Tag Archives: Trilobe Scale

Pseudaonidia trilobitiformis (Green): Trilobe Scale

California Pest Rating for
Psuedaonidia trilobitiformis (Green)
Pseudaonidia trilobitiformis (Green): Trilobe Scale
Photo Credit: National Bureau of Agricultural Insect Resources (NBAIR)
Pseudaonidia trilobitiformis (Green):  Trilobe Scale
Hemiptera: Diaspididae
Pest Rating:  A

Initiating Event:

Pseudaonidia trilobitiformis is commonly intercepted by CDFA and presently has a temporary rating of “Q”.  A pest rating proposal is required to determine a permanent pest rating.

History & Status:

BackgroundPseudaonidia trilobitiformis is a polyphagous, widespread armored scale insect.  Known hosts include:  Agavaceae: Agave mexicana1, Cordyline sp.1, Cordyline neo-caledonyca1, Dracaena sp.1; Anacardiaceae: Anacardium sp.1, Anacardium occidentale1, Mangifera sp.1, Mangifera indica1, Nothopegia colebrookiana1, Schinus molle1, Schinus terebinthifolius1, Sclerocarya caffra1; Annonaceae: Annona sp.1, Annona reticulata1, Annona squamosa1, Cananga odoratum1; Apocynaceae: Acocanthera abessinica1, Carissa carandas1, Carissa madagascariensis1, Carissophyllum sp.1, Catharanthus roseus1, Cerbera oppositifolia1, Echites sp.1, Nerium sp.1, Nerium indicum1, Nerium oleander1, Ochrosia oppositifolia1, Plumeria acutifolia1, Plumeria rubra1, Thevetia sp.1, Thevetia peruviana1, Trachelospermum foetidum1; Araceae: Monstera deliciosa1, Philodendrom sp.1, Pothos aureus1; Arecaceae: Cocos nucifera1, Dictyosperma alba1, Elaeis guineensis1, Hyphaene thebaica1; Bignoniaceae: Crescentia cujete1, Pyrostegia venusta1; Boraginaceae: Cordia myxa1; Bromeliaceae: Ananas sativa1; Caricaceae: Carica papaya1; Combretaceae: Terminalia arjuna1, Terminalia catappa1; Corylaceae: Corylus sp.1; Ebenaceae: Diospyros sp.1, Diospyros eriantha1, Diospyros kaki1; Euphorbiaceae: Aleurites sp.1, Aleurites fordi1, Aleurites moluccana1, Aleurites montana1, Codiaeum sp.1, Gelonium lanceolatum1, Hura crepitans1, Jatropha curcas1; Fabaceae: Acacia simplicifolia1, Acacia spirorbis1, Bauhinia sp.1, Bauhinia monandra1, Bauhinia variegata1, Cassia sp.1, Cassia siamea1, Cassia spectabilis1, Clitoria terneata1, Crotalaria sp.1, Dalbergia sp.1, Dalbergia championii1, Derris indica1, Mucuna bennettii1, Pithecolobium unguis-cati1; Fagaceae: Quercus sp.1; Flacourtiaceae: Flacourtia ramontchi1, Hydnocarpus wightiana1, Scolopia oldhamii1; Fumariaceae: Fumaria sp.1; Guttiferae: Calophyllum inophyllum1; Hydrangeaceae: Hydrangea sp.1; Lauraceae: Cinnamomum zeylanicum1, Laurus nobilis1, Machilus sp.1, Persea sp.1, Persea americana1, Persea gratissima1; Lecythidaceae: Barringtonia asiatica1; Liliaceae: Taetsia neocaledonica1; Magnoliaceae: Michelia champaca1; Malvaceae: Hibiscus sp.1; Marantaceae: Maranta sp.1; Meliaceae: Xylocarpus obovatus1; Moraceae: Artocarpus sp.1, Artocarpus altilis1, Artocarpus communis1, Artocarpus heterophyllus1, Artocarpus incisa1, Artocarpus integrifolius1, Brosimum utile1, Cudrania cochinchinensis1, Ficus sp.1, Ficus awkeotsang1, Ficus benghalensis1, Ficus elastica1, Ficus pumila1, Ficus religiosa1, Ficus repens1, Ficus retusa1, Ficus scandens1, Ficus swinhoei1, Ficus thonningii1, Ficus trichoclada1, Ficus wightiana japonica1; Myrtaceae Eugenia sp.1, Eugenia jaboticaba1, Myrtus sp.1, Psidium sp.1, Psidium cattleianum1, Psidium guajava1; Naucleaceae: Cephalanthus sp.1; Nyctaginaceae: Bouganvillea sp.1; Oleaceae: Jasminum sp.1; Passifloraceae: Passiflora sp.1, Passiflora edulis1, Passiflora laurifolia1, Passiflora quadrangularis1; Pittosporaceae: Pittosporum sp.1; Polygonaceae: Coccoloba uvifera1; Punicaceae: Punica granatum1; Rhamnaceae: Ziziphus sp.1, Ziziphus spina-christi1; Rosaceae: Eriobotrya japonica1, Mespilus germanica1, Prunus domestica1, Pyrus sp.1, Rosa sp.1; Rubiaceae: Coffea sp.1, Coffea arabica1, Coffea liberica1, Ixora sp.1, Ixora coccinia1; Rutaceae: Citrus sp.1, Citrus aurantium1, Citrus aurantium bigaradia1, Citrus bergamia1, Citrus decumana1, Citrus grandis1, Citrus histrix1, Citrus limetta1, Citrus limon1, Citrus maxima1, Citrus nobilis unchiu1, Citrus sinensis1, Murraya exotica1; Santalaceae: Santalum austro-caledonicum1; Sapindaceae: Dodonaea viscosa1, Euphoria longana1, Litchi sinensis1; Sapotaceae: Achras sapota1, Mimusops sp.1, Mimusops elengi1; Solanaceae: Capsicum sp.1, Capsicum annuum1, Capsicum frutescens1; Sterculiaceae: Theobroma cacao1; Theaceae: Camellia sp.1, Camellia japonica1, Eurya japonica1, Thea japonica1; Thymelaeaceae: Peddiea africana1; Tiliaceae: Grewia sp.1; Verbenaceae: Premna sp.1, Tectona grandis1; Vitaceae: Vitis vinifera1.

