Forest Pests: Insects, Diseases & Other Damage Agents

Csóka, György (2003): Levélaknák és levélaknázók - Leaf mines and leaf miners. Hungarian Forest Research Institute. Erdészeti Turományos Intézet, Agroinform Kiadó, Budapest, 192 pp.

Feeding inside a mine evidently means protection from many points of view. This protection is efficient mainly against abiotic factors. Leaf miners larvae will not be washed down by rain or blown out by wind. The microclimate within the leaf tissues decreases the risk of desiccation, the leaf's epidermis protects against the harmful UV radiation.

Feeding within the leaf tissue can provide a selective diet minimising the negative effects deriving from the host's defence.

Larval life of most leaf mining species is tightly tied to one single leaf. This fact brings significant disadvantages into the picture. The leaf miner's larva due its restricted mobility is more vulnerable to natural enemies. This fact is believed to be the main reason of the usually high parasitoid caused mortally among leaf miners compared to free feeders.

Leaf mining nearly always means a very close, intimate relationship between plant and insect. Therefore most of the leaf miners can live only on one or a few closely related plant species. Therefore hosts shifts common among free feeders are very rare among leaf miners. If the given plant species becomes rare or less abundant because of some reason, the food source of a leaf miner can decrease significantly.

The fate of a leaf miner larva is strongly depends on the mother's choice, whether she choose good or bad location. Breaking down the branch or the falling down the leaf before maturation likely causes death of the larva, contrary to free feeders which can easily move to a new leaf. Most of the leaf miner larvae can not even move to a new leaf when free feeders chew the leaf, not rarely together with the mines.

Feeding inside the leaf tissue restricts the body size ab ovo. Leaf miners are regularly very small. The leaf mining moths for example are the midgets of their order. Wingspan of some species hardly reaches the 3 mm. The small body size usually means shorter life span, restricted dispersal ability and higher vulnerability to the environment.

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