Project Number: 3020-43000-034-013-N
Project Type: Non-Funded Cooperative Agreement
Start Date: Aug 1, 2022
End Date: Jul 31, 2027
Objective 1A: Link trap captures of E. giganteana to plant vigor and/or pest phenology and GDD Objective 1B: Develop trap-based threshold or GDD model for E. giganteana to guide management of insecticides Objective 2A: Identify sex pheromone for E. giganteana. Objective 2B: Elucidate mechanism for mating disruption in E. giganteana in laboratory and field. Objective 2C: Field validation of mating disruption of E. giganteana in Silphium.
Objective 1A: Field phenology data will be generated for two years according to the parameters found in Ruiz et al. (in press). Each field will have three transects spaced at least 10 m apart. Each trap within the transect will be spaced 10 m apart. In total, there will be n = 3 replicates of each semiochemical treatment per field site. The number of E. giganteana, and number of Lepidopteran nontargets will be counted on each sticky card. This information will be linked with GDD model predictions for pest phenology. To determine a lower developmental threshold, the temperature at which larvae start to actively feed after overwintering will be used as a surrogate measure. Overwintering larvae will be place in environmental chambers set at constant temperatures of 7.2, 12.8, 18.3, 23.9, and 29.4°C and 16:8 L:D cycle into individual plastic cups (5 oz) with an excised leaf disc from Silphium. The disc will be photographed at 3, 7, and 14 d after the addition of larvae. A total of n = 20 larvae will be used per temperature. Images will be processed using the software ImageJ to determine the amount of feeding. Objective 2A: Treatments will include three males and females alone or together, and six females alone or together. Moths will be placed into a screw top headspace chamber (500 mL capacity; 10.2 × 12.7 cm D: H). Headspace will be collected and analyzed with GC-MS. Objective 2B: E. giganteana moth males will be exposed to different concentrations of their sex pheromone (none, low, medium, or high) for a short (10 s) or extended (48 h) interval, and then their antennal response to the female-produced sex pheromone will be evaluated using electroantennographic detection (EAD). A total of n = 10 replicate moths will be used per treatment combination. A follow-up experiment will be done with a subset of treatments in a large release recapture assay with the sex pheromone and clear sticky cards under constant temperature conditions. Objective 2C: In the third year, a field validation of the mating disruption trial will be performed. In three fields, mating disruption will be implemented, while three paired fields will act as an untreated control. MD dispensers will deploy pheromone at a high rate over at least a 2 week interval. MD will be deployed from first capture of E. giganteana until the last individual is captured in the season using monitoring traps.