Characteristics of galls Eurosta solidaginis (Diptera: Tephritidae) and their relation to mortality of gall inhabitants
1988
Walton, R.
Eurosta solidaginis (Fitch), the goldenrod gall fly, and its suite of predators and parasitoids provide an excellent system for the study of the dynamics of prey species and their enemies. The object of this study was to discover the effects of gall and quadrat characteristics on the fate of galls, and to asses the impact of each mortality source on Eurosta survival. Galls on goldenrod, Solidago altissima, in two large (700 m2) plots were followed through three field seasons (1982-84). Gall characteristics (diameter and height) and goldenrod cover were recorded as well as the eventual fate of each gall's inhabitant. A fertilization experiment was conducted to determine whether galls were more likely to be formed on healthier host plants. Five sources of mortality were examined: early larval failure, parasitism from either of two chalcid parasitoids, Eurytoma obtusiventris (Gahan) or Eurytoma gigantea (Walsh) (Hymenoptera: Eurytomidae), predation by mordellid beetle larvae, and predation by birds. Characteristics of quadrats (number of Solidago stems per quadrat and physiological condition of plants in the quadrat) were not reliable predictors of gall density within quadrats. Gall diameter is the only gall characteristic that reliably indicated fate. All predated or parasitized galls were smaller than those of survivors, with the exception of those predated by birds, which were significantly larger. Early larval death and predation by mordellid beetles caused the greatest mortality; however, mortality from birds probably has the most potential for population regulation.
Show more [+] Less [-]AGROVOC Keywords
Bibliographic information
This bibliographic record has been provided by National Agricultural Library