1a. Objectives (from AD-416):
1) Compare abundance in and movement between adjacent plantings of almonds and pistachios; 2) compare almond meal and phenyl propionate as female attractants; and 3) characterize minimal grouping of timed aerosol dispensers (puffers) necessary for complete elimination of males captured in traps baited with virgin female navel orangeworm.
1b. Approach (from AD-416):
1) Mark-capture with protein markers and mark-release-recapture with fat-soluble dye will be used in conjunction with grids of traps baited with virgin females (for males) and almond meal (for females) to characterize movement and obtain estimates of adult abundance. 2) Sticky traps and bucket traps containing almond meal and phenyl propionate will be placed in replicated blocks in almonds and pistachios, with each block also including a virgin-baited flight trap for comparison. 3) Two north-south columns of three puffers each will be placed in replicated blocks in pistachios at inter-puffer distances of 209 or 148 feet, and three sticky traps baited with virgin females will be placed in a north-south line equidistant between the two lines of puffers, with the center traps directly between the two middle puffers and the other two traps directly north and south at a distance half that of the inter-puffer distance. Traps will be tended over 9 to 15 weeks between May and August.
3. Progress Report:
The navel orangeworm (NOW) is the most important insect pest of pistachios, a crop worth >$1 billion per year unprocessed. NOW abundance in pistachios was quantified in three periods, phenyl propionate was examined as an attractant for monitoring NOW, and the minimal configuration of timed aerosol dispensers (puffers) needed to consistently disrupt mating was determined. This project contributes to objective 2c of the parent project. The abundance of NOW is lower in pistachios in early July compared to earlier or later generations (April-May and August-September, respectively). Traps baited with phenyl propionate captured significantly fewer adults than traps with unmated females as a pheromone source, but significantly more moths than traps baited with almond meal. In the spring traps baited with phenyl propionate captured =0.5x as many moths as pheromone traps, but later in the year the number of males captured with phenyl propionate was 1/10th of the number captured in pheromone traps. The sex ratio of moths captured varied from week to week within generations of navel orangeworm. Unknown physiological factors may cause male and female response to change differently with age, and NOW response to phenyl propionate may vary with the presence or concentration of unknown plant-associated volatiles. A group of six puffers in two columns, with 105 feet between puffers, comprises a minimum configuration for consistently high depression of males captured in traps baited with unmated females as a pheromone source. Characterization of the period of least NOW abundance, development of new and more affective attractants for monitoring, and identification of a minimum configuration for small-plot for testing of the ability of puffers to disrupt sexual communication is providing improved options for the management of NOW in pistachios.