Research makes headway in curbing invasive moth

Sunday June 10, 2018

By Joe Lihundi

Tranquility News Reporter, Arusha

A PhD candidate with Nelson Mandela African Institute of Science and Technology (NM-AIST) based in Arusha, Tanzania, has made a major breakthrough in the control of a devastating tomato pest.

The tomato leaf mining moth or tuta absoluta, as it is known among scientists, has been threatening to wipe out the world’s popular staple vegetable since 1917 when it was first spotted in South America where the crop originated.

Besides tomato, the alien pest also attacks other crops from the same family of solanaceaous, including potatoes, pepper, eggplant, and a favourite traditional vegetable for Arusha and its environs popularly known as mnafu.

Tuta absoluta spread to Europe in 2006 before it found its way to Egypt, Sudan and Ethiopia in 2010 and to Kenya in East Africa in 2013. Its presence in Tanzania was felt in October 2014, when it destroyed hundreds of acres of tomato farms at Engarenanyuki Ward in Arumeru District, Ausha Region.

A tomato pest found on the leaf of the plant at a farm at Engarenanyuki Ward in Arusha, Tanzania.

Tanzania Agriculture Sample Census shows the 945,087-square-kilometre country produced 518,312 metric tonnes of tomatoes a year before the breakout of the pest.

Engarenanyuki Ward, home to over 3,000 tomato smallholder farmers, where the vegetable is grown four times a year, produced over 26,000 metric tonnes per season and about 104,000 metric tonnes a year, before the majority of farmers abandoned the crop.

One of the tomato growers, Mr Gideon Mbise, 44, did not only build a four-bedroom house out of the crop, but also paid school fees for his four children. “One of them is studying at Arusha Technical College now,” he explains.

Tomatoes from Engarenanyuki were not only eaten in the country’s major cities of Arusha, Mwanza and Dar es Salaam, but also reached dining tables in Nairobi and Mombasa, Kenya, as well as in Europe.

After the breakout of the pest, barely a fifth of the harvest was realised, pushing up the price of vegetable beyond the reach of the majority of the poor folks.

Ms Never Mwambela, 33, a PhD candidate at Nelson Mandela African Institute of Science and Technology based in Arusha, Tanzania, is developing an organic pesticide against tomato leaf miner.

From Engarenanyuki, the butterfly-related insect spread to Kilimanjaro, Manyara, Tanga, Morogoro and Iringa regions before it crossed border to Uganda, Zambia, Malawi, South Africa and Lesotho.

With an acute shortage of the key ingredient of savoury meals, traders have since been cashing in on high demand of tomato in kitchens of most of the affected areas, compelling some chefs to resort to carrot in their recipes.

Just a month after the breakout of the pest, for instance, tomato prices in Arusha soared by 375 per cent. A carton of tomato was sold at Sh60,000 (about $27), up from Sh16,000 (about $7), earning traders millions of shillings in return.

The tomato farm gate prices in Morogoro stood at Sh50,000 (about $22) per carton, up from Sh5,000 (about $2) before the pest struck the region.

The pest has defied almost all chemical control attempts elsewhere, as it hides itself inside the plant’s leaf or soil into which many pesticides cannot easily penetrate.

In collaboration with my supervisors, we discovered a disease which kills the pest,” Ms Never Mwambela, a PhD candidate at Nelson Mandela African Institute of Science and Technology based in Arusha, Tanzania.

Huge costs farmers and consumers of the vegetable incur prompted the PhD candidate in Life Science and Bioengineering, Ms Never Mwambela, 33, to embark on a research immediately after she joined the NM-AIST in 2015.

“We’ve been in the laboratory for two plus years now looking for ways of containing the pest. I thank God I am in final touches,” the soft spoken researcher says.

The objective of her research is to use biological methods for containing the pest without affecting the environment and the health of consumers of the crop, as is the case with most chemical pesticides.

“In collaboration with my supervisors, we discovered a disease which kills the pest,” she explains. The organic pesticide does not have any side effect to crops, consumers or environment-friendly insects such as bees.

Ms Mwambela though is still in final stages of her research, already farmers surrounding her nine demonstration plots scattered around three mostly affected regions of Arusha, Morogoro and Iringa cannot wait to buy the pesticide she is developing.

Mr Charles Nko, 56, a tomato grower at Engarenanyuki ward in Arusha, Tanzania, who had abandoned the cash crop following the breakout of tuta absoluta in 2014, admires the vegetable produced at a demonstration plot on which an organic pesticide was applied on trial.

