click beetle | Pest Rating Proposals and Final Ratings

California Pest Rating for

Click Beetle | Conoderus posticus (Eschscholtz)

Coleoptera: Elateridae

Pest Rating: A

PEST RATING PROFILE

Initiating Event:

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

History & Status:

Background: Adult Conoderus posticus have a typical elaterid body form, are brown in color, and measure approximately 6 mm in length (Eschscholtz, 1822; Johnson et al. 2017). The larvae of Elateridae are referred to as wireworms and typically live underground or inside decomposing plant tissue. Many species are omnivorous, the larvae feeding on plant roots as well as insects, and some are considered to be both plant pests as well as predators of pests (Robertson, 1987). Pest species attack crops including sugarcane, peanuts, and potatoes. The biology of C. posticus is poorly known. The species was found in bat guano in caves in Cuba; it is not known what it was feeding on in that environment, but it may have been seeds (Peck et al. 1998). Larvae of other, better-studied species of Conoderus are known to feed on plant roots.

Worldwide Distribution: Conoderus posticus is apparently native to the Caribbean, Central America, and South America. The species has been introduced to Hawaii and Mediterranean Europe (Denux and Zagatti, 2010; Johnson et al. 2017; Platia and Kakiopoulos, 2014).

Official Control: Conoderus posticus is not known to be under official control anywhere.

California Distribution: Conoderus posticus is not known to be present in California (Symbiota Collections of Arthropods Network).

California Interceptions: Conoderus posticus has not been intercepted in California.

The risk Conoderus posticus would pose to California is evaluated below.

Consequences of Introduction:

1) Climate/Host Interaction: Conoderus posticus has become established in the Mediterranean region, which has a climate similar to much of California. Little is known regarding its biology, but many Conoderus species possess generalist feeding habits, and posticus likely does as well. Therefore, Conoderus posticus 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: Little is known regarding the biology of Conoderus posticus. Many Conoderus species are generalists, feeding on many different plant 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: Conoderus species can fly, as they are collected at light (Stone and Wilcox, 1979). Therefore, it 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: The genus Conoderus includes species that are pests of various crops. Little is known about the biology of posticus, but it likely feeds on plant roots, like other species in the genus. If it was established in California, it could become a pest of agriculture, lowering crop yield. 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: As stated under Economic Impacts, Conoderus posticus may feed on plant roots and could potentially impact native plants in California if it was established here. There are species of plants in California that posticus has not yet encountered, and it could have an impact in this state greater than that seen where this beetle is already present. 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 Conoderus posticus: 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: Conoderus posticus 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 uncertainty regarding the ability of Conoderus posticus to successfully establish in California, as it is probably a generalist feeder and it has a proven ability to become established in areas with a Mediterranean climate. There is, however, much uncertainty regarding its potential for economic or environmental impact. On one hand, no reports were found of this species being a pest or having an impact on the environment anywhere it has become established. It is possible (perhaps likely) that it would have no significant economic or environmental impact in California if it was established here. However, as a subterranean feeder, it is possible that there exists economic impact of this species that has not been recognized but instead has been attributed to other species of “wireworms” or to underground insects in general. In this case, it could be a significant pest but be unrecognized as such. Environmental impacts, if there are any, are even more likely to have gone unrecognized.

Conclusion and Rating Justification:

Conoderus posticus is a poorly-known species in a genus that includes significant agricultural pests. The species is not known to occur in California. If it was established in this state, it could have an economic and/or environmental impact. For these reasons, an “A” rating is justified.

References:

Denux, O. and Zagatti, P. 2010. Coleoptera families other than Cerambycidae, Curculionidae sensu lato, Chrysomelidae sensu lato and Coccinelidae. Chapter 8.5. BioRisk. 4(1): 315-406.

Eschscholtz, F. 1822. Entomographien. Erste Liererung. G. Reimer, Berlin. 128 pp.

Johnson, P.J., Ogura-Yamada, C., Krushelnycky, P.D., and Samuelson, G.A. 2017. Conoderus posticus (Eschscholtz) (Coleoptera: Elateridae), a new state record for Hawai’i, and a key to local species. Bishop Museum Occasional Papers. 119: 19-22.

Norris, D.M. 1957. Bionomics of the southern potato wireworm, Conoderus falli Lane. 1. Life history in Florida. Proceedings of the Florida State Horticultural Society. 70: 109-111.

Platia, G. and Kakiopoulos, G. 2014. Interesting records of beetles from Greece, with description of a new species (Coleoptera, Elateridae and Plastoceridae). Boletín de la Sociedad Entomológica Aragonesa. 54: 117-120.

Robertson, L.N. 1987. Food habits of pasture wireworm, Conoderus exsul (Coleoptera: Elateridae). New Zealand Journal of Zoology. 14: 535-542.

Seal, D.R. 2011. A wireworm Conoderus rudis (Brown) (Insecta: Coleoptera: Elateridae). University of Florida, Entomology and Nematology Department, UF/IFAS Extension.

Stone, M.W. and Wilcox, J. 1979. Population build-up of two introduced Conoderus elaterid species in California (Coleoptera: Elateridae). The Coleopterists Bulletin. 33(4): 473-475.

Symbiota Collections of Arthropods Network. Accessed March 9, 2018. http://scan1.acis.ufl.edu

Williams, E.M. and Galbreath, R.A. 1987. Diet and development in Conoderus exsul and Agrypnus variabilis (Coleoptera: Elateridae). New Zealand Journal of Zoology. 14: 85-88.

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

3/15/18 – 4/29/18

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