Date of this Version
Proceedings of the 23rd North American Prairie Conference, August 2012, University of Manitoba in Winnipeg
The Prairie Naturalist 46: 4-14. August 2014
Native prairie restorations in many regions of the United States have been hindered by various herbivores consuming plant reproductive parts or products. I conducted field studies of a population of largeleaf wild indigo (Baptisia lactea) on a restored prairie in southeastern Minnesota during the growing seasons of 2010–2012 to determine the cause(s) of repeated reproductive failure. I assessed plants for browsing damage caused by white-tailed deer (Odocoileus virginianus) during the period of flowering and with a deer exclosure experiment involving caged and non-caged plants. I compared reproductive output (numbers of seed pods, viable seeds) of caged plants to non-caged plants at the end of the growing season. I conducted surveys for Say’s blister beetles (Lytta sayi) during plant flowering in June, and for indigo weevils (Apion rostrum) in seed pods at the end of the wildindigo growing season. Deer browsing damaged 46% of wild indigo plants, destroying 14% of the flowers of the indigo population during June. Neither the numbers of seed pods nor viable seeds differed significantly between caged and non-caged plants in October. Blister beetles were present and consumed wild indigo flowers only during June 2011, but numbers exceeded 25 beetles/ wild indigo plant. High weevil abundances ( = 3.1 weevils/seed pod, SD = 2.3) in 2010 (n = 88) and 2011 (n = 27) resulted in heavy seed predation and high seed pod abortion. Overall seed production averaged/plant during 2010 and 2011, with more than 80% of plants not producing a single viable seed. Taken together, browsing by deer, herbivory by blister beetles and weevils, and pollination failure reduced potential reproductive output of the Kramer Ridge wild indigo population by >99% during the study period.