Pest control pesticides effect

Many factors affect the mechanisms and kinetics of sorption and transport processes. For instance, differences in the chemical stmcture and properties, ie, ionizahility, solubiUty in water, vapor pressure, and polarity, between pesticides affect their behavior in the environment through effects on sorption and transport processes. Differences in soil properties, ie, pH and percentage of organic carbon and clay contents, and soil conditions, ie, moisture content and landscape position climatic conditions, ie, temperature, precipitation, and radiation and cultural practices, ie, crop and tillage, can all modify the behavior of the pesticide in soils. Persistence of a pesticide in soil is a consequence of a complex interaction of processes. Because the persistence of a pesticide can govern its availabiUty and efficacy for pest control, as weU as its potential for adverse environmental impacts, knowledge of the basic processes is necessary if the benefits of the pesticide ate to be maximized. 

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. 

Whenever applied, IPM practices have consistendy resulted in decreases in insecticide applications of 50 to 90% over conventional spray programs. By encouraging natural enemies, IPM practices markedly decrease the rigor of natural selection by pesticides that is responsible for resistance. Natural enemy preservation also prevents the great fluctuations and suiges in insect pest populations observed after the injudicious use of broad-spectrum insecticides. Under the IPM concept, insecticides are generally used when other practices are inadequate and the pest population reaches the economic threshold. In order to make the IPM concept effective, insecticides must be used as selectively as possible, with minimal disturbance to all other elements of the ecosystem. Thus IPM practices are essentially blueprints for the proper use of insecticides in insect pest control. 

With the extensive use of pest control chemicals in agriculture and industry, residues of organochlorine pesticides and polychlorinated biphenyls (PCBs) have been discovered to elicit toxicological effects on aquatic organisms and wildlife. It is well known that these compounds are lipophilic (meaning attraction to fat... 

In the preparation of commercial pesticide formulations, the biochemical and toxic properties undergo phenomenal modifications. These reactions (and the effects thereof) are called synergism, antagonism, and additive effects. In pest control management, different OPs are mixed to achieve quick knock-down effects, and absence of residues effects, for the better killing of crop pests (Table 5-2). 

Side by side with this growth of knowledge there has been increasing concern that the implications of the large-scale utilization of synthetic chemicals be fully understood. Chemical methods of pest control have conferred such spectacular benefits on agriculture and the health of mankind that it has become difficult to conceive that these benefits could be offset or outweighed by serious disadvantages. Some of these effects are extremely subtle others, such as the development of pesticide resistance, rapidly become obvious because no further economic benefit is obtained by continued pesticide use. 

Chemical control is the most widely practised method for vector and pest control in the Region. However, appropriate pesticide use is hampered, inter alia, by the lack of capacity, coordinated mechanisms and funding for the registration, purchase, application and quality control of products absence of effective systems for monitoring use and lack of implementation of existing rules and regulations. 

The Food Quality Protection Act (FQPA) in the USA and the Pest Control Products Act (PCPA) in Canada mandate that potential risks to infants and small children be specifically addressed. When assessing the food use of a pesticide, in order to assure that there is a reasonable certainty that no harm will result to infants and children from aggregate exposure to the pesticide s chemical residues , the FQPA and PCPA in the case of threshold effects call for an additional tenfold margin of safety for the pesticide chemical residue and other sources of exposure to be applied to estimating risks to infants and children. A different margin of safety may be used only if, on the basis of reliable data, such a margin will be safe for infants and children. In Canada, these same requirements also apply to non-food-use pesticides. 

Maize is grown in most U.S. states, where European com borer and Southwestern com borer are major lepidopteran insect pests. The transgenic CiylAb protein expressed in Bt maize can provide protection against these two pests. Control of these insect pests depends among others on the timing of pesticide applications, because the larvae spent part of their life inside maize stalks where pesticides may not be effective at all. 

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