Insecticides plant-based

Plant-based insecticides, which break down quickly and don t stay in the environment, are available for organic... 

George, J., Bais, H.P. and Ravishankar, GA. (2000) Biotechnological production of plant-based insecticides. Crit. Rev. BiotechnoL, 20,49 77. 

Rose, R. I. 2006. Tier-based testing for effects of proteinaceous insecticidal plant-incorporated protectants on non-target arthropods in the context of regularoty risk assessments. GMOs in Integrated Plant Production OBC/wprs Bull. 29 143-150. 

By the broadest definition, natural products can be plant based or microbe based or of animal origin. Even mineral-based materials are naturally occurring, for example, insecticides such as arsenates, arsenites, selenium, thallium, lead, and copper, and fluorides such as cryolite and sodium fluoride. Many of them are not especially safe or biodegradable. Green chemistry indicates that a chemical is natural, but it also implies that it is safe for humans and pets, nontoxic in the environment, and rapidly and fully biodegradable. 

Hill, N. et al. Plant based insect repellent and insecticide treated bed nets to protect against malaria in areas of early evening biting vectors double blind randomised placebo controlled clinical trial in the Bolivian Amazon. BMJ. 335 (7628) 1023 (2007). Randomised, double-bhnd control trial of p-menthane diol repellent against malaria in Bolivia. BMJ, 55, 2007. 

Bar-Zeev and Ben-Tamar used cloth treated with insect repellent to test for anti-ovipositional activity against mosquitoes in a laboratory however, their objective was to assess anti-ovipositional activity of the chemicals against mosquitoes as a simple technique for repellent bioassay. Kuthiala et al. used electrophysiological assay methods to show that the repellent deet combined with ethyl propionate reduced oviposition response against Aedes aegypti. Bentley and Day reviewed mosquito oviposition ecology and discussed the repellency of certain insecticides and other natural products that deterred oviposition. Table 21.1 and Table 21.2 list other smdies and reports on oviposition repellents, anti-oviposition compounds, or oviposition deterrents. The materials included extracts and oils from natural plant-based and synthetic chemicals. 

The utilization of natural insecticides and synthetic insecticides based upon natural insecticides has been an interest of research for more than 50 years. In that period a wide variety of phytochemicals acutely toxic to insects have been identified. This discussion will be limited to three of these plant based insecticides. A review of the literature for the identified natural insecticides, antifeedants and growth regulators found in plants, except for the pyrethroids and insect hormones, has recently appeared (Addor, 1995). 

These chemorational techniques have generated great interest in, and high expectations for, the acceleration of development of innovative pesticides. However, many purportedly successful appHcations of QSAR procedures have reHed on the quaHtative insights traditionally associated with art-based pesticide development programs. Retrospective QSAR analyses have, however, been helpful in identifying the best compounds for specific uses (17). Chemorational techniques have also found some appHcations in the development of pesticides from natural product lead compounds, the best known examples being the synthetic pyrethroid insecticides (19) modeled on the plant natural product, pyrethmm. 

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. ... 

Oxime carbamates are generally applied either directly to the tilled soil or sprayed on crops. One of the advantages of oxime carbamates is their short persistence on plants. They are readily degraded into their metabolites shortly after application. However, some of these metabolites have insecticidal properties even more potent than those of the parent compound. For example, the oxidative product of aldicarb is aldicarb sulfoxide, which is observed to be 10-20 times more active as a cholinesterase inhibitor than aldicarb. Other oxime carbamates (e.g., methomyl) have degradates which show no insecticidal activity, have low to negligible ecotoxicity and mammalian toxicity relative to the parent, and are normally nondetectable in crops. Therefore, the residue definition may include the parent oxime carbamate (e.g., methomyl) or parent and metabolites (e.g., aldicarb and its sulfoxide and sulfone metabolites). The tolerance or maximum residue limit (MRL) of pesticides on any food commodity is based on the highest residue concentration detected on mature crops at harvest or the LOQ of the method submitted for enforcement purposes if no detectable residues are found. For example, the tolerances of methomyl in US food commodities range from 0.1 to 6 mg kg for food items and up to 40 mg kg for feed items. ... 

In the field of organic phosphorus compounds there is a wealth of highly toxic compounds from which to pick a potential insecticide. The ultimate choice will be based not only on toxicity to a certain group of insect species, but on volatility, stability, safety in handling and applying, and freedom from plant injury, spray-residue and translocation hazards, and long-term toxicity to man and animals. 

What to do Remove overwintering brassica plants as soon as they have finished cropping. This should be done by mid-spring. Bury plant debris deep in a compost pile, or in a compost trench. Examine young plants regularly from early summer to fall and squash any colonies of eggs or young. Pesticides Insecticidal soap pyrethrum plant oils and starch-based sprays. 

What to do Check plants regularly, especially the stems and the undersides of the leaves, for the presence of scale. Where an Infestation Is light, individual scales can be removed easily with a fingernail or a cotton swab. Pesticides Insecticidal soap plant-oil-based products. 

The discovery of prontosil was fortuitous and was not based on rationale design. There are a large number of pesticides which fall in the same category as prontosil, i.e., they are active by virtue of their susceptibility to metabolic or chemical modification to active intermediates. The classical example of an insecticide of this type is parathion, a phosphorothionate ester which in animals or plants is oxidatively desulfurated to the potent anticholinesterase paraoxon O). The insecticidal activity of parathion was known for several years before the purified material was shown to be a poor anticholinesterase and that metabolic activation to paraoxon was necessary for intoxication. 

The downward systemic movement of ONCOL (structure given earlier), a new insecticide derived from carbofuran, has been observed (19). A significant amount of radioactivity was observed in the roots of cotton and bean plants treated topically at the base of bifoliate or trifoliated leaves with [carbamate carbonylONCOL. Downward movement of the radiolabeled material may be explained by hydrolytic degradation of the ethoxycarbonyl moiety in ONCOL to the carboxylic acid derivative, the acid function serving as a downward moving carrier. 

Insect steroid metabolism has two biochemically distinctive components dealkylation of phytosterols to cholesterol and polyhydroxylation of cholesterol to ecdysone. We will focus on the first of these. Lacking the ability to synthesize sterols de novo, insects instead have evolved a dealkylation pathway to convert plant sterols to cholesterol(7-10). The dealkylation pathways are apparently absent in most other higher and lower organisms, which can convert mevalonate to squalene and thence into sterols( ). Specific insecticides are possible based on these biochemical differences. 

Strict liability pools risks by product negligence pools risks by customers. In the case of chemicals, the inefficiencies created by product-specific rather than customer-based insurance vary from product to product. Whereas cancer risks from drinking chlorinated water probably do not vary among users even when care levels differ, cancer risks to infants whose parents spray insecticides on tomato plants probably differ greatly depending on whether the infants are upwind or downwind of the spraying. 

Various plant extracts are allowed under most organic guidelines, provided that they are not formulated in petroleum-based synergists or carriers. However, they are only rarely used, primarily as insecticides (Table 4.1). Compost extracts are used more frequently, and are commercially formulated these days (Litterick ef al. 2004). They can be very effective in disease control, depending on the starting material, the composting and fermentation procedures, and the final microbial activity. 

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