Statistically Analyzing the Influence of Solidago altissima Gall Volume on Eurosta solidaginis Larvae Survivability

Goldenrods are clonal plants on which Eurosta solidaginis oviposits its eggs, ultimately leading to a gall being formed in the peduncle of the goldenrod. The common predators of E. solidaginis larvae include Eurytoma gigantea, Eurytoma obtusiventris, and Mordellistena unicolor. This investigation studied the relationship between a species’ occurrence and the volume of the galls the species occupied. Approximately three hundred goldenrod plants were randomly collected and brought from two fields in Rochester, New York. The gall’s diameters were measured to calculate its volume, and the inhabiting species was gathered based on the interior characteristics of the gall. The data was used to perform Welch’s t-tests in order to determine if a notable difference in means of gall volume existed for each species. While M. unicolor and E. solidaginis occurrence did not change with different gall volumes, E. gigantea and E. obtusiventris exhibited proclivity towards galls of smaller and larger volumes, respectively. Therefore, it was concluded that E. solidaginis’ survivability was irrelevant to the gall’s volume and that E. gigantea and E. obtusiventris occurrence increased inversely and proportionally to gall volume, sequentially.

Statistically Analyzing the Influence of Solidago altissima Gall Volume on Eurosta solidaginis Larvae Survivability

Goldenrods are clonal plants on which Eurosta solidaginis oviposits its eggs, ultimately leading to a gall being formed in the peduncle of the goldenrod. The common predators of E. solidaginis larvae include Eurytoma gigantea, Eurytoma obtusiventris, and Mordellistena unicolor. This investigation studied the relationship between a species’ occurrence and the volume of the galls the species occupied. Approximately three hundred goldenrod plants were randomly collected and brought from two fields in Rochester, New York. The gall’s diameters were measured to calculate its volume, and the inhabiting species was gathered based on the interior characteristics of the gall. The data was used to performWelch’s t-tests in order to determine if a notable difference in means of gall volume existed for each species. While M. unicolor and E. solidaginis occurrence did not change with different gall volumes, E. gigantea and E. obtusiventris exhibited proclivity towards galls of smaller and larger volumes, respectively. Therefore, it was concluded that E. solidaginis’ survivability was irrelevant to the gall’s volume and that E. gigantea and E. obtusiventris occurrence increased inversely and proportionally to gall volume, sequentially.

Distribution of the Specialist Aphid Uroleucon nigrotuberculatum (Homoptera: Aphididae) in Response to Host Plant Semiochemical Induction by the Gall Fly Eurosta solidaginis (Diptera: Tephritidae)

Many plants use terpenoids and other volatile compounds as semiochemicals. Reception of plant volatiles by conspecifics may trigger a defensive phytochemical response. These same compounds can also function as host recognition signals for phytophagous insects. In this experiment, we find that when the specialist gall-forming fly Eurosta solidaginis (Fitch; Diptera: Tephritidae) attacks its tall goldenrod (Solidago altissima (L.; Asterales: Asteraceae)) host plant, the fly indirectly induces a phytochemical response in nearby tall goldenrod plants. This phytochemical response may, in turn, act as a positive signal attracting the goldenrod specialist aphid Uroleucon nigrotuberculatum (Olive; Hemiptera: Aphididae). Laboratory-based experiments exposing ungalled tall goldenrod plants to the volatiles released by E. solidaginis galls demonstrated a consistent increase in foliar terpenoid concentrations in ungalled plants. Analysis of tall goldenrod stem and gall tissue chemistry revealed induction of terpenoids in gall tissue, with a simultaneous decrease in green leaf volatile concentrations. Field experiments demonstrated a consistent spatial relationship in tall goldenrod foliar terpenoid concentrations with distance from an E. solidaginis gall. Both laboratory and field experiments establish consistent induction of the terpene β-farnesene, and that this compound is a strong positive predictor of U. nigrotuberculatum aphid presence on goldenrod plants along with plant biomass and several other foliar terpenoids. These findings suggest E. solidaginis induced phytochemistry, especially β-farnesene, may be acting as a kairomone, driving aphid distribution in the field.