Biological Control Agent: Altica carduorum Guer.

Invasive Plant Species Attacked: Canada thistle (Cirsium arvense)

Type of Agent: Foliar feeding beetle

Status

Description and Biology

Adult:

Metalic blue-black, 4 mm long adults emerge in late spring or early summer and feed on young thistle leaves. The beetle needs to recognize its host plant by biting into it. The feces created from feeding on Canada thistle attract the opposite sex, causing them to congregate. Dispersal occurs when adults take frequent flights and deposit feces on adjacent plants, allowing the opportunity for another population to develop. Adult beetles spend most the day on the leaf surfaces, moving through sunlit and shaded sites. After a pre-oviposition period, females lay eggs over two months onto the underside of thistle leaves. This generation emerges in mid to late summer, but does not ovipost. Instead they prepare to overwinter, entering the soil in the fall.

Egg:

Eggs incubate for about one week. High levels of humidity may be required for successful egg development.

Larva and pupa:

After hatching, young larvae feed on the lower leaf surface. When mature, they drop to the soil, bury to about 1 cm deep and pupate.

Overwintering stage:

Larvae enter the soil in the fall and overwinter near host plants.

Location and effectiveness of attack

Larvae and adult are strictly foliar feeders.

Predicted and native habitat

Altica carduorum establishes on irrigated or non-irrigated cropland, field and fence borders, fallow land and pastures. Dense stands of vigorous growing plants are required to increase populations. High levels of humidity are necessary, therefore, prairie environments may be unsuitable.

In Asia it is often found at sites surrounded by dry steppe as well as in moist zones of mountainous regions.

British Columbia Experiences

Origin:

A. carduorum populations released in BC originated from Switzerland and France. A biotype of A. carduorum found in China was investigated, but, not approved for release in Canada.

History:

A. carduorum was first introduced into BC in 1964 near Victoria. This location received a second population the following year. Two more release sites near Victoria were made in 1968 and 1969. Another release made in 1967 in the Okanagan had a few adults and eggs survive one year. This site was also supplemented with two more populations over the next two years. Development in all the release areas may have interfered with its potential to establish.

Habitat:

A. carduorum has been released into the Bunchgrass, Coastal Douglas-fir and Coastal western hemlock biogeoclimatic zones in BC.

Field results:

There has been no confirmation of establishment at any of the release sites. The area of the releases near Victoria have now been developed and no thistle could be found at one location. The second location near Victoria still had some thistle remaining in 2003, but no agents were found. However, in 2005, there was a possible dispersal sighting more than 60 km from the nearest releases. At the Okanagan release, the site was developed into a park a year or two after the 1969 release was made and the thistle was mowed. Recent efforts have been made to determine if the beetle dispersed before the release site was destroyed.

Collection for redistribution

Not available for general distribution at this time.

Notes

Observed adult movement between sun and shade is believed to be thermoregulatory.

References

Harris, P. 2006. Altica carduorum - "Canada thistle beetle". Calif. Dept. Food and Agric. November 15, 2006.
http://el.erdc.usace.army.mil/emrrp/emris/emrishelp3/
altica_carduorum_canada_thistle_beetle_pac.htm

Mason, P. G. and J. T. Huber. Biological control programmes in Canada, 1981 - 2000.

MFR staff observations and comments.

Lactin, D. J., P. Harris, D. L. Johnson, F. H. Wan and A. G. Thomas. 1997. Modelling and mapping geographic ranges to evaluate weed biocontrol agents: A case study using Altica carduorum (Coleoptera: Chrysomelidae) and Cirsium arvense (Asteraceae).

Wan, F. H and P. Harris. 1996. Host finding and recognition by Altica carduorum , a defoliator of Cirsium arvense. Entomologia Experimentalis et Applicata, 80: 491-496.

Wan, F. H, P. Harris, L. M. Cai and M. X. Zhang. 1995. Host specificity of Altica carduorum Guer. (Chrysomelidae: Coleoptera), a defoliator of Cirsium arvense (L.) Scop. (Asteraceae) from North-western China. Biocontrol Science and Technology (1996) 6: 521-530.