Pest control compounds

The environmental fate and behavior of compounds depends on their physical, chemical, and biochemical properties. Individual OPs differ considerably from one another in their properties and, consequently, in their environmental behavior and the way they are used as pesticides. Pesticide chemists and formulators have been able to exploit the properties of individual OPs in order to achieve more effective and more environment-friendly pest control, for example, in the development of compounds like chlorfenviphos, which has enough stability and a sufficiently low vapor pressure to be effective as an insecticidal seed dressing, but, like other OPs, is readily biodegradable thus, it was introduced as a more environment-friendly alternative to persistent OCs as a seed dressing. 

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. 

Trialkyltin and triaryltin compounds possess powerful biocidal properties. These are manifested to a high degree only when the tin atom is combined directly with three carbon atoms, as in trialkyl compounds (R3SnX) biocidal effects are at a maximum when the total number of carbon atoms attached to Sn is 12. These compounds are used as fungicides, insecticides and as pest control in agricultural applications29. 

This compound has been prepared by Schrader2 and by Pest Control, Ltd.3 Its translocation in the plant has been studied4 using the compound containing radioactive phosphorus.5 Compound (XX) is further discussed on p. 172. 

A problem in trying to use these results in developing potential pest control agents is that none of these compounds is likely to penetrate either the cuticle or the CNS of insects effectively, since all are fully ionized at physiological pH. Derivatization of the polar groups would be one possible solution to this problem. The formamidines and imidazolines generally do not suffer from this problem since they have pKas which are lower than those of the related phenylethylamines and thus are at least partly in the free base form at pH 7. 

The synthesis of pheromones remains an important cornerstone of pheromone research and development. The initial synthesis of an insect pheromone serves not only to confirm the structural identification, but also provides authentic material for either laboratory or field bioassay. Oftentimes, larger quantities of the pheromones are desired for the development of monitoring and pest control methods. The scale up of the synthesis of complex pheromone compounds is often a major bottleneck in the practical application of pheromones. Also, the unusual structure of some pheromone compounds beckons synthetic chemists to apply new methodology in order to show off their methods. 

Non-crop plants associated with the crop species offer possibilities for allelopathic weed control. In this study Brassica campestris (wild mustard), which is an important weed in Santa Cruz County, and broccoli, a common crop, were intercropped, The allelopathic potential of both species and the changes in this potential throughout their life cycle were demonstrated with experiments in the laboratory. Effects of different planting densities and sowing time of canpestris on the crop yield are analyzed. Preliminary steps to separate the physiologically active compound(s) are described. The possibilities for the use of Brassica campestris in agroecosystem design as a non-crop plant that promotes pest control are described. 

The introduction of pest control methods is often a result of the broad-spectrum activity of compounds that have been commercialised in other crop situations. Control of locusts, for example, is an important aspect of crop protection in much of Africa and the Middle and Far East. The... 

Bioavailability from Environmental Media. Diazinon can be absorbed following inhalation, dermal, or oral exposures. Absorption through the skin is of major concern for exposures of farmers, farm workers, commercial applicators, or homeowners related to the use of diazinon as an insecticide or nematocide (Davis et al. 1983). Absorption via inhalation is a major concern particularly with respect to indoor exposures to diazinon within 2 days postapplication of the compound as a pest control agent in commercial buildings and homes (Currie et al. 1990 Jackson and Lewis 1981 Lenhart and Kawamoto 1994 Williams et al. 1987). Additional information on the concentrations of diazinon in indoor air and in groundwater from domestic wells, particularly from environments near hazardous waste sites, is needed to determine the bioavailability of diazinon in these media. 

Carbamates are also used as insecticides and again, their trade names are probably familiar if you have done any serious gardening and pest control. The use of these compounds is restricted to certain parts of the growing cycle and specific non-food produce. Notice their low degree of dermal toxicity. Carbaryl, for example, is used topcially in some countries to get rid of head lice. It was the misuse of Temik several years ago on watermelons in California which... 

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