Category Archives: A-Rated

“A”
A pest of known economic or environmental detriment and is either not known to be established in California or it is present in a limited distribution that allows for the possibility of eradication or successful containment. A-rated pests are prohibited from entering the state because, by virtue of their rating, they have been placed on the of Plant Health and Pest Prevention Services Director’s list of organisms “detrimental to agriculture” in accordance with the FAC Sections 5261 and 6461. The only exception is for organisms accompanied by an approved CDFA or USDA live organism permit for contained exhibit or research purposes. If found entering or established in the state, A-rated pests are subject to state (or commissioner when acting as a state agent) enforced action involving eradication, quarantine regulation, containment, rejection, or other holding action.

A-Rated, Coleoptera, Insects, Mites & Earthworms

Dwarf Siberian pine beetle | Dryocoetes pini

California Pest Rating  for
Dwarf Siberian Pine Beetle | Dryocoetes pini
Coleoptera: Curculionidae: Scolytinae
Pest Rating: A

 

PEST RATING PROFILE

Initiating Event:

Dryocoetes pini is currently Q-rated.  A permanent pest rating proposal is required to support an official pest rating.

History & Status:

Background: This bark beetle measures approximately 2.5 mm in length.  Adults tunnel through the phloem (inner bark), where eggs are laid.  The larvae feed on the phloem.  This species has been reported to feed on pine (Pinus spp.), larch (Larix spp.), fir (Abies spp.), and spruce (Picea spp.) (European and Mediterranean Plant Protection Organization; Niijima, 1909).  The beetle is apparently not known as a significant pest in its native range (European and Mediterranean Plant Protection Organization).  Dryocoetes species are usually considered “secondary pests” and only attack dead, injured, or otherwise compromised host trees (Vega & Hofstetter, 2014).  At least one species, Dryocoetes confusus Swaine, is a serious pest of fir trees; it is apparently the most destructive member of the genus in North America (CABI,  2017; Hansen, 1996; Vega & Hofstetter, 2014).  The pathogenic fungus Grosmannia dryocoetis is associated with D. confuses (Vega & Hofstetter, 2014).  Similar fungi may also be associated with other Dryocoetes species, including D. pini.

Worldwide Distribution: Dryocoetes pini occurs in the Russian Far East, China, South Korea, and Japan (European and Mediterranean Plant Protection Organization; Park, 2016; Shiraki, 1952).  The species is not known to be present in North America.

Official Control: This species is not known to be under official control anywhere.

California Distribution: This species does not appear to be present in California (Symbiota Collections of Arthropods Network).

California Interceptions: This species is not known to have been intercepted in California.

The risk Dryocoetes pini would pose to California is evaluated below.

Consequences of Introduction:

1) Climate/Host Interaction: This species appears to occur primarily in areas with a temperate climate. It is possible that it could thrive in a large portion of California if it was introduced.  The tree genera that this species is known to feed upon occur throughout California.  Therefore, Dryocoetes pini receives a High (3) in this category.

– 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: As stated above, Dryocoetes pini has been reported from several coniferous genera. Therefore, pini receives a Medium (2) in this category.

– 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: Dryocoetes pini is presumably capable of flight. Movement of wood (especially firewood) is a likely pathway for the human-aided dispersal of this species if it was to be introduced.  Reproductive potential is unknown for this species.  Therefore, pini receives a Medium (2) in this category.

– 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: Dryocoetes pini has been reported to be associated with several genera of conifers, including Pinus.  There is a possibility that, if this species was to be introduced to California, it could have a different impact than what is observed in its native range, including killing trees, which could reduce yield of timber.  Significant infestations also have the potential to impact the recreational value of forests.  Therefore, it receives a Low (1) in this category.

Economic Impact:  A

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: 1

– 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: Major outbreaks of bark beetles have the potential to kill large numbers of trees, which can have long-lasting impacts. Such impacts could include changes in forest composition, destabilization of soil, and even fire dynamics (Jenkins et al., 2008).  There are rare or threatened conifers in California that could be impacted by the introduction of pini.  Therefore, it receives a High (3) in this category.

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

Environmental Impact: A, B

 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 to California for Dryocoetes pini: Medium (11)

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: Dryocoetes pini is not known to occur in California.  It receives a Not established (0) in this category.

