Location: Commodity Protection and Quality Research
Project Number: 2034-43000-043-079-A
Project Type: Cooperative Agreement
Start Date: Jul 1, 2025
End Date: Jun 30, 2026
Objective:
The overall goal is to quantify and improve field performance of mass-released navel orangeworm (NOW) for sterile insect technique (SIT), and to develop best practices for area-wide pest management programs utilizing NOW SIT. Objectives addressed by the cooperator in this agreement include: 1) Develop pupal collection methods and evaluate the use of x-rays to sterilize NOW pupae; 2) Improve methods to monitor sterile male activity in the field; 3) Develop baseline methods and data for field mark-release-recapture experiments with mass-release NOW produced in California; 4) Develop new molecular genetic tools to support SIT research; and 5) Characterize the response of NOW to phenyl propionate (PPO) to increase its utility for monitoring.
Approach:
DEVELOP PUPAL COLLECTION METHODS AND EVALUATE THE USE OF X-RAY
Experiments will determine if x-ray sterilization remains effective when several hundred cocooned pupae are irradiated at the same time. If this is confirmed, then irradiation of cocoons will be further examined with minimal removal of diet. The response variable for survival will be progeny surviving to the pupal stage.
IMPROVE METHODS TO MONITOR STERILE MALE ACTIVITY IN THE FIELD
Markers for spermatophores of irradiated moths will be developed using RNA extraction and sequencing to identify genes expressed, and PCR to confirm these identifications. In addition, past research on externally applied liquid fluorophores will be extended to examine marking adults in larger bulk groups, and also examine marking pupae in this manner. As before, marking effectiveness will be determined by scoring detection following 1, 3, 7, and 14 days of field exposure.
BASELINE METHODS AND DATA FOR MARK-RELEASE-RECAPTURE WITH LOCALLY PRODUCED NOW
Navel orangeworm will be reared in large batches (>10,000), gathered as pupae, and released in cooperator orchards with grids of traps for males and females. Releases will with either mixed-sex groups of NOW sterilized by x-ray irradiation, or males isolated as pupae.
NEW MOLECULAR GENETIC TOOLS TO SUPPORT SIT RESEARCH
NOW embryos will be injected with CRISPER constructs and analyzed genotypically and phenotypically at the adult stage to develop a female-lethal strain. In addition, digital drop PCR will be developed to use adult gut contents to determine the larval host of NOW captured in the field.
RESPONSE OF NOW TO PPO
Laboratory Y-tube assays and field videography will be used to determine the time of night that males and females respond to phenyl propionate. The field experiment will also track response of females to ovipositional bait, since that is poorly characterized in the available literature.
Further description of methods for all objectives can be found in the accompanying Statement of Work (SOW).