Nicotinic insecticides

The use of plant extracts for insect control dates into antiquity the use of Paris green as an insecticide for control of the Colorado potato beetle in 1867 probably marks the beginning of the modern era of chemical control of injurious insects. The development of lead arsenate followed later in the nineteenth century for gypsy moth control. The commercial production of nicotine insecticides, the production of calcium arsenate at the time of the first world war, and the use of fluorine, arsenical, and cyanide compounds, as well as other inorganic chemicals for insect control, were important steps in pest control. These chemicals were applied largely by dilute high pressure sprays or dusts. 

Mayer and coworkers128 discovered that kojic acid is a moderately effective activator for nicotine insecticides. When tested against the melon worm (Diaphania hyalinata L.) and the southern armyworm (Prodenia eridania Cram.), kojic acid (alone) was not toxic but the toxicity of a 5% nicotine sulfate-pyrophyllite dust was increased 35 %, and that of a 5 % nicotine bentonite-bentonite spray by some 50%, by the addition of 5% of kojic... 

The skin absorption of nicotine and subsequent adverse effects make it an effective pesticide. Nicotine poisoning occurs primarily by children coming into contact with nicotine insecticides or tobacco products. 

Rogers, A. J., Denk, L. D. and Wax, P. M. 2004. Catastrophic brain injury after nicotine insecticide ingestion. Journal of Emergency Medicine, 26 169-172. 

The fatal dose of nicotine is approximately 40 mg, or 1 drop of the pure liquid. This is the amount of nicotine in two regular cigarettes. Fortunately, most of the nicotine in cigarettes is destroyed by burning or escapes via the "sidestream" smoke. Ingestion of nicotine insecticides or of tobacco by infants and children is usually followed by vomiting, limiting the amount of the alkaloid absorbed. 

Tofranil (a tranquilizer), parathion, endrin, and nicotine (insecticides), amo-barbital (a sedative) and disulfiram (used in the treatment of chronic alcoholism) have been detected (Alha et ai, 1960) in the stomach, stomach contents, and liver of cadavers by infrared spectroscopy of acetone extracts and by other confirmatory methods. 

Uses Intermediate, catalyst in preparation of esters, hardening agent in plastics, activator for nicotine insecticides catalyst for coatings Properties Lt. amber, cl. to si. hazy liq. dens. 1.2 g/cc vise. 9-12 cs 65% act. Elvanol 71-30 [DuPont/Pkg. Ind. Polymers DuPont Canada]... 

The major effect of smoking t. is inhaling the alkaloid nicotine ( insecticides). Its content varies around 3-5% N. rustica), the latter reaching as much as 12% in special breeds for pharmaceutical applications and as insecticide. Other sources of industrial nicotine are waste t. from the cigarette industry. 

Nicotine is used as a contact insecticide for aphids attacking fmits, vegetables, and ornamentals, and as a fumigant for greenhouse plants and poultry mites. Nicotine sulfate is safer and more convenient to handle and the free alkaloid is rapidly Hberated by the addition of soap, hydrated lime, or ammonium hydroxide to the spray solution. Nicotine sprays commonly contain 0.05—0.06% nicotine, and nicotine dusts, 1—2% nicotine. 

The best source of the alkaloids is commercial nicotine or the concentrated tobacco extracts, used as horticultural insecticides. The average alkaloidal content of tobacco leaf is about 4,- and does not as a rule exceed 6, per cent. In 1,026 parts of the total alkaloids of Kentucky tobacco, Pictet and Rotschy found nicoteine 20, nicotimine 5 and nicotelline 1, the rest being nicotine, but, as Markwood has pointed out. 

Tobacco and its alkaloids have long ceased to have any therapeutic importance, but their extensive use as insecticides and the demand for nicotine for the manufacture of nicotinic acid have stimulated interest in processes of extraction and methods of estimation. On the latter subject there is a voluminous literature, of which critical resumes have been published by various authors.Recent work on this subject has been specially concerned with (1) the development of miero- and semi-miero-methods suitable for estimating nieotine in tobacco smoke and the distribution of nieotine on sprayed garden produce, in treated soils and in tobaeeo leaves,(2) the study of conditions necessary to ensure satisfactory results in using particular processes, " and (3) methods of separation and estimation of nicotine, nomicotine and anabasine in mixtures of these bases. ) In the United States and in Russia considerable interest is being shown in the cultivation of types of tobacco rich in nicotine, in finding new industrial uses for tobacco and its alkaloids, and in possible by-products from tobacco plants such as citric and malic acids, i " Surveys of information on tobacco alkaloids have been published by Jackson, i Marion and Spath and Kuffner. ... 

Many pesticides are not as novel as they may seem. Some, such as the pyre-throid and neonicotinoid insecticides, are modeled on natural insecticides. Synthetic pyrethroids are related to the natural pyrethrins (see Chapter 12), whereas the neo-nicotinoids share structural features with nicotine. In both cases, the synthetic compounds have the same mode of action as the natural products they resemble. Also, the synthetic pyrethroids are subject to similar mechanisms of metabolic detoxication as natural pyrethrins (Chapter 12). More widely, many detoxication mechanisms are relatively nonspecific, operating against a wide range of compounds that... 

Nicotine Acts on nicotinic receptor Neonicotinoids An insecticide in its own... 

Nicotine is a component of Nicotiana tabacum, the tobacco plant. It is toxic to many insects because of its action upon the nicotinic receptor of acetyl choline. It has served as a model for a new range of insecticides, the neonicotinoids, which also act upon the nicotinic receptor (Salgado 1999). 

Beta nicotinic acid to 6-hydroxy nicotinic acid 3-substituted pyridine to a building block for imidacloprid (an insecticide) R-Cyanohydrins from benzaldehydes and HCN ... 

Neonicotinoids are potent broad-spectrum insecticides that exhibit contact, stomach and systemic activity. Acetamiprid, imidacloprid, nitenpyram, thiamethoxam and thiacloprid are representatives of the neonicotinoid insecticides (Figure 1). The mechanism of action is similar to that of nicotine, acting on the central nervous system causing irreversible blocking of postsynaptic nicotinic acetylcholine receptors (nAChR). Neonicotinoid insecticides are often categorized as antagonists of the... 

With the exception of nicotine, the agricultural chemicals derived from plants are probably among the least hazardous to man (6). Nicotine itself is one of the most efficient insecticides. Nicotine can cause serious poisoning or death if swallowed, inhaled, or absorbed through the skin. 

---