–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:

7) The final score is the consequences of introduction score minus the post entry distribution and survey information score: Medium (11)

Uncertainty:

There is little information available on this species, so it was necessary to draw upon information regarding other species in the genus as well as other bark beetle genera.  There are also no examples of introductions involving this species, so assessment of the impacts of this species requires speculation.

Conclusion and Rating Justification:

Bark beetles can have significant impacts on forests.  One native species in the genus Dryocoetes, D. confusus, is an important pest in western forests.  Even though there is little information on the biology of D. pini, it seems justifiable to use caution and assign it an “A” rating.

References:

CABI.  2017.  Invasive Species Compendium. Wallingford, UK: CAB International. www.cabi.org/isc

European and Mediterranean Plant Protection Organization.  Forest pests on the territories of the former USSR.

https://www.eppo.int/QUARANTINE/special_topics/forestry_project/EPPOforestry_project.pdf

Hansen, E.M.  1996.  Western balsam bark beetle, Dryocoetes confusus Swaine, flight periodicity in northern Utah.  Great Basin Naturalist.  56(4): 348-359.

Jenkins, M.J., Hebertson, E., Page, W., & Jorgensen, C.A.  2008.  Bark beetles, fuels, fires and implications for forest management in the Intermountain West.  Forest Ecology and Management.  254: 16-34.

Niijima, Y.  1909.  Die Scolytiden Hokkaidos unter Berücksichtigung ihrer Bedeutung für Forstschäden.  The Journal of the College of Agriculture, Tohoku Imperial University.  3: 109-179.

Park, S.  2016.  Taxonomic review of Scolytinae and Platypodinae (Coleoptera: Curculionidae) in Korea.  Ph.D. thesis.  Seoul National University.

Shiraki, T.  1952.  Catalogue of injurious insects in Japan.  Preliminary Study Number 71.  General Headquarters, Supreme Commander for the Allied Forces, Economic and Scientific Section, Natural Resources Division.  133 pp.

Symbiota Collections of Arthropods Network.  Accessed March 2, 2018. http://scan1.acis.ufl.edu

Vega, F.E. & Hofstetter, R.W.  2014.  Bark beetles: Biology and ecology of native and invasive species.  Academic Press.  640 pp.

Author:

Kyle Beucke, 1220 N Street, Room 221, Sacramento, CA, 95814, 916-403-6741, plant.health[@]cdfa.ca.gov

Responsible Party:

Jason Leathers, 2800 Gateway Oaks, Sacramento CA 95833, (916) 654-1211, plant.health[@]cdfa.ca.gov

Comment Period:* CLOSED

4/9/18 – 5/24/18

*NOTE:

You must be registered and logged in to post a comment.  If you have registered and have not received the registration confirmation, please contact us at plant.health[@]cdfa.ca.gov.

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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

 

Posted by ls 

A-Rated, Weeds

Alligatorweed | Alternanthera philoxeroides

California Pest Rating for
white flower with green leaves
Alligatorweed | Alternanthera philoxeroides
Family:  Amaranthaceae
Pest Rating: A | Proposed Seed Rating: R
PEST RATING PROFILE
Initiating Event:

There was a recent find of alligatorweed in Solano County; this is the first detection in northern California in many years.

History & Status:

Background: Alligatorweed is a perennial herb with horizontal to ascending stems to 1 m long, rooting at the nodes. The flowers are small and borne in small heads with white floral bracts. Like many aquatic emergent, it has distinctive submerged and emersed forms. The submerged form has hollow, floating, emergent and submerged stems. Terrestrial plants have solid stems. Typically, plants grow rooted in soil in shallow water and form dense, interwoven floating mats that extend over the surface of deeper water. Mats can become quite dense and nearly impenetrable. The floating mats can break away and follow currents to colonize new sites. Mats disrupt the natural ecology of a site by reducing light penetration and crowding out native species. Serious infestations can create anoxic, disease-promoting, and mosquito-breeding conditions.

Worldwide Distribution: This weed is found in wet, disturbed areas. It is also a weed of rice and sugar cane fields in tropical and subtropical regions. Native to southern Asia, alligatorweed is now found in tropical and subtropical regions around the world. It is considered an invasive species in Australia, China, New Zealand, and Thailand. Alligatorweed has been introduced throughout the southeastern United States from Virginia to Texas.

