Defoliation of Melaleuca rhaphiophylla by native Sawflies ... · Defoliation of Melaleuca...

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Defoliation of Melaleuca rhaphiophylla by native Sawflies on Peaceful Bay Road, 28 February 2019 Allan Wills Department of Biodiversity, Conservation and Attractions, Locked Bag 2 Manjimup 6258. Predisposing conditions: Narrow remnant edge of vegetation adjacent to pasture and road with marked ecotonal changes across short distances. Some nutrient enrichment from pasture? Brackish? shallow water table. Prognosis: Naturally occurring Pterygophorinae sawfly which are phytovores on Melaleuca spp.have escaped normal population controls such as parasitoids and are causing defoliation of Melaleuca rhaphiophylla. M. rhaphiophylla is an important component of biomass cover on this Irwin Inlet margin and chronic extensive loss of tree cover may lead to opportunities for weed incursion into the conservation estate on the east side of the Peaceful Bay road. This defoliation needs further monitoring.

Transcript of Defoliation of Melaleuca rhaphiophylla by native Sawflies ... · Defoliation of Melaleuca...

Page 1: Defoliation of Melaleuca rhaphiophylla by native Sawflies ... · Defoliation of Melaleuca rhaphiophylla by native Sawflies on Peaceful Ba y Road, 28 February 2019 . Allan Wills .

Defoliation of Melaleuca rhaphiophylla by native Sawflies on Peaceful Bay Road, 28 February 2019

Allan Wills

Department of Biodiversity, Conservation and Attractions, Locked Bag 2 Manjimup 6258.

Predisposing conditions:

Narrow remnant edge of vegetation adjacent to pasture and road with marked ecotonal changes across short distances. Some nutrient enrichment from pasture? Brackish? shallow water table.

Prognosis:

Naturally occurring Pterygophorinae sawfly which are phytovores on Melaleuca spp.have escaped normal population controls such as parasitoids and are causing defoliation of Melaleuca rhaphiophylla. M. rhaphiophylla is an important component of biomass cover on this Irwin Inlet margin and chronic extensive loss of tree cover may lead to opportunities for weed incursion into the conservation estate on the east side of the Peaceful Bay road. This defoliation needs further monitoring.

Page 2: Defoliation of Melaleuca rhaphiophylla by native Sawflies ... · Defoliation of Melaleuca rhaphiophylla by native Sawflies on Peaceful Ba y Road, 28 February 2019 . Allan Wills .

Location of defoliation: Along Peaceful Bay Road adjacent to Irwin Inlet

<< Location of defoliation

Page 3: Defoliation of Melaleuca rhaphiophylla by native Sawflies ... · Defoliation of Melaleuca rhaphiophylla by native Sawflies on Peaceful Ba y Road, 28 February 2019 . Allan Wills .

Symptoms: About 30% of Melaleuca rhaphiophylla trees affected by almost complete defoliation

Page 4: Defoliation of Melaleuca rhaphiophylla by native Sawflies ... · Defoliation of Melaleuca rhaphiophylla by native Sawflies on Peaceful Ba y Road, 28 February 2019 . Allan Wills .

Causal Agent: Pterygophorinae sawfly larvae.

Page 5: Defoliation of Melaleuca rhaphiophylla by native Sawflies ... · Defoliation of Melaleuca rhaphiophylla by native Sawflies on Peaceful Ba y Road, 28 February 2019 . Allan Wills .

Intact leaves:

Regenerating axillary buds: