Food security and livelihoods at risk as destructive pest invades Tanzania
April 20, 2015
The fast spreading and highly destructive papaya mealybug reaches Tanzania
A new destructive pest is rapidly spreading through the coastal areas of Tanzania around Dar es Salaam and Zanzibar, attacking important food crops such as papaya and cassava, and ornamental plants such as hibiscus and frangipani. Scientists at the International Institute of Tropical Agriculture (IITA)have identified it as the Papaya mealybug (Paracoccus marginatus). In recent years, this highly invasive pest has also been spreading and causing damage in many Asian and West African countries. From its origin in Mexico, it was first observed on the African continent in Ghana in 2010 from where it spread to Bénin, Nigeria, Togo, and Gabon. This discovery in Tanzania means that the rest of East Africa is now likely to be affected as well. Mealybug are tiny, white, flat insects which suck the life out of plants. The preferred host is papaya, but the insect also affects a wide range of crops including cassava, beans, coffee, pepper, melon, guava, tomato, eggplant, cotton, and jatropha. Therefore, if not controlled, the pest may cause widespread damage and loss of livelihoods for many farmers in the country. The papaya mealybug appear as white fluffy spots on the undersides of leaves, branches, and fruit, often accompanied by an unsightly black, sticky substance coating these surfaces―this is a result of a sugary excretion which attracts mold. The affected plants don’t grow properly and farmers are unable to sell the often misshapen, discolored, and (in severe cases) completely shrivelled fruits. According to Dr James Legg, IITA entomologist, and one of the scientists who is leading the efforts to contain the pest after first noticing the damage in his home garden, the papaya mealybug is currently one of the most destructive and rapidly spreading invasive insect species. “In Tanzania,” he said, “we have observed the pest along the coastal belt around Dar es Salaam and its environs, mostly on papaya, cassava, and ornamental plants such as hibiscus and frangipani. We need to carry out a survey throughout the country to determine the full extent of spread and the range of plants affected.” “Samples sent to IITA’s Biological Control Center for Africa, Cotonou, Bénin, have been positively identified by the entomologist Dr Georg Goergen. Now that we know with what we are dealing we need to act fast. The pest can easily spread throughout the East African region causing major damage and threatening the food security and incomes of tens of thous ands of Tanzanian farmers.” The mealybug are easily blown by the wind or carried by ants from one plant to another. They are transported longer distances by people who unknowingly carry infested plants or fruit from one part of the country to another, or from country to country. Efforts are under way from IITA, the Ministry of Agriculture, Food Security and Cooperatives (MAFSC), and the United Nations Food and Agriculture Organization (FAO) to mobilize funds to use biocontrol agents to contain the pest before it gets out of h and. This involves introducing its natural enemies, such as parasitoids―extremely tiny insects that lay their eggs inside the papaya mealybug. As the eggs hatch, tiny worm-like “larvae” emerge which then eat the mealybug from the inside out! Mr Elibariki Nsami from the National Biological Control Programme (NBCP) of MAFSC said that biological control was the only effective way to manage the menace as most pesticides were not effective since mealybug are coated with a protective wax. “The biocontrol mechanisms are safe as they are very specific and attack only the papaya mealybug. They are also cheap, cost effective, and safe for the environment.” It will also be important to set up a surveillance system to track the spread of the pest in the country and the wider region and to create awareness among the farmers and general public on how to control it. ### For more information: Dr James Legg, Entomologist, IITA-Tanzania, j.legg@cgiar.org Mr Elibariki Nsami, Senior Research Officer, NBCU, bio_nsami@yahoo.com Andrea Gros, Head of Communication, IITA HQ, a.gros@cgiar.org Catherine Njuguna, Communication Officer, IITA-Tanzania, c.njuguna@cgiar.org For more photos and images on the pest: https://www.flickr.com/photos/iita-media-library/sets/72157649235568383/ About IITA, www.iita.org IITA is one of the world’s leading research partners in finding solutions for hunger, malnutrition, and poverty. Its award-winning research for development (R4D) approach addresses the development needs of tropical countries. IITA works with partners to enhance crop quality and productivity, reduce producer and consumer risks, and generate wealth from agriculture. IITA is a nonprofit organization founded in 1967 and governed by a Board of Trustees. IITA works on the following crops: cowpea, soybean, banana/plantain, yam, cassava, and maize. IITA is a member of CGIAR, a global agriculture research partnership for a food secure future.Contributed by
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