Weevil | Oxydema longula (Boheman) | Pest Rating Proposals and Final Ratings

California Pest Rating for

Weevil | Oxydema longula (Boheman)

Coleoptera: Curculionidae

Pest Rating: C

PEST RATING PROFILE

Initiating Event:

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

History & Status:

Background: Oxydema longula is a weevil that measure 5-5.5 mm in length and is black and shining (Boheman, 1859). The species occurs in a variety of dead and decaying plant material, and the larvae are reported to feed in dead ferns and bamboo and rotting wood (Blackburn and Sharp, 1887; Swezey, 1922; Swezey, 1925; Swezey, 1954). This weevil has been reported to be associated with living plants as well. For example, it bored into rubber trees and “matured” sisal plants and “riddled” a papaya tree in Hawaii (Kuhns, 1908; Smith and Bradford, 1908; Van Dine, 1906). The species has also been intercepted on cordyline (Hunt, 1954). These records do not necessarily indicate that this weevil attacks living plant tissue. The boring in rubber trees occurred in rubber tapping injuries. Regarding the sisal plant records, this plant is harvested via removal of older leaves, so the burrowing of the weevil could have exploited dead tissue resulting from harvesting injuries. The weevil(s) intercepted on cordyline could simply have been using the plant as shelter, or it could have been feeding on a dead portion of the plant.

Little information was found on the biology of the genus Oxydema, but Oxydema fusiforme Wollaston is reported to feed on rotting plant material, including rotting wood and boards and dead morning glory vines (Hawaiian Entomological Society, 1922; Hawaiian Entomological Society, 1935; Loschiavo and Okumura, 1979).

Synonyms of Oxydema longula include Oxydema longulum (Boheman), Oxydema longulus (Boheman), Pseudolus longulus (Boheman), and Rhyncolus longulus Boheman. Information reported for these synonyms was considered in this proposal.

Worldwide Distribution: Oxydema longula is reported from Hawaii (all islands), Midway Atoll, and Saipan Island (Konishi, 1956; Suehiro, 1960; Zimmerman, 1940). It may be native to Hawaii and introduced to the other areas.

Official Control: Oxydema longula is not known to be under official control anywhere.

California Distribution: Oxydema longula is not known to be present in California.

California Interceptions: Oxydema longula has been intercepted 12 times on various plant products from Hawaii, including cut flowers (CDFA Pest and Damage Report Database, 2018).

The risk Oxydema longula would pose to California is evaluated below.

Consequences of Introduction:

1) Climate/Host Interaction: Oxydema longula is found in areas with a tropical to subtropical climate. Climate may limit this weevil’s potential distribution in California. This weevil apparently feeds on a wide variety of decaying plant material. Presence of food is not expected to be a limiting factor in its potential distribution in California. Therefore, Oxydema longula receives a Medium (2) in this category.

Score: 2

– 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: Oxydema longula is reported to feed on a wide variety of rotting plant material. Therefore, it receives a High (3) in this category.

Score: 3

– 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: Another species of Oxydema, fusiforme, was collected at light in Hawaii, so it presumably flies (Browne, 1942). Oxydema longula is presumed to fly as well. Therefore, it receives a Medium (2) in this category.

Score: 2

– 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: Oxydema longula has not been reported to cause economic damage. The available evidence strongly suggests that it feeds on dead, rotting plant material. Therefore, it receives a Low (1) in this category.

Economic Impact:

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: Oxydema longula apparently feeds on dead plant material. The species is therefore not expected to threaten living plants. However, it could compete with native insects that also feed on dead plant material. Therefore, it receives a Medium (2) in this category.

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

Environmental Impact: A

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:

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 Oxydema longula: Medium (10)**

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: Oxydema longula is not known to be present 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 (10)

Uncertainty:

There is a possibility that O. longula may feed on living plant tissue, although the available reports generally state dead (often rotting) plant material as the food.

Conclusion and Rating Justification:

Oxydema longula is a weevil that is reported to feed on dead plant material. This saprophagous lifestyle suggests that it does not pose an economic or environmental risk to California. For these reasons, a “C” rating is justified.

References:

Blackburn, T. and Sharp, D. 1885. Memoirs on the Coleoptera of the Hawaiian Islands. The Scientific Transactions of the Royal Dublin Society 3:119-300.

Boheman, C. H. 1859. Coleoptera. pp. 113-218 in Kongliga Svenska Fregatten Eugenies. P.A. Norstedt & Söner, Stockholm.

Browne, A. C. 1942. Insects taken at light at Kalawahine Place, Honolulu. Proceedings of the Hawaiian Entomological Society 11:151-152.

CDFA Pest and Damage Report Database. 2018. Oxydema longula. Plant Health and Pest Prevention Services. CA Department of Food and Agriculture. Accessed April 16, 2018: https://pdr.cdfa.ca.gov/PDR/pdrmainmenu.aspx

Hawaiian Entomological Society. 1922. November 3, 1921. Proceedings of the Hawaiian Entomological Society 5:32-35.

Hawaiian Entomological Society. 1935. April 5, 1934. Proceedings of the Hawaiian Entomological Society 5:12-16.

Hunt, J. 1954. List of intercepted plant pests, 1954. United States Department of Agriculture.

Konishi, M. 1955. Cossoninae of Marcus Island. Insecta Matsumurana 19:64.

Kuhns, D. B. Noted on Maui insects. Proceedings of the Hawaiian Entomological Society 2:93.

Loschiavo, S. R. and Okumura, G. T. 1979. A survey of stored product insects in Hawaii. Proceedings of the Hawaiian Entomological Society 13:95-118.

Smith, J. G. and Bradford, Q. Q. 1908. The ceara rubber tree in Hawaii. Bulletin of the Hawaii Agricultural Station 16:1-30.

Suehiro, A. 1960. Insects and other arthropods from Midway Atoll. Proceedings of the Hawaiian Entomological Society 17:289-298.

Swezey, O. H. 1922. Insects attacking ferns in the Hawaiian Islands. Proceedings of the Hawaiian Entomological Society 5:57-65.

Swezey, O. H. 1925. The insect fauna of trees and plants as an index of their endemicity and relative antiquity in the Hawaiian Islands. Proceedings of the Hawaiian Entomological Society 6:195-209.

Swezey, O. H. 1954. Forest entomology in Hawaii. Bernice Bishop Museum Special Publication 44:1-265.

Symbiota Collections of Arthropods Network. Accessed April 27, 2018. http://scan1.acis.ufl.edu

Van Dine, D. L. 1906. Report of the entomologist. Report on Agricultural Investigations in Hawaii 1906:38-59.

Zimmerman, E. C. 1940. Synopsis of the genera of Hawaiian Cossoninae with notes on their origin and distribution. Occasional Papers of Bernice P. Bishop Museum, Honolulu, Hawaii 15:271-293.

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

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