Location: Chemistry Research
Project Number: 6036-22430-001-006-R
Project Type: Reimbursable Cooperative Agreement
Start Date: Oct 1, 2019
End Date: Jul 31, 2022
Objective 1: Characterize the volatiles emitted by three Roseau cane genotypes in the presence and absence of scale infestations and other stresses. Objective 2: Develop methods for assessing the effects of volatile compounds on the behavior of N. biwakoensis and its parasitoids. Objective 3: Utilize methods developed in Objective 2 to investigate whether volatile emission is partly responsible for differences in resistance of Roseau cane genotypes to the
Objective 1: Sampling of volatiles will be conducted using mobile sampling equipment and methods developed by co-PI Alborn. Sampling will be conducted from scale-infested and uninfested Roseau cane plants both in the field (at scale-infested and uninfested sites in the MRD) and in the greenhouse. Greenhouse-grown plants will be artificially infested with scale insects or left uninfested. Later experiments will also characterize the impacts of field-relevant stresses such as salinity on volatile emissions. Analysis of volatiles collected from plants by thermal desorption/GC-MS will be conducted in co-PI Alborn’s lab. These experiments should reveal genotypic differences in volatile emission by P. australis as well as effects of stress and herbivory on volatile emission. Objective 2: Bioassays to evaluate the effects of volatile compounds on the behavior and performance (e.g., population growth, mortality, developmental time) of scale insects will be developed by the LSU AgCenter post-doctoral scientist in consultation with LSU AgCenter and USDA-ARS CMAVE co-PIs. The currently used bioassay of scale behavior involves observations of settling by scale crawlers (the only mobile stage of the insect) on cut stems of Roseau cane as well as quantification of scale population growth on whole plants. These currently used bioassays will be used as starting points for the development of choice and no-choice assays. These assays may involve the use of small arenas or olfactometers to quantify behavioral choices of crawlers for different host plants. Natural mixtures of volatiles as well as pure synthetic compounds may be used. Assays will also be developed to determine whether volatile compounds emitted by P. australis are attractive to any of the three parasitoid species found associated with N. biwakoensis in the MRD. Objective 3: Using the experimental methods developed in Objective 3, experiments will be designed and executed to determine if differences in volatile emission by injured or uninjured plants of the Delta, Gulf, and European genotypes are associated with differences in resistance of these three genotypes to N. biwakoensis.