The antifeedant activity of 20 plant essential oils, constituents from clove stem oil and related compounds were tested against the third instar larvae from both moth Spodoptera litura and Spodoptera exigua by used leaf dipping bioassay. Among the oils tested, clove stem (94%), thyme oil red (85%), and savory oil (80%) were showed high antifeedant activity against both S. litura and S. exigua third instar larvae. Thyme oil white (91%), geranium (90%), and cinnamon bark oil (85%) were shown high antifeedant activity against only S. exigua when compare other oils. The other plant essential oils were showed moderate (40-50%) or low (>20%) antifeedant activity against third instar larvae of both S. litura and S. exigua. The most active clove stem oil constituents were indentified by GC-MS. The major constituents eugenol (95%), farnesene (81%) and structurally related compounds isoeugenol (96%), nerolidol (80%) were showed significant antifeedant activity against both S. litura and S. exigua. Global efforts to reduce the level of highly toxic synthetic insecticides in the agricultural environment justify further studies on the essential oils and their constituents describes as potential insecticides for the control of moth population with antifeedant activity.

From the methanol crude extracts of the tree of heaven (Ailanthus altissima) leaves, the antifeedant substance was isolated and bioassayed with different concentrations against diamondback moth (Plutella xylostella) larvae. The antifeeding activity was evaluated by measuring the feeding area during 24 hr after inoculation. Methanol extracts showing antifeeding activity at 5000 ppm was subsequently fractionated into hexane, chloroform, ethyl acetate and water layer. Third larvae of diamondback moth was tested to each fraction layer. Chloroform layer shows the highest antifeeding activity and the layer was purified by silica gel open column chromatography. The C22 and C23 fractions showed higher antifeeding ratio with 96 and 86%, respectively, and then these two fractions were re-isolated by ODS open column chromatography. As a result, both fractions in methanol 40% (v/v) showed antifeeding ratio over 90%. The C221 fraction showed insecticidal activity in all fraction, however, C231 fraction was showed the antifeeding activity only in C2311 fraction. The C2311 fraction judging to have antifeeding activity was re-isolated and purified by HPLC and recycling, and finally obtained the bioactive substances (C23111) with antifeeding ratio with 88%. The structure of bioactive materials isolated was confirmed by LC-mass and 1H-NMR(500 MHz), 13C-NMR(100 MHz).

This study was performed to investigate the feeding behavior of sweetpotato whitefly, Bemisia tabaci using the DC-EPG and the each developmental periods of biotype Q against nine varieties of red pepper. The result was showed that biotype Q did not feed and develop in the Nokkwang variety. In order to analyze the antifeedant, three feeding-preferred varieties (Cheongpungdaegun, Cheonyang, and Sannedeul) and non-preferred variety (Nokkwang) was tested for their sugar compounds using HPLC (ELSD Detector). The detected sugars were erythritol, xylose, xylitol, fructose, glucose, mannitol, and sucrose. In feeding-preferred varieties, the sugar such as erythritol, xylose, and xylitol were present at higher quantity than Nokkwang variety, however, fructose was existed lower quantity than Nokkwang variety. Subsequent bioassay for antifeedant activity, only xylitol showed repelled at lower concentration; however, attracted at higher concentration. Therefore, it is believed that xylitol may play a key role in the variety choice of red pepper by Q biotype of sweetpotato whitefly.