Location: Tropical Crop and Commodity Protection Research
Project Number: 2040-43000-018-036-I
Project Type: Interagency Reimbursable Agreement
Start Date: Aug 1, 2023
End Date: Jul 31, 2024
Objective:
(1) Isolate and identify volatile chemicals from liquid torula yeast bait that is attractive to female oriental fruit fly.
(2) Determine an optimum combination of attractive chemicals for the most effective lure.
(3) Develop a controlled release dispenser for use as a lure in a trap.
Approach:
1. Isolate and identify volatile chemicals from liquid torula yeast (TY) bait that is attractive to female oriental fruit fly (OFF): The volatile compounds emitted by liquid TY bait will be sampled through an adsorbent material. The trapped volatiles will be extracted with a solvent. A coupled gas chromatograph/electroantennographic detection (GC-EAD) will be used to determine which compounds from TY are detected by the fly antennae. The identification of EAD-active volatile compounds will be conducted using GC-MS by mass spectral matches to library spectra as well as by retention time matches to available authentic standards. Quantification of the EAD-active compounds and their relative ratio will be made from the adsorbent collection (solvent extract) based on total ion abundances from GC-MS analyses using standard curves generated for the respective EAD-active compounds.
2. Determine an optimum combination of attractive chemicals for the most effective lure: Laboratory assays will be conducted using beaker traps as described in Roh et al (2021). Field tests will use multilure trap. Chemicals tested will be dispensed from rubber septa or from vials as used in prior development (Cha et al. 2012, 2014). Key attractant chemicals involved in female OFF attraction to TY bait will be determined using a series of laboratory bioassays and field trapping experiments. During the first year project, we will first conduct drop-out experiment, which will involve putting together a multi-component blend composed of all of the EAD-active compounds (i.e. full blend), and then comparing the full blend to blends that are missing single compounds, along with negative (no lure) and positive control (TY) traps. This approach will simplify the blend by eliminating compounds that do not contribute to blend attractiveness.
3. Develop a controlled release dispenser for use as a lure in a trap: The key attractant blend(s) resulted from drop-out experiment will be used to develop and further evaluate a lure in a controlled release dispenser. We will release chemicals from polypropylene vials (8 ml) with chemical release through holes in the vial lids. A field experiment will determine the relationship between attractant release rate from vials and capture of female OFF in traps. The chemicals will be mixed together according to the ratio in TY headspace or in equal proportions by volume, and the mixture will be placed in an 8 ml polypropylene vial, on cotton. The attractant release rate will be varied by altering the diameter of the hole in the lid, with larger holes (1~12 mm) providing greater diffusion of the chemicals from the vial.
