California Pest Rating for
Acanthococcus lagerstroemiae (Kuwana): Crapemyrtle Scale
Synonym: Eriococcus lagerstroemiae
Pest Rating: A
PEST RATING PROFILE
In July 2015 the United States Department of Agriculture (USDA) inquired about California’s position on deregulating Eriococcus lagerstroemiae (Acanthococcus lagerstroemiae). A pest rating proposal is required to determine a permanent pest rating.
History & Status:
Background: Acanthococcus lagerstroemiae is a scale insect that feeds on the branches, twigs, trunk, stems, and leaves of its host-plants1. It also feeds on the fruit of persimmon1. Heavy infestations of the scale are not known to be fatal to trees but they do have significant aesthetic impacts that often lead to host removal1. Layers of the scale on plants lead to extensive honeydew deposits, growth of sooty mold, dieback, decline, and decrease in the number and size of flowers1. The sooty mold turns trunks, leaves, and twigs charcoal black1. Known hosts of the scale include: Buxaceae: Korean boxwood (Buxus microphylla koreana2); Combretaceae: axlewood (Anogeiussus latifolia2), Anogeiussus sp.2; Ebenaceae: persimmon (Diospyros kaki2); Euphobiaceae: food wrapper plant (Mallotus japonicas2), needlebush (Glochidion puberum2); Fabaceae: Dalbergia sp.2, soybean (Glycine max2); Lythraceae: crapemyrtle (Lagerstroemia indica2); Japanese crapemyrtle (Lagerstroemia japonica2), giant crapemyrtle (Lagerstsoemia flosreginae2); Moraceae: fig (Ficus carica2); Myrtaceae: Myrtus sp.2; Oleaceae: border privet (Ligustrum obtusifolium2); Punicaceae: pomegranate (Punica granatum2); Rosaceae: paradise apple (Malus pumila2); Chinese quince (Pseudocydonia sp.1); Rubus sp.; Ulmaceae: Chinese hackberry (Celtis sinensis). The primary hosts are considered to be crapemyrtle, persimmon, Chinese quince, and pomegranate1. Acanthococcus lagerstroemiae may be transported long distances when infested plants or fresh plant parts are moved.
Worldwide Distribution: Acanthococcus lagerstroemiae is native to China, India, Japan, South Korea, and possibly Mongolia1. It was found in Texas in 2004. Since then it has spread throughout eastern Texas and to four counties in Arkansas, seven in Louisiana, five in Oklahoma, one in Tennessee, one in Virginia, and one in Mississippi1.
Official Control: Acanthococcus lagerstroemiae is not known to be under official control in any other states or nations3. However, the USDA proposal would keep the scale actionable in Hawaii1.
California Distribution: Acanthococcus lagerstroemiae has never been found in California.
California Interceptions: Acanthococcus lagerstroemiae has never been intercepted by CDFA.
The risk Acanthococcus lagerstroemiae (Crapemyrtle scale) would pose to California is evaluated below.
Consequences of Introduction:
1) Climate/Host Interaction: Acanthococcus lagerstroemiae is expected to establish throughout plant hardiness zones 6-101. This corresponds to almost all of California. Host plants of the scale are grown throughout the state as ornamentals and crops. Crapemyrtle scale is likely to establish a widespread distribution in California and receives a High (3) 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: Acanthococcus lagerstroemiae is known to feed on a variety of plants in twelve families, many of which are widely cultivated in California. 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: Acanthococcus lagerstroemiae has 2-4 generations per year and each adult female lays an average of 220 eggs1. The scales may disperse long distances when infested plants or fresh plant parts are moved. They may also be spread by wind or by hitchhiking on plants, animals, or equipment. Crapemyrtle 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: In Asia Acanthococcus lagerstroemiae is the major pest of crapemyrtle trees, and is also a serious pest of pomegranate and persimmon trees. If this scale insect were to establish in California it is expected to lower yields in pomegranate and persimmon groves. It is also likely to lower the value of persimmon fruit and all host nursery stock. Since the USDA has proposed to keep crapemyrtle scale actionable in Hawaii, this scale is also likely to disrupt markets for California fruit and nursery stock if it were to establish in the state. Crapemyrtle scale is not expected to change cultural practices, vector other organisms, injure animals, or interfere with water supplies. Acanthococcus lagerstroemiae 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: If Acanthococcus lagerstroemiae were to establish in California it is not likely to lower biodiversity, disrupt natural communities, or change ecosystem processes. It is not likely to directly affect threatened or endangered species or disrupt critical habitats. It is very likely to trigger new treatment programs in orchards and by residents who find infested plants unsightly. Crapemyrtle, pomegranate, and persimmon trees are common ornamentals in California and are likely to be significantly affected by this pest. Many of the host trees have been removed from areas in Texas where the scale has established1. Crapemyrtle 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 Acanthococcus lagerstroemiae (Crapemyrtle Scale): High (14)
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: Acanthococcus lagerstroemiae has not been found in California. The severe aesthetic impacts attributed to infestations of the scale and ease of detection since it is the only bark scale known to occur on crapemyrtle1 make it unlikely that this pest is present anywhere in California. Crapemyrtle scale 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.
The final score is the consequences of introduction score minus the post entry distribution and survey information score: High (14)
It is possible that this scale could colonize additional host plants in California.
Conclusion and Rating Justification:
Acanthococcus lagerstroemiae has not been found in California and it is expected to have significant economic and environmental impacts if it were to establish in the state. An “A” rating is justified.
1 Miller, Leah. 2015. NPAG Report Eriococcus lagerstroemiae Kuwana: crapemyrtle scale. New Pest Advisory Group (NPAG).
2 SEL Catalogue Query Results/ScaleNet: Acanthococcus lagerstroemiae (Kuwana). http://www.sel.barc.usda.gov/catalogs/eriococc/Acanthococcuslagerstroemiae.htm
3 USDA Phytosanitary Certificate Issuance & Tracking System (PCIT) Phytosanitary Export Database (PExD). https://pcit.aphis.usda.gov/pcit/
Jason Leathers, 1220 N Street, Sacramento, CA, 95814, (916) 654-1211, plant.health[@]cdfa.ca.gov.
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Pest Rating: A
Posted by ls