generally has an attraction to clay and loam soil particles. It binds very aggressively to organic matter, which can tie it up and make it unavailable to the plants that are being treated. Pure sand soils do not hold imidacloprid well.

Imidacloprid has a very low risk of water contamination. Despite widespread testing, imidacloprid is rarely found in surface water or well water. In all instances, the amounts found were from 0.5 ppb to 7 ppb. Such extremely low concentrations are evidence of the chemical's low mobility and rapid decomposition. In comparison, the EPA tolerance for imidacloprid in eggs is 0.3 ppm. On hops (used for making beer), the EPA allows 3 ppm.

Major soil metabolites include imidacloprid nitrosimine, imidacloprid desnitro, hydroxynicotinic acid, and imidacloprid urea
Urea
Urea or carbamide is an organic compound with the chemical formula CO2. The molecule has two —NH2 groups joined by a carbonyl functional group....

, which ultimately degrade to chloronicotinic acid, CO2, and bound residues. Long-term soil dissipation studies in apple orchards and with seed-treated barley crops showed little accumulation of imidacloprid residues in soil with repeated applications. Imidacloprid does not bio-accumulate.

Toxicology

Imidacloprid, like many insecticides is highly toxic to honeybees with a contact acute LD50 = 0.078 ug a.i./bee and an acute oral LD50 = 0.0039 ug a.i./bee. Several 10-day chronic oral studies published in peer-reviewed literature have demonstrated NOAEC values ranging from < 4 ppb to 10 ppb in honey bees and bumble bees. The olefine and hydroxy metabolites of imidacloprid, which are found in plants, are very toxic to honeybees. A large number of published studies have also shown that low levels of imidacloprid and its metabolites produce sublethal and behavioral effects in bees, including disorientation and effects on foraging, learning performance, motor coordination, and food consumption. Chronic or long-term toxicity to bees is still not well understood despite the large number of field studies that have been conducted. Effects of imidacloprid on brood and queen are also not known.

Imidacloprid is considered to be moderatly toxic to certain birds. In bobwhite quail (Colinus virginianus), imidacloprid was determined to be moderately toxic with an acute oral LD50 of 152 mg a.i./kg. This is a very large amount that would not likely be found with normal use. Birds seem to avoid treated plants and seeds. It was slightly toxic in a 5-day dietary study with an acute oral LC50 of 1,420 mg a.i./kg diet, a NOAEC of < 69 mg a.i./kg diet, and a LOAEC = 69 mg a.i./kg diet. Birds exposed in studies to these large quantities exhibited ataxia, wing drop, opisthotonos, immobility, hyperactivity, fluid-filled crops and intestines, and discolored livers. In a reproductive toxicity study with bobwhite quail, the NOAEC = 120 mg a.i./kg diet and the LOAEC = 240 mg a.i./kg diet. Eggshell thinning and decreased adult weight were observed at 240 mg a.i./kg diet.

Overall, imidacloprid poses little or no danger to fish and mammals. It requires large doses for adverse effects.

Overdosage

Persons who might orally ingest acute amounts would experience emesis, diaphoresis
Diaphoresis
Diaphoresis is excessive sweating commonly associated with shock and other medical emergency conditions.Diaphoretic is the state of perspiring profusely, or something that has the power to cause increased perspiration....

, drowsiness and disorientation. This would need to be intentional since a large amount would need to be ingested to experience a toxic reaction. In dogs the LD 50 is 450 mg/Kg of body weight. Blood imidacloprid concentrations may be measured to confirm diagnosis in hospitalized patients or to establish the cause of death in postmortem investigations.

