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Prays oleae Bernard
Prays oleellus F.

Insecta, Lepidoptera, Plutellidae .

Olive kernel borer, Olive moth

Description, Biology, Life Cycle, Damage, Common Names, Images


[R]Description
- Adult: length 6-7 mm. Fore wings grey with silvery tone and small scattered dark spots. Hind wings are of uniform grey with frayed margins. Grey scales with a silvery tones cover the body and legs (*) .
- Egg: Sub-ovate, flat somewhat convex; length 0.5 mm. Immediately after laying eggs are whitish (*) becoming darker later as the embryo grows. They turn yellow if aborted.
- Larva: General colour green with light brown tones (*) ; maximum length 7-8 mm by 1.5 mm width.
- Pupa: the pupa is enclosed by a whitish lightly built cocoon of silk threads and measures about 6 mm by 2 mm. It is brown, elongate, sub-coniform with tapered distal end.

[R]Biology
- Host plants: olive, filaria Phillyrea spp., privet Ligustrum spp., jasmine.
- Adults: The species passes the winter period as a miner larva in the leaves. Adults emerge from pupae found on the outside of the mines but protected by leaves held together by silk threads. Sometimes pupae are found in cracks and crevices in the trunk and branches. Adult life-span depends on the generation and the prevailing weather conditions: 15 to 24 days is the rule but it may attain extend to 45 ays. Each female can lay more than 250 eggs but 100 is more usual.
Oviposition starts immediately after mating, the number of eggs laid per day increasing until the 5th day and then decreasing.
- Eggs: The site of oviposition varies with the generation: on the calyxes of the floral buds held together by silk threads; on the fruitlets when they begin to grow or on the leaves.
Incubation takes 5 days at 25░C but usually takes 8 days.
- Larvae: According to the generation the larvae grow among the calyxes of the floral buds, held together by silk threads, inside the fruit stone or as miner in the leaves. During their development larvae pass through 5 instars over 3 to 4 weeks or over several months as is the case with the larvae living as miners in the leaves.
- Pupa: The pupal phase takes place in a cocoon formed among the flower debris and twigs. It may occur in cracks and crevices in the trunk protected by woody particles or in the soil. Life-span: 10-15 days.

[R]Life Cycle
- Three yearly generations are typical of this species. Each one is associated during the larval stage to different parts of the host.
The adults of the 3rd generation or winter generation, appear in April-May usually coinciding with the swelling of the floral buds. First-generation larvae attack the flower buds. The 2nd-generation larvae grow inside the olive stone kernels. The 3rd-generation larvae are leaf miners.

[R]Damage
- The type of damage depends on the attacked tissue. The damage (leaf drop) done by the leaf or winter generation (phyllophagous) is seldom serious (*) .
On the contrary damage caused by the flower (anthophagous) generation can be important. These larvae directly destroy the flowers or cause the abortion of the flower bunches covered by silken threads spun by the larvae when passing from one bud to the next (*) .
The fruit (or carpophagous) generation larvae cause the premature drop of the fruits when they bore into the kernel of the olive fruit or later when they try to vacate the fruit to pupate (*) .


[R]Common Names
DE: Olivenmotte ES: Pollila del olivo FR: Teigne de l'olivier IT: Tignola dell'olivo PT: Traša da oliveira GB: Olive kernel borer, Olive moth

[R] Images

  1. Prays oleae (Bernard) (BASF)
    Mines produced by larvae on leaves of olive
  2. Prays oleae (Bernard) 2nd larva generation devouring an olive leaf (Arambourg Y. / INRA Antibes)
  3. Prays oleae (Bernard) Moth on olive tree (Arambourg Y. / INRA Antibes)
  4. Prays oleae (Bernard) Egg laid in contact with olive flower buds (Arambourg Y. / INRA Antibes)
  5. Prays oleae (Bernard) Damage on an olive tree The 1st generation larvae consume all the flowers in succession, coating them with silky threads.
  6. Prays oleae (Bernard) Damage on olive fruitlets Caused by the 3rd generation larvae. The central section is destroyed.

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