Md. Wasim Aktar
Pesticide Residue Laboratory, Department of Agricultural Chemicals, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur-741252, Nadia, West Bengal, India
Introduction Pesticides are found as usual contaminants in soil, air, and water, and on non-target vegetation in our urban landscapes. Once there, they can harm plants and animals ranging from a tight suggestion soil microorganisms and insects, non-target plants, fish, birds, and other wildlife. Table 1 summarizes the harmful effects to non-target organisms of some commonly used urban herbicides.
Table 1 . Harmful effects of selected herbicides on non-target organisms Source: Sanders, 1969
Fish When pesticides contaminate water they can be harmful to the fish that are living there. Insecticides can be particularly toxic to fish. Chlorpyrifos, a usual contaminant of urban streams,18 is very highly toxic to fish, and has caused fishkills in waterways near treated fields or buildings.1,2 Diazinon, additionally commonly found in urban streams,18 is acutely toxic to many species of fish, including salmon.3 Herbicides additionally can be toxic to fish. According to the EPA, studies show that trifluralin, an full of life ingredient in the weed-killer Snapshot, is highly to very highly toxic to both cold and warmwater fish.4 It was additionally shown in a sequence of different tests to bring about vertebral deformities in fish.5 Oryzalin, the full of life ingredient of Surflan, additionally is 'highly toxic' to fish.6 The weed-killers Ronstar and Roundup are additionally acutely toxic to fish.7,8 The toxicity of Roundup is likely due to the the high toxicity of one of the inert ingredients of the product. In addition to direct acute toxicity, some herbicides may produce sublethal effects on fish that reduce their chances for survival and threaten the population as a complete. Glyphosate or glyphosate-containing products can bring about sublethal effects such as erratic swimming and labored breathing which augment the fishs chance of being eaten.9,10 2,4-D herbicides caused physiological stress responses in sockeye salmon,11 and reduced the food gathering competencies of rainbow trout.12
Other Aquatic Animals and Plants In addition to fish, other marine or freshwater animals are endangered by pesticide contamination. 2,4- D or 2,4-D containing products have been shown to be harmful to newts,13 frogs,14 crabs,15 shellfish,16 and other aquatic species.17,18 The weed-killer trifluralin is moderately to highly toxic to aquatic invertebrates, and highly toxic to estuarine and marine organisms like shrimp and mussels. Diuron is additionally highly toxic to aquatic invertebrates.19 Since herbicides are designed to kill plants, it makes sense that herbicide contamination of water could have devastating effects on aquatic plants. In one look into, oxadiazon was found to severely reduce algae amplify.20 Algae is a staple organism in the food chain of aquatic ecosystems. Studies watching at the impacts of the herbicides atrazine and alachlor on algae and diatoms in streams showed that even at fairly low levels, the chemicals broken cells, blocked photosynthesis, and stunted amplify in varying ways.20 Another main elegance of organisms is the cyanobacteria. Cyanobacteria are living in aquatic environments as well as soil, and play a necessary role in nitrogen fixation, aiding plants convert atmospheric nitrogen into nitrate compounds that the plant can use. Trifluralin was found to inhibit the amplify of two usual cyanobacteria at all levels of utility.21
Insects and Spiders In addition to killing insect pests, insecticides obviously have the skill to harm non-target insects such as a tight suggestion natural predators and pollinators. Less obviously, weed-killers additionally can be harmful to a tight suggestion insects. One look into found that exposure to freshly dried Roundup (glyphosate) killed over 50 percent of three species of a tight suggestion insects: a parasitoid wasp, a lacewing and a ladybug. Over eighty percent of a fourth species, a predatory beetle was killed.22 Moderate doses of the herbicide 2,4-D severely impaired honeybee brood production. 