Insecticide resistance is caused by genetic changes in an insect. These increase the insect’s ability to overcome the effects of different chemicals. This means that certain species of mosquito are becoming resistant to some of the substances designed to kill them
Since 2000, progress in malaria control has resulted primarily from expanded access to vector control interventions, particularly in sub-Saharan Africa. However, these gains are threatened by emerging resistance to insecticides among Anopheles mosquitoes. According to the latest World malaria report, 68 countries reported mosquito resistance to at least 1 of the 5 commonly-used insecticide classes in the period 2010-2017; among these countries, 57 reported resistance to 2 or more insecticide classes.