Urophora affinis is a species of tephritid or fruit flies in the genus Urophora

Urophora

Urophora is a genus of tephritid or fruit flies in the family Tephritidae.-Species:*U. acompsa *U. acuticornis*U. adjacens *U. aerea *U. affinis...

of the family Tephritidae

Tephritidae

Tephritidae is one of two fly families referred to as "fruit flies", the other family being Drosophilidae. Tephritidae does not include the biological model organisms of the genus Drosophila , which is often called the "common fruit fly". There are nearly 5,000 described species of tephritid...

. It has been released in the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 and Canada as a biocontrol agent to control spotted knapweed. U. affinis became established in Montana in 1973.

Life History

U. affinis is multivoltine and overwinters as a larva in knapweed flower heads. In June, adults oviposit on seed heads. Each female can produce about 120 eggs. It has been shown to reduce seed production in knapweed (spotted and diffuse) by up to 95% but that is insufficient for effective management of either species. Overwintering Urophora larvae are heavily preyed upon by deer mice Peromyscus maniculatus

Peromyscus maniculatus

Peromyscus maniculatus is a rodent native to North America. It is most commonly called the Deer Mouse, although that name is common to most species of Peromyscus and is fairly widespread across the continent, with the major exception being the southeast United States and the far north.Like other...

. The inability of Urophora species to control knapweed led to the introduction of other biocontrol agents, including the weevils Larinus minutus

Larinus minutus

Larinus minutus is a species of true weevil known as the lesser knapweed flower weevil. It is used as an agent of biological pest control against noxious knapweeds, especially diffuse knapweed and spotted knapweed....

and Bangasternus fausti

Bangasternus fausti

Bangasternus fausti is a species of true weevil known as the broad-nosed seed head weevil. It is used as an agent of biological pest control against noxious knapweeds, particularly spotted knapweed , squarrose knapweed Bangasternus fausti is a species of true weevil known as the broad-nosed seed...

, which also attack seed heads of kanpweed. In cage experiments, larvae of Larinus minutus

Larinus minutus

Larinus minutus is a species of true weevil known as the lesser knapweed flower weevil. It is used as an agent of biological pest control against noxious knapweeds, especially diffuse knapweed and spotted knapweed....

and Bangasternus fausti

Bangasternus fausti

Bangasternus fausti is a species of true weevil known as the broad-nosed seed head weevil. It is used as an agent of biological pest control against noxious knapweeds, particularly spotted knapweed , squarrose knapweed Bangasternus fausti is a species of true weevil known as the broad-nosed seed...

have been shown to consume the developing U. affinis. Reproduction of U. affinis was reduced by L. minutus.