Pseudaulacaspis brimblecombei Williams: Waratah Scale

California Pest Rating for

Pseudaulacaspis brimblecombei Williams: Waratah Scale¹

Hemiptera: Diaspididae

Pest Rating: A

PEST RATING PROFILE

Initiating Event:

Pseudaulacaspis brimblecombei is commonly intercepted by California’s high risk programs and occasionally by dog teams. This armored scale insect is currently assigned a temporary rating of “Q” and is therefore in need of a permanent pest rating.

History & Status:

Background: Pseudaulacaspis brimblecombei is an armored scale insect that typically feeds on the underside of host plant leaves. It is considered a minor pest of macadamia nut production and ornamental proteas¹. Known hosts include Agavaceae: cabbage tree (Cordyline australis¹), mountain cabbage tree (Cordyline indivisa¹); Iridaceae: New Zealand iris (Libertia ixioides¹), Libertia sp.¹; Proteaceae: Chilean firetree (Embothrium coccineum¹), Leucadendron sp.⁴, Leucospermum sp.⁴, river lomatia (Lomatia myricoides¹), Macadamia sp.^1,2, king protea (Protea cynaroides⁴), oleanderleaf protea (Protea nerifolia¹), Protea protea⁴, Protea sp.⁴, Gippsland waratah (Telopea oreades¹), waratah (Telopea speciosissima^1,2), Telopea sp.¹; Rutaceae: wharangi (Melicope ternata¹); Xanthorrhoeaceae: New Zealand flax (Phormium tenax⁴).

Worldwide Distribution: Pseudaulacaspis brimblecombei is native to Australia². From there it has spread to New Zealand² and has been found in greenhouses in Europe³. Interceptions also show that it is present in some plant nurseries and cut flower production sites in Hawaii.

Official Control: Pseudaulacaspis brimblecombei is not known to be under official control in any other states or nations. However, all species of Pseudaulacaspis are listed as quarantine pests by Japan and the Republic of Korea⁵.

California Distribution: Pseudaulacaspis brimblecombei has never been found in the environment of California.

California Interceptions: Between November 24, 2004 and January 5, 2015 Pseudaulacaspis brimblecombei was intercepted 86 times on shipments of cut flowers and nursery stock from Hawaii.

The risk Pseudaulacaspis brimblecombei (waratah scale) would pose to California is evaluated below.

Consequences of Introduction:

1) Climate/Host Interaction: Host plants of Pseudaulacaspis brimblecombei are commonly grown as ornamentals in coastal and southern California. The scale is expected to be able to establish wherever these are grown. Waratah scale receives a Medium (2) in this category.

Evaluate if the pest would have suitable hosts and climate to establish in California. Score:

– Low (1) Not likely to establish in California; or likely to establish in very limited areas.
– Medium (2) may be able to establish in a larger but limited part of California.
– High (3) likely to establish a widespread distribution in California.

2) Known Pest Host Range: Pseudaulacaspis brimblecombei is known to feed on 18 species of plants in 5 families. It receives a Medium (2) in this category.

Evaluate the host range of the pest. Score:

– Low (1) has a very limited host range.
– Medium (2) has a moderate host range.
– High (3) has a wide host range.

3) Pest Dispersal Potential: Scale insects are capable of rapid reproduction and Pseudaulacaspis brimblecombei has demonstrated a propensity to spread long distances on cut flowers and nursery stock. Crawlers may also spread locally by wind or by hitchhiking on clothing, equipment, or other animals. Waratah scale receives a High (3) in this category.

Evaluate the natural and artificial dispersal potential of the pest. Score:

– Low (1) does not have high reproductive or dispersal potential.
– Medium (2) has either high reproductive or dispersal potential.
– High (3) has both high reproduction and dispersal potential.

4) Economic Impact: Pseudaulacaspis brimblecombei is considered a minor pest of macadamia nut production and ornamental proteas¹. There are a few commercial growers of macadamia nuts in southern California who may find their yields reduced by this insect. Proteas are also common in the nursery industry and growers may find their yields reduced as unsightly infested plants may be destroyed. The establishment of waratah scale in California may also increase crop production costs by both macadamia nut and protea producers. California producers of cut flowers and nursery stock may experience disruptions in trade as both Japan and Korea consider species of Pseudaulacaspis quarantine pests⁵. Waratah scale receives a High (3) in this category.

