An.culicifacies හි DDT ප්රතිරෝධය මුලින්ම අනාවරණය විය
In 1969, potential resistance to DDT was detected by the Anti-Malaria Campaign, which is believed to be a major cause for the resurgence of malaria island-wide. By 1974, DDT resistance was established in all vector species. Public opposition to indoor DDT spraying also contributed to vector control failure. Consequently, selective residual spraying under strict supervision was adopted.