Insecticide resistance is defined as a genetically based decrease in the susceptibility of an insect population over time, in response to long-term exposure to an insecticide. There is a change in the genetics of a population that allows individuals from a previously susceptible population to survive. Resistant populations inherit traits that reduce their susceptibility to individual insecticides. In other words, parasites develop resistance to a chemical substance through natural selection: the most resistant organisms are those that survive and pass on their genetic traits to their offspring (Miller, 2004). Resistance develops in all agricultural insects and resistant individuals are initially quite rare in pest populations. The development of resistance in camps is influenced by various factors. These include biological, genetic Biological factors are generation time, number of descendants per generation, and migration. Genetic factors are the frequency and dominance of the resistance gene, the fitness of the resistance genotype, and the number of different resistance alleles. Genetics and intensive application of insecticides are two of several factors responsible for the development of insecticide resistance. Insects with genes that confer resistance to a particular insecticide or class of insecticides survive treatment and are then “selected” to pass this resistance on to subsequent generations. In an insect population there may be some individuals who carry resistance genes. These genes arise from mutations and are rare. In the natural environment the mutant insect is typically impaired, weaker and produces fewer offspring. After exposure to insecticides, insects that do not carry the resistance genes die, thus allowing individuals... middle of paper... to assess their mortality after exposure to a range of insecticide doses and outcomes compared to those of standard susceptible populations. According to Yu and Nguyen (1992) another method is to use biochemical detection assays to establish resistance by measuring changes in frequencies of resistance genes in field populations under different selective pressures. Many efforts have been made to determine the biochemical or physiological changes underlying resistance to Bt. It has been established that the Diamondback moth has reduced toxin binding to the midgut epithelium as an important resistance mechanism (Perez and Shelton, 1996). The immunological method is also available, but only for specific high esterases, in collaboration with laboratories that have access to the antiserum. No monoclonal antibodies are yet available for this purpose.