Biological Control Agent: Cochylis atricapitana (Stephens)
Invasive Plant Species Attacked: Tansy Ragwort
(Senecio jacobaeae)
Type of agent: Root crown feeding moth
Status
Primary
Description and Biology
Adult:
Cochylis atricapitana are very delicate, fragile moths, 3 mm long with a 7 mm wingspan.
Forewings are tan coloured with irregular brown, black and grey marks. A dark tuft
of scales project upward from behind its head. The first generation females lay eggs
individually onto veins on the underside of bolted stalk leaves. Capable of multiple
generations each year, it is more common to find adults from May to June and again from July
to August. The second generation females oviposit eggs in the fall onto rosette leaves.
Both generations will oviposit about 150 eggs each.
In the south of France, seven generations
are produced. During the day, adults remain close to the ground near or on the plants,
taking flight near dusk, and becoming active during the night. The sex ratio is 1:1.
Egg:
The oval, flat eggs, 0.5 x 0.3 mm, are initially translucent white and gradually change
to yellow. Developing larvae can be observed through the egg surface. Eggs incubate
for five days.
Larva and pupa:
New larvae are creamy white with a black head, the body darkening to tan as it ages.
There are five larval instars, which develop in 33 days when temperatures are 24°C.
First generation larvae mine the leaf and mid vein, then move to stems where they will either
mine through the stems or move upward and feed on shoots and flowers. Second generation
larvae move from rosette leaves downward to the root crown, feeding and developing until hibernation.
Evidence of presence can be detected by black feces located near the base of small central
rosette leaves. If they overwinter in the fourth instar, feeding resumes the following
spring, as they make their way upward into the lower central shoot area to pupate. If they
overwinter in the fifth instar, they move to the soil and pupate the following spring.
Pupae are light brown, 7 x 1.5 - 2.0 mm and are enclosed in a creamy white silken cocoon that
changes to pink. As the new adult exit, it discards its pupal case at the exit point,
which may occur from the plant crown, stem or bud.
Overwintering stage:
They can overwinter as fourth instar larvae or full grown fifth instar.
Location and effectiveness of attack
Larvae feeding in actively growing stems will cause the stems to thicken, and the leaves
to bunch, which interferes with floral development. Larvae mining roots and older stems
can kill the plant.
Predicted and native habitat
C. atricapitana is adapted to a wide variety of habitats where tansy ragwort grows,
including high elevations. It is recommended for areas with early winters where the season
may be too short for other controlling agents such as Longitarsus spp.
Native distribution includes North Africa, western and central Europe, England, Sweden,
Poland, the former Czechoslovakia and south Russia. In south-east Europe it is most common
in west coast locations when tansy ragwort is abundant.
British Columbia Experiences
Origin:
The C. atricapitana releases in BC originate from Spanish populations
obtained from Australia.
History:
C. atricapitana was first released in the Fraser Valley and near Nanaimo in 1991.
Release efforts continued throughout the Coastal Forest Region until 1996.
In 1994, 70 larvae infested plants were transplanted into the tansy ragwort
infestation in the Okanagan. The moth easily established in the coastal
climate, but did not establish in the southern interior. In 2008, a second
attempt was made by transferring 59 larvae infested roots into the Okanagan.
Habitat:
C. atricapitana has been released into the Coastal Douglas-fir,
Coastal western hemlock and Interior Douglas-fir biogeoclimatic zones.
Establishment and dispersal is restricted to the Coastal Douglas-fir and Coastal
western hemlock zones. No establishment has been found outside the coastal
habitats.
Field results:
In the lower mainland, larvae and adults can both be found in early August.
No establishment of C. atricapitana has occurred at southern interior
locations. The adults do not feed on the plants and are extremely small
and difficult to locate, therefore, monitoring larvae is preferred over sweeping
or observing adults.
Not available for general distribution at this time.
Notes
C. atricapitana can exist with L. jacobaeae on the same plants because they
feed in different parts of the root.
Previously known as Epoecilia atricapitana
References
Harris, P. 2003. Classical biological control of weeds established biocontrol
agent Cochylis atricapitana (Stephens). Root-crown feeding moth. Agriculture
and Agri-Food Canada. http://res2.agr.ca/lethbridge/weedbio/agents/acocatr_e.htm
Meander Valley Weed Strategy. 1999. Leaf and crown boring moth. November 28,
2006. http://www.hotkey.net.au/~d.elliott/cochylis.htm
MFR staff observations and comments
Powell, G. W., A. Sturko, B. Wikeem and P. Harris. 1994. Field guide to the
biological control of weeds in British Columbia. B.C. Min. For. Res. Prog.
Schroeder, D., P. Harris and P. Iselin. 1989. Investigations on Cochylis
atricapitana (Stephens) (Lep.: Cochylidae), a candidate agent for the biological control
of Senecio jacobaea L. (Compositae) in North America. CABI. Final Report. 32 p.
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