Cyphocleonus achates
Encyclopedia
Cyphocleonus achates is a species of true weevil
known as the knapweed root weevil. It is native to southern Europe and the Mediterranean and is used as an agent of biological pest control
against noxious knapweeds
, especially spotted knapweed
(Centaurea maculosa).
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. In their native range, most C. achates overwinter as 2nd instar
s, though in the introduced range, the vast majority overwinter as 1st instars.
. It has not been shown to attack native flora.
C. achates was released to the Hiawatha National Forest
in Michigan's Upper Peninsula in summer 2009.
Curculionidae
Curculionidae is the family of the "true" weevils . It was formerly recognized in 1998 as the largest of any animal family, with over 40,000 species described worldwide at that time...
known as the knapweed root weevil. It is native to southern Europe and the Mediterranean and is used as an agent of biological pest control
Biological pest control
Biological control of pests in agriculture is a method of controlling pests that relies on predation, parasitism, herbivory, or other natural mechanisms...
against noxious knapweeds
Centaurea
Centaurea is a genus of between 350 and 600 species of herbaceous thistle-like flowering plants in the family Asteraceae. Members of the genus are found only north of the equator, mostly in the Eastern Hemisphere; the Middle East and surrounding regions are particularly species-rich...
, especially spotted knapweed
Centaurea maculosa
Centaurea maculosa, the spotted knapweed, is a species of Centaurea native to eastern Europe.It has been introduced to North America, where it is considered an invasive plant species in much of the western United States and Canada. In 2000, C. maculosa occupied more than in the US.Knapweed is a...
(Centaurea maculosa).
Life History
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 larvaLarva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
emerges from the egg and tunnels into the root cortex where it feeds on the plant tissue. Sometimes a gall
Gall
Galls or cecidia are outgrowths on the surface of lifeforms caused by invasion by other lifeforms, such as parasites or bacterial infection. Plant galls are abnormal outgrowths of plant tissues and can be caused by various parasites, from fungi and bacteria, to insects and mites...
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. In their native range, most C. achates overwinter as 2nd instar
Instar
An instar is a developmental stage of arthropods, such as insects, between each molt , until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or assume a new form. Differences between instars can often be seen in altered body proportions, colors, patterns, or...
s, though in the introduced range, the vast majority overwinter as 1st instars.
Biocontrol in North America
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. C. achates is thought to be responsible for a recent (2000s) observed decline in spotted knapweed, but this decline may also be attributable to a recent severe drought. The weevil prefers spotted knapweed, but it is sometimes found on diffuse knapweedDiffuse knapweed
Diffuse Knapweed , also known as White Knapweed or Tumble Knapweed, is a member of the genus Centaurea in the family Asteraceae. It is native to Asia Minor , the Balkans, , Ukraine, and southern Russia. Diffuse knapweed is an annual or biennial plant, generally growing to between 10 and 60 cm...
. It has not been shown to attack native flora.
C. achates was released to the Hiawatha National Forest
Hiawatha National Forest
Hiawatha National Forest is a National Forest in the Upper Peninsula of the state of Michigan in the United States. Commercial logging is conducted in some areas. The United States Forest Service administers this National Forest; it is physically divided into two subunits, commonly called the...
in Michigan's Upper Peninsula in summer 2009.