Sri Lankan Weevil | Myllocerus undecimpustulatus undatus

California Pest Rating
Myllocerus undecimpustulatus undatus: Sri Lankan weevil
Coleoptera: Curculionidae
  Former Pest Rating:  A
CURRENT Pest Rating: A
Initiating Event:

Myllocerus undecimpustulatus undatus has been rated A by CDFA. Due to recent interceptions in California, a pest rating proposal is required.

History & Status:

Background: Myllocerus undecimpustulatus undatus Marshall, the Sri Lankan weevil, is a plant pest with a wide range of hosts. This weevil spread from Sri Lanka into India and then to Pakistan where it is considered a pest of more than 20 crops. In the United States, the Sri Lankan weevil was first identified on citrus sp. in Pompano Beach a city in Broward County Florida1.

Adult Sri Lankan weevils vary in length from approximately 6.0 to 8.5 mm; the female weevil is slightly larger than the male by 1.0 to 2.0 mm. In this genus, 336 species recognized are from Southeast Asia. These weevils can feed on more than 80 different plants species. These include, citrus, cotton, sweet potato, fig, loquat, plum, mango and mahogany3.

Worldwide Distribution: The Sri Lankan weevil is native to southern India, Sri Lanka and Pakistan. It has been reported from Southeast Asia (including China and Japan), Africa, the Palearctic, Indonesia, Australia and the United States (Florida)3.

Official Control: The Sri Lankan weevil is listed as a harmful organism in the Republic of Korea5.

California Distribution: The Sri Lankan weevil is not reported in California; however, there have not been any recent surveys to confirm this.

California Interceptions: The Sri Lankan weevil was intercepted by CDFA’s high risk inspections, border stations, dog teams, and nursery inspections. Between January 1, 2000 and March, 2017, this insect was intercepted six times, typically on nursery stock and fresh plant parts from Florida4.

The risk Sri Lankan weevil would pose to California is evaluated below.

Consequences of Introduction:

1) Climate/Host Interaction: The Sri Lankan weevil can feed on a variety of field crops, nursery stocks, and fruits of California. The Sri Lankan weevil may establish in larger, but limited, warm agricultural and metropolitan areas of California. It receives a Medium (2) 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: The Sri Lankan weevil has a wide range of hosts and it can feed on almost 80 different kinds of plant species3.  Since, host species are grown throughout California. 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: Female Myllocerus may lay up to 360 eggs over a 24-day period, and larvae emerge in 3-5 days. The Sri Lankan weevil eggs are laid directly on organic material at the soil surface, a common substrate in California. Eggs are less than 0.5 mm, ovoid and usually laid in clusters of 3-5. The eggs are white or cream-colored at first, then gradually turn brown when they are close to hatching1. It receives a High (3) 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: The Sri Lankan weevil is well-known for causing significant damage to agricultural crops and fruits products, especially young plants. Leaf-feeding adults damage the foliage of ornamental plants, fruit trees, and vegetables, whereas the larvae injure root systems; this decreases crop value and yield. Peach growers in Florida are reported to be having a difficult time managing damage from the weevil. It receives a High (3) in this category.

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

Economic Impact: A, B, C

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: The Sri Lankan weevil is not expected to lower biodiversity, disrupt natural communities, or change ecosystem processes. It is not expected to directly impact threatened or endangered species. It can increase production costs to growers if they perform any treatment to control infestations. It is not expected to have significant impacts on cultural practices, home/urban gardening, or ornamental plantings. The Sri Lankan weevil receives a Medium (2) in this category.

Evaluate the Environmental impact of the pest to 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 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 Sri Lankan weevil: High (13)

Low = 5-8 points

Medium = 9-12 points

High = 13-15 points

6) Post Entry Distribution and Survey Information: The Sri Lankan weevil 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: Score -0

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:

The Sri Lankan weevil is intercepted six times in California. There have not been any detection surveys conducted recently to confirm its presence. The environment of California is highly favorable for the Sri Lankan weevil therefore, the uncertainty about this species is high.

Conclusion and Rating Justification:  

The Sri Lankan weevil is not established in California, it would be expected to have significant economic and environmental impacts if it were to establish in the state.  An “A” rating is justified.

References:
  1. Anita Neal 2013.  University of Florida.   Accessed on 3-20-17.

http://entnemdept.ufl.edu/creatures/orn/sri_lankan_weevil.htm

  1. Charles W. O’Brien, Muhammad Haseeb, Michael C. Thomas. Pest weevil from Indian Subcontinent. Florida  Dept. Of Agricultural. Accessed on 3-20-17.

http://www.freshfromflorida.com/content/download/10795/141061/ent412.pdf

  1. Pest Alert. Florida dept. Of Agriculture & consumer services. Accessed on 3-20-17.

http://www.famu.edu/cesta/iframeapps/Invasive_Weevil_Species/Desktop/Myllocerus_undatus_Marshall_-_Sri_Lanka_Weevil_or_Asian_Grey_Weevil.htm

  1. Pest and Damage Record Database, California Department of Food and Agriculture, Plant Health and Pest Prevention Services.

http://phpps.cdfa.ca.gov/user/frmLogon2.asp

  1. USDA Phytosanitary Certificate Issuance & Tracking System (PCIT) Phytosanitary Export Database (PExD). Accessed on 3-20-17.

https://pcit.aphis.usda.gov/pcit/


Responsible Party:

Javaid Iqbal, California Department of Food and Agriculture; 1220 N Street, Sacramento, CA 95814; Tel. (916) 403-6695; plant.health[@]cdfa.ca.gov.


Comment Period:  CLOSED

July 7, 2017 – August 21, 2017


NOTE:

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Pest Rating: A