Mr Gabriel Isangya, a tomato grower, has diversified his entrepreneurship to a motorcycle taxi business popularly known as bodaboda in East Africa following the outbreak of the invasive pest more than tripling the cost of producing his cash crop.

He sprayed different types of chemical pesticides on the crop after every two weeks to prevent the tomato moth from destroying his crop to no avail.

Ms Mwambela, one of Mr Gabriel’s regular passengers, offered him free of charge the pesticide on trial which, to his astonishment, killed the tomato moth instantly after spraying it on the crop only once.

The good performance of his tomato farm impressed other farmers at Namala Village on the fringes of the NM-AIST campus; prompting them to plead with Gabriel to show them the shop he bought such an effective pesticide.

The desperate Namala villagers represent 45,000 smallholder farmers engaged in the production of fruits and vegetables, including tomato, in northern Tanzania alone.


NM-AIST is one in a network of the sub-Saharan Africa’s Pan-African Institutions of Science and Technology tasked to train and develop scientists and engineers on the continent. It operates through two major areas of academic and research and innovation and it boasts hosting a number of research centres since its inception seven years ago. These include centres for Research on Agricultural Advancement; Teaching Excellence and Sustainability in Food and Nutritional Security; Water, Infrastructure and Sustainable Energy; Innovative Technology and Energy; Centre of Excellence in ICT in East Africa as well as Cyber Security and Commerce Computing. Each centre strives to attract top graduate and scientists from all over the world to assist it in its mission of teaching, research, supervision and student coaching. It also establishes links with societies and industries for its research to find their ways into application.

Dr Ernest Mbega, one of the supervisors of the PhD candidate, who is in her final year, says the research reflects the NM-AIST slogan, which targets the society and industry.

Upon completion of essential procedures of the research in progress, including registration of the organic pesticide by relevant authorities; mass production and distribution will follow.

Prof Hulda Swai, the director of the African Centre for Research, Agricultural Advancement, Teaching Excellence and Sustainability (Creates), says Ms Mwambela will be kept at NM-AIST for a two-year incubation period to develop a prototype for the pesticide.

“The prototype will then attract investors for mass production of the pesticide,” she explains. The Creates project has in collaboration with the government of Tanzania and the World Bank invested $10,000 in each of 84 NM-AIST students carrying out research on different challenges facing the society.

The five-year project will see 160 Masters and 60 PhD students graduate in their studies. “Ms Mwambela is just the first fruit of the project, the impact of the research of many others students will continue being felt,” Prof Swai says.

We’ve suffered for a great deal ever since the pest invaded the crop in 2014,” Mr Charles Nko, tomato grower at Engarenanyuki Ward in Arusha, Tanzania.

Following the mounting pressure from farmers, the institution will do all it takes to empower Ms Mwambela to fast track regulatory and scientific procedures for the pesticide to reach the farmers in the near future, the NM-AIST Acting Vice Chancellor, Prof Karoli Njau, says.

“We’ve suffered for a great deal ever since the pest invaded the crop in 2014,” says Charles Nko, 56, who has been growing tomato for 24 years before he surrendered it to the pest locally known as Kanitangaze at the Engarenanyuki area.

With a capital of between Sh50,000 and Sh80,000 he used for buying farming implements and paying labourers, Mr Nko used to harvest 120 crates of tomatoes per acre. A 40-kilogram crate of tomato fetched him up to Sh50,000, he recalls.

Upon invasion of the tomato moth, nevertheless, he had to pump in a capital of Sh1.5 million per acre only to harvest barely 50 crates, he regrets.

Ms Afrasion Lema, 50, a mother of five children, is among farmers who successfully used an organic pesticide on trial for killing armyworms on their maize farms at Engarenanyuki Ward in Arusha, Tanzania. PHOTOS | JOE LIHUNDI

However, the pesticide applied at demonstration plots in his area has renewed his hope of growing the crop again once he is assured of its supply.

The Engarenayuki agricultural officer, Mr Solomon Mziray, says owing to good performance of tomatoes on demonstration plots in the ward, farmers are flocking to his office daily, asking for the organic pesticide on trial.

The researcher thought the pesticide would be effective to tomato alone, but farmers themselves have of late proved it to be useful even to maize and cabbage, Mr Mziray says.

“We believe tomato production will resume this season in the ward if the government chips in to support the expert and the NM-AIST in mass production of the pesticide,” he adds.

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