Each cage will contain a uniform density of planted starthistle plants. Cages will be used to confine insects onto the plants. Objective three: This experiment will look at the mechanisms by which prescription 'grazing' and biological control can be manipulated to achieve a synergistic effect and maximize the damage caused to yellow starthistle plants. Selected three-species combinations will also be used. Insect will be introduced into each cage in every paired combination of four insect species. Objective two : We will use standard insect rearing cages to confine the insects onto the plants. Twenty ungrazed plants in the control paddocks and twenty grazed plants in the early spring, late spring, and early summer grazed paddocks. Every two weeks during the growing season (March through August), we will determine the phenological stage of This clipping procedure will allow us to determine the proportion of starthistle grazed relative to grasses and other forbs. We will also clip forage from ten plots and determine the biomass of yellow starthistle, other forbs, and grasses in each of the controls and grazed pastures before, during, and after each grazing period. Before the first grazing period, we will randomly place and permanently mark fifteen plots in each paddock and measure the density of starthistle and estimate basal cover of perennial grasses in each plot to determine the effects of grazing season on yellow starthistle growth and reproduction. These treatments will be applied in four replications with appropriate controls resulting in sixteen paddocks. Project Methods Objective one: Sheep will be grazed in small paddocks in each of three starthistle growth stages (rosette, bolting, late-bud/pre-spiny).

Integrating biocontrol agents