1a. Objectives (from AD-416):
1-Develop a media type of "patch or rod" containing embedded basil oil and determine the rate of diffusion during storage, evaluating the effect of the release of oil aroma on the mortality rate, feeding rate and repellency to insects. An insect such as Sitophilus oryzae (rice weevil) will be used because it is an important a contaminant of cereals and easy to raise in the laboratory. 2-To characterize the physicochemical properties of the broadcast medium and evaluate the rate of diffusion of active compounds during storage.
1b. Approach (from AD-416):
The physical matrix or patch will be developed by polymer engineers at the University of Quebec. Various concentrations of basil or other essential oils will be embedded in the polymer matrix. The patch emitting basil oil aroma in various concentrations will be tested for their effects on rice weevil mortality, repellency and feeding in a series of bioassays.
3. Progress Report:
The goal of the cooperative agreement is to develop a diffusion delivery medium for bioactive compounds of natural plant product origin which contributes to objective 1 of the in-house project, "Develop new or improved postharvest treatments, including alternatives to methyl bromide, for tropical fruit, vegetable, and ornamental crop exports to ensure security against quarantine pests and to meet quarantine requirements of U.S. trading partners". Plant essential oils have potential as fumigants to control pests in stored products. Irradiation is also an option for control of these pests. The biological activity of basil essential oil (Ocimum basilicum L.) with and without irradiation was tested against the stored product pest rice weevil and two pathogenic fungi of rice. The effectiveness of irradiation treatment against rice weevil and the fungi was enhanced by exposure to basil oil. At 120 h, rice weevils exposed to 2 and 4% of basil essential oil were 5.4 and 7.8 times more sensitive to irradiation, respectively, compared to control weevils treated only by irradiation. The radiation dose of 0.8 kGy and 10% basil oil was the optimal condition for preventing fungal growth (100% inhibition) in rice after 96 hours of incubation. Basil oil fumigation increased the radiation sensitivity of rice weevil and two pathogenic fungi and may have potential as a means to prevent damage by pests and preserve the quality of stored products.