California Pest Rating Proposal for
Pink Hibiscus Mealybug | Maconellicoccus hirsutus (Green)
Current Pest Rating: A
Proposed Pest Rating: B
Comment Period: 4/25/18 – 6/9/18
August 26, 2014, Dr. Gillian Watson identified Maconellicoccus hirsutus from a sample collected on 100 heavily infested silk oak trees at a golf course in Rancho Mirage, Riverside County. The mealybug was previously eradicated from Riverside County in 2011. Follow-up surveys have revealed that the pest is now widespread and abundant in Riverside County. An updated pest rating proposal is needed to determine future direction.
History & Status:
Background: Maconellicoccus hirsutus is a highly polyphagous mealybug that feeds on the stems, leaves, buds, fruit, and roots of plants in more than 200 genera in 77 plant families1,2. Economically important hosts include grapes, citrus, avocado, cotton, Prunus spp., Solanum spp., and ornamentals. While feeding, the mealybug injects toxic saliva into plants that inhibits cell enlargement, causing stunting of new growth and curling and contortion of leaves7. Entire plants may be stunted and deformed7. High populations can lead to the death of plants7. The mealybug can spread long distances through the trade in host plants and fruit.
Worldwide Distribution: Maconellicoccus hirsutus is considered to be native to southern Asia1,2 and has invaded much of the Caribbean, Africa, Asia, Australia, Oceania, and South America. In North America it has been found in Mexico, Florida, Georgia, Louisiana, Texas, and Imperial and Riverside counties, California3. It has recently been detected and is under eradication in Tennessee6.
Official Control: Maconellicoccus hirsutus is listed as a quarantine pest by many nations including Antigua and Barbuda4, Bermuda4, Brazil4, Cayman Islands4, Chile4, Colombia4, Costa Rica4, Ecuador4, El Salvador4, Guatemala4, Honduras4, Israel4, Jamaica4, Japan4, Republic of Korea4, Mexico4, Morocco4, Nicaragua4, Panama4, Paraguay4, Peru4, South Africa4, Turkey4, Uruguay4, and the European Union2.
California Distribution: Maconellicoccus hirsutus has been present in Imperial County since 1999. The mealybug was detected in Riverside County in 2011 and successfully eradicated by the county. The mealybug was detected again in Riverside County in 2014 infesting 100 silk oak trees at a golf course.
California Interceptions: Maconellicoccus hirsutus is occasionally intercepted on fruit or plants headed for destinations within California, most often on longan fruits.
The risk Maconellicoccus hirsutus (pink hibiscus mealybug) would pose to California is evaluated below.
Consequences of Introduction:
1) Climate/Host Interaction: Maconellicoccus hirsutus, due to its polyphagous nature, is likely to encounter suitable hosts throughout California. The present distribution of the mealybug corresponds to USDA plant hardiness zones 9-131, which encompasses much of California. Pink hibiscus mealybug 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: Maconellicoccus hirsutus is known to feed on plants in more than 200 genera in 77 plant families. The mealybug receives a High(3) 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: Pink hibiscus mealybug has a high reproductive rate. Each female lays 150-600 eggs and there can be up to 15 generations per year2. The crawlers of this mealybug are reported to be very active and are capable of spreading to nearby plants; furthermore, they may be dispersed by wind or by hitchhiking on clothing, equipment, or animals. The mealybugs may also be spread long distances through the movement of infested plants or fruit. Maconellicoccus hirsutus 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: Maconellicoccus hirsutus has been present in Imperial County since 1999, where it has been successfully controlled by biological control agents. No economic damages in California are presently attributed to this pest. In the presence of effective biological control, the mealybug is not expected to lower crop yields. In the absence of effective biological control, yields are likely to be reduced (see uncertainty section below). As it feeds on a wide variety of ornamentals, the mealybug may increase crop production costs in nurseries by triggering new chemical treatments to ensure clean nursery stock. The mealybug is listed as a quarantine pest by many nations and its presence is likely to disrupt markets for California fresh fruit. Pink hibiscus mealybug is not expected change cultural practices, vector pestiferous organisms, injure agriculturally important animals, or interfere with the delivery or supply of water for agricultural uses. Maconellicoccus hirsutus receives a Medium (2) 