Description, Biology, Life Cycle, Damage, Common Names, Images
- A highly polyphagous insect, reported on more than 120 plant species.
Attacks numerous vegetable plants: celery, tomato capsicum, melon, onion, leek, mangold, potato, pea, and various ornamental plants, mostly in glasshouses, particularly gerbera (*) .
- The larva lives by mining leaves (*) and passes through 3 larval instars. Once fully developed, the larva usually cuts a half-moon-shaped opening in the upper epidermis of the leaf, escapes and pupates (*) , usually in the soil; in the case of a particularly severe infestation, the puparium may remain on the leaf near to the entrance to the gallery.
Adults feed on flower nectar and liquids oozing from lesions on the leaves caused by females using their oviscapt.
The pre-imaginal cycle length varies depending on the temperature and the host plant.
The larval phase of the cycle is very brief at optimum temperatures: 4 days at 30°C and 7 to 8 days at 20°C. 1 to 2 weeks elapse between pupating and adult emergence (at 30 and 20°C, respectively).
Adults may live for 15 to 30 days, females living longer than males.
Development ceases at temperatures lower than 7.5 or 12.9°C, depending on the stage and the host plant; the optimum temperature is around 25°C; above 30°C, larval mortality increases.
The main damage is caused by larvae mining the leaves; it is particularly severe in nursery or recently transplanted seedlings, which may die.
Older plants more readily tolerate attacks by this pest. However, if the infestation is severe, photosynthetic capacity is reduced, thus causing a slowing in the development of flowers and fruits.
On ornamental plants, damage may be due both to larvae and to adult females piercing the leaves to lay their eggs; many countries do not accept the importing of plants or cut flowers with a single blemish.
In North America, this leaf miner is particularly harmful to chrysanthemums and celery; in France and the Netherlands it mostly attacks tomato, while in Italy, gerbera is most frequently damaged.
Biological control of this pest has become common practice; in France, the Netherlands and the United Kingdom, the entomophagous insect Diglyphus isaea is commercialized for glasshouse use (tomato).
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