Mosquitoes organochlorines

Aldrin/dieldrin Pesticide - organochlorine - bioaccumulates - used to control mosquitoes and termites Importation and manufacture prohibited in the US in 1987... 

The development of strains resistant to insecticides is an extremely widespread phenomenon that is known to have occurred in more than 200 species of insects and mites, and resistance of up to several 100-fold has been noted. The different biochemical and genetic factors involved have been studied extensively and well characterized. Relatively few vertebrate species are known to have developed pesticide resistance and the level of resistance in vertebrates is low compared to that often found in insects. Susceptible and resistant strains of pine voles exhibit a 7.4-fold difference in endrin toxicity. Similarly pine mice of a strain resistant to endrin were reported to be 12-fold more tolerant than a susceptible strain. Other examples include the occurrence of organochlorine insecticide-resistant and susceptible strains of mosquito fish, and resistance to Belladonna in certain rabbit strains. 

The pest mosquito Aedes nigromacul Ls of the vast San Joaquin valley of California went resistant to organochlorines by 1951, to parathion by 1960, to fenthion by 1965, and to chlorpyrifos (Dursban) by 1970. At present reliance is placed on larvicidal oils, the juvenile-hormone mimic methoprene (Altosid) and the insect growth regulator diflubenzuron (Dimilin), — and on better management of surplus irrigation water. Residual sprays for housefly control, at first so spectacular with the organochlorines, had to move into the OP compounds, which were then knocked out in... 

The name of this insecticide is to many people synonymous with environmental pollution, and it is therefore an important example in this chapter but the story is not simple. DDT is an abbreviation for the chemical name of the insecticide dichloro-diphenyl-trichloroethane. It contains five chlorine atoms and is hence called an organochlorine compound. It was first made in 1874 but not found to be an insecticide until 1939 by Paul Muller. It was used extensively in the Second World War for the control of insects such as lice and mosquitoes, carriers of the diseases typhus and malaria. It was very effective in controlling these pests, and the diseases they carried, and undoubtedly thousands of soldiers lives were saved. Since then, the lives of millions of people throughout the world have also been saved by this insecticide both as a result of the reduction of these and other diseases and as a result of the improvement in crop yields which has reduced starvation. Indeed, in 1953 it was estimated that the use of DDT for malaria eradication had saved 50 million lives and averted more... 

DDT or 1,1-(2,2,2-trichloroethylidene)bis [4-chlorobenzene] Organochlorine Nerve poison, affecting sodium balance of nerve membranes, nonsystemic contact and stomach action Mosquito control for malaria eradication for crop use replaced by less persistent products 11-21... 

Mitema and Gitau reported low levels of a-BHC, P-BHC, aldrin, dieldrin, lindane and p,p -DDT in Nile perch from Lake Victoria. The p,p -DDT and its metabolites formed the largest proportion of the organochlorine pesticide residues in the fish samples. The presence of these residues was attributed to the previous use of the pesticides in agriculture and aerial control of mosquitoes in the Lake Victoria region. Studies conducted in other parts of the country revealed similar trends of pesticide contaminations. Wandiga reported residues of aldrin, a-endosulfan, dieldrin, endrin, DDT, DDE, DDD and lindane in seawater, seaweeds, sediments, and fish. They found residue levels ranging from 0.503-9.025 ng/g in sea water, 0.584-59.00 ng/g in sediments, and concentrations of 1011 ng/g and 418 ng/g of p,p -DDT and p,p -DDD, respectively, in fish. 

The use of pesticides in Kenya dates back to the colonial era. The major areas of application include agricultural pest control and the public health control of mosquitoes, snails, and tsetse flies. However, with the rapid development of resistance of pests to the chemicals, coupled with environmental persistence, most of the organochlorines have been banned for agricultural use and restricted in the case of public health vector control. Nevertheless, there are detectable residue levels of these compoimds in amounts that lead to concern for food chain magnification. These levels arise either fi om previous application or unscrupulous use through illegal means. 

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