Evaluate the economic impact of the pest to California using the criteria below. Score:

A. The pest could lower crop yield.
B. The pest could lower crop value (includes increasing crop production costs).
C. The pest could trigger the loss of markets (includes quarantines).
D. The pest could negatively change normal cultural practices.
E. The pest can vector, or is vectored, by another pestiferous organism.
F. The organism is injurious or poisonous to agriculturally important animals.
G. The organism can interfere with the delivery or supply of water for agricultural uses.

– Low (1) causes 0 or 1 of these impacts.
– Medium (2) causes 2 of these impacts.
– High (3) causes 3 or more of these impacts.

5) Environmental Impact: Pseudaulacaspis brimblecombei is not expected to lower biodiversity, disrupt natural communities, or change ecosystem processes. The scale is not expected to directly affect any threatened or endangered species or disrupt any critical habitats. Waratah scale may trigger new private treatment programs by producers of macadamia nuts and ornamental proteas and by residents who find infested ornamental plants unsightly. Proteas are common ornamental plants and could be significantly impacted by this insect. Waratah scale receives a High (3) in this category.

Evaluate the environmental impact of the pest on California using the criteria below.

A. The pest could have a significant environmental impact such as lowering biodiversity, disrupting natural communities, or changing ecosystem processes.
B. The pest could directly affect threatened or endangered species.
C. The pest could impact threatened or endangered species by disrupting critical habitats.
D. The pest could trigger additional official or private treatment programs.
E. The pest significantly impacts cultural practices, home/urban gardening or ornamental plantings.

Score the pest for Environmental Impact. Score:

– Low (1) causes none of the above to occur.
– Medium (2) causes one of the above to occur.
– High (3) causes two or more of the above to occur.

**Consequences of Introduction to California for Pseudaulacaspis brimblecombei (Waratah scale): High (13)**

Add up the total score and include it here.

– Low = 5-8 points
– Medium = 9-12 points
– High = 13-15 points

6) Post Entry Distribution and Survey Information: Pseudaulacaspis brimblecombei has never been found in the environment of California and receives a Not established (0) in this category.

Evaluate the known distribution in California. Only official records identified by a taxonomic expert and supported by voucher specimens deposited in natural history collections should be considered. Pest incursions that have been eradicated, are under eradication, or have been delimited with no further detections should not be included.

– Not established (0) Pest never detected in California, or known only from incursions.
– Low (-1) Pest has a localized distribution in California, or is established in one suitable climate/host area (region).
– Medium (-2) Pest is widespread in California but not fully established in the endangered area, or pest established in two contiguous suitable climate/host areas.
– High (-3) Pest has fully established in the endangered area, or pest is reported in more than two contiguous or non-contiguous suitable climate/host areas.

Final Score:

The final score is the consequences of introduction score minus the post entry distribution and survey information score: High (13)

Uncertainty:

Recent surveys for mealybugs on proteas growing in the environment of coastal and southern California would have been likely to detect populations of Pseudaulacaspis brimblecombei but did not find the insect. Nevertheless, based on the large number of interceptions it is likely that some of the scale insects remained undetected and entered California. It is possible that some of these scales could have established in limited areas of California.

Conclusion and Rating Justification:

Pseudaulacaspis brimblecombei has never been found in the environment of California and is likely to have significant economic impacts to the nursery, cut flower, and macadamia nut industries in California. Waratah scale may also have significant environmental impacts by triggering new chemical treatments and damaging ornamental plantings. An “A” rating is justified.

References:

¹SEL Catalog query results: http://www.sel.barc.usda.gov/catalogs/diaspidi/Pseudaulacaspisbrimblecombei.htm

²Miller, Dug, Yair Ben-Dov, Gary Gibson, and Nate Hardy. ScaleNet. http://scalenet.info/validname/Pseudaulacaspis/brimblecombei/

³Malumphy, C. and A.J. Halstead. 2012. First incursions in Europe of four Australasian species of armoured scale insect (Hemiptera: Diaspididae). British Journal of Entomology and Natural History 25(4): 193-197. http://www.cabi.org/isc/abstract/20123419544

⁴California Department of Food & Agriculture Pest Detection Record Database

⁵USDA Phytosanitary Certificate Issuance & Tracking System (PCIT) Phytosanitary Export Database (PExD). https://pcit.aphis.usda.gov/pcit/