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Top Shoot Borer

Scientific Name
Scirpophaga excerptalis
Scientific Author
Walker, 1863
Taxonomy
(Lepidoptera:Crambidae)
Status
Exotic species - absent from Australia
Reliability
High
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Diagnostic Images

Adult male
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Caption
Gusap Madang Prov. B. Rutu 24.vii.1996 PNG
Source
S. Anderson DAFF Biosecurity
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Diagnostic Images (15)
Diagnostic Notes
Common symptoms of infestation are the appearance of parallel rows of ‘shot holes’ on leaves, a red streak caused by mining the inside of the midrib, dead hearts and a bunchy top appearance of shoots (Arora 2000).

The young larvae tunnel through the unexpanded leaves and cause a series of parallel horizontal holes to appear across the blade of the unfolded leaf (Sallam et al 2010). More mature infested plants show irregular, yellow patches on the underside of leaves. The larvae attack the growing point and continue to tunnel into the main stem of the plant. The 3rd generation causes the highest losses in cane yield, sucrose and commercial sugar (Sallam & Allsopp 2003).

Scirpophaga excerptalis lay their eggs in masses on the lower surface of sugarcane leaves covering their eggs with hairs from their orange red anal tufts. Young larvae enter the midrib of the first leaf and tunnel from the lower epidermis to emerge through the upper epidermis. Usually only one larvae survives due to food competition in the growing point of the stem (Sallam & Allsopp 2003).

Head with the frons smooth; labial palpi porrect, about 1.5 times the diameter of the compound eye, sometimes slightly longer but never more than twice the diameter of the eye; ocelli small and present; antennae simple in both sexes, profusely ciliated in males, sparsely in females, about half the length of forewing-costa in males and two-fifths the length females.

Forewing

Vein R1 anastomised fully with Sc, arising almost in line with Cu1b below; R2 a little before upper angle of cell; R3 + R4 stalked, the stalk generally shorter than R4 which is longer than R3; R5 from below the upper angle of cell; M1 below R5; M2-M3 very close to each other but not connate; Cu1a slightly before lower cell angle, close to M3 and in line with the origin of R2 above; Cu1b from before the cell angle and Cu1a.

Hindwing

Sc free till about cell angle, beyond which it is anastomised with Rs for halfway toward margin; M1 from cell angle; M2-M3, Cu1a, Cu1b as in forewing; frenulum single in both sexes (Arora 2000).

♂ head with the frons white, labial palpi white, sometimes suffused with fuscous; antennae generally dark. Thorax upper side white, underside pale ochreous, suffused with fuscous; legs generally white on inner side, fuscous on outer side generally throughout up to claws, particularly on forelegs, fuscous suffusion sometimes reduced in tibia of mid- and hind legs. Abdomen white on upper side, pale ochreous on underside. Wings slightly shining white on upper side, pale ochreous on underside, sometimes suffused with fuscous, without or with a dark prominent spot at lower angle of cell in forewing.

♀ as in male but legs are more shining white, with less of fuscous suffusion on underside. Anal tufts brilliant orange-red.

Genitalia

♂ uncus moderately long, gnathos slightly wrinkled at apex; subteguminal process a long spine; valva expanded distally; manica with 2 sclerotized bands, at one end bearing a group of spines; aedeagus slender, vesica with coarse spines.

♀ ostium bursae broad, wrinkled, strongly sclerotized, lined with spines; ductus bursae membranous; corpus bursae with dense spines (Lewvanich 1981).

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More Information
Specimen Contact
DAFF Biosecurity Darwin
Author
S. Anderson & L. Tran-Nguyen
Created
24/02/2012 11:47 AEST
Last Updated
24/02/2012 19:21 AEST
Citation
S. Anderson & L. Tran-Nguyen (2012) Top Shoot Borer (Scirpophaga excerptalis) Updated on 2/24/2012 7:21:31 PM Available online: PaDIL - http://www.padil.gov.au.
Image Use
Free for use under the Creative Commons Attribution 3.0 Australia License

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