Submitted to: Biological Control Symposium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 7/17/2007
Publication Date: 1/1/2008
Citation: Hinz, H.L., Schwarzlander, M., Gaskin, J.F. 2008. Does Phylogeny Explain the Host -Choice Behaviour of Potential Biological Control Agents for Brassicaceae Weeds? Biological Control Symposium Proceedings. p. 410-417. Interpretive Summary: Four invasive mustard species are currently being studied for biological control. A phylogenetic approach to host testing (determining if close relatives are most at risk for being attacked by the control agent) has so far been hampered by the fact that the evolutionary relationships of taxa within the mustards were unclear. We correlate evolutionary relationships of plants with how much they are likely to be attacked by a control agent. In one of the two cases, evolutionary relationship explained control agent plant preference. The importance of other factors, specifically secondary metabolite profile and morphological characteristics for the host choice behaviour are currently being investigated.
Technical Abstract: Four invasive Brassicaceae are currently being studied for biological control at the CABI Centre in Switzerland. A phylogenetic approach to host testing has so far been hampered by the fact that the evolutionary relationships of taxa within the Brassicaceae were unclear. Recently, a new phylogeny of the Brassicaceae, largely based on molecular studies, has been proposed. This presented a unique opportunity to relate host range test results for some of our Brassicaceae agents to the new phylogeny. The host range of Ceutorhynchus scrobicollis Nerensheimer & Wagner, a root-crown mining weevil investigated as a potential agent for Alliaria petiolata (Bieb.) Cavara & Grande (garlic mustard) appeared to closely follow the new classification (significant linear relationship between phylogenetic distance and host range test results). However, for Ceutorhynchus cardariae Korotyaev, a gall-inducing weevil considered as biocontrol agent for Lepidium draba L. (hoary cress), phylogenetic distance of the test species to the target weed did not explain a significant amount of the variation in host preference or suitability. These results question the general applicability of the centrifugal phylogenetic method, where it is assumed that species more closely related to the target are at greater risk of attack than species more distantly related. The importance of other factors, specifically secondary metabolite profile and morphological characteristics for the host choice behaviour of C. cardariae are currently being investigated.