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: Maconellicoccus hirsutus is not expected to lower biodiversity, disrupt natural communities, or change ecosystem processes. Algodones Dunes sunflower (Helianthus niveus tephrodes), Bakersfield cactus (Opuntia basilaris var. treleasei), and small-leaved rose (Rosa minutifolia) are listed as threatened or endangered plants in California and are potential hosts of this mealybug. An infestation of the mealybug in Riverside County in 2011 was eradicated by the county, indicating that the presence of this pest may trigger additional official treatment programs. Additional treatments are also likely in the nursery industry and by residents who find infested plants unsightly. In some cases, the mealybug is likely to be managed by biological control programs such that it does not significantly impact cultural practices, home/urban gardening, or ornamental plantings. However, due to its extremely high reproductive rate and broad host range it is likely to sometimes cause significant damage to ornamental plants as it encounters them before biological control agents. Maconellicoccus hirsutus 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: 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 Maconellicoccus hirsutus (pink hibiscus mealybug): 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: Maconellicoccus hirsutus is only known to be established in Imperial and Riverside counties. The mealybug receives a Low (-1) 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(13)
There have been no recent statewide surveys for the mealybug, so it may have a larger distribution within California. In the absence of surveys or official control, trading partners are likely to regulate the entire state, so range expansions of pink hibiscus mealybug may not trigger new impacts on fruit exports. Pheidole megacephala (bigheaded ant) has recently been detected in California. This is an aggressive ant that is likely to tend pink hibiscus mealybug and consume all parasites and predators it encounters, reducing the effectiveness of biological control5. As bigheaded ant expands its range through southern California it is likely to facilitate the invasion of Maconellicoccus hirsutus and may disrupt the presently successful biological control program. If this were to occur, yield of economically important crops such as almonds, peaches, pistachios, walnuts, olives, and citrus may be reduced. Crop quality and production costs by increase in the long term. This may elevate the economic impact of the pest to High (3).
Conclusion and Rating Justification:
Maconellicoccus hirsutus is a highly polyphagous mealybug with a limited distribution within California at present. If it enters commercial fruit groves and vineyards the presence of the mealybug is likely to close or restrict export markets for fresh fruit. If found outside of its present distribution, it will likely trigger treatment or biological control programs. However, pink hibiscus mealybug has been known to be present in California since 1999 and is not under official control. Therefore, the A-rating can longer be justified. A “B” rating is now the appropriate rating.
1Culliney, T.W. 2014. Deregulation Evaluation of Established Pests (DEEP); DEEP Report on Maconellicoccus hirsutus (Green): Egyptian hibiscus mealybug, pink hibiscus mealybug.
2Data sheets on quarantine pests: Maconellicoccus hirsutus. 2005. European and Mediterranean Plant Protection Organization. OEPP/EPPO Bulletin 35, 413-415. http://www.eppo.int/QUARANTINE/insects/Maconellicoccus_hirsutus/DS_Maconellicoccus_hirsutus.pdf
3Ben-Dov, Y. 2014. ScaleNet, Maconellicoccus hirsutus. Available online at http://www.sel.barc.usda.gov/catalogs/pseudoco/Maconellicoccushirsutus.htm Accessed on 9 April 2014.
4USDA Phytosanitary Certificate Issuance & Tracking System (PCIT) Phytosanitary Export Database (PExD). https://pcit.aphis.usda.gov/pcit/
5Buckley, Ralf and Penny Gullan. 1991. More aggressive ant species (Hymenoptera: Formicidae) provide better protection for soft scales and mealybugs (Homoptera: Coccidae, Pseudococcidae). Biotropica 23(3): 282-286. http://www.jstor.org/discover/10.2307/2388205?uid=3739560&uid=2&uid=4&uid=3739256&sid=21104122016081
6NAPIS; Email updated dated September 2, 2014. http://pest.ceris.purdue.edu/capsreview.php?code=IRAWBIA
7Hoy, Marjorie A., Avas Hamon, and Ru Nguyen. 2006. Common name: pink hibiscus mealybug. University of Florida Featured Creatures. http://entnemdept.ufl.edu/creatures/orn/mealybug/mealybug.htm
Jason Leathers, 2800 Gateway Oaks, Sacramento CA 95833, (916) 654-1211, plant.health[@]cdfa.ca.gov
4/25/18 – 6/9/18
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