Laportea aestuans | Pest Rating Proposals and Final Ratings

California Pest Rating for

West Indian Woodnettle | Laportea aestuans

Family: Urticaceae

Pest Rating: C | Proposed Seed Rating: N/A

PEST RATING PROFILE

Initiating Event:

Laportea aestuans currently has a Z rating, and was recently found in San Luis Obispo County. A permanent pest rating proposal is required to support an official pest rating.

History & Status:

Background: Laportea aestuans is an annual herb belongs to the nettle family growing up to 1 m tall. It has fleshy and slightly woody stem with both stinging and nonstinging hairs. Leaves are alternate and broadly oval with serrated margins; petiole is reddish in color. The tiny flowers are greenish yellow in color and occur in clusters on a 4-10 cm long peduncle². This plant can grow from sea level up to 1300 m altitude. It occurs along roads and in other disturbed locations in forest or woodland areas. It grows in partial shade and sometimes in rock crevices¹.

Laportea aestuans is native to tropical Africa. It is widely distributed throughout the western and eastern hemisphere tropics and subtropics, including Central America, the West Indies, India, Sumatra and Java. In the US, it can be found in California and Florida¹.

Laportea aestuans is considered an agricultural weed because of its invasive characteristics, but it is used as food source and in traditional medicine in Africa. It hosts root-knot nematode (Meloidogyne spp.), a pest of banana plantations which is “A” rated and a quarantine pest in California. It is a known host of African cassava mosaic virus, an important pest of the major African food crop Cassava (Manihot esculenta)^{1, 2}.

Worldwide Distribution: Laportea aestuans is widely distributed in tropical Africa, from Senegal eastward to Eritrea and southward to Angola, Zimbabwe and Mozambique, and in Madagascar. It also reported in tropical Asia and tropical America².

Official Control: Laportea aestuans is not declared or considered noxious by any State government authorities⁵.

California Distribution: It was introduced to California and collected as greenhouse weed in San Bernardino and Riverside counties³. It was also growing in the UC Riverside Botanical Garden in 1995.

California Interceptions: Laportea aestuans was intercepted three times between January, 1990 up to December, 2016. One specimen recently was collected in San Luis Obispo county on January 6, 2017 through regulatory pathways (Pest and Damage Report Database, CA Department of Food and Agriculture)⁴.

Consequences of Introduction:

1) Climate/Host Interaction: Laportea aestuanswas collected in San Bernardino and Riverside counties. It may remain a weed of greenhouses. Therefore, Laportea aestuans receives a Low (1) 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 Laportea aestuans do not require any one host, but grows 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: Laportea aestuans reproduces only by seed. Seeds are dispersed by animals, water runoff and by the movement of contaminated agricultural tools. It receives at Medium (2) in this category.

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: Laportea aestuans had not yet had an impact on agricultural lands and future possible impacts are unknown. It could possibly effect the normal cultural practices by growing in dense stands. It receives a Low (1) in this category.

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

Economic Impact: D

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: Laportea aestuans had not spread widely only found in greenhouse situation in California. If it does spread, it might trigger new treatments by land managers. It receives a Medium (2) in this category.

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

Environmental Impact: 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: 2

– 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 Laportea aestuans (West Indian woodnettle): Medium (9)

–Low = 5-8 points

–Medium = 9-12 points

–High = 13-15 points

6) Post Entry Distribution and Survey Information: Laportea aestuans has been reported only in greenhouses in San Bernardino and Riverside counties³. It receives a Low (-1) 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: -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.

Final Score:

The final score is the consequences of introduction score minus the post entry distribution and survey information score: Low (8)

Uncertainty:

Laportea aestuans entered California and appeared in greenhouses habitat. So, there is low uncertainty.

Conclusion and Rating Justification:

Conclusions of the harm(s) associated with this pest to California using all of the evidence presented above: Proposed Rating: based on the score listed above the pest is a low risk. A “C” rating is recommended.

References:

Brink, M., 2009. Laportea aestuans (L.) Chew. Record from PROTA4U. Brink, M. & Achigan-Dako, E.G. (Editors). PROTA (Plant Resources of Tropical Africa), Wageningen, Netherlands. Accessed January 19, 2017 http://www.prota4u.org/protav8.asp?p=Laportea+aestuans

Derek Arakaki and Christopher Lao. 2012. Pest advisory No. 12-02. Dept. of Agriculture Hawaii. Accessed January 19, 2017 https://hdoa.hawaii.gov/pi/files/2013/01/Laportea-aestuans-NPA.pdf

Calflora: Information on California plants for education, research and conservation, with data contributed by public and private institutions and individuals, including the Consortium of California Herbaria. 2016. Berkeley, California. Accessed January 19, 2017 https://www.calflora.org/cgi-bin/species_query.cgi?w here-calrecnum=8755

Pest and Damage Record Database, California Department of Food and Agriculture, Plant Health and Pest Prevention Services. Accessed 1-19-2017. http://phpps.cdfa.ca.gov/user/frmLogon2.asp

USDA Phytosanitary Certificate Issuance & Tracking System (PCIT) Phytosanitary Export Database (PExD). Accessed January 19, 2017 https://pcit.aphis.usda.gov/pcit/