Biological Control Agent:  Aceria malherbae Nuzzaci

Invasive Plant Species Attacked:  Field bindweed (Convolvulus arvensis)

Type of Agent:  Foliar feeding mite

Status

Primary

Description and Biology

Adult:

The mites are microscopic, yellow-white and worm-like. Their soft bodies have ring shaped parts (annulate) and have two pairs of legs on their combined head and thorax body. They become active in May through November.  Eggs are laid into the galls created by their feeding. Their activity slows during the hot summer months and later resumes when cooler temperatures return. Multi-generations occur every 10 days during the summer.

Egg:

Eggs are round and translucent.

Larva and pupa:

Mites do not have a larvae stage, instead, they develop from nymph to adult (nymphs are juvenile versions of the adult parents). The two nymph stages appear similar to the adults, but lack genital openings. Feeding and development occur within the galls.

Overwintering stage:

Adults and nymphs overwinter below the soil surface on root buds.

Location and effectiveness of attack

Adults and nymphs feed on upper leaf surfaces, causing them to distort and curl tightly inward, which enclose around the mites.  Leaves thicken and become fuzzy textured and develop a rough, grainy surface.  Leaves may turn yellow or red and are often brown by November. Aceria malherbae attack prevents the natural elongated twining growth of the bindweed, which is replaced with shortened tightly curled leaves.  Late season feeding reduces the plants ability to store nutrients.  Heavy attack can prevent flowering.

Predicted and native habitat

The preferred habitat for A. malherbae is unknown.  It requires high humidity for active development.   

A. malherbae's distribution occurs in Greece, Italy, France, central and southern Europe and northern Africa. The life cycle of A. malherbae is closely tied to its host plant development during the growing season.

British Columbia Experiences

Origin:

The populations released in BC originate from Thessaloniki, Greece.

History:

In 1992, the first A. malherbae treatment was made in Kamloops.  Two more releases were made in 1994 and 1998 in the south Silmilkameen and at Grand Forks.  Short term establishment was found only at one site.  In 2008 another attempt to establish the mites was made in the north Okanagan. 

Habitat:

A. malherbae releases have been made in the Bunchgrass, Interior Douglas-fir and Ponderosa pine biogeoclimatic zones.  Short-term establishment has been found in the Bunchgrass zone.

Field results:

One year after the original release was made in Kamloops, fire went through the site and shortly after that it was excavated.  Field bindweed persists on the site, but, no establishment has been found.   At the release in the south Similkameen, the plants are exhibiting some, but not all, symptoms of attack.  Although the area is dry, microhabitat conditions provide shade and moisture. The adjacent drip irrigation also adds to the humidity of the site.  A third treatment in the Boundary area did not show any establishment when monitored.  At this location a severe windstorm and a 'dust-devil' went through the site one day after the treatment was made.  In 2008 another A. malherbae was made in the north Okanagan, but it is too early to determine the status of this site.

Collection for redistribution

Not available for general distribution at this time.

Notes

Formerly known as A. convolvuli.

References

Carey, Tressa.  2005.  Aceria malherbae bindweed gall mite.  Biological control agent links.  March 18, 2005.  http://mtwow.org/Aceria-malherbae.htm

Davis, Tami.  2004.  Field bindweed (Convolvulus arvensis).  2004-09-27. http://www.mtwow.org/field-bindweed-ID.html

Laliberte, Andrea S.  1994.  Field bindweed (Convolvulus arvensis L.) and its control, with an emphasis on biological control.  Univ. College of the Cariboo, Dept. of Natural Resources Sci. Work term report.

Rees, N. E., Quimbly, Jr., P. C., G. L. Piper, E. M. Coombs, C. E. Turner, N. R. Spencer, L. V. Knutson (editors).  1996.  Biological control of weeds in the west.

Rosenthal, Sara S.  No date.  Request for introduction and releases of Aceria (Eriophyes) convolvuli against Convolvulus arvensis in the United States.  USDA-AR-WRRC-PPR-BCW, Albany California.