Cyphocleonus achates

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Cyphocleonus achates
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Coleoptera
Family: Curculionidae
Genus: Cyphocleonus
Species: C. achates
Binomial name
Cyphocleonus achates
Fahraeus

Cyphocleonus achates is a species of true weevil known as the knapweed root weevil. It is used as an agent of biological pest control against noxious knapweeds, especially spotted knapweed (Centaurea maculosa).

The adult weevil is dark gray and white speckled and 14 to 15 millimeters long. The female lays about 100 eggs during her 8- to 15-week adult lifespan. The eggs are deposited one by one in notches the female digs into the root crown of the knapweed. The larva emerges from the egg and tunnels into the root cortex where it feeds on the plant tissue. Sometimes a gall is produced in the feeding area. Adults feed on the leaves but it is the larva that does the most damage to the plant. Small plants can be killed by the larva's destruction of the root tissue.

This weevil is native to southern Europe and the Mediterranean. It was first released as a knapweed biocontrol in the 1980s in the United States. It is established in much of the western United States and there is evidence that it reduces knapweed biomass. The weevil prefers spotted knapweed, but it is sometimes found on diffuse knapweed. It has not been shown to attack native flora.

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[edit] References

Coombs, E. M., et al., Eds. (2004). Biological Control of Invasive Plants in the United States. Corvallis: Oregon State University Press, 212.