Damage based identification key for endophagous herbivores on Common Reed (Phragmites australis) |
 |
|||||
| Author:
Patrick Häfliger © |
CABI
Europe - Switzerland, Rue des Grillons 1, CH-2800 Delémont |
|||||
|
||||||
| The
Twin-Spotted Wainscot Archanara geminipuncta (Haworth) (Lep.: Noctuidae) |
|||||||||
|
|||||||||
Biology: Larvae hatch between mid-April and mid-May. Right after hatching, larvae move to a young shoot and enter through an internode in the middle of the stem. At the beginning of their development up to 7 larvae can live together in the same shoot. Larvae of the twin-spotted wainscot molt five times, mining in 3 to 4 shoots before pupating in June/July in shoots. After the first change of shoot, only one larva per shoot can be found. Adults emerge between mid July and mid August, and live for one to two weeks. Females lay up to 240 eggs in rows under the leaf sheaths of common reed shoots (picture 47). Description: Larva up to 4.7 cm long; larval body whitish with several black spots on each segment; head capsule and parts of the neck shield and anal plate dark-brown/black (picture 52). Pupa 17 to 24 mm long, reddish-brown, head upwards. Adults brown winged, with two white spots on the forewings (picture 40). Feeding pattern/damage: Freshly hatched larvae enter an internode in the middle of a shoot and at this entry point sever the shoot tip from the base within 24 hours (picture 67). Afterwards, the first three instars feed only above the growing point. Often not only the shoot tips but also the entire shoots are killed. Such shoots are all smaller than 1 m and can be recognized by a tiny entrance hole (0.4-0.5 mm wide) on an internode, the distinct severance of the internode with the entrance hole right above a node, and a 1-1.3 mm wide exit hole above the growing point. However, the tip is often broken off above the severance. Feces can only be found above the growing point. From the first change of shoot in the third instar onwards, larvae feed also in the upper shoot internodes which are partly packed with feces. The shoot tips are distinctly dead (picture 6), but shoots often develop sideshoots on 1-4 nodes below the damage. Exit holes are always above entrance holes. Holes made by mature larvae are 2-2.5 mm wide. A plugged entrance hole nearly 2 mm wide and an emergence window (6x3 mm) prepared by the larva indicate the presence of a pupal chamber (picture 59). Pupae can be found head upwards in undamaged internodes of lower shoot parts of both damaged and undamaged shoots (minimum base diameter 5 mm). Damage caused by the twin-spotted wainscot is very similar to that of the other three stem-mining wainscots. Distribution: Europe References: Bretherton et al., 1983; Tscharntke, 1990; Häfliger et al., 2006 |
|
||||||||
| 2/04/07 | webmaster webdesign k.i.s.s. helmut recher |
© CABI Europe - Switzerland |