Official Control: Alligatorweed has had a CDFA rating of A as a pest in California for decades. The population in Los Angeles County has been managed intermittently over the years by the county, but it still persists.  It has official status as a weed in Alabama, Arizona, Arkansas, California, Florida, South Carolina, and Texas.

California Distribution:  Alligatorweed occurs in several southern California counties. It also has been detected in Contra Costa and Kings Counties, where it is eradicated. There was a recent find of 2 colonies in southern Solano County.

California Interceptions: Alligatorweed has been sent to CDFA by land managers.

The risk Alternanthera philoxeroides (alligatorweed) poses to California is evaluated below.

Consequences of Introduction:

1) Climate/Host Interaction: Risk is Medium (2), as the plant occurs in wetlands such as the Delta and creeks and rivers, as well as irrigation canals and watering ponds. These habitats are limited but widely distributed in California.

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: Most plants do not require any one host, but grow wherever ecological conditions are favorable. 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: Risk is Medium (2). Alligatorweed can spread rapidly via water movement and on boats and equipment as stem fragments. It is also grown as an aquarium plant and occasionally discarded into waterways. Seeds evidently are not produced in the United States.

Evaluate the natural and artificial dispersal potential of the pest.

– 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: Risk is High (3), as the plant can lower crop yields in rice fields, trigger state or international quarantines, and force changes in cultural practices by blocking canals. It has spread widely in the southeast, and has proven difficult to eradicate both there and in California. Its mats can improve habitat for mosquito larvae, leading to larger mosquito populations.

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

Economic Impact: A, C, D, E, G

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: Risk is High (3) as alligatorweed could further invade the water systems of California, disrupt natural wetland communities and potentially lower biodiversity by invading wetlands. The dense growth impedes water movement, blocks the growth of native plants, and reduces available habitat for water birds and fish. Its invasion in the Delta and its tributaries could degrade habitat of rare species such as Mason’s lilaeopsis (Lilaeopsis masonii), Sacramento River Chinook salmon (Oncorhynchus tshawytscha),  and Giant garter snake (Thamnophis gigas).  Its presence would trigger additional control measures.

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

Environmental Impact: A, C, 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 to California for Alternanthera philoxeroides (alligatorweed) : High (13)

-Low = 5-8 points

-Medium = 9-12 points

–High = 13-15 points

6) Post Entry Distribution and Survey Information: Alligatorweed currently is known from 3-4 populations in northern and southern California. It receives a Medium (-2) 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:

Score: -2

-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: Medium (11)

Uncertainty:

Uncertainty is low, as alligatorweed has established in wetlands in California and other states. There is some uncertainty as to the actual distribution of this plant in California, as, like some other aquatic weeds, it is likely to be overlooked.

Conclusion and Rating Justification:

Conclusions of the harm(s) associated with this pest to California using all of the evidence presented above:

Proposed Rating: Despite its limited ability to disperse between watersheds, this is a potentially significant weed in California of both natural wetlands and irrigation canals. Because of its potential economic impacts, it deserves an A rating, as it has proven tenacious and is actively spreading.

References:

Baldwin, B. G., D. H. Goldman, D. J. Keil, R. Patterson, T. J. Rosatti, and D. H. Wilken, editors. 2012. The Jepson manual: vascular plants of California, second edition. University of California Press, Berkeley.

Consortium of California Herbaria. Accessed 10/3/2017:  ucjeps.berkeley.edu/consortium/

Florida Dept of Agriculture Weed of the Month: Alternanthera sessilis. Accessed 10/3/2017: http://www.freshfromflorida.com/Divisions-Offices/Plant-Industry/Plant-Industry-Publications/Weed-of-the-Month/April-2011-Alternanthera-Sessilis

Invasive Plant Atlas of the Mid-South. alligatorweed. Accessed 10/3/2017:    https://www.gri.msstate.edu/ipams/species.php?CName=Alligatorweed

Responsible Party:

Dean G. Kelch, Primary Botanist; California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 403-6650. plant.health[@]cdfa.ca.gov.

