California Pest Rating
Ceroplastes rusci (L.): Fig wax scale
Former Pest Rating: A
CURRENT Pest Rating: A
February 26, 2014, USDA distributed a Deregulation Evaluation of Established Pests (DEEP) report proposing to change the status of Ceroplastes rusci, fig wax scale, from actionable to non-actionable for the continental United States. The scale would remain actionable for Hawaii and the Pacific territories. The insect is currently assigned a rating of “A” by CDFA, so a pest rating proposal is needed to determine future direction.
History & Status:
Background: Ceroplastes rusci is considered a serious pest of fruit trees in many countries2. Fig wax scale feeds by inserting its stylet into host leaves, shoots, and fruit2. Heavy infestations of the scale cause yellowing, loss of foliage, and poor fruit set2. The scale is polyphagous, feeding on a wide variety of plants in at least 48 families1. Economically important hosts include almond, grape, citrus, pistachio, avocado, cotton, fig, palms, pear, and many ornamentals. Ceroplastes rusci can move long distances through the shipment of infested palm trees as well as other host plants and plant parts.
Worldwide Distribution: Ceroplastes rusci is thought to be native to tropical Africa2. From there it has spread to parts of the Caribbean, Europe, southwestern Asia, Vietnam, and southern South America1. The scale has been known to be in Florida since 19941.
Official Control: Ceroplastes rusci is considered a quarantine pest by Australia2 and probably other nations. The USDA proposal also recommends that it remain a quarantine pest for Hawaii.
California Distribution: Ceroplastes rusci has never been found in the environment of California.
California Interceptions: Ceroplastes rusci is regularly intercepted by California, most often on palm nursery stock from Florida.
The risk Ceroplastes rusci (Fig wax scale) would pose to California is evaluated below.
Consequences of Introduction:
1) Climate/Host Interaction: The present distribution of Ceroplastes rusci corresponds to USDA plant hardiness zones 8-13. This indicates that the scale would be able to establish a widespread distribution over most of California. The polyphagous nature of the scale makes it likely to encounter suitable hosts throughout this area. Ceroplastes rusci receives a High(3) in this category.
Evaluate if the pest would have suitable hosts and climate to establish in California. Score: 3
– 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: Ceroplastes rusci feeds on a wide variety of plants in at least 48 families. The scale receives a High(3) in this category.
Evaluate the host range of the pest. Score: 3
– 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 have high reproductive potential. Fig wax scale frequently moves long distances in the trade of infested palm trees and other host plant products. Ceroplastes rusci receives a High(3) in this category.
Evaluate the natural and artificial dispersal potential of the pest. Score: 3
– 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: Ceroplastes rusci feeds on many economically important crops where it has the potential to reduce fruit set2, lowering crop yield. The scale is likely to increase production costs in the nursery and fruit industries and lower the value of nursery stock by disfiguring plants with its presence. Fig wax scale is treated as a quarantine pest by Australia and possibly other nations. The USDA proposal also recommends that the scale remain actionable in Hawaii. This has the potential to trigger a loss of markets, especially for California’s fresh fruit exports. Fig wax scale can also vector plant viruses2. Ceroplastes rusci receives a High(3) in this category.
Evaluate the economic impact of the pest to California using the criteria below. Score:
Economic Impact: A, B, C, E
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.
Economic Impact Score: 3
– 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: Ceroplastes rusci is not expected to lower biodiversity, disrupt natural communities, or change ecosystem processes. There are no threatened or endangered plants in California that are likely to be host species. Fig wax scale is not expected to disrupt critical habitats. The scale may trigger additional treatment programs in the nursery and fruit industries and by residents who find infested plants unsightly. It is not expected to significantly impact cultural practices, home/urban gardening, or ornamental plantings. Ceroplastes rusci receives a Medium(2) in this category.
Evaluate the environmental impact of the pest on California using the criteria below.
Environmental Impact: D
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.
Environmental Impact Score: 2
– 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 Ceroplastes rusci (Fig wax 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: Ceroplastes rusci has never been detected 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.
The final score is the consequences of introduction score minus the post entry distribution and survey information score: High(14)
There have been no formal surveys for Ceroplastes rusci and it is frequently intercepted on palms, so there could be localized populations of the scale within the state.
Conclusion and Rating Justification:
If Ceroplastes rusci were to enter and establish in California it would find many of our high-value crops to be suitable hosts including almond, grape, citrus, pistachio, avocado, cotton, fig, palms, pear, and many ornamentals. The scale is likely to have significant impacts on these crops including lower yield, increased production costs, lost markets in Hawaii, Australia and other nations, and increased plant pathogen transmission. Environmental impacts of the scale are expected to be limited to increased treatments by residents and in the nursery and fruit industries. An A-rating is justified.
1Culliney, T.W. 2014. Deregulation Evaluation of Established Pests (DEEP); DEEP Report on Ceroplastes rusci (L.): Fig wax scale.
2Vu, Nga Thi, Rod Eastwood, Chat Thi Nguyen, and Lam Van Phan. 2006. The fig wax scale Ceroplastes rusci (Linnaeus) (Homoptera: Coccidae) in south-east Vietnam: Pest status, life history and biocontrol trials with Eublemma amabilis Moore (Lepidoptera: Noctuidae). Entomological Research 36: 196-201. http://www.oeb.harvard.edu/faculty/pierce/people/eastwood/resources/pdfs/Ceroplastes-2006.pdf
Jason Leathers, 1220 N Street, Sacramento, CA, 95814, (916) 654-1211, plant.health[@]cdfa.ca.gov.
Comment Period: CLOSED
12/21/2016 – 2/4/2017
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