Toxicology of Insecticides : Development of Resistance in Urban Pests

Since last two decades, the excessive and broad spectral usage of pesticides has achieved remarkable momentum in agriculture dependant countries like Pakistan. Pesticides are undoubtedly considered as a group of toxic chemicals that are introduced into the environment; most of which include insecticides, herbicides, fungicides, rodenticides and fumigants. These toxic compounds have some residues which retain in environment and not only contaminate it, but also develop resistance in target organisms against these chemicals. Frequent and repeated application of insecticides generally reduces the effectiveness and it results in the development of resistance in target pest against these insecticides. In general case, when whole population of targeted pests is selected by killing the susceptible individuals, it usually results in the emergence of resistant strains.