*NOTE:

You must be registered and logged in to post a comment.  If you have registered and have not received the registration confirmation, please contact us at plant.health[@]cdfa.ca.gov.

Pest Rating: A | Proposed Seed Rating: R

Posted by ls

A-Rated, Ratings, Vertebrate Pests

Nutria | Myocastor coypus

California Pest Rating for
Nutria  |  Myocastor coypus
Pest Rating: A
PEST RATING PROFILE
Initiating Event

On March 30, 2017 a suspected Nutria (Myocastor coypus) was turned in to California Department of Fish and Wildlife staff in Merced County. It was confirmed by the local Department of Fish and Wildlife Services trapper.  The animal was found living in a managed wetland (duck hunting club) adjacent to the Grasslands Ecological Area in Merced County.

History & Status

Background: 

Nutria are large aquatic rodents that may easily be confused with the even larger North American Beaver (Castor Canadensis). Their long rat-like tail is the primary distinguishing characteristic when compared to the large paddle shaped tail of the beaver. Nutria are herbivores that may consume up to 25% of their body-weight per day, in addition they are wasteful feeders focusing on roots and tubers while discarding up to 90% of the plant matter they harvest. They may impact crops and landscape plantings in areas adjacent to water ways, damage water conveyance and storage structures, undermine roads and vector parasites and diseases to humans and livestock. Nutria are primarily nocturnal, though lack of predatory pressure or the influence of human feeding may cause an increase in daytime activity. Nutria are prolific breeders, females may have 2-3 liters per year with an average of 4-5 offspring per liter. Young become sexually active between four and six months of age. Nutria nest in dense vegetation and construct burrows for protection from cold temperatures. Burrows can range from 6-45 meters in length. Nutria have been found to cause significant damage to wetland and riparian habitats and are considered agricultural pests in many parts of the world. In the early 1900’s they were purposefully introduced in many parts of the world to supplement the trapping of furbearing animals for the fur trade. In nature, their populations are primarily limited by harsh winters, commercial trapping and large predators such as alligators or large snakes. Nutria have successfully established in brackish estuarine waters around the United States, however they are not capable of natural immigration in to California with its mountains, deserts and coastline borders.

map for predicted suitable habitat
Figure 1. Geographical extent of predicted suitable nutria habitat (based on 2003 – 2007 mechanistic model) in the contiguous United States compared to the status of nutria populations by state. (Sheffels 2013)

Worldwide Distribution: 

Native to South America. Nutria are a common invasive species in the Southeastern United States. Blamed for significant impacts and loss of wetlands in the Mississippi Delta as well as the Chesapeake Bay. They are widespread in the Pacific Northwest, including Oregon, Washington and Southern British Columbia. Nutria have been successfully introduced and established in every continent other than Australia and Antarctica (Chesapeake Bay Nutria Eradication Project 2016).

Official Control:

A bounty system has been used in the past in Louisiana. During the 2009-2010 trapping season the state of Louisiana paid a $5 per animal bounty on 445,963 Nutria harvested for a total of $2,229,815 (Coastwide Nutria Control Program).

When necessary USDA – Wildlife Services will control localized populations of Nutria.  In 2002 an eradication program was initiated in the state of Maryland. As of 2016 all known populations had been removed from the Delmarva Peninsula of the Chesapeake Bay in Maryland. Surveillance is currently ongoing to verify eradication (Chesapeake Bay Nutria Eradication Project 2016).

Washington State requires any trapped Nutria to be immediately euthanized and prohibits their movement (Washington Invasive Species Council 2016).

Nutria are Considered an agricultural pest in China. Nutria eradication is underway in Japan. They are known to be responsible for damage to fish ponds in Israel. Nutria are considered a pest in Western Europe but a valuable resource in Eastern Europe where fur has higher value. England initiated a trapping eradication in 1981 and declared eradication in 1989. There are numerous Nutria eradication programs in France. They are considered a pest in Germany due to damage to dams. Nutria are also considered a pest of rice production in Italy. (Carter and Leonard 2002)

California Distribution:

There are historical reports of Nutria from Elizabeth Lake, Stanislaus River and Los Angeles County. The first introduction to the United States occurred at Elizabeth Lake California in 1899 which failed due to breeding failures. The California Department of Food and Agriculture conducted an eradication program for a feral population of Nutria from the Stanislaus River during the 1960’s. Eradication was achieved by 1978 (National Wetlands Research Center 2015).

