Early warning and preventive control is the strategy adopted by locust-affected countries in Africa and Asia to try to stop locust plagues from developing and spreading. In the 1920s-1930s, locust control became a major field for international cooperation. The International Agricultural Institute developed several programmes aimed at exchanging data about the desert locust and international conferences were held in the 1930s: Rome in 1931, Paris in 1932, London in 1934, Cairo in 1936, and Brussels in 1938. Colonial empires were heavily involved in these attempts to control locust pests, which affected heavily the Middle East and parts of Africa. The USSR also used locust control as a way to expand its influence in the Middle East and Central Asia.