Dysmicoccus texensis (Tinsley): A Mealybug

California Pest Rating
Dysmicoccus texensis (Tinsley): A Mealybug
Hemiptera: Pseudococcidae
Former Pest Rating: Q
FINAL Pest Rating: A
Initiating Event:

Dysmicoccus texensis is regularly intercepted by CDFA and presently has a temporary rating of “Q”.  A pest rating proposal is required to assign a permanent pest rating.

History & Status:

Background:  Dysmicoccus texensis is a mealybug that is often found feeding on plant roots, where large populations prevent water and nutrient absorption, weaken plants, and reduce crop yields3.  It is considered a pest of great pest importance on coffee in Brasil3 (Rubiaceae: Coffea sp.1).  It has also been observed feeding, sometimes on aerial plant parts, on other hosts including: Anacardiaceae: Mangifera indica1; Araceae: Dieffenbachia sp.1; Bromeliaceae: Vriesea macrostachya1; Euphorbiaceae: Manihot esculenta1; Fabaceae: Acacia cornigera1, Acacia veracruzensis1, Acacia sphaerocephala1, Acacia farnesiana1, Inga inga1, Inga ruiziana1, Inga punctata1, Inga laurina1, Trifolium sp.1; Malvaceae: Theobroma cacao1, Theobroma amplexicaule1, Meliaceae: Guarea sp.1; Musaceae: Musa textilis1, Musa paradisiaca1; Myrtaceae: Psidium guajava1; Polygonaceae: Coccoloba sp.1; Rutaceae: Citrus latifolia1; Citrus aurantium1; Solanaceae: Solanum sp.1.  Coffee root mealybug may be transported long distances through commerce in infested plants or plant parts.

Worldwide Distribution: Dysmicoccus texensis is native to the Neotropical region including southern Texas, Mexico, Central America, and South America1.  It is also found in the Bahamas, Jamaica, Puerto Rico, Trinidad, and the U.S. Virgin Islands1.

Official Control: Dysmicoccus texensis is not known to be under official control in any other states or nations2.

California Distribution:  Dysmicoccus texensis has never been found in the environment in California.

California Interceptions Dysmicoccus texensis was intercepted 44 times by CDFA’s border stations, dog teams, and high risk programs between January 1, 2000 and December 31, 2014.  The mealybug was found on limes, grapefruit, bananas, bell peppers, sugar apple, and aerial parts of unidentified plants.

The risk Dysmicoccus texensis (coffee root mealybug) would pose to California is evaluated below.

Consequences of Introduction: 

1) Climate/Host Interaction: Host plants of Dysmicoccus texensis are commonly grown in California as both crops and ornamentals. Dysmicoccus texensis is likely to establish wherever hosts 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:

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 texensis is known to feed on at least 24 species of plants in 13 families.  It receives a Medium (2) 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: Mealybugs have high reproductive rates and may be dispersed long distances by the movement of infested plants or fresh plant parts.  They may also be dispersed locally by wind or by hitchhiking on clothing, equipment, or animals.  Dysmicoccus texensis 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: Although known hosts of Dysmicoccus texensis include economically important crops such as Citrus and Solanum, it is primarily considered a pest of coffee.  Yields of other crops are not likely to be significantly reduced.  However, the mealybug may increase production costs in the nursery industry.  It has potential to lower the value of nursery stock by disfiguring plants with its presence.  Although D. texensis is not known to be considered a quarantine pest, several of California’s trading partners are significant producers of coffee.  Since the mealybug is well documented as a serious pest of coffee, it is reasonable to expect that its presence could trigger disruptions of fresh fruit exports.  Dysmicoccus texensis 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: Dysmicoccus texensis is not expected to lower biodiversity, disrupt natural communities, or change ecosystem processes.  Trifolium is a host of D. texensis and several species of Trifolium are listed as threatened or endangered plants in California.  These potential hosts include showy Indian clover (Trifolium amoenum), Pacific Grove clover (Trifolium polyodon), and Monterey clover (Trifolium trichocalyx).  Dysmicoccus texensis is not expected to disrupt critical habitats.  The mealybug may trigger new chemical treatments in orchards and the nursery industry.  It is not expected to have significant impacts on cultural practices, home/urban gardening, or ornamental plantings.  Dysmicoccus texensis 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:

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 texensisHigh (13)

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 texensis has never been found in the environment of California. 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: High (13)

Uncertainty:

There have not been any recent surveys for Dysmicoccus texensis.  It is possible that it could be present in some parts of the state.

Conclusion and Rating Justification:

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

References:

1 Miller, Dug, Yair Ben-Dov, Gary Gibson, and Nate Hardy.  ScaleNet.  Dysmicoccus texensis is the valid name.  http://scalenet.info/validname/Dysmicoccus/texensis/

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

3 Neves, Pedro Manuel Oliveira Janeiro, Lenira Viana Costa Santa-Cecília, Jair Campos de Moraes, Luís Cláudio Paterno Silveira, and Alcides Moino Junior. 2006. Coffee root mealybug biology control entomopathogenic nematodes. Universidade Federal de Lavras.  http://www.openthesis.org/documents/Biologics-aspects-Dysmicoccus-texensis-Tinsley-331392.html


Responsible Party:

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


Comment Period:  CLOSED

The 45-day comment period opens on Jun 22, 2016 and closed on Aug 6, 2016.


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Consequences of Introduction:  1. Climate/Host Interaction: [Your comment that relates to “Climate/Host Interaction” here.]

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Pest Rating: A