1a. Objectives (from AD-416):
Optimize and implement non-pheromonal blends for control and monitoring of the female navel orangeworm.
1b. Approach (from AD-416):
Using recently PMR-discovered efficacious volatile blends, personnel from the PMR laboratory will develop, analyze, and optimize blends for use in field trials. Personnel from Paramount Farming Company (cooperator and co-investigator) will assemble, distribute to almond and pistachio orchards, monitor, collect, and analyze traps with blend formulations.
3. Progress Report:
Because the active flights of navel orangeworm moths (NOW) are between March and October of each year, the majority of the work completed during this grant period was the laboratory-based electrophysiological evaluation of almond and pistachio volatiles. This work evaluated the antennal response of male and female NOW to individual components and simple blends. This was achieved by electroantennographic (EAG) analysis which measures the electrochemical signal produced by moth antennae when puffs of individual components are passed across exposed antennae. For background reference, the USDA-ARS and Paramount Farming Company (PFC) researchers tested a series of volatile blends based on almond hull split volatile emissions during the 2011 growing season [Beck et al. manuscript submitted to Chemoecology March 2012 – Almond hull split and damage volatiles attractive to male and female NOW (Amyelois transitella)]. The most consistent blend, Blend A, was found to be more effective in trapping female navel orangeworm moths than the current monitoring standard, almond meal. More surprising was that Blend A also attracted male NOW – something almond meal does not do. The goal of the USDA-ARS laboratory during this period was to continue to perform EAGs on pistachio- and almond-based volatiles and to develop a simple blend that elicited a greater antennal response than Blend A. While the EAG results obtained do not imply field trapping activity, the larger EAG values for the Test blends suggest greater receptivity, unknown if attractant or repellant, toward the blend by NOW antennae. The goal of this portion of the project is to screen simple blends for greater EAG activity than Blend A. The blends in the above table have been forwarded to the UC Riverside (UCR) Co-PD for laboratory-based behavioral assays as well as to PFC’s Co-PD for 2012 field for trapping studies. Several kinds of laboratory-based behavioral assays are available to assess female responses to host-emitted odors. These include wind tunnels, Y-tubes (both deliver odors in airflow) and static-air systems that rely on landing or entrance into ports where the surrounding environment is still air. UCR efforts to date have been aimed at development of a discriminating laboratory assay. A hexagonal screened cage (1.8 meter high and 1.4 meter across) in a controlled environment room is being used. The assay cage is set on a slowly revolving platform to minimize position effects caused by slight differences in light levels and low level air currents. Approximately 100 males and female NOW are added to the cage daily and attraction is measured by capture in a sticky trap. Almond meal is used as a positive control for moth response and the testing of synthetic blends will begin shortly once moth responses are confirmed statistically with an appropriate number of replicates. The USDA will continue EAG studies on individual components and simple volatile blends. At present >50 of the 135 individual compounds of interest have been evaluated. This includes both male and female NOW antennae in replicates of 4-7 (each replicate is a separate pair of antennae). PFC will continue placing volatile blends in pistachio and almond orchards for evaluation of NOW attractancy. Replicates of five per randomized block for one week intervals will be performed, as well as NOW moth capture numbers as compared to almond meal. UCR will continue development of laboratory-based bioassay and will begin incorporating synthetic blends for optimization. The goal will be to have produced 5-10 blends that exhibit sufficient attractancy for a year-long trapping study the following year. If early blend formulations are more active than Blend A, the project will continue optimization by placing successful blends in dispersive membranes and test membranes head-to-head with current dispersive containers, thus eliminating the solvent. The results of this research, to date, show great promise in developing a lure for NOW and, thus, reduce the risks NOW presents towards aflatoxin contamination of tree nuts. This project contributes to the overarching goal of the parent project.