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Athalia rosae (L.)
Athalia colibri (Christ)

Insecta, Hymenoptera, Tenthredinidae .

Coleseed saw-fly

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

- Adult: length 6 to 8 mm (*) . The male is smaller than the female. The hind part of the body is yellowish to yellowish-orange. The head and sides of the thorax are shiny black. The transparent wings have a darker front edge. There is no visible narrowing between the thorax and the abdomen.
- Larva: length 16 to 18 mm. The skin is wrinkled, and dotted with several small papillae. Recently hatched larvae are pale grey to greenish in colour, older larvae change colour to become dark green to black on the back and grey on the ventral surface.
The head capsule is shiny black. In addition to the three pairs of thoracic legs, the larva has 7 pairs of ventral abdominal prolegs and an anal pair (*) .
- Egg: laid in a small cell made by the female with the oviscapt on the edge of a leaf (*) .

- Adult: emerges in May and June, leaves the ground and mates on the same day. Egg laying commences a few days later. After feeding, the females laterally incise the leaves in a sawtooth pattern and deposit their eggs one by one in the small chambers, constructed for preference on yellow leaves. Fecundity of the females is approximately 300 eggs.
- Egg: embryonic development lasts 6 to 8 days. Unfertilized eggs produce male larvae.
- Larva: at 20°C, the larvae consume twice their own weight in 24 hours. After moulting, the exuviae remain on the leaf. Pupation occurs after 10 to 13 days in the upper layers of the ground at a depth of 1 to 5 cm, inside a cocoon.
The final larval stage hibernates underground in a cocoon.

[R]Life Cycle
- There can be up to 3 generations per annum.
- In July-August, the second sawfly generation appears and lays its eggs on plants grown as green manure and fodder crops. Under favourable weather conditions, a third generation occurs, causing damage to winter rape.
Wind-assisted, this sawfly is able to undertake long migratory flights.
- A low percentage of the population may enter diapause at the pupal stage.
- The young larvae strip the underside of leaves or make holes in them (economic damage insignificant), whereas older larvae, dark in colour, eat the leaves from the underside and from the edge, leaving only the veins (skeletization) (*) .
In the event of swarming, total defoliation may occur (*) .
- On Sinapis alba, the oldest larvae also devour the pods.

Spread from Europe to the Far East (Korea), North and South Africa and also North America.

[R]Common Names
DE: Kohlrübenblattwespe, Rübsenblattwespe ES: Oruga de los nabos FR: Tenthrède de la rave IT: Tentredine delle crucifere PT: Atália do nabo GB: Coleseed sawfly, Turnip sawfly

[R] Images

  1. Athalia rosae (L.) (Coutin R. / OPIE)
    Adult Female about to lay eggs on leaf of rape.
  2. Athalia rosae (L.) (Coutin R. / OPIE)
    Egg-laying The female is cutting the edge of the leaf to insert its eggs (arrowed).
  3. Athalia rosae (L.) (Coutin R. / OPIE)
    Young larvae on turnip
  4. Athalia rosae (L.) (Coutin R. / OPIE)
    Larva Typical resting posture of final-instar larva.
  5. Athalia rosae (L.) (BASF)
    Larval infestations and damage
  6. Athalia rosae (L.) (BASF)
    Damage to rape

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HYPPZ on line : Species (scientific name), Pests (common names), Glossary, Crops.

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