Recent modeling of Nutria distribution and climate change predict that California is highly suitable for Nutria establishment and spread. The mountainous terrain and disconnected hydrological units are the only barrier between Northern California and the Nutria infested waterways of Southern Oregon (Jarnevich et al. 2017).

California Interceptions:

One adult Nutria was trapped in a managed wetland (duck hunting club) adjacent to the Grasslands Ecological Area in Merced County. There are anecdotal reports of additional Nutria sightings from the duck club caretaker.

Consequences of Introduction

The risk Nutria would pose to California is evaluated below.

Problems associated with high Nutria populations fall into several categories: destruction of marsh habitat, destruction of water control structures such as dykes and levees, destruction of agricultural crops, and the fact that the animals can serve as repositories of a variety of diseases.

1) Climate/Host Interaction: Evaluate if the pest would have suitable hosts and climate to establish in California. Score: 3

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.

Recent modeling data found that the majority of California could provide suitable habitat for Nutria. High elevations and deserts being the only limiting factors. Nutria could easily move throughout the inland waterways and irrigation networks.

2) Known Pest Host Range: 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.

Nutria are an aquatic species. Distribution would be limited to areas adjacent to waterways. Rivers, streams, estuaries and irrigation canals would all be suitable habitat. The interconnected waterways throughout the Sacramento-San Joaquin River and Delta and irrigated lands are all susceptible to Nutria establishment.

3) Pest Dispersal Potential: 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.

Nutria could naturally disperse throughout the entire Sacramento-San Joaquin Bay-Delta watershed which covers over 75,000 square miles from Tehachapi to the Cascades Mountain Range. They could also establish around natural and man-made lakes, reservoirs, irrigation canals and other waterbodies.

4) Economic Impact: Evaluate the likely economic impacts of the pest to California using the criteria below. Score: 3

Economic Impact: A, B, E, G

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.

Nutria have shown to damage rice and orchards/vineyards potentially lowering crop yield and causing losses.  There is also potential for them to disrupt water delivery to crops and spread contaminants impacting food safety.  They are known to vector liver flukes and other parasites to livestock, damage water conveyance and storage infrastructure.

5) Environmental Impact: Evaluate the environmental impact of the pest on California using the criteria below. Score: 3

Environmental Impact: A, B, C, 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.

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.

Nutria have contributed to massive wetland destruction and land loss. Nutria could feed directly on threatened or endangered wetland and riparian plants. Nutria have created eat-outs completely denuding vast areas of habitat, their burrowing activity also contributes to increased siltation of waterways which can impact fish habitat. Many areas of the United States currently have control and eradication programs targeting Nutria. In addition to being agricultural pests and damaging the environment Nutria have also impacted urban and residential landscaping, transmit parasites to animals and humans and become aggressive towards humans and pets.

Consequences of Introduction to California for Nutria:

Add up the total score and include it here. (14)

Low = 5-8 points

Medium = 9-12 points

High = 13-15 points

6) Post Entry Distribution and Survey Information: 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. (-1)

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.

Nutria have successfully been eradicated from California in an area close to the current location of the detections. There is only one other documented introduction in 1899 which failed to establish. There are no PDR records of other encounters in the State.

Final Score

The final score is the consequences of introduction score minus the post entry distribution and survey information score: (13)

Uncertainty

It is important to separate out uncertainty from risk. Use this section to evaluate any uncertainty associated with the introduction of the pest to California.

The three primary limiting factors of Nutria populations are harsh winters, commercial trapping and large predator populations. California has very mild winters compared to other infested areas of the world. Fur trapping is a very insignificant activity in California due to social as well as regulatory constraints and low fur prices. California does not have large populations of predators nor predators large enough to effectively take Nutria. The Southeastern U.S. has alligators and the portions of Africa that have not been impacted have many different species of large carnivores.

Conclusion and Rating Justification

Proposed rating of A.

