Source: IRIN News

Army worms have destroyed about 50,000 acres (20,000 ha) of maize and other crops in northern and southeastern Tanzania and the situation is likely to worsen in the next few weeks, National Army Worms Forecasting Services Centre Coordinator Wilfred Mushobozi has said.

"The situation is extremely grave," he said on Friday in the northern town of Arusha, the centre's headquarters.

He said about 30,000 acres (12,000 ha) of crops had already been lost in Kiteto, in the Simanjiro District of Manyara Region.

Mushobozi said the worms were likely to reach other districts in the central, northern and southern parts of the country. Worms have already been spotted in Babati District, the headquarters of the newly-created Manyara Region in northwestern Tanzania. They have also been observed in urban and rural Iringa as well as the districts of Mufindi and Kilolo in the south of the country. Mushobozi said the worms would soon "engulf" Tanzania's designate capital, Dodoma.

Meanwhile, the managing director of Tanseed International (a private seed and farming enterprise), Isaka Mashauri, said the worms had destroyed 50 acres (20 ha) of his farm in Kilosa District in the southwestern region of Morogoro. An official of the Msimba Seed Farm in the same area said he had lost about 140 acres (56 ha). A farmer can usually produce about 15 bags of maize per acre.

Earlier in February the forecasting services centre warned the public to take precautions, in the wake of the anticipated invasion by the worms in 10 of the country's 25 regions. The centre said the regions most prone to the worm attack this year were Dodoma, Iringa, Lindi, Mbeya, Morogoro, Mtwara, Rukwa, Ruvuma, Singida and Tabora.

The worms, scientifically known as Spodoptera exempata, devour all green plants in their path and breed fast making them difficult to control.

This worm invasion comes on the back of a drought in East Africa that has already worsened Tanzania’s food security situation. Prime Minister Edward Lowassa announced two weeks ago that the country needed about 100,000 tonnes of food up to April, to salvage the food situation in the drought-stricken areas.

A document on the African army worm compiled by the Regional Army Worm Programme of Desert Locust Control Organisation for Eastern Africa says that different insecticides, in a variety of formulations, could be used effectively against worms. The choice of insecticide varies with the extent of the outbreak. While DDT is still used in the control of army worm outbreaks in some countries in East Africa, there is worldwide concern that it contaminates the environment.

Continuous use of compounds such as dieldrin and endrin has been effective against the worm. However, they are also not recommended because of their high mammalian toxicity. Safer and faster acting materials such as cypermethrin are increasingly being used.

In Eastern Africa where frequent outbreaks of the worm occur, larval densities are often in excess of 1,000 per square metre and may cover tens or even hundreds of square kilometres, the forecasting services centre said.

Army worm forecasts are based on information from a number of sources, the most important being networks of light and pheromone traps distributed over Eastern Africa and operated nightly under the supervision of trap operators.

Various other factors are taken into account such as the incidence and extent of recent outbreaks of larvae and the current weather conditions, particularly the winds which influence the direction of moth migration.

The young larvae at first eat the upper and lower surface tissue of the leaves. As the larvae become older and increase in size, they are able to bite through the entire leaf, starting from the edges and usually eating all but the midrib. Heavy infestation results in total loss of leaves often leading to severe crop loss or necessitating replanting.

Tanzania last experienced an army worm attack in 1996, when thousands of hectares of crops were destroyed.