Approved biocontrol agents currently established and/or being evaluated
- Leafy spurge (Euphorbi esula) with five species of Aphthora beetle species.
- Scentless chamomile (Matricaria perforate) with the seed weevil Omphalapion hookerorum widespread, the stem mining weevil Microplontus edentulus poorly established (one site in Alberta) and the gall midge Rhopalomyia triplurospermi widespread.
- Purple loosestrife (Lythrum salicaria) with foliage feeding beetles Galerucella calmariensis and Galerucella pusilla established and the status of the root weevils Nanophyes marmoratus and Hylobius transversovittatus uncertain.
- Cleavers (Galium spurium) had the gall mite Cecidophyes rouhollahi approved for introduction, however the mite was not able to overwinter in Western Canada.
- Dalmatian toadflax (Linaria dalmatica) with the stem-mining weevil Mecinus janthiniformis (previously called M. janthinus), a seed feeding weevil, Rhinusa antirrhini and defoliating moth Calophasia lunula in British Columbia.
- Yellow toadflax (Linaria vulgaris) with the root-galling weevils Rhinusa linariae and R. neta and the flower-feeding beetle Brachypterolus pulicarius. The defoliating moth Calophasia lunula, though introduced to western Canada, has only established in British Columbia. The stem mining weevil Mecinus janthinus has established in British Columbia and potentially sites in Alberta.
- Diffuse Knapweed (Centaurea diffusa) and Spotted Knapweed (Centaurea stobebe subsp. micranthos) have 12 biological control agents released in Canada. The most successful at biological control are the seed head weevil Larinus minutus and the root weevil Cyphocleonus achates, which are only established in British Colombia and Alberta.
- Houndstongue (Cynoglossum officinale) with the root weevil Mogulones crucifer established where the weed occurs in British Colombia and Alberta.
Insect agents currently being tested
- Yellow toadflax (Linaria vulgaris) with testing of a stem mining weevil Mecinus heydeni and a stem galling weevil Rhinusa pilosa
- Dalmatian toadflax (Linaria dalmatica) with testing of a stem-galling weevil Rhinusa brondelii and a stem mining Mecinus sp.
- Common Tansy (Tanacetum vulgare) with testing on shoot boring weevil Micoplontus millefolii and flower-feeding moth Isophrictis striatella.
Trials focusing on inundative biological control are also underway. These often tend to work best as biopesticide formulations. There are several potential bioherbicides; however, difficulties in formulations and market preferences mean that they might not currently be manufactured.
- The first pathogen to be registered as a bioherbicide was the fungus Colletotrichum gloeosporioides f.sp malvae (Figure 11) for control of round-leaved mallow (Malva pusilla) in field crops (Figure 12).
- Control of dandelion (Taraxacum officinale) through Sclerotinia minor IMI 344141 or Phoma macrostoma isolate 94-44B.
Other target weeds for inundative biological control are wild oat, green foxtail, Canada thistle, cleavers and oxeye daisy.