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Cassava, one of the world's major food crops is grown throughout the\ntropical regions of the world. Cassava originated in the neotropics; it\nwas introduced into West Africa from Brazil by slave traders in the\n1500's, and taken to Asia during the 17th century. Consequently the\ngreatest diversity of cassava pests, as well their natural enemies is\nfound in the neotropics. Several species depress yield significantly;\nthese include mites ( Mononychellus spp.), mealybug ( Phenacoccus\nherreni ), the cassava hornworm ( Erinnyis ello ), the burrowing bug\n( Cyrtomenus bergi ), whiteflies ( Aleurotrachelus socialis ,\nAleurothrixus aepim ), thrips ( Frankliniella williamsi ), and\nlacebugs ( Vatiga manihotae , V. illudeus and Amblystria machalana ).\nMites, mealybugs, thrips and lacebugs attack cassava primarily during\ndry periods, causing severe leaf necrosis. The hornworm will feed on\ncassava leaves throughout the long growing cycle of the crop, although\nsevere attacks usually coincide with the onset of rains. Burrowing bugs\nfeed directly on cassava roots, rendering them unacceptable for the\ncommercial market. In the early 1970's, the cassava green mite,\nMononychellus tanajoa\tand the cassava mealybug P. manihoti were\ninadvertently introduced to Africa from the neotropics. These pests\nhave since spread throughout most of the cassava-growing regions of\nAfrica, causing severe crop losses. The unauthorized movement of\ncassava germplasm, between and within continents, involves a risk of\naccidentally introducing additional pests. Control strategies are based\non host plant resistance, biological control and cultural practices.\nAdequate levels of resistance have been identified for mite and\nwhiteflies and moderate levels for mealybugs. Burrowing bug damage is\nless on varieties with high HCN concentration. Many species of natural\nenemies have been identified for mites, mealybugs and the cassava\nhornworm. A granulosis virus is effective in the management of hornworm\npopulations. Chemical pesticide application to control cassava pests is\ndiscouraged and efforts are being made to develop Integrated Pest\nManagement (IPM) programmes which do not incorporate pesticide use.