Worldwide Distribution: Although it was first found in Sri Lanka, the native range of Pseudaonidia trilobitiformis is uncertain.  From its origin it has spread through much of Africa, Asia, Australia, the Pacific, South America, and Central America1.  In the continental United States the scale is known to be present in Florida1.

Official Control: Pseudaonidia trilobitiformis is listed as a quarantine pest by Japan, the Republic of Korea, and New Zealand2.

California Distribution:  Pseudaonidia trilobitiformis has never been found in the environment of California.

California Interceptions Between January 1, 2000 and December 31, 2014 Pseudaonidia trilobitiformis was intercepted by CDFA’s dog teams, border stations, and high risk programs 139 times.  These interceptions have occurred on a wide variety of commodities from Hawaii, Florida, Mexico, and many other countries in Central and South America.  Many of the interceptions are on mango.

The risk Pseudaonidia trilobitiformis (trilobe scale) would pose to California is evaluated below.

Consequences of Introduction: 

1) Climate/Host Interaction: Host plants of Pseudaonidia trilobitiformis are grown throughout California as agricultural crops and ornamentals.  The scale insect is likely to establish wherever these plants 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: Pseudaonidia trilobitiformis is highly polyphagous.  The scale insect is known to feed on more than 174 plant species in 50 families.  It 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: The biology of Pseudaonidia trilobitiformis is not well documented.  However, scale insects have high reproductive rates.  They are capable of moving long distances through commerce in infested plants and plant parts.  Trilobe scale 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: Trilobe scale is known to feed on many plants that are economically important in California including citrus, avocado, and grapes.  However, despite its polyphagous nature and widespread distribution, Pseudaonidia trilobitiformis is not well-documented to be a plant pest and is therefore not expected to lower crop yields.  It may increase crop production costs as growers may treat to control scale populations for quarantine purposes.  Trilobe scale is listed as a quarantine pest by several of California’s trading partners.  The presence of this scale in California may have significant impacts on California fresh fruit exports.  Trilobe scale is not expected to change normal cultural practices, vector other pestiferous organisms, injure animals, or interfere with water supplies.  Pseudaonidia trilobitiformis 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: If Pseudaonidia trilobitiformis were to enter California it is not expected to lower biodiversity, disrupt natural communities, or change ecosystem processes.  It may directly affect threatened or endangered species, such as Rosa minutifolia (small-leaved rose), by feeding on them.  It is not expected to disrupt critical habitats.  It may trigger additional private treatment programs in fruit production and nursery industries.  Since it is not well-documented as a pest in other locations, trilobe scale is not expected significantly impact cultural practices, home/urban gardening, or ornamental plantings.  Pseudaonidia trilobitiformis 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 Pseudaonidia trilobitiformis (Trilobe Scale):  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: Pseudaonidia trilobitiformis 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)


Although it is not well-documented as a pest in other localities, Pseudaonidia trilobitiformis could have a more significant impact in California.

Conclusion and Rating Justification:

Pseudaonidia trilobitiformis has never been found in California and would be likely to have significant economic and environmental impacts if it were to enter the state.  An “A”-rating is justified.


1 SEL Catalog Query Results.  http://www.sel.barc.usda.gov/catalogs/diaspidi/Pseudaonidiatrilobitiformis.htm


2 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.

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Pest Rating:  A

Posted by ls