Dysmicoccus grassii (Leonardi): Alazon Mealybug

California Pest Rating
Dysmicoccus grassii (Leonardi): Alazon Mealybug
Hemiptera: Pseudococcidae
Former Pest Rating:  A
Current Pest Rating: A

 

Initiating Event:

Dysmicoccus grassii is frequently intercepted by CDFA and requires a pest rating proposal to support its pest rating.

History & Status:

BackgroundDysmicoccus grassii is a polyphagous mealybug that feeds on tropical and subtropical plants and where it is commonly found feeding around the peduncle of fruit1.  This feeding can cause yellowing and rot of green fruit1.  The mealybug is considered to be a pest of bananas in the Canary Islands and Nigeria1.  Known hosts include: Anacardiaceae: mango (Mangifera indica2) ; Annonaceae: sugar apple (Annona squamosa2); Asparagaceae: Mexican grass tree (Dasylirion longissimum2); Asteraceae: Eupatorium odoratum2; Bignoniaceae: calabash tree (Crescentia cujete2); Bromeliaceae: pineapple (Ananas comosus2), Andrea inermis2; Caricaceae: papaya (Carica papaya2) ; Combretaceae: tropical almond (Terminalia catappa2); Cucurbitaceae: chayote (Sechium edule2); Euphorbiaceae: Codiaeum spp.2; Fabaceae: Acacia spp.2; Lauraceae: Persea spp.2; Liliaceae: Asparagus spp.; Lythraceae: pomegranate (Punica granatum2); Malvaceae: Theobroma cacao1,2; Melastomataceae: Melastoma spp.2; Moraceae: Artocarpus spp.2, weeping fig (Ficus benjamina2); Musaceae: Musa acuminata2, Musa sapientum2, Musa spp.2; Passifloraceae: passion fruit (Passiflora edulis2); Polygonaceae: sea grape (Coccoloba uvifera2); Rubiaceae: coffee (Coffea arabica2), robusta coffee (Coffea canephora1); Verbenaceae: teak (Tectona grandis2).  Dysmicoccus grassii may be transported long distances when infested plants or fresh plant parts are moved.

Worldwide Distribution: Dysmicoccus grassii is considered to be native to Central and South America1.  From there it has spread to Malaysia, the Canary Islands, France, Italy, Sicily, and Nigeria2.

Official Control: Dysmicoccus grassii (including its synonym D. alazon) are listed as harmful organisms by China, Japan, the Republic of Korea, and Egypt3.

California DistributionDysmicoccus grassii has never been found in the environment of California.

California Interceptions:  Between January 1, 2000 and December 31, 2014 Dysmicoccus grassii was intercepted by CDFA’s dog teams, border stations, and high risk programs 134 times.  These interceptions are typically on fruit or plants from Florida and Mexico.  It was also found in one nursery in Los Angeles County on plants imported from Florida.

The risk Dysmicoccus grassii (alazon mealybug) would pose to California is evaluated below.

Consequences of Introduction: 

1) Climate/Host Interaction: Host plants of Dysmicoccus grassii are commonly grown in California and the mealybug is expected to be able to establish wherever these are grown. It receives a High (3) in this category.

Evaluate if the pest would have suitable hosts and climate to establish in California.  Score: 1

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: Dysmicoccus grassii is known to feed on at least 25 species of plants in 22 families.  However, many of these are tropical plants that are not commonly grown in California.  It receives a Medium (2) in this category.

Evaluate the host range of the pest. Score: 2

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 are capable of rapid reproduction and can be transported long distances when infested plants or fresh plant parts are moved.  They may also disperse locally by crawling, wind, or by hitchhiking on clothing, equipment, or animals.  Dysmicoccus grassii 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: Dysmicoccus grassii can disfigure unripe fruit when it feeds and might lower crop yields.  It may reduce the value of nursery stock by disfiguring plants with its presence.  The presence of the mealybug may disrupt markets for California agricultural commodities as several of California’s trading partners consider it a harmful organism.  Dysmicoccus grassii receives a High (3) in this category.

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

Economic Impact: A, B, C

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: Dysmicoccus grassii is not expected to lower biodiversity, disrupt natural communities, or change ecosystem processes.  It is not expected to directly affect threatened or endangered species or disrupt critical habitats.  The mealybug could trigger additional private treatment programs in orchards, the nursery industry, and by residents who find infested plants or fruit damage unacceptable.  Many of the host plants of Dysmicoccus grassii are commonly grown as ornamentals and in home/urban gardens in California and may be significantly impacted.  The mealybug receives a High (3) in this category.

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

Environmental Impact: D, 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.

Score the pest for Environmental Impact.

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 Dysmicoccus grassii (Alazon 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: Dysmicoccus grassii has never been found 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.

Final Score:

The final score is the consequences of introduction score minus the post entry distribution and survey information score: High (14)

Uncertainty:

Dysmicoccus grassii is frequently intercepted by CDFA.  Presumably, it enters California at other times undetected.  It is possible that it has been introduced and is established in some localities.  Alternatively, it could be failing to establish.

Conclusion and Rating Justification:

Dysmicoccus grassii has never been found in the environment of California and is likely to have significant economic and environmental impacts.  An “A” rating is justified.

References:

1 Culik, Mark P., David dos Santos Martins, and Penny J. Gullan. 2006. First records of two mealybug species in Brazil and new potential pests of papaya and coffee. Journal of Insect Science 6(23): 1-6. http://jinsectscience.oxfordjournals.org/content/jis/6/1/23.full.pdf

2 Miller, Dug, Yair Ben-Dov, Gary Gibson, and Nate Hardy.  ScaleNet.  http://scalenet.info/validname/Dysmicoccus/grassii/

3 USDA Phytosanitary Certificate Issuance & Tracking System (PCIT) Phytosanitary Export Database (PExD).  https://pcit.aphis.usda.gov/pcit/


Responsible Party:

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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Pest Rating: A