Tag Archives: Gray Sugarcane Mealybug

Gray Sugarcane Mealybug | Trionymus boninsis (Kuwana)

California Pest Rating for
Image of a Gray Sugarcane Mealybug. Click on image for photo citation.
Click on image for photo citation.
Gray Sugarcane Mealybug | Trionymus boninsis (Kuwana)
Hemiptera: Pseudococcidae
Pest Rating: A


Initiating Event:

Trionymus boninsis has been intercepted on January 18, 2017 at a nursery in Los Angles during a regulatory inspection. This species has a temporary Q rating. A pest rating proposal is required to support an official pest rating.

History & Status:

Background: Trionymus boninsis, known as the gray sugarcane mealybug, is a mealybug species common on sugarcane growing areas of the world. It is generally found on the stem under the leaf blade and tended by various ant species. Trionymus boninsis is currently known to feed on plants of 11 families and 31 genera, and is found often on grasses other than sugarcane, including Sorghum and corn, but also on coconut, Ipomeas and Citrus among others (Williams & Granara de Willink 1992; Garcia Morales et al. 2016).

Worldwide Distribution: Trionymus boninsis is recorded to be present in ASIA, Bonin Islands, Formosa, Japan, AFRICA, Egypt, Mauritius, AUSTRALASIA and PACIFIC ISLANDS, Australia, CarolineIs. Hawaiian islands, Marianas. New Caledonia, New Guinea, NORTH AMERICA, Mexico, United States, CENTRAL AMERICA and WEST INDIES, Panama, West Indies, SOUTH AMERICA, Brazil, Surinam, Venezuela. (CABI 2016).

U.S. Distribution: Trionymus boninsis has been reported only in Florida, Georgia, Louisiana and Mississippi (Garcia Morales et al. 2016).

U.S. Quarantine Interceptions: Trionymus boninsis has been intercepted 13 times at United States ports of entry between 1995 and 2012. This species is commonly collected on sugarcane from every warm part of the world where sugarcane is grown. It is also reported from 10 families of host plants, predominantly species of grasses (Miller et al. 2014).

Official Control: Trionymus boninsis has been listed as a harmful organism by the republic of Korea (USDA APHIS- PCIT 2017).

California Distribution:  Trionymus boninsis has not been found in the natural environment in California.

California Interceptions:  Trionymus boninsis has been found multiple times by CDFA through border station inspections, dog team inspections, and high risk pest exclusion activities and nursery regulatory inspections. Between January 1990 and October 2017, it has been intercepted 10 times.

The risk Trionymus boninsis (gray sugarcane mealybug) would pose to California is evaluated below.

Consequences of Introduction: 

1) Climate/Host Interaction: Sugarcane is not commonly grown in California. Grasses are common throughout the state. However Trionymus boninsis attacks grasses in temperate and warm areas. If this species were to get established in state it can attack grasses in deserts areas. It 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: Trionymus boninsis is a common pest of Sugarcane but is also found on other plants in 11 families including many grasses, maize, sorghum and rice. It is also reported to occur on weeds especially Lactuca in the water canals around sugarcane farms (M. Moghaddam 2006).  There is a record of this species on Citrus sp. (Marotta 1987), and there is the chance that it could become established throughout Citrus growing areas in California. It receives a High (3) in this category as some of its potential hosts in California are staple crops.

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: Mealybugs have high reproductive rate and can spread long distances by movement of infested plant parts. Sugarcane mealy bugs can survive for up to four months in the leaf sheaths attached to canes. Several species of ants can help spread the mealybugs from infested to healthy canes. Among other factors affecting the number of mealybugs include rainfall pattern tightness of leaf sheath and incidence of predators and parasites (Inkerman et al. 1986). It 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: Trionymus boninsis is a widespread pest in sugar cane growing areas of the world. This species also attacks grasses in warm and warm temperate areas. This species could significantly impact cultural practices in citrus, maize and rice growing areas of California. Currently, sugarcane is being planted on a small scale in the Imperial Valley for research (Western farm press, 2001). If boninsis were to establish, it could lower the quality and value of these crops. This species is capable of transmitting Sugarcane bacillifrom badnavirus (SCBV) through infected sugarcane setts. It receives a High (3) in this category

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

Economic Impact: B, D, 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: Since mealybugs are spread by ants, chemical treatments for ant control may have detrimental environmental impacts because of their slow degradation (Kessing & Mau 2007). If this species were to establish in California, it may trigger new chemical treatments in areas where host grasses are present.

