Insecticides of natural origin

The insecticidal effect of Ryana surpasses that of the other insecticides of natural origin, as well as of a major part of chlorinated hydrocarbon insecticides (Clark and Laudani, 1953). Ryanodin entering the insect organism in 2-5 ppm quantities substantially reduces oxygen uptake, which results in paralysis. 

Plants of the genus Piper, in particular P. nigrum, have been valued from antiquity to the present day for their organoleptic and medicinal properties. Indeed, black pepper, from the dried fruit of the latter species, remains the most widely consumed and important spice in the modern world [1,2] and is still used in traditional medicine [3]. In recent years, attention has also focused on the insecticidal properties of some Piper species [4]. Interest in insecticides of natural origin has been heightened by environmental and other problems associated with widespread use of broad spectrum synthetic pesticides. Two earlier reviews [4,5], of somewhat limited scope, focus specifically on a few unsaturated Piper amides in the context of their insecticidal potential. 

S. Dev and O. Koul, Insecticides of Natural Origin, Amsterdam, The Netherlands Hardwood Academic, 1997. 

Several compounds are used as insecticides where little is known about their biochemical mode of action or whether they are general toxicants. Some have been around for many years, some are of natural origin and others are living organisms that predate on insects. 

This section will cover several widely used insecticidal products of natural origin, and also a growth promoting agent, gibberelUc acid. It discusses, in order, pyrethrum and pyrethrins, nicotine, rotenone, sabadiUa, bacillus thur-ingiensis, and gibbereUic acid. 

Crosby DG (1971) Minor insecticides of plant origin. In Jacobson MJ, Crosby DG (eds) Naturally occurring insecticides. Dekker, New York, pp 177-239 Cukierman S (1991) Inactivation modifiers of Na currents and the gating of rat brain Na channels in planar lipid membranes. Pfliigers Arch 419 514-521 Daly JW, Myers CW, Warnick JE, Albuquerque EX (1980) Levels of batrachotoxin and lack of sensitivity to its action in poison-dart frogs (Phyllobates). Science 208 1383-1385... 

The further classification of conventional insecticides, acting chiefly on the insect nervous system, is a chemical one compounds of natural origin, arsenic compounds, chlorinated hydrocarbons, organophosphorus compounds, carbamates, and other compounds. 

The cultivation of plants intended for homeopathic use must be carried out under special conditions which exclude the use of chemical fertilizers, pesticides, herbicides, insecticides and fungicides. Only fertilizers of natural origin may be used. 

Crosby, D. G., Minor insecticides of plant origin, in Naturally Occurring Insecticides (M. Jacobson and D. G. Crosby, eds.), 177-239, Marcel Dekker, Inc., New York, 1971. 

In order to slow or halt rainforest destruction, high value nontimber products from native spedes offer perhf s the only source of income for local communities capable of competing with timber and cattle-raising. Such products include special nutrients (especially P-carotene and vitamin E), perfumes and aromatherapy materials, animal ration from wastes, toilet soap of rainforest origin, natural insecticides, exudates and balsams for mainly topical medicinal use, pharmaceutical products of natural origin. 

In general, exempt colorants have less coloring power than certified colorants and thus have to be used at higher concentrations. Some, particularly those of plant origin, tend to be less stable, more variable in shade, and therefore more compHcated to use than certified colorants, and are more likely to introduce undeskable flavors and odors into the products in which they are incorporated. Also, depending on thek nature and origin, exempt colorants can vary substantially in composition from batch to batch, are more likely to be contaminated with undeskable trace metals, insecticides, herbicides, and bacteria such as Salmonella and can be more difficult to obtain in steady supply compared with certified colorants. 

The concept of bioisosterism has been used to theoretically evaluate structural variation Organophosphorous Agrochemicals within the lead structures of synthetic or natural origin prior to and during the preparation Insecticides (Tables 17.3a,b). Oiganophorous of molecules of specified efficacy, safety, sta- insecticides bind to Acetylcholinesterase (AchE),... 

They may be a source of structures for screening. They may possess activity that is applicable to pest control directly or after structural modification of the original structure. Finally, the recognition of their function in nature may suggest new approaches to pest control. However, their practical application may be limited by economics. Resistant plants are important in managing insect pests and their resistance may arise from many factors. Some plants contain insecticidal principles that may be exploited. Compounds that modify Insect behaviour are not directly lethal, but may be valuable in pest control. However, their efficacy may be difficult and costly to determine. 

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