Black Twig Borer | Xylosandrus compactus (Eichhoff) | Pest Rating Proposals and Final Ratings

California Pest Rating for

Black Twig Borer | Xylosandrus compactus (Eichhoff)

Coleoptera: Curculionidae: Scolytinae

Pest Rating: A

PEST RATING PROFILE

Initiating Event:

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

History & Status:

Background: Xylosandrus compactus is a small (adult females are 1.4-1.7 mm long; males are flightless and smaller, 1-1.1 mm long) ambrosia beetle (Wood, 1982). As in other ambrosia beetles, adults and larvae feed on fungus that grows in galleries excavated by the adult beetle. Living twigs (less than 2 cm in diameter) of healthy trees and shrubs are attacked (Wood, 1982). Affected branches wilt and die; the symbiotic fungus may be the cause of much of this damage. Apparently, this damage does not usually result in the death of an adult tree, but death has been reported in seedlings and young trees. For example, seedlings of mahogany (Swietenia macrophylla) in Peru and soursop (Annona muricata) in Brazil were killed (Delgado and Couturier, 2010; Oliveira et al., 2008). Non-lethal damage by this beetle still causes economic losses, for instance, in coffee (Bittenbender and Smith, 1999; Burbano et al., 2012). Xylosandrus compactus is reported to attack hundreds of species (in 62 families) of shrubs and trees. Hosts include crop and ornamental trees, for example, avocado, sycamore, magnolia, dogwood, coffee, and eucalyptus (Chong et al., 2009; Greco and Wright, 2015). In Hawaii, a variety of native trees are attacked by this species, including seedlings of Acacia koa (Burbano et al., 2012). Native trees in Italy were attacked over an area of 13 hectares, and some trees were killed. Tree species affected include Quercus ilex and Viburnum tinus (Vannini et al., 2017). Adult female X. compactus mate with males before leaving their developmental gallery, and they can also reproduce via arrhenotokous parthenogenesis (an unmated female lays unfertilized eggs that develop into males; the female mates with her male progeny and then deposits fertilized eggs, which develop into females).

Worldwide Distribution: Xylosandrus compactus is reported from tropical Africa, Europe, southeast Asia, New Zealand, tropical Pacific islands (including Micronesia), the Caribbean, South America (including Brazil, Guyana, and Peru), and the United States (Hawaii and the southeastern United States) (Wood, 2007). The species is native to Asia, and was presumably introduced to the other portions of its current distribution, including the United States (Burbano et al., 2012).

Official Control: Xylosandrus compactus is listed as a quarantine pest by Brazil, Israel, and the European Union (EPPO, 2017).

California Distribution: Xylosandrus compactus is not known to occur in California (Bright and Stark, 1973; Symbiota Collections of Arthropods Network).

California Interceptions: Xylosandrus compactus has been intercepted at least six times in California on shipments of plants from Hawaii (PDR # 008573, 1238977, 1239464, 1335578, 1225854, and 053234).

The risk Xylosandrus compactus would pose to California is evaluated below.

Consequences of Introduction:

1) Climate/Host Interaction: Xylosandrus compactus has become established in many parts of the world, from Mediterranean Europe to tropical South America. This suggests that it has a wide climatic tolerance. The beetle feeds on hundreds of species of plants in 62 families. These facts suggest that compactus could become established over a wide portion of California. Therefore, it 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: Xylosandrus compactus is known to feed on hundreds of species of plants in 62 families. Therefore, it receives a High (3) 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: Female Xylosandrus compactus Sibling mating and parthenogenesis means that a single adult female emerging from its gallery can establish a new population. Therefore, it receives a High (3) 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: Xylosandrus compactus is considered an economically-significant pest. The species attacks hundreds of species of plants and poses a threat to economically-important trees, including avocado and coffee, both of which are currently grown in California. Damage to these trees could lower crop yield and increase production costs. The beetle can kill tree seedlings, so poses a problem for tree nurseries and the establishment of trees in forests. In addition, like all ambrosia beetles, compactus carries fungi that may be pathogenic. If established in California, this beetle could develop an association with other species of pathogenic fungi already present in the state. Therefore, it receives a High (3) in this category.

