Tag: zoology

Pesticides have had some of their most striking effects on birds, particularly those in the higher trophic levels of food chains, such as bald eagles, hawks and owls. These birds are often rare, endangered and susceptible to pesticide residues, such as those occurring from the bioconcentration of organochlorine insecticides through terrestrial food chains. Pesticides may kill grain and plant-feeding birds and the elimination of many rare species of ducks and geese has been reported. Populations of insect-eating birds, such as partridges, grouse and pheasants have decreased due to the loss of their insect food in agricultural fields through the use of insecticides. Thus, the correct answer is option D.

In 1972, the 'Environmental Protection Agency' banned the use of DDT in the United States as well as the use of pesticides, such as endrin and dieldrin. As a result, the levels of these persistent compounds in the environment have decreased in most areas, thus, the reproductive success of brown pelicans has increased.

Minor pests are the species that feed or oviposit on the crop plants but usually do not inflict damage of economic importance and often their effect on the plant is indiscernible.
A pest is "a plant or animal detrimental to humans or human concerns (as agriculture or livestock production)"; alternative meanings include organisms that cause nuisance and epidemic disease associated with high mortality.

Phytophthora palmivora has been used as an post emergent mycoherbicide to control milkweed or strangler vine, a major problem on citrus in south Florida. It controls the weed by a root and stem rot and girdling the stems of infested plant near the soil surface, resulting in the death of seedlings and the older plants.

Agent orange was a powerful mixture of chemical defoliants used by U.S. military forces during the Vietnam war to eliminate forest cover for north Vietnamese, as well as crops that might be used to feed them. The U.S. program of defoliation, codenamed Operation Ranch Hand, sprayed more than 19 million gallons of herbicides over 4.5 million acres of land in Vietnam from 1961 to 1972.

Bacterial blight is a serious disease of field peas that is caused by the pathogens Pseudomonas syringae pv. pisi and Pseudomonas syringae pv. syringae. 

Aldrin is an organochlorine insecticide that was widely used until the 1970s, when it was banned in most countries. It is a colourless solid. Before the ban, it was heavily used as a pesticide to treat seed and soil. It is a chlorinated hydrocarbon. Thus, option C is correct. A carbamate is an organic compound derived from carbamic acid (NH2COOH). Thus, option D is wrong. Malathion is an organophosphate parasympathomimetic which binds irreversibly to cholinesterase. Malathion is an insecticide of relatively low human toxicity. It is not a chlorinated hydrocarbon. Thus, option A is wrong. Pyrethrum was a genus of several Old World plants now classified as Chrysanthemum or Tanacetum which are cultivated as ornamentals for their showy flower heads. Thus, option B is wrong. 

Most of organochlorine pesticides are highly soluble in fat of animals. Further, these chemicals are resistant to be metabolized, so they start accumulating in the bodies of animals.