Unmanned Aerial Systems Trials for Release of Sterile Insect Technique Navel Orangeworm

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The joint APHIS–CDFA Navel Orangeworm (NOW) Sterile Insect Technique (SIT) Program in California currently relies on a fixed‑wing Cessna 206 for sterile NOW releases. However, this method has consistently produced low and highly variable recapture rates (less than 0.1 percent), indicating that fixed‑wing aerial release may be biologically and operationally unsuitable for NOW.In contrast, manual (hand) releases conducted in Arizona have yielded recapture rates one to three orders of magnitude higher, suggesting that the challenge lies with the release method rather than insect quality. This substantial disparity, combined with the high cost and limited operational resilience of the fixed‑wing platform, underscores the need to evaluate alternative release technologies. Future pilot availability is also uncertain.Given advances in Unmanned Aerial Systems (UAS), associated equipment, and release methods, UAS-based delivery may offer improved cost savings, operational flexibility, and efficiency compared to the current aircraft‑based approach. The program is under increasing pressure to enhance efficiency and effectiveness, reduce costs, and plan for operational contingencies—including pilot availability. Stakeholders have also expressed interest in emerging technologies such as UAS for SIT applications.Accordingly, this is a valuable area for further exploration to potentially improve program savings, efficacy, and long‑term sustainability. APHIS‑PPQ has therefore initiated an evaluation of UAS‑based NOW SIT releases, including preliminary field trials, to inform program direction and assess whether operational changes or future investments are warranted to support the long‑term viability of the APHIS NOW SIT program.