Effects of Potassium Salt of Vegetable Oils and Essential Oils on Oviposition Behavior of the Oriental Fruit Fly, Bactrocera dorsalis (Diptera: Tephritidae)

• Main Authors: Syuan-Yi Lin, 林軒毅
• Other Authors: 顏瑞泓
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/52317996995885764678

碩士 === 國立臺灣大學 === 農業化學研究所 === 104 === The oriental fruit fly, Bactrocera dorsalis (Hendel), is a very destructive insect pest and is widely distributed in tropical and sub-tropical regions of the world. Fruit are damaged by the oviposition behavior of the female fruit fly and lose its commercial value. B. dorsalis will infest over 100 species of host plants including economic and non-economic fruits. Of these host plants, guava, citrus, mango and jujube are important economic fruits in Taiwan. Most strategies in Taiwan are focused on reducing the number of B. dorsalis in the field, or using bags to protect fruit directly from fruit fly, which is an expensive and labor-intensive method. Thus, it is necessary to develop more environmentally safe methods which protect fruit directly. In previous studies, mineral oils, vegetable oils, essential oils and other extracts of plant were shown to have potential for controlling B. dorsalis. However, they are all hydrophobic materials, and the addition of synthetic surfactant is necessary for use. This is contradictory to the original intention of avoiding the use of synthetic compounds. The objective of this study was to saponify vegetable oils to make it into potassium salt of vegetable oils which have the characteristics of surfactant. And we evaluated the effect of 4 potassium salt of vegetable oils and 15 essential oils on oviposition behavior of B. dorsalis and their mechanism by using the choice and non-choice test. The relation between fatty acid composition of vegetable oils and the effect on oviposition behavior will also be investigated. And the potassium salt of vegetable oil and essential oil that exhibits the strongest effect were selected to determine the effect of a mixture of potassium salt of vegetable oil and essential oil on oviposition behavior. The result showed that potassium salt of vegetable oils prevented B. dorsalis from making oviposition punctures on guava, which reduced the number of eggs in guava. In four vegetable oils, potassium salt of sunflower seed oil contains the largest proportion of long-chain unsaturated fatty acid and showed the strongest effect. In choice test, 1% solution showed 57.1% of puncture deterrence index. And 2% solution reached 34.4 and 51.5% of puncture deterrence index and oviposition deterrence index in choice test respectively, and reduced the number of punctures by 61.0% in non-choice test. The results showed that as the proportion of long-chain unsaturated fatty acid in vegetable oils increased, the effect will also increase. In 15 essential oils, lemongrass essential oil showed the strongest repellent effect on B. dorsalis and significantly reduced not only cumulative landing of female fruit fly on the ovitraps, but also the number of eggs laid. At a concentration of 1 mL/L, it showed 26.0 and 18.6% of repellency index and oviposition deterrence index in choice test respectively. After mixing the potassium salt of sunflower seed oil and lemongrass essential oil, the effect of potassium salt of sunflower seed oil on preventing fruit fly from making oviposition punctures was reduced. On the other hand, because of the addition of lemongrass essential oil, the effect of reducing the number of eggs increased. The mixture of 2% potassium salt of sunflower seed oil and 1 mL/L lemongrass essential oil showed the strongest effect. The mixture reached 51.5 and 62.5% of puncture deterrence index and oviposition deterrence index in choice test respectively, and 48.0% of oviposition deterrence index in non-choice test. This study showed that mixing the potassium salt of sunflower seed oil and lemongrass essential oil will increase the effect on controlling B. dorsalis.