1a. Objectives (from AD-416):
The overall goal of this project is to ensure strategic application of chemicals to control navel orangeworm (NOW) in almonds by mapping the environmental fate and transport of insecticides, particularly degradative pathways involving solar photolysis.
1b. Approach (from AD-416):
This research will integrate laboratory, model ecosystem, and field studies for the purpose of tracing the signature of organic agrochemicals through the environment. The specific approach involves: 1) developing methods of spectroscopic and mass spectrometric analysis of pyrethroids, 2) probing the direct and indirect sunlight-mediated photolysis of pyrethroids through a combination of kinetic modeling and byproduct analyses, 3) characterizing the chemical constituents of nut hulls as related to sun-light mediated degradation, and 4) relating sunlight-mediated degradation to the relative toxicity of pyrethroids and resulting products.
3. Progress Report:
This Assistance Type Cooperative Agreement was established to support Objective 1 of the in-house project and is related to finding postharvest methyl bromide alternatives and techniques for improving methyl bromide fumigations. Navel orangeworm (NOW) is a key insect pest of almonds that results in production and postharvest losses for industry. The goal of this project is to ensure strategic application of chemicals to control NOW in almonds by mapping the environmental fate and transport of insecticides, particularly degradative pathways involving solar photolysis. The direct photolysis products of bifenthrin were chemically characterized. Using benchmark photosentizers and transient oxidants, the products resulting from indirect photolysis were also characterized. After chronological mapping abiotic and microbiological degradative pathways over the course of a growing season, the timing of spray applications can be modified in order to optimize NOW control. Research has contributed to delayed onset of insecticide resistance – a critical management tool, enhanced potential to mitigate maximum residue levels (MRL)-based export barriers, and improved environmental stewardship through reduced insecticide use.