Coffee
Coffee Leaf Miner
Leucoptera sp.
Insect
In a Nutshell
- Occurrence of irregular brown spots on the upper leaf surface.
- Appearance of pale yellow trails under coffee leaf epidermis.
- Presence of large necrotic patches.
Can also be found in
Coffee
Symptoms
Initially, mines are formed and later develop over a large surface area leading to large necrotic patches. The larvae are present in the mines and feed on the mesophyll. Leaves become impaired and photosynthesis is unable to take place. Plants become defoliated and eventually die off.
Recommendations
Organic Control
Crop management practices and landscape structure can affect insect communities and the ecosystem services provided by natural enemies, enhancing their diversity and abundance. Ecologically complex coffee systems are associated with a higher biodiversity of parasitoid wasps, ants, and other predators. However, no significant attempt was made to use these natural enemies as biological control. Pheromones can be used to manipulate or disrupt the natural behaviours of insects to reduce population levels.
Chemical Control
Always consider an integrated approach along with preventive measures and available biological treatments. Currently, coffee growers use neurotoxic insecticides, such as organophosphates, carbamates, pyrethroids, neonicotinoids, and diamides. However, chemical controls are insufficient and can lose their effectiveness because their use can lead to pest resistance.
What caused it?
The damage is caused by the larvae of Coffee Leaf Miner (CLM), which only feeds on coffee leaves. The adults mate at night and females lay eggs on the upper surface of coffee leaves. Pre oviposition time is 3.6 days at 20°C. On average, each egg is about 0.3 mm and they are difficult to see with the naked eye. On hatching, the larvae leave the lower side of the eggs that are in contact with the upper leaf epidermis and get into the leaves. The larvae are transparent and reach 3.5 mm in length. The larvae feed on the mesophyll of the leaves and create mines in the leaves. The mines cause necrosis, decreasing the photosynthetic leaf surface. This leads to a lower photosynthetic rate of the plants and a subsequent depletion of the plant. The larval phase has four instars. Larvae leave the mines and weave a silk X-shaped cocoon, usually in the axial region of the leaf, forming the pupae. Usually, more pupae are found in the lower side of the plant where dead leaves accumulate. From pupae, adults emerge with an average body length of 2 mm and a wing span of 6.5 mm. They have white hair scales with long antennae that reach the end of the abdomen and are brownish-white and frilled wings. On the emergence of the adults from the pupae, they mate and lay eggs, restarting the cycle. The incidence of the pest is favoured by dry seasons and high temperatures.
Preventive Measures
- Ideally, the first generation of CLM should be controlled effectively to prevent a growing population throughout the year.
- Practice regular monitoring using the Delta trap to control the insect population.
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