Insecticides characteristics

These comprise a water-based or water-soluble resin and plant secondary compounds having insecticidal characteristics. They exhibit insect repellence, antifeedance and oviposition deterrence. 

Chemical Designations - Synonyms 0-0-Dimethyl S-[(4-Oxo-l,2,3-Benzotriazine-3(4H)-yl)Methyl] Phosphorodithioate, Gurthion Insecticide, Gusathion Insecticide Chemical Formula CiqHijNjOjPSj. Observable Characteristics — Physical State (as normally shipped) Solid Color Brown Odor No data. 

Pyridine is a polar, stable, relatively unreactive liquid (bp 115°C) with a characteristic strong penetrating odor that is unpleasant to most people. It is miscible with both water and organic solvents. Pyridine was first isolated, like pyrrole, from bone pyrolysates. Its name is derived from the Greek for fire (pyr) and the suffix idine used to designate aromatic bases. Pyridine is used as a solvent, in addition to many other uses including products such as pharmaceuticals, vitamins, food flavorings, paints, dyes, rubber products, adhesives, insecticides, and herbicides. Pyridine can also be formed from the breakdown of many natural materials in the environment. 

Ryanodine is a neutral plant alkaloid from Ryania speciosa and was used as an insecticide. It also has been well known by the characteristic action on mammalian skeletal muscle of slowly developing, and intensive and irreversible contracture. Ryanodine binds specifically to the open RyR channel at the stoichiometry of 1 mol/mol homotetramer with a high affinity (ATD nM) and leads the channel to ryanodine modified state characteristic of long-lasting subconductance ( 50% of normal) opening. At higher concentration, it blocks the channel. 

Dihexyl sulfosuccinate is used to improve the wetting and spreading characteristics of water-soluble pesticide sprays. In liquid fertilizers, insecticides, and fungicides, dioctyl sulfosuccinate will increase their penetrating ability. 

Methods utilizing characteristic physical properties have been developed for several chlorinated hydrocarbon insecticides. Daasch (18) has used infrared spectroscopy for the analysis of benzene hexachloride. By this means it is possible to determine the gamma-isomer content, as well as that of the other isomers of technical benzene hexachloride, provided the product is substantially free of the higher chlorinated cyclohexanes. 

As the value of these two new chemicals for insecticides became more evident, the need for extended experimental and test work was definitely established. It was necessary to determine chemical formulas, work out analytical methods, obtain knowledge of various physical and chemical characteristics, and complete evaluation of insecticidal action as well as toxicity and effect of residues. Toxicity was concerned with not only insects but humans and other warm-blooded animals. Residual studies included information on persistence and type and amount of residue. This information, once accumulated, must be correlated with similar information on other insecticides. 

With reference to the surface deposits accruing from orchard application of insecticides, certain characteristics which enhance their value as implements in the chemical control of many species of insects—physical persistency and chemical stability—may also be conducive to the contamination of the harvested fruits with potentially deleterious residues. 

A high degree of insecticidal activity per unit weight, effectiveness against many species of insects, prolonged residual effect combined with rapid knockdown, compatibility with various vehicles, and availability under wartime conditions are among the most important military characteristics of insecticides. No present insecticide is entirely satisfactory. 

The properties of insecticides are, in military parlance, called characteristics. Many of these characteristics are of importance in both military and civilian usage, but because of the vast difference between military and civilian operations, certain properties of insecticides become extremely important to the armed services, and in many instances are more important to the military economy than to the civilian economy. 

Possibly the most important single military characteristic is a high degree of insecticidal activity per unit weight. The necessity for this requirement may be more fully appreciated when it is realized that approximately 3 tons of equipment and supplies per individual soldier are necessary during the assault stages of an invasion, and 0.75 ton of supplies and equipment per man is necessary to maintain one combat soldier for one month in the field. With this vast amount of equipment and supplies for each individual soldier, the weight of each specific item needed for his support must be critically scrutinized. 

Another extremely important military characteristic is effectiveness against many different species of insects without the development of resistant strains. Every insecticide that must be added to the military list of supplies geometrically increases the difficulties of procurement and distribution. At the present time, nineteen different insecticides and insect repellents and four different rodenticides are issued by the Army Quartermaster. These figures do not include the different formulations of insect repellents issued under the same stock number. The three basic insect repellents are dimethyl phthlate, Indalone, and Rutgers 612. These repellents are issued either alone or in various combinations, further complicating the supply situation because of the variation in efficiency of these substances against different species of mosquitoes in different parts of the world. 