It receives a High (3) in this category.

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

Environmental Impact: A, 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.

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 of Annona/Gray Pineapple Mealybug into California:  High (14)

-Low = 5-8 points

-Medium = 9-12 points

         -High = 13-15 points

6) Post Entry Distribution and Survey Information: Trionymus boninsis has not been found in the natural or agricultural environment of California. Therefore, it 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: (14)


Trionymus boninsis has been intercepted many times by CDFA through regulatory pathways.  There have not been any recent surveys for Trionymus boninsis. If it goes undetected, there is a good possibility that it can spread in the state based on its rapid dispersal potential. Its main host is sugarcane and although it attacks citrus, maize and rice, it is not known how serious a pest it could be on these crops.

Conclusion and Rating Justification:

Trionymus boninsis has not been found in the natural or agricultural environment in California. If this species were to become established in California, there could be significant economic and environmental impacts. Based on all the above evidence, an “A” rating is proposed at this time.


CAB International 2016: Dysmicoccus boninsis. [Distribution map]  https://www.cabdirect.org/cabdirect/abstract/20056600116

García Morales M, Denno BD, Miller DR, Miller GL, Ben-Dov Y, Hardy NB. 2016.ScaleNet: A literature-based model of scale insect biology and systematics. Database. doi: 10.1093/database/bav118. http://scalenet.info. http://scalenet.info/catalogue/Trionymus%20boninsis/ Accessed 10/23/2017

Inkerman, P.A., N. J. Ashbolt, Mary Carver and D. J. Williams. 1986. Observation on the pink sugarcane mealy bug, Saccharicoccus sacchari (Cockerell) in Australia (Homoptera: Pseudococcidae)  http://www.issct.org/pdf/proceedings/1986/1986%20Inkerman%20Observations%20on%20the%20Pink%20Sugarcane%20Mealybug%20in%20Australia.pdf

Kessing JLM, Mau RFL, 2007. Dysmicoccus neobrevipes (Beardsley). Crop Knowledge Master.  http://www.extento.hawaii.edu/kbase/crop/type/d_neobre.htm

Marotta, S. 1987 An annotated list of the Italian mealybugs. Bollettino del Laboratorio di Entomologia Agraria ‘Filippo Silvestri’. Portici 43: (1986, Supplement): 107-116. 

Miller, D., A. Rung, G. Parikh, G. Venable, A.J. Redford, G.A. Evans, and R.J. Gill. 2014. Scale Insects, Edition 2. USDA APHIS Identification Technology Program (ITP). Fort Collins, CO. Accesed 10/23/2017 http://idtools.org/id/scales/

Moghaddam, M. 2006. The mealybugs of southern Iran (Hem.: Coccoidea: Pseudococcidae). Journal of Entomological Society of Iran, 26(1), 1-11.

Pest and Damage Report Database: Plant Health and Pest Prevention Services, California Department of Food and Agriculture: Accessed 10/19/2017

Western farm press.  2001. Sugarcane: California’s triple threat? http://www.westernfarmpress.com/sugarcane-californias-triple-threat

USDA Phytosanitary Certificate Issuance & Tracking System (PCIT): Phytosanitary Export Database (PExD), Accessed 10/19/2017  https://pcit.aphis.usda.gov/PExD/faces/ReportFormat.jsp


Raj Randhawa, 1220 ‘N’ Street, Room 221, Sacramento CA 95814, (916)403-6617, raj.randhawa@cdfa.ca.gov

Responsible Party:

Jason Leathers, 1220 N Street, Sacramento, CA, 95814, (916) 654-1211, plant.health[@]cdfa.ca.gov.

Comment Period: * CLOSED

1/5/2018 – 2/19/2018


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Pest Rating: A


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