Utetes canaliculatus (Gahan, 1915)

Almost all of the biological information on this species is published under the name Opius lectus.

For additional information, see the Utetes page.

Taxonomic History / Nomenclature
Senior subjective synonym of Opius lectus Gahan, 1919; almost all of the biological information on this species is published under the name Opius lectus.

This species was originally described as Opius canaliculatus by Gahan (1915). It was later formally transferred from Opius to Utetes by Wharton (1997). Utetes had been recognized as a subgenus of Opius by Fischer (1972), and later elevated to generic rank by Wharton (1988). However, most of the species that attack Tephritidae were not formally transferred to Utetes until 1997, after Utetes had been redefined (Wharton 1997).

Widespread in the Nearctic Region, though not recorded from the Southwest.
Biology / Hosts
The detailed investigations by Prokopy and Webster (1978) demonstrated that Utetes canaliculatus (reported as Opius lectus) oviposits in the host eggs, a biological trait of interest to biological control workers. (This trait is discussed in more detail in the section treating the genus Fopius.) Utetes canaliculatus has been recorded from several different species of Rhagoletis, including R. pomonella. A transient pheromone applied to fruit surfaces by R. pomonella serves as an attractant to U. canaliculatus (Prokopy and Webster 1978). Although the presence of the pheromone is not required for U. canaliculatus oviposition, it stimulates the female to stay on the fruit and initiate antennal tapping. In field experiments in Michigan, Feder observed lower rates of U. canaliculatus (reported as Opius lectus) parasitism in Rhagoletis pomonella that infested apples than in R. pomonella that infested hawthorn, their ancestral host fruit (Feder 1995). Utetes canaliculatus females were unable to penetrate to the interior of the apples with their short ovipositors, creating an enemy-free space for the fly larvae.
Biology and Behavior
Univoltine, overwintering as fourth instar larvae in the host puparium. Females search for fly larvae in attached fruit (as opposed to fruit that has fallen to the ground) (Feder 1995). Earlier studies, mostly on levels of parasitism, were conducted by Monteith (1971, 1977).
Biological Control
Parasitism levels were hypothesized to be too low to be of use in controlling populations of R. pomonella in Quebec based on detailed life history tables for this pest (Cameron and Morrison 1977).