Uses

The most widely used applications for imidacloprid in California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

 are pest control in structures, turf
Lawn
A lawn is an area of aesthetic and recreational land planted with grasses or other durable plants, which usually are maintained at a low and consistent height. Low ornamental meadows in natural landscaping styles are a contemporary option of a lawn...

 pest control, grape
Grape
A grape is a non-climacteric fruit, specifically a berry, that grows on the perennial and deciduous woody vines of the genus Vitis. Grapes can be eaten raw or they can be used for making jam, juice, jelly, vinegar, wine, grape seed extracts, raisins, molasses and grape seed oil. Grapes are also...

 growing, and head and leaf lettuce
Lettuce
Lettuce is a temperate annual or biennial plant of the daisy family Asteraceae. It is most often grown as a leaf vegetable. It is eaten either raw, notably in salads, sandwiches, hamburgers, tacos, and many other dishes, or cooked, as in Chinese cuisine in which the stem becomes just as important...

 growing. Other widespread crop uses are rice
Rice
Rice is the seed of the monocot plants Oryza sativa or Oryza glaberrima . As a cereal grain, it is the most important staple food for a large part of the world's human population, especially in East Asia, Southeast Asia, South Asia, the Middle East, and the West Indies...

, grains/cereal
Cereal
Cereals are grasses cultivated for the edible components of their grain , composed of the endosperm, germ, and bran...

s including corn (maize
Maize
Maize known in many English-speaking countries as corn or mielie/mealie, is a grain domesticated by indigenous peoples in Mesoamerica in prehistoric times. The leafy stalk produces ears which contain seeds called kernels. Though technically a grain, maize kernels are used in cooking as a vegetable...

), potato
Potato
The potato is a starchy, tuberous crop from the perennial Solanum tuberosum of the Solanaceae family . The word potato may refer to the plant itself as well as the edible tuber. In the region of the Andes, there are some other closely related cultivated potato species...

es, vegetable
Vegetable
The noun vegetable usually means an edible plant or part of a plant other than a sweet fruit or seed. This typically means the leaf, stem, or root of a plant....

s, sugar beet
Sugar beet
Sugar beet, a cultivated plant of Beta vulgaris, is a plant whose tuber contains a high concentration of sucrose. It is grown commercially for sugar production. Sugar beets and other B...

s, fruit
Fruit
In broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...

, cotton
Cotton
Cotton is a soft, fluffy staple fiber that grows in a boll, or protective capsule, around the seeds of cotton plants of the genus Gossypium. The fiber is almost pure cellulose. The botanical purpose of cotton fiber is to aid in seed dispersal....

, and hops. Target insects include sucking insects (e.g., aphid
Aphid
Aphids, also known as plant lice and in Britain and the Commonwealth as greenflies, blackflies or whiteflies, are small sap sucking insects, and members of the superfamily Aphidoidea. Aphids are among the most destructive insect pests on cultivated plants in temperate regions...

s, whiteflies
Whitefly
The whiteflies, comprising only the family Aleyrodidae, are small hemipterans. More than 1550 species have been described. Whiteflies typically feed on the underside of plant leaves.-Agricultural threat:...

, leafhopper
Leafhopper
Leafhopper is a common name applied to any species from the family Cicadellidae. Leafhoppers, colloquially known as hoppers, are minute plant-feeding insects in the superfamily Membracoidea in the order Hemiptera...

s and planthopper
Planthopper
A planthopper is any insect in the infraorder Fulgoromorpha within the Hemiptera. The name comes from their remarkable resemblance to leaves and other plants of their environment and from the fact that they often "hop" for quick transportation in a similar way to that of grasshoppers. However,...

s, thrips, scale
Scale insect
The scale insects are small insects of the order Hemiptera, generally classified as the superfamily Coccoidea. There are about 8,000 species of scale insects.-Ecology:...

s, mealybug
Mealybug
Mealybugs are insects in the family Pseudococcidae, unarmored scale insects found in moist, warm climates. They are considered pests as they feed on plant juices of greenhouse plants, house plants and subtropical trees and also acts as a vector for several plant diseases.-Distribution:Mealybugs...

s, bugs
Hemiptera
Hemiptera is an order of insects most often known as the true bugs , comprising around 50,000–80,000 species of cicadas, aphids, planthoppers, leafhoppers, shield bugs, and others...

, psyllids, and phylloxera
Phylloxera
Grape phylloxera ; originally described in France as Phylloxera vastatrix; equated to the previously described Daktulosphaira vitifoliae, Phylloxera vitifoliae; commonly just called phylloxera is a pest of commercial grapevines worldwide, originally native to eastern North America...

