The South American tomato leafminer (Tuta absoluta) is a recently arrived pest in Europe which cannot be ignored. Capable of destroying tomato and other Solanaceae crops, it demands effective control using a wide range of measures, which are outlined in a recently published leaflet in ENDURE’s Training in Integrated Pest Management series.
Controlling Tuta Absoluta , a new invasive pest in Europe , written by researchers at Spain’s IRTA research institute in Cabrils, outlines the range of measures which can be taken to control this tiny moth, which was first found in Spain in 2006 and has since spread around the Mediterranean basin and to countries in both central and northern Europe.
The importance of effectively controlling Tuta absoluta stems from both its rapid reproduction potential (a life cycle of 24 to 76 days depending on environmental conditions, with each female usually producing between 40 and 50 eggs, and sometimes up to 260) and the range of damage it causes. Tomato plants can be infested from seedlings through to mature plants, with the main damage caused to leaves and fruits. In severely infested crops, yield losses can reach 100%.
The leaflet stresses the importance of detecting symptoms early, particularly eggs and small galleries produced by young larvae. The abundance of males on the crop or in the area can be assessed using traps containing sex pheromones.
The authors identify a range of control measures that can be employed. These include cultural methods, such as screening greenhouse vents and installing double-doors, and management of plant material. The latter includes starting with transplants free of the pest and, in cases where pest damage is low, removing any leaves, stems and fruits affected by larvae or pupae and placing them in plastic bags. They stress the importance of not leaving infested material from pruning or weeding on the ground and destroying crop residues as soon as possible after harvesting.
Biological controls can be used, including predatory bugs such as Macrolophus pygmaeus (commercially available as Macrolophus caliginosus ) and Nesidiocoris tenuis which are large consumers of eggs. In the Mediterranean production areas, these two species naturally colonise tomato crops not sprayed with broad spectrum insecticides and are also released in greenhouse tomato crops.
Parasitoids are the most widely used natural enemies of T. absoluta in South America, where the pest originates, say researchers. In Europe, parasitoids have been found parasitising T. absoluta larvae in the Mediterranean area with at least two species of Necremnus identified in Spain and Italy. Regarding parasitoids of T. absoluta eggs, Trichogramma acheae has been identified as a potential biological control agent of the pest and is currently being released in commercial tomato greenhouses.
Researchers say the effectiveness of entomopathogens against T. absoluta is poorly documented, with the exception of Bacillus thuringiensis var. kurstaki, which has been used extensively to control the pest in crops where IPM programmes based on biological control are applied.
Chemical control is difficult, say researchers, because the larvae live inside leaves, fruits and stems. Furthermore, pests such as T. absoluta , with a high reproductive capacity and very short generations, have an increased risk of developing resistance, say researchers. “It is therefore crucial to avoid systematic applications, and only apply treatments according to pest population density and crop damage following the recommendations of advisers,” they write.
They conclude: “To control the pest effectively it is critical to combine all the control measures available and not to rely only on insecticide sprays. It is very important to pay attention to the side effects of pesticides on natural enemies, especially predatory bugs. As these individuals often have a slow establishment process, the insecticide should be selected carefully, especially in the early growth stages of the crop.”
For further information
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|Training in Integrated Pest Management Five: Controlling Tuta absoluta , a new invasive pest in Europe||
Training in Integrated Pest Management Five [pdf - 820.85 kB]
|Book from the ENDURE tomato case study team: Implementation of IPM programmes on European greenhouse tomato production areas||Click here|
|Tomato case study leaflet: Evaluation of Tools to Manage Whiteflies in Europe||
Tomato Case Study Guide Number 1 [pdf - 534.90 kB]
|Consult all ENDURE publications||Click here|