Location: Commodity Protection and Quality Research
Project Number: 2034-43000-043-032-T
Project Type: Trust Fund Cooperative Agreement
Start Date: May 1, 2021
End Date: Feb 28, 2024
Objective:
1) Determine the how exposure to low temperatures and unusual motion affects subsequent fitness of navel orangeworm used for sterile release.
2) Compare recapture of sterile navel orangeworm released into plots with and without mating disruption.
Approach:
To address objective 1, a series of tests will examine the effect of a two-day exposure to shipping temperature (4C) on NOW at various ages (26, 28, and 30 days post egg) shortly before and after adult emergence from the pupa. Survival and the proportion of adults leaving flight cylinders will be compared between these temperature treatments and a fourth control treatment (NOW never exposed to cold). In addition, groups of larvae will be placed in diet in shallow containers (similar to the shipping containers used by Phoenix for larvae) and either placed on a shaker for 24 hours or left undisturbed during this time. After this treatment the larvae will be transferred to another batch of diet (as we routinely do with larvae arriving from Phoenix), allowed to develop until the end of the last larval instar, sexed, and reared to adult. Predictor variables will be the shaking treatment and sex. Initial response variables: 1) will be the number of larvae observed at the top of or out of the diet at the end of the 24 hr when treated larvae are shaken, and 2) dry weight of adults on the day of emergence.
To address objective 2, laboratory assays will build on previous studies that have shown anemotactic flight of gravid NOW females to crude almond oil. Methods used will be similar to those we recently used to examine the impact of strain, irradiation, and shipping of NOW males on wind tunnel flights to a pheromone source. Briefly, the ability of females to lock on plume, fly upwind to the odor source, and contact the source will be compared between unirradiated females and females irradiated using the dose and conditions selected in objective 1. In addition, replicate plots with various densities of mating disruption are obtained within an orchard without mating disruption by either treating a square with mating disruption dispensers place in the corners of the square, or with meso-dispensers placed a various relevant spacings within these squares. Use of several mating disruption intensities, ranging from none to equivalent to commercial treatment, provides a more robust comparison of the impact of mating disruption on capture efficiency in an attractant. Grids of traps will be placed in such plots baited with either PPO alone or PPO enhanced with a pheromone will be compared with (as negative controls) a pheromone monitoring lure, or a blank trap.