), beetle
Beetle
Coleoptera is an order of insects commonly called beetles. The word "coleoptera" is from the Greek , koleos, "sheath"; and , pteron, "wing", thus "sheathed wing". Coleoptera contains more species than any other order, constituting almost 25% of all known life-forms...

s (e.g., longhorn beetle
Longhorn beetle
The longhorn beetles are a cosmopolitan family of beetles, typically characterized by extremely long antennae, which are often as long as or longer than the beetle's body...

s, leaf beetle
Leaf beetle
Beetles in the family Chrysomelidae are commonly known as leaf beetles. This is a family of over 35,000 species in more than 2,500 genera, one of the largest and most commonly encountered of all beetle families....

s, Colorado potato beetle
Colorado potato beetle
The Colorado potato beetle , also known as the Colorado beetle, the ten-striped spearman, the ten-lined potato beetle or the potato bug, is an important pest of potato crops. It is approximately 10 mm long, with a bright yellow/orange body and five bold brown stripes along the length of each...

s, rice water-weevil
Weevil
A weevil is any beetle from the Curculionoidea superfamily. They are usually small, less than , and herbivorous. There are over 60,000 species in several families, mostly in the family Curculionidae...

s, wireworms, grub
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...

s, and flea beetle
Flea beetle
Flea beetles is a general name applied to the small, jumping beetles of the leaf beetle family . They make up the tribe Alticini, which is a part of the subfamily Galerucinae, though they were historically classified as a subfamily in their own right...

s), and others (e.g., leafminers, some diptera
Diptera
Diptera , or true flies, is the order of insects possessing only a single pair of wings on the mesothorax; the metathorax bears a pair of drumstick like structures called the halteres, the remnants of the hind wings. It is a large order, containing an estimated 240,000 species, although under half...

, termite
Termite
Termites are a group of eusocial insects that, until recently, were classified at the taxonomic rank of order Isoptera , but are now accepted as the epifamily Termitoidae, of the cockroach order Blattodea...

s, locust
Locust
Locusts are the swarming phase of short-horned grasshoppers of the family Acrididae. These are species that can breed rapidly under suitable conditions and subsequently become gregarious and migratory...

s, and flea
Flea
Flea is the common name for insects of the order Siphonaptera which are wingless insects with mouthparts adapted for piercing skin and sucking blood...

s).

As an insecticide spray, it is used on a wide variety of agricultural crops, ornamentals, and turf. It is also marketed for termite control, for flea control on pets, and for household cockroach control.

A systemic insecticide

Imidacloprid, which is a systemic pesticide, is readily taken up by plant root
Root
In vascular plants, the root is the organ of a plant that typically lies below the surface of the soil. This is not always the case, however, since a root can also be aerial or aerating . Furthermore, a stem normally occurring below ground is not exceptional either...

s and translocates up into the plant leaves, pollen, and nectar via the xylem
Xylem
Xylem is one of the two types of transport tissue in vascular plants. . The word xylem is derived from the Classical Greek word ξυλον , meaning "wood"; the best-known xylem tissue is wood, though it is found throughout the plant...

. Insects that eat the leaves or plant fluids may be killed, and pollinators that feed on the pollen and nectar may be exposed to imidacloprid. The products Confidor and Admire are intended for application via irrigation
Irrigation
Irrigation may be defined as the science of artificial application of water to the land or soil. It is used to assist in the growing of agricultural crops, maintenance of landscapes, and revegetation of disturbed soils in dry areas and during periods of inadequate rainfall...

, application to the soil
Soil
Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...

, or on foliage, while Gaucho
Gaucho
Gaucho is a term commonly used to describe residents of the South American pampas, chacos, or Patagonian grasslands, found principally in parts of Argentina, Uruguay, Southern Chile, and Southern Brazil...

 is intended for use as a seed
Seed
A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...

dressing, applied to the seed before sowing.

Imidacloprid is the active ingredient in Bayer's Advantage brand flea drops.

Sources


External links

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