Economic Impact: A, B, E

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: Xylosandrus compactus attacks a diversity of plants and would be expected to damage numerous species of plants in California if it became established here. The fact that it is known to attack such a wide variety of plants means it is likely that some endangered plants could also be at risk. This risk is demonstrated by the fact that this beetle attacked native trees in Italy, including species of Quercus and Viburnum, genera which include native California species. This beetle attacks ornamental trees, causing dieback of branches (Hayato, 2007). 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, 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.

**Consequences of Introduction to California for Xylosandrus compactus: High (15)**

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: Xylosandrus compactus 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: High (15)

Uncertainty:

There is little uncertainty regarding the potential for Xylosandrus compactus to become established in California. There also seems to be little uncertainty regarding the potential of this species to become a pest in this state, because it has done so in other areas to which it was introduced and it attacks such a wide variety of plants.

Conclusion and Rating Justification:

Xylosandrus compactus is a highly polyphagous pest that has demonstrated an ability to become established in many areas worldwide and impact crop, ornamental, and native plants. The species is not known to be present in California, and its potential introduction to this state poses a risk of economic and environmental damage. For these reasons, an “A” rating is justified.

References:

Bittenbender, H. C. and V. E. Smith. 1999. Growing coffee in Hawaii. College of tropical agriculture and human resources. University of Hawaii at Manoa, Honolulu, HI. 40 pp.

Bright Jr., D.E. and R.W. Stark. 1973. The Bark and Ambrosia Beetles of California. University of California Press. 169 pp.

Burbano, E.G., Wright, M.G., Gillette, N.E., Mori, S., Dudley, N., Jones, T., and M. Kaufmann. 2012. Efficacy of traps, lures, and repellents for Xylosandrus compactus (Coleoptera: Curculionidae) and other ambrosia beetles on Coffea arabica plantations and Acacia koa nurseries in Hawaii. Environmental Entomology. 41(1): 133-140.

Chong, J.-H., Reid, L., and M. Williamson. 2009. Distribution, host plants, and damage of the black twig borer, Xylosandrus compactus (Eichhoff), in South Carolina. Journal of Agricultural and Urban Entomology. 26(4): 199-208.

Delgado, C. and G. Couturier. 2010. Xylosandrus compactus (Coleoptera: Curculionidae” Scolytinae), a new pest of Swietenia macrophylla in the Peruvian Amazon. Boletin de la Sociedad Entomolόgica Aragonesa. 47: 441-443.

EPPO. 2017. EPPO Global Database. Accessed October 12, 2017. https://gd.eppo.int

Greco, E.B. and M.G. Wright. 2015. Ecology, biology, and management of Xylosandrus compactus (Coleoptera: Curculionidae: Scolytinae) with emphasis on coffee in Hawaii. Journal of Integrated Pest Management. 6(1): 1-8.

Hayato, M. 2007. Note on the dieback of Cornus ﬂorida caused by Xylosandrus compactus. Bulletin of the Department of Forest Microbiology, Forestry and Forest Products Research Institute. 6(1): 59-63.

Oliveira, C.M., Flechtmann, C.A.H., and M.R. Frizzas. 2008. First record of Xylosandrus compactus (Eichhoff) (Coleoptera: Curculionidae: Scolytinae) on soursop, Annona muricata L. (Annonaceae) in Brazil, with a list of host plants. The Coleopterists Bulletin. 62(1): 45-48.

Symbiota Collections of Arthropods Network. Accessed February 15, 2018. http://scan1.acis.ufl.edu

Vannini, A., Contarini, M., Faccoli, M., Della Valle, M., Rodriguez, C.M., Mazzetto, T., Guarneri, D., Vettraino, A.M., and S. Speranza. 2017. First report of the ambrosia beetle Xylosandrus compactus and associated fungi in the Mediterranean maquis in Italy, and new host–pest

Associations. EPPO Bulletin. 0(0): 1-4.

Wood, S.L. 1982. The bark and ambrosia beetles of North and Central America (Coleoptera: Scolytidae), a taxonomic monograph. Brigham Young University. 1359 pp.

Wood, S.L. 2007. Bark and ambrosia beetles of South America. Brigham Young University. 900 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

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