Nutria have proven to be a significant agricultural pest in other parts of the world with similar climates and cropping systems to California. Significantly impacted crops include rice, orchards and vineyards. In addition, Nutria are a known vector of ectoparasites and diseases. Livestock are particularly susceptible to liver flukes if exposed to water soiled by Nutria excrement (Menard et al.2000). Nutria have caused extensive damage to waterways, water storage and conveyance as well as adjacent rights-of-way. Of particular concern would be the thousands of miles of earthen canal, dikes and levees comprising much of the Central Valley irrigation infrastructure (Witmer et al. 2012).

Nutria have caused extreme environmental degradation to wetlands around the United States. Their feeding behavior can produce “eat outs” which eliminate the aquatic vegetation which contains wetland and marsh soils. The subsequent erosion is extremely damaging to wetlands. In addition, this erosion combined with their burrowing activity has the potential to damage fish habitat through increased siltation. In the Chesapeake Bay estuary one of the most heavily impacted habitat types is the Spartina sp. complex similar to much of the San Francisco Bay estuary.

Due to the documented negative impacts to agriculture and the environment of Nutria establishment and the high probability of eradication in California, a rating of A is justified.

References

Carter, Jacoby, and Billy P. Leonard. “A Review of the Literature on the Worldwide Distribution, Spread of, and Efforts to Eradicate the Coypu (Myocastor coypus).” Wildlife Society Bulletin (1973-2006), vol. 30, no. 1, 2002, pp. 162–175.  www.jstor.org/stable/3784650

Chesapeake Bay Nutria Eradication Project.  “U.S. Fish and Wildlife Service Species of Concern Fact Sheet: Nutria.” (2016) Aquatic Nuisance Species Task Force.  https://www.fws.gov/chesapeakenutriaproject/

Coastwide Nutria Control Program. “Home. Nutria Control Program” (2007) Louisiana Department of Wildlife and Fisheries.  http://www.nutria.com/site9.php

Jarnevich CS, Young NE, Sheffels TR, Carter J, Sytsma MD, Talbert C “Evaluating simplistic methods to understand current distributions and forecast distribution changes under climate change scenarios: an example with coypu (Myocastor coypus).” (2017) NeoBiota 32: 107-125. https://doi.org/10.3897/neobiota.32.8884

Menard A; M. L’Hostis, G. Leray, S. Marchandeau, M. Pascal, N. Roudot, V. Michel and A. Chauvin “Inventory of Wild Rodents and Lagomorphs as Natural Hosts of Fasciola hepatica on a Farm Located in a Humid Area in Loire Atlantique (France)” (2000), Parasite, 7, 77-82 http://dx.doi.org/10.1051/parasite/2000072077

National Wetlands Research Center. “Worldwide Distribution, Spread of, and Efforts to Eradicate the Nutria (Myocastor coypus).”(2015) United Stated Geological Survey (USGS). https://www.nwrc.usgs.gov/special/nutria/namerica.htm

Pasko, Susan and Anne Marie Eich, “Species of Concern Fact Sheet: Nutria” (2011) Aquatic Nuisance Species Task Force.  https://www.anstaskforce.gov/spoc/nutria.php

Sheffels, Trevor Robert, “Status of Nutria (Myocastor coypus) Populations in the Pacific Northwest and Development of Associated Control and Management Strategies, with an Emphasis on Metropolitan Habitats” (2013).Dissertations and Thesis.Paper 665. http://pdxscholar.library.pdx.edu/cgi/viewcontent.cgi?article=1664&context=open_access_etds

Washington Invasive Species Council. “Stop the Invasion. Nutria, Myocastor coypus” (2016) Washington Department of Fish and Wildlife. http://www.invasivespecies.wa.gov/documents/priorities/NutriaFactSheet.pdf

Witmer, Gary; Sheffels, Trevor R.; and Kendrot, Stephen R., “The Introduction, Impacts, And Management of a Large, Invasive, Aquatic Rodent in The United States” (2012). USDA National Wildlife Research Center – Staff Publications. Paper 1215. http://digitalcommons.unl.edu/icwdm_usdanwrc/1215/

Responsible Party:

David Kratville, Senior Environmental Scientist, California Department of Food and Agriculture, 3294 Meadowview Road, Sacramento, CA 95832. Phone: 916-262-1102, plant.health[@]cdfa.ca.gov.

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Pest Rating: A

Posted by ls