BY SAMIRA ABUELGASIM MOHAMED-ICIPE
August 17,2016, Nairobi. The South American moth, tomato leafminer, Tuta absoluta is a major threat to tomato production. In its trans-Atlantic invasion the pest was first detected in Spain and quickly spread across the region becoming the prime pest of tomato in many parts of the Eurasian and African continents.
In Africa, the pest is swiftly moving southwards, and this is facilitated by the continuous vegetable cultivation across political borders, absence of effective surveillance mechanisms and the lack of phytosanitary expertise for interception of infested vegetables, coupled with the ever-growing tourism and increasing intra-continental trade which is making the invasion of the entire continent by T. absoluta grievous threat.
This is further compounded by the lack of efficient natural enemies to combat this pest in Africa. In Kenya, the pest was first detected at Mpeketoni in March 2014 during surveillance activity carried out jointly by the international Centre of Insect Physiology and Ecology and Kenya Plant Heath Inspectorate Service.
Infestation of tomato by T. absoluta often results in significant reduction in yield and quality of the fruits. Fruits can be attacked soon after formation and the galleries left by feeding larvae provide opportunities for the development of secondary pathogens leading to fruit rot. Beside the direct losses on fruit quality and quantity, indirect losses are associated with quarantine restrictions imposed by importing countries to prevent the entry and establishment of T. absoluta.
Following the invasion and wide spread of this in Kenya, tomato yield losses of up to 100% have been reported in all the counties where the pest have been detected, threatening tomato production and export, thus affecting the livelihood of millions of tomato growers and others stakeholders along the tomato value chain, most of them women. Furthermore, the pest is also a threat to important African indigenous vegetable such as night shade.
For management of this pest the Kenyan tomato growers have resorted to the use of broad spectrum insecticides to combat the exploding populations of this pest that negatively impacted on the natural enemies’ population and biodiversity at large. Moreover, the South American experience showed that T. absoluta has developed resistance to several classes of synthetic insecticides such as organophosphates and pyrethroids.
The International Center of Insect Physiology and Ecology, Nairobi, Kenya, under a BMZ funded project and in collaboration with national and international partners in Europe and South America, has identified a potent fungal isolate which is currently in its final stage of testing for potential use as a bio-pesticide for management of this pest. In collaboration with one of the international partner, The International Potato Center (CIP), Lima, Peru, we are introducing an efficient parasitoid for classical biological control of this pest.
Additionally, and in collaboration with the same partner we are developing a novel attract and kill product for control of this pest.
Although icipe is developing an eco-friendly IPM approach to combat this pest (as described above). Currently we advise the famers to;
(1) Use the commercially available Tuta absoluta male lure for mass trapping.
(2) Practice extensive field and green house sanitation.
(3) Destroy plant residues after the end of tomato harvesting.
(4) Avoid continuous planting of tomato and other solanous vegetable in the same field.
(5) Remove alternative wild host plants from and around tomato field and green house.
(6) Use double door for green house and ensure it is insect proof.
(7) Practice extensive field and green house sanitation.
(8) Avoid movement of fruits and other planting materials from infested to other areas.
(9) Monitoring Tuta absoluta using Tuta pheromone baited delta trap.
However, these management approaches have to be employed on an area-wide scale for best suppression of the pest. Also, extension and quarantine officers need to be trained on bio-ecology and various management options of the pest. In addition, there is an urgent need to create awareness among tomato and other vegetable growers on the economic importance of this pest and the threat it poses to tomato production.