Augmentative releases of commercial biological control agents for Russian wheat aphid management in winter wheat

摘要

The effectiveness of augmentative biological control in Russian wheat aphid, Diuraphis noxia (Mordvilko), management in dryland winter wheat was evaluated. The two species of commercially reared predators that were released for control of Russian wheat aphid were Hippodamia convergens Guerin-Meneville and Chrysoperla rufilabris Stephans. There were no effects of cage exclusion on Russian wheat aphid per tiller after releases of the natural enemies in 1994 and 1997. Fewer Russian wheat aphid per tiller were found in the plots with no exclusion on two post-release dates for 1995. There were no effects of cage exclusion of natural enemies on percentage infested tillers except for the first post-release sample date in 1994 and the first and second post-release dates in 1995 where fewer percent infested fillers were found in the plots with no exclusion. Differences observed in 1995 could have been due to lower Russian wheat aphid population densities or high precipitation that occurred during the 1995 experimental period. Plant biomass production was not affected by natural enemy exclusion. Grower reported yields in 1994 and 1997 were lower than the county average. The augmentative release of commercial biological control agents did not have a measurable economic benefit in this study. [References: 27]