Another extremely important military characteristic is prolonged residual effect combined with rapid knockdowm. Although, at the present time, we have some chemicals which give a comparatively long residual effect, and other chemicals which give a relatively quick knockdown, the military still require more prolonged residual effect and more rapid knockdown in their insecticides. 

The last, but by no means the least, important of the military characteristics is availability under wartime conditions. Materials are classified as strategic, critical, and non-critical in this respect A strategic material is one that must be imported into the United States a critical material is one that is available in the United States but, because of either limited plant facilities or excessive demands, becomes nonavailable a noncritical material is one that is readily available in. sufficient amounts under wartime conditions. An insecticide to be of value to the military forces must be readily available under wartime conditions, must not be dependent upon the importation of certain essential materials, and must not impose a burden upon plant facilities in the United States. 

The only military characteristic which has been met adequately at the present time is that of a high degree of insecticidal activity per unit weight. The other requirements are not being met adequately by the insecticides in commercial production at this time and a vast amount of research is necessary before the armed forces can be furnished with an insecticide which is entirely satisfactory for military needs. 

On the basis of results reported in this paper, it would appear that partition chromatography will find other applications in analysis of insecticide formulations. The method possesses a certain degree of specificity in that the partition behavior of the compounds being studied is a characteristic property. 

Making a list, Muller outlined the desirable characteristics of an ideal insecticide. It should be toxic to insects but harmless to mammals, fish, and plants act rapidly have no irritating odor and be inexpensive. To his list, Muller added two more properties. The ideal insecticide should affect as many kinds of insects as possible, and it should be chemically stable for a long time. Finally, Muller decided to use as a starting point Geigy s mothproofing compound, the chlorinated hydrocarbon that was extremely stable on woolens. Thus, from the beginning, Muller s search contained the seeds of its own disaster. In the future, it would kill beneficial as well as harmful insects, and it would persist for decades in the environment. 

DDT met all but one of Muller s ideal characteristics for an insecticide. It was a cheap, contact poison without objectionable odors. It was stable in air and light. Because it was so powerful, extremely small doses could be used. And finally, it dissolved so poorly in water that warm-blooded organisms absorbed only traces of it. The fact that DDT dissolves well in oils did not seem dangerous only later did scientists realize that, because DDT accumulates in animal fat and mammals milk, it becomes increasingly more concentrated in predator species as it moves up the food chain. DDT s only failing, as far as Muller s original conception was concerned, was that it did not kill immediately. 

Colorless to white crystalline solid with a characteristic odor. This material is hazardous through inhalation, skin absorption, and ingestion, and produces local skin/eye impacts. Used industrially as an insecticide and acaricide. 

As described in the section on Cross-resistance in this chapter, it was found that some insect species showed extremely low cross-resistance to three ingredients, pyrethrins as well as d-allethrin and prallethrin, although they developed resistance to photostable synthetic pyrethroids. The latter two compounds of d-allethrin and prallethrin have quite similar chemical structures and the same configuration as cinerin I (an ingredient of pyrethrins). It is considered preferable to develop pyrethroids retaining the characteristics of natural pyrethrins and household insecticides containing them in the perspectives of safety and low cross-resistance. 

Figure 7 shows the course of development of various synthetic pyrethroids developed by retaining chrysanthemic acid as the acid moiety and modifying the alcohol moiety. Numerous useful compounds with favorable characteristics have been derived from the structural modification of natural cinerin I (7). These underlined compounds have been put into practical use as active ingredients, mainly for household insecticides. 

Although structurally-diverse as evidenced above, the insecticidal pyrethroids still conform to a unique, operationally-defined, structure-activity relationship based on the physical characteristics and three-dimensional shape of the entire molecule conforming to those originally evidenced in the natural pyrethrins [13]. From this relationship, it becomes apparent that there is no single molecular aspect or reactive moiety that serves as a true toxophore for the pyrethroids and that their actions at target sites are dependent upon the entire stereospecific structure of these insecticides [1]. 

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