Location: Commodity Protection and Quality Research
Project Number: 2034-43000-043-046-I
Project Type: Interagency Reimbursable Agreement
Start Date: Jun 1, 2022
End Date: Aug 31, 2023
Objective 1, determine whether cold acclimation and/or modified atmospheres can improve navel orangeworm (NOW) male tolerance of collection and transport conditions encountered in sterile insect technique (SIT) Second objective is to test whether performance is improved in a new strain developed by USDA-APHIS Phoenix Rearing Facility. And the third objective is to determine whether sex pheromone can be used to separate sexes and perform males-only releases. Co PI will Test methods for improved standardization of sanitation and pesticide treatments to be incorporated along with NOW SIT into a larger context of Integrated Pest Management
1) Cold acclimation and/or modified atmospheres to improve male performance. Cold acclimation: Larvae and pupae will be acclimated for one or two weeks using exposure to 10C, adults challenged with 4C for 72 hours, then test with flight cylinders. Modified atmosphere: Experiments in a flow-through system mixing nitrogen and compressed air will determine low oxygen threshold causing coma but not death. Flight mill tests will compare sublethal effects of exposure to this threshold oxygen level for 72 hours at between various temperatures between 4 and 20C. 2) Test whether performance of a new strain. Lab tests will compare performance of males and females on flight cylinders between the new and the currently used strain following exposure to 4C for 72 hours. Mark-release-recapture experiments will compare recovery of males and females of the new and current strain in pheromone and bait traps (females) following release in small experiment station plots and commercial orchards. 3) Sex pheromone for separation of sexes. Experiments will be performed to in a flow-through system to determine if high concentration of sex pheromone can be used to prevent mating of male and female NOW that emerge in close proximity. Experiments with a glass Y-tube olfactometer will be used to test the hypothesis that males move upstream to high pheromone sources, but females do not. 4) Field scale replicated tests of movement and impact of sterile NOW. Replicated experiments in 640 acre pistachio orchard will use recapture in grids of pheromone and bait traps of sterile NOW following mass release to quantify rate of dispersal and effect of orchard edges. Grids of pheromone and bait traps in replicate pairs of 160 acre almond orchards will compare sterile and wild NOW males and females in SIT treatment. In addition harvest samples will be used to compare damage. Co PI will Yield and damage data for almonds and pistachios will be compared with data from three different mummy assessment methods used the previous winter to determine the relationship between intensity of sampling and damage predictions. Coverage and impact will be compared between insecticide treatments using filter papers hung mid-canopy. The impact of these treatments on insects will be assessed by laboratory assessments of survival and development of larvae after placing egg clusters are placed on the treated filter papers 1 or 1, 2, or 3 weeks after treatment. Data from previous studies and from the experiments described above will be shared with project participants in field days and grower meetings to obtain consensus on appropriate tactics and therefore greater uniformity of practice among project participants.