The fly effect: A volatile cue from the gall fly Eurosta solidaginis can induce season long changes in insect communities associated with Solidago altissima

Solidago altissima (tall goldenrod) is one of the few plant species known to respond to volatile cues from both plants and insects. When exposed in greenhouse experiments to the putative sex pheromone of its specialist gall fly Eurosta solidaginis or herbivore-induced plant volatiles (HIPVs) from neighboring plants, S. altissima alters its defensive status, decreasing galling and amounts of co-occuring herbivory. In field settings, however, the influence of these volatile cues on ecology of S. altissima and its insect community is poorly understood.
We established a four-year 4x3 factorial experiment with four levels of exposure to volatile cues (control, fly emission, HIPV, or fly emission + HIPV) and three levels of plant genotype (S110, JC109 or both genotypes together) with 72 plots (six replicates). We exposed plots to volatile cues early in the growing season and then measured for four weeks plant height, leaf damage, and apical bud damage. Data from year one suggests that differences in damage type, damage amount, plant growth rate, and galling insect community structure may emerge as a response to the volatile cues. Data from year two will begin to clarify these emerging differences.