|
Type of organism
flea beetle
Plant species attacked
Click on image to view larger photo.
If images are downloaded and used from the ODA web site please be sure to credit the photographer.
Impact on target plant
The larvae of the flea beetles feed on the roots and buds causing plant mortality. Adults feed on leaves and flowers, and can cause severe defoliation during outbreaks.
Collection and release
collect adults with sweep net in June-July. Release 500+.
Distribution
This flea beetle has been released in 9 counties and recovered in 8.
History and comments
Three flea beetles, Aphthona cyparissiae, Aphthona flava, and Aphthona nigriscutis were introduced in 1989. A. nigriscutis and A. cyparissiae are well established, but have been slow to increase and spread. A. cyparissiae is usually a small portion mixed in with the other more common species, and has not been much of a contribution to leafy spurge control. It is quite difficult to tell apart from the more common A. nigriscutis. Since 1994, several release sites in central and E OR have shown significant depression of leafy spurge density by A. nigriscutis, A. cyparissiae, and A. lacertosa. These beetles have provided some limited control but not like the spectacular widespread results that were observed in Montana, North Dakota, and Wyoming. The heavier clay soils may limit the efficacy of the flea beetles in Oregon. Several populations have been harvested for redistribution. The impact of A. nigriscutis which works best in drier, sandy soils, may be compounded by a Wolbachia bacterium, which causes high mortality in males, resulting in female biased populations.
|