The greatest constraint to economic development was a chronic shortage of labour. The indigenous Bubi population of Bioko, pushed into the interior of the island and decimated by alcoholic addiction, venereal disease, smallpox and sleeping sickness, refused to work on plantations. Working their own small cocoa farms gave them a considerable degree of autonomy. Moreover, the Bubi were protected from the demands of the planters from the late 19th century by the Spanish Claretian missionaries, who were very influential in the colony and eventually organised the Bubi into small mission theocracies reminiscent of the famous Jesuit Reductions of Paraguay. Catholic penetration was furthered by two small insurrections protesting the conscription of forced labour for the plantations, in 1898 and 1910, which led to the Bubi being disarmed in 1917 and left them dependent on the missionaries.