Location: Tropical Crop and Commodity Protection Research
Project Number: 2040-43000-018-015-I
Project Type: Interagency Reimbursable Agreement
Start Date: Aug 16, 2021
End Date: Aug 31, 2023
Objective:
1. Identify key bioactive deterrent compounds from 11-component candidate oviposition deterrent mixture to B. dorsalis, A. suspensa and other invasive fruit flies.
2. Determine optimum and minimal effective doses of the key compound(s).
3. Evaluate the efficacy of the deterrent(s) on oviposition.
4. Determine the phytotoxicity and impact that the deterrent(s) have on host fruit quality.
Approach:
1. Objective 1: ARS-Hilo and ARS-Miami will rear B. dorsalis and A. suspensa on artificial diet, respectively. Individual chemical compounds responsible for the oviposition reduction for B. dorsalis (ARS-Hilo) and A. suspensa (ARS-Miami and APHIS-Miami) will be determined from the OviX, a mixture of 11 candidate oviposition deterrents, in two choice oviposition bioassays. Two guava infused agar plates as artificial oviposition substrates (in 50 mm diameter petri dish; one untreated control and one treated with one of the 11 OviX compounds at 20 mg, dissolved in hexane or in water and a surfactant will be placed inside a cage (30 x 30 x 30 cm). Twenty 14-d-old mated B. dorsalis or A. suspensa females will be added to each cage and allowed to oviposit for 72 hr. Number of eggs laid on guava agars will be counted using a dissecting microscope.
2. Objective 2: Optimum and lowest effective concentrations of each key deterrent compound will be determined for B. dorsalis and A. suspensa through dose-response tests (2, 0.2, 0.02 mg) using the two choice bioassay (described above).
3. Objective 3: Individual deterrents for B. dorsalis and A. suspensa will be formulated as a blend (key-component blend) at their optimal concentrations or at the lowest bioactive concentrations dissolved in hexane or in water- surfactant mixture. The key-component blends for B. dorsalis and A. suspensa will be evaluated for oviposition deterrence on papaya and guava, respectively, in the laboratory and field. In two-choice tests, two host fruits (papaya or guava for B. dorsalis and guava for A. suspensa; one untreated control and one treated with a key-component blend) will exposed to 14-d-old mated females over 72 hr in a cage. No-choice assays will be conducted using the same set up but with one fruit, either treated with a key-component blend or untreated control, per cage. Prototypes of sprayable formulations will be prepared by mixing key deterrent components for B. dorsalis or A. suspensa, respectively, in water, surfactant and emulsifier mixture and evaluated for the efficacy using laboratory two-choice assay described above. The sprayable formulations will be evaluated on field grown papaya and guava in Hawaii and Florida. The longevity of the deterrents will be also evaluated by comparing the rate of B. dorsalis and A. suspensa oviposition on aged guava juice agars treated with oviposition deterrents (0, 3, 7, and 14 days).
4. Objective 4: After a key-component blend or blank control treatment on papaya or guava as conducted in laboratory bioassays (Objective 3), fruits will be stored at 23°C and weight and color parameters of each fruit will be measured at 3 day interval post treatment over 2 weeks. Colors of each fruit will be measured on surface using a spectrometer for luminosity, chroma, and hue angle.