23 The herbicide oxadiazon is additionally toxic to bees, which are pollinators.24 Herbicides may hurt insects or spiders indirectly as well, such as when they destroy the foliage that these animals need for food and shelter. For example, spider and carabid beetle populations declined when 2,4-D applications destroyed their natural habitat.25 Birds The insecticide diazinon is notorious for causing chook kills. Over 50 incidents involving the deaths of up to one thousand birds have been documented in every vicinity of the U.S.95 Diazinon is so deadly to birds that the EPA estimates that amongst 15 and eighty minutes of grazing on diazinon treated turf is satisfactory to kill a chook.26 Non-target birds may additionally be killed if they ingest poisoned grains set out as bait for pigeons and rodents.27, 28 Avitrol, a commonly used pigeon bait, poses a sizable skill for ingestion by non target grain feeding birds. It can be deadly to small seed-eating birds.29 rodifacoum, a usual rodenticide, is highly toxic to birds. It additionally poses a secondary poisoning hazard to birds that may feed on poisoned rodents.30 Herbicides additionally can be toxic to birds. lthough trifluralin was considered practically nontoxic to birds in studies of acute toxicity, birds exposed multiple times to the herbicide experienced diminished reproductive success in the variety of cracked eggs. Exposure of eggs to 2,4-D reduced a success hatching of chicken eggs,33 and caused feminization or sterility in pheasant chicks.31 Herbicides additionally can adversely effect birds by destroying their habitat. Glyphosate treatment in clear cuts caused dramatic decreases in the populations of birds that had lived there.32
Beneficial Soil Microorganisms One spoonful of healthy soil has millions of tiny organisms including fungi, micro organism, and rather loads of others. These microorganisms play a key role in aiding plants utilize soil nutrients needed to grow and thrive. Microorganisms additionally lend a hand soil store water and nutrients, regulate water flow, and filter pollutants.34 The heavy treatment of soil with pesticides can bring about populations of a tight suggestion soil microorganisms to decline. According to soil scientist Dr. Elaine Ingham, If we lose both micro organism and fungi, then the soil degrades. Overuse of chemical fertilizers and pesticides have effects on the soil organisms that are similar to human overuse of antibiotics. Indiscriminate use of chemicals might work for rather loads of years, but after awhile, there arent satisfactory a tight suggestion soil organisms to hold onto the nutrients.35 For example, plants depend on a ramification of of soil microorganisms to transform atmospheric nitrogen into nitrates that plants can use. Common landscape herbicides disrupt this process: triclopyr inhibits soil micro organism that transform ammonia into nitrite36; glyphosate reduces the amplify and exercise of both free-living nitrogen-fixing micro organism in soil37 and those who are living in nodules on plant roots38; and a pair of,4-D reduces nitrogen fixation by the micro organism that are living on the roots of bean plants,39,40 reduces the amplify and exercise of nitrogen-fixing blue-green algae, 41,42 and inhibits the transformation by soil micro organism of ammonia into nitrates.forty three,44 Mycorrhizal fungi grow with the roots of many plants and lend a hand in nutrient uptake. These fungi additionally can be broken by herbicides in the soil. One look into found that oryzalin and trifluralin both inhibited the amplify of certain species of mycorrhizal fungi.forty five Roundup has been shown to be toxic to mycorrhizal fungi in laboratory studies, and some damaging effects were seen at concentrations lower than those found in soil following typical applications. 46,forty seven Triclopyr was additionally found to be toxic to several species of mycorrhizal fungi,forty eight and oxadiazon reduced the number of mycorrhizal fungal spores.forty nine
Conclusion Pesticides have contaminated approximately every an facet of our environment. Pesticide residues are found in soil and air, and in surface and ground water round the nation, and urban pesticide uses contribute to the problem. Pesticide contamination poses significant risks to the environment and non-target organisms ranging from a tight suggestion soil microorganisms, to insects, plants, fish, and birds. Contrary to usual misconceptions, even herbicides can bring about harm to the environment. In fact, weed killers can be principally problematic since they are used in relatively massive volumes. The ultimate way to reduce pesticide contamination (and the harm it causes) in our environment is for all of us to do our part to use safer, non-chemical pest control (including weed control) methods.
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