Coccus viridis (Green Scale)
Pest Rating: A
PEST RATING PROFILE
Coccus viridis is regularly intercepted and has an internal CDFA rating of A. A pest rating proposal is required to support a permanent pest rating.
History & Status:
Background: Coccus viridis is classified as a soft scale4. It is an insect pest of citrus and other plants and is found outdoors and in greenhouses in Florida1. Compared to armored scales, green scales secrete very little wax. Reproduction occurs exclusively without fertilization. Populations are composed solely of females and males have never been recorded. Green scale is polyphagous and has a wide host range that includes vegetable, fruits and ornamental crops. Economically important hosts include Annona, Anthurium, avocado, cacao, celery, coffee, flowering ginger, guava, lime, macadamia, orange, orchids and plumeria4. In Florida, the preferred wild host is groundsel bush, Baccharis halimifolia L. Preferred cultivated hosts include gardenia and ixora1. Coccus viridis can be brought into greenhouses with the introduction of infested host material or by hitchhiking on clothing or equipment.
Worldwide Distribution: Coccus viridis occurs in tropical regions of the world and is thought to originate in Brazil. Presently it is distributed in Asia, Bangladesh, Burma, Cambodia, India, Indonesia, Laos and throughout tropics with the exception of Australia1,8.
Official Control: Coccus viridis is listed as a harmful organism by Jordan, Republic of Korea, New Zealand, Venezuela and Mexico9.
California Distribution: Coccus viridis has never been detected in California’s environment.
California Interceptions: Coccus viridis has been intercepted multiple times in the state through dog teams, nursery regulatory inspections and high risk pest exclusion programs.
The risk Coccus viridis (green scale) would pose to California is evaluated below.
Consequences of Introduction:
1) Climate/Host Interaction: Hosts plants of Coccus viridis are grown throughout California and this insect presents the possibility of spread and establishment wherever the hosts are grown within the State. It receives a High (3) in this category.
Evaluate if the pest would have suitable hosts and climate to establish in California.
– 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: Coccus viridis is polyphagous and has a host list spanning 57 plant families. It receives a High (3) in this category.
Evaluate the host range of the pest.
– 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: Coccus viridis is parthenogenetic and oviparous1. It reproduces by eggs or the birthing of live young off-springs. Scale species produce large number of eggs and can be easily transported with the movement of infested plant material. Unlike most scale species, the adults of Coccus viridis are mobile. It receives at 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: Coccus viridis may occur on cultivated hosts in commercial nurseries and can result in quarantines of infested plant material. It can impact a number of commercially grown crops in California including avocado, celery, lime and orange. This could negatively impact trade of California grown commodities to other states and intrastate commerce. Honeydew secreted by Coccus viridis on the host, serves as a medium for sooty mold fungus to grow. Sooty mold reduces marketability of the fruit (Elmer and Brawner, 1975). Large populations of green scale can cause yellowing, defoliation, reduction in fruit set and plant vigor. It receives a High (3) 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: In eastern North America Coccus viridis attacks Baccharis halimifolia. The closely related coyote brush (Baccharis pilularis) is possibly the most common shrub in CA. Certain federally endangered species such as Alameda whipsnake (Masticophis lateralis euryxanthus) and Least Bell’s Vireo (Vireo bellii pusillus) rely on the coastal scrub habitat dominated by coyote brush. Therefore, Coccus viridis could lower biodiversity, disrupt critical habitat, or change ecosystem processes. Coccus viridis infestations on cultivated hosts in commercial nurseries might trigger additional treatments by nursery growers. It 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
– 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 Coccus viridis (Green Coffee Scale): High (15)
–Low = 5-8 points
–Medium = 9-12 points
–High = 13-15 points
6) Post Entry Distribution and Survey Information: Coccus viridis has never been found in 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.
The final score is the consequences of introduction score minus the post entry
distribution and survey information score: High (15)
Damage occurs only if Coccus viridis is present in large numbers on a host plant. Single scale on a plant does not cause much damage. There are no surveys done recently for the evaluation of its status in CA. Since most of the host plants are commonly grown throughout California, it could easily spread and get established in the State.
Conclusion and Rating Justification:
Coccus viridis has never been found in California and might cause significant economic and environmental impacts if this pest were to get established in California. Currently, an “A” rating is justified.
1Dekle, G.W.( Retired), Florida Department of Agriculture and Consumer Resources, Division of Plant Industry and Fasulo, T.R. ( Retired), University of Florida
2Govt. of western Australia- Department of Agriculture- Farm note
3Ministry of Iran- Detection and quarantine guide for insects
4Mau, Ronald F.L. and Kessing, Jayma L. Martin, Department of Entomology, Honolulu, Hawaii
5Bug guide- Identification, Images & Information for Insects, Spiders and Their Kin for the United States and Canada.
6Plant wise Technical Factsheet
7Scale insect Factsheet – Coccidae
8Distribution Maps for Plant Pests
9USDA-Phytosanitary Certificate Issuance and Tracking System (PCIT)- Phytosanitary Export Database ( PExD)
10Pest and Damage Record Database, California Department of Food and Agriculture, Plant Health and Pest Prevention Services.
Raj Randhawa, Senior Environmental Scientist; California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 654-0312; plant.health[@]cdfa.ca.gov.
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Pest Rating: A
Posted by ls