California Pest Rating for
Vryburgia succulentarum Williams: mealybug
Pest Rating: A
PEST RATING PROFILE
Vryburgia succulentarum is currently Q-rated. A permanent pest rating proposal is required to support an official pest rating.
History & Status:
Background: Vryburgia succulentarum is a mealybug that occurs on succulent plants. Adult females reach 3.1 mm in length (Williams, 1985). This mealybug has been found on, and presumably feeds on plants in the families Aizoaceae, Cactaceae, and Crassulaceae (García Morales et al., 2016; Moghaddam, 2015; Williams, 1985). Little else is known about the biology of this species. Most Vryburgia species are native to Africa and are associated with succulent plants (Li and Suh, 2012). Some Vryburgia species are capable of inflicting significant damage to succulents. For example, V. trionymoides can kill succulents and is a greenhouse pest in California (Stocks, 2016). Mealybugs in other genera that attack succulents have even been used as biological control agents of invasive cacti in Australia and South Africa (Aguirre et al., 2016).
Worldwide Distribution: Vryburgia succulentarum is reported to occur in southern Australia, Iran (in greenhouses), South Africa, and Tasmania (García Morales et al., 2016; Moghaddam, 2015). This species may be native to Africa; if so, the other localities represent introductions.
Official Control: Vryburgia succulentarum is not known to be under official control anywhere.
California Distribution: Vryburgia succulentarum is not known to be present in California (Symbiota Collections of Arthropods Network).
California Interceptions: Vryburgia succulentarum has not been intercepted in California (CDFA Pest and Damage Report Database, 2018).
The risk Vryburgia succulentarum would pose to California is evaluated below.
Consequences of Introduction:
1) Climate/Host Interaction: The full distribution of succulentarum may not be fully known. However, this species has been reported from areas in Australia and Tasmania that have Mediterranean and temperate climates (Atlas of Living Australia; Williams, 1985). Therefore, much of California could have a suitable climate for this species. There are many members of the families Cactaceae and Crassulaceae in California, so there are many potential host plants. It appears likely that this mealybug could establish over a large portion of California. Therefore, V. succulentarum receives a High (3) in this category.
– 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: This mealybug has been reported to be associated with three families of succulent plants. Therefore, it receives a Medium (2) in this category.
– 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: This mealybug has been intercepted multiple times on plants in quarantine, so it is evidently capable of being spread artificially on infested plants (García Morales et al., 2016). The Cactaceae and Crassulaceae include many popular landscaping plants, so this mode of dispersal is likely. Therefore, it receives a Medium (2) in this category.
– 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: The primary economic impact that is anticipated to occur if Vryburgia succulentarum becomes established in California is damage to cacti and succulents. Nursery production of these plants were worth $83 million in 2016 in California, an increase of 15% from the previous year. Continued growth appears likely, as water shortages in the state encourage the use of drought-tolerant plants. Production of cacti and succulents appears to be concentrated in San Diego County (CDFA Nursery Program, 2018; San Diego County Department of Agriculture, Weights and Measures). If it became established in the state, Vryburgia succulentarum could lower yield and increase production costs of cacti and succulents in California nurseries. Therefore, it receives a Medium (2) in this category.
Economic Impact: A, B
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: 2
– 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: There are numerous rare members of the families Cactaceae and Crassulaceae in California. For example, bright green dudleya (Dudleya virens insularis) and Bakersfield cactus (Opuntia basilaris treleasei) (Calflora). If V. succulentarum became established in this state, these plants could be threatened. In addition, if V. succulentarum attacks succulent plants in residential or other areas, this could trigger treatments. Therefore, it receives a High (3) in this category.
Evaluate the environmental impact of the pest on California using the criteria below.
Environmental Impact: B, E
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.
Environmental Impact Score: 3
– 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 Vryburgia succulentarum: Medium (12)
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: Vryburgia succulentarum is not known to occur in California. It receives a Not established (0) in this category.
–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.
7) The final score is the consequences of introduction score minus the post entry distribution and survey information score: Medium (12)
The distribution and biology of V. succulentarum are poorly known. The most significant unknown in this proposal is the ability of this mealybug to damage the plants that it feeds upon. At least one species in the genus is reported to be a pest, but it may not be of economic significance.
Conclusion and Rating Justification:
Vryburgia succulentarum is a mealybug that attacks succulents, including Cactaceae and Crassulaceae. This mealybug, which is not known to occur in California, poses a threat to native California species and to the nursery industry as well. For these reasons, an “A” rating is justified.
Aguirre, M. B., Diaz-Soltero, H., Claps, L. E., Saracho Bottero, A., Triapitsyn, S., Hasson, E., and Logarzo, G. A. 2016. Studies on the biology of Hypogeococcus pungens (sensu stricto) (Hemiptera: Pseudococcidae) in Argentina to aid the identification of the mealybug pest of Cactaceae in Puerto Rico. Journal of Insect Science 16:1-7.
Atlas of Living Australia website. Accessed March 29, 2018: http://www.ala.org.au
Calflora: Information on California plants for education, research and conservation, with data contributed by public and private institutions and individuals, including the Consortium of California Herbaria. Accessed March 26, 2017: http://www.calflora.org
CDFA Nursery Program. 2018. Value of California nursery products. Nursery Advisory 01-2018:1-2.
CDFA Pest and Damage Report Database. 2018. Vryburgia succulentarum. Plant Health and Pest Prevention Services. CA Department of Food and Agriculture. Accessed April 5, 2018: http://phpps.cdfa.ca.gov/user/frmLogon2.asp
García Morales, M., Denno, B. D., Miller, D. R., Miller, G. L., Ben-Dov, Y., and Hardy, N. B. 2016. ScaleNet: A literature-based model of scale insect biology and systematics. Accessed March 28, 2018: http://scalenet.info
Ji, J. and Suh, S.-J. 2012. A list of scale insects (Hemiptera: Coccoidea) intercepted in quarantine on imported succulent plants in Korea 2006-2010. Insecta Mundi 0272:1-5.
Moghaddam, M. 2015. New records of mealybug species in Iran with discussions on morphological variations (Hemiptera, Coccoidea: Pseudococcidae). Entomologica Fennica 26:122-131.
San Diego County Department of Agriculture, Weights and Measures. County of San Diego Crop Statistics & Annual Report (2016). Accessed June 18, 2018: https://www.sandiegocounty.gov/content/dam/sdc/awm/docs/AWM_2016_Crop_Report.pdf
Stocks, I. 2016. A mealybug – Vryburgia trionymoides (DeLotto) (Pseudococcidae). Florida Department of Agriculture and Consumer Services, Division of Plant Industry. Accessed: April 5, 2018: http://entnemdept.ufl.edu/creatures/ORN/MEALYBUG/vryburgia_trionymoides.htm
Symbiota Collections of Arthropods Network. Accessed March 28, 2018: http://scan1.acis.ufl.edu
Williams, D. J. 1985. Australian mealybugs. British Museum of Natural History, London.
Kyle Beucke, 1220 N Street, Room 221, Sacramento, CA, 95814, 916-403-6741; plant.health[@]cdfa.ca.gov.
Jason Leathers, 2800 Gateway Oaks, Sacramento CA 95833, (916) 654-1211, plant.health[@]cdfa.ca.gov
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6/20/18 – 8/4/18
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Pest Rating: A
Posted by ls