Tuta absoluta, also Tomato Leafminer, is a one of the most destructive crop pests that causes immerse damage on tomato fruits in Kenya. Any tomato farmer who has witnessed the leafminer’s destructive nature will tell you that early tuta absoluta identification is critical for effective control.
But as Purity Kabuba writes in the daily nation “. . . this might be a challenge because the adult moth is only active during the night. In addition, the eggs are only 0.5mm, therefore, it may be difficult to see with naked eyes. ”
Tomato is the main host for Tuta Absoluta but the pest also attacks the following crops:
Biology & Life-stages of the Tomato Leaf-miner
Tuta absoluta belongs to the Gelechiidae family of moths. The larvae of most species in this family (including Tuta absoluta, Tomato pinworm, Potatoe tuber moth and Groundnut leaf miner) ” feed internally on various parts of their host plants, sometimes causing galls “
The underside of tomato leaves, bud stems and calyx of unripe fruits are all perfect breeding locations for the tomato leaf miner; It is at these points where the female moth lays close to 260 tiny eggs .
The eggs stay for seven days before becoming larvae, a stage that can last upto 12 days (this is the most destructive stage) (see figure 1).
Tuta Absoluta eggs are cylindrical and creamy white to yellow or brownish. Eggs are mainly deposited on the underside of leaves. Adult females live for 10 to 15 days while a male lives for 7 to 14 days. The leaf miner’s lifespan is also is determined by temperature variations.
The larvae burrow into the host’s stalk or tunnel on the underside of the leaf. This leads to drying of leaves and early defoliation. Fully-grown larvae fall to the ground in a silken thread and pupate there. Pupation takes ten days and is characterised by a brown color on plant
Indirect tuta damage happens when fungi and bacteria make their way into the damaged fruit, leading to fruit rot.
Spread and movement
Tuta Absoluta is usually spread through seedlings, containers and tomato fruits. Potential introduction points include tomato distribution centers and open-air markets . The pest may also move through Soil and production greenhouses.
Tuta Absoluta Management
Farmers can manage and control Tuta Absoluta in two stages , namely:
- Detection & Identification
- Control methods
The use of insect traps baited with the female-produced sex pheromone is an effective technique to detect and identify the leaf-miner.
These traps can be used for mass trapping and reduce the numbers in a greenhouse , especially when tight doors and insect exclusion nets are used.
As the name implies, mass trapping of Tuta Absoluta involves ” placing a higher number of traps in the crop field in various strategic positions to remove a sufficiently high proportion of male insects from the pest population.” Notably, mass trapping is usually used to complement other control measures such as the use of insecticides.
Some of the effective control methods include crop isolation and planting tomatoes and other crops in greenhouses to leverage technology such as screening vents.
Clean seedlings ensure they are pest free and what was infected, the residue destroyed. Crop rotation will also help with non-host crops.
Other control methods include Sprinkler irrigation and soil solarisation help to control these pests.
There is also Tuta Absoluta Biological control which can be divided into three categories
- Classical biological control
- Augmentative biological control
- Conservation biological control.
Another way to manage Tuta absoluta is by the use of their natural enemies. Egg and larval parasitoids, for example, have proved useful in areas as Colombia. Farmers can also use other tomato pest control methods including;
- Predators such as spiders, wasps, lacewings, and ants
- Growing banker crops and nector plants
- Habitat manipulation