Submitted to: International Symposium on Biological Control of Weeds
Publication Type: Proceedings
Publication Acceptance Date: 10/31/2014
Publication Date: 12/2/2014
Citation: Milbrath, L.R., Davis, A.S. 2014. Pre-release biological control agent recommendations for swallow-wort (Vincetoxicum spp.) informed by demographic matrix models. International Symposium on Biological Control of Weeds. p. 69.
Technical Abstract: Weed biological control workers have advocated for the advance assessment of agent efficacy in order to minimize the release of host-specific but ineffective agents. One method involves demographic matrix modeling of target weed populations in order to identify plant life stage transitions that contribute the most to population growth of the plant and hence should be targeted for disruption. In turn, this information can help identify guilds of potentially effective agents, thus informing pre-release recommendations and increasing the success rate of weed biological control programs. We have parameterized a five life-stage matrix model for the swallow-wort biological control program. Pale swallow-wort (Vincetoxicum rossicum) and black swallow-wort (V. nigrum) are herbaceous, perennial, viny milkweeds introduced from Europe (Apocynaceae-subfamily Asclepiadoideae). Both species are becoming increasingly invasive in a variety of natural and managed habitats in the northeastern United States and southeastern Canada. Demographic transitions were measured in field studies for both swallow-wort species in open field and, for pale swallow-wort, forest habitats in New York State (N = six populations). Vital rates estimated included germination, survival, maturation (growth to the next life stage), and fecundity (viable seeds produced per plant). Elasticity analyses have identified several potentially important transitions for one or both species of swallowwort: survival of vegetative juvenile, small flowering and large flowering plants; growth of seedlings, juveniles and small flowering plants to the next life stage; and reproduction of small and large flowering plants. Perturbation analyses using published impact data of candidate biological control agents will be presented, and release recommendations will be given.