Let the Bugs Do the Work
The NWIPC is always looking for new and better ways to eliminate invasive plants. One interesting way is bring in a natural predator of the weed to attack and control its growth and spread. This is called "biocontrol". This fall, the Ministry of Forests and Range (MFR) with help from the NWIPC released the weevil Rhinusa antirrhini on Dalmatian and Common toadflax plants at two locations within city of Prince George.
The weevil R. antirrhini is one of several biocontrol agents that have been through extensive testing to be sure that it will not attack native plants. Adult weevils feed on the pollen and lower parts of toadflax plants. Female lay eggs in the flowers and the eggs hatch in about two weeks. The emerging larvae feed on the toadflax seeds. After the weevils mature they feed for a short time on the toadflax stems before moving into the soil to overwinter. All this feeding reduces the number of seeds produced and lowers the survival of attacked plants.
The two Prince George release sites will be checked in 2008 to see if the weevil survived the winter. The goal is to have the weevil reduce the number of plants and its seed production. The weevil is not expected to get rid of all the toadflax plants, only weaken them. To eradicate all toadflax plants other control methods like hand-pulling or herbicide application would have to be used.
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