Insecticidal activity of active component isolated from Ruta chalepensis leaves was examined against maize weevil, Sitophilus zeamais and compared with two different bioassay system, such as direct contact and fumigant method. The methanol extract of R. chalepensis leaves had strongly (+++) insecticidal activity at 50 mg/disk against S. zeamais. Methanol extract of R. chalepensis was partitioned with hexane, chloroform, ethyl acetate, butanol and water fraction, successively. In this result, the highest activity was shown in chloroform fraction against S. zeamais. Biologically active compound derived from chloroform fraction of R. chalepensis extract was purified by using SiO2 column chromatography and prep-HPLC. The insecticidal constituent of R. chalepensis was identified as quinoline-4-carboxaldehyde by various chromatography and spectroscopic analysis methods. At 2.5 mg/disk, the most toxic activity against S. zeamais was exerted by the direct contact method (100%), followed by the fumigant method (23%). These results revealed that the contact toxicity showed 4.35 times greater than the respiration toxicity. Furthermore, these results indicate that quinoline- 4-carboxaldehyde could be useful as a new preventive agent against damage caused by stored-product insects.

The aim of this study was to evaluate light emitting diodes (LEDs) as the potential attractants against Spodoptera exigua on various wavelengths, light intensity and light duration, and compared to that of commercial control, flourescent lamp. The phototactic response to S. exigua was tested by single and complex wavelengths. The single wavelengths were composed as follows: blue (470 nm), green (520 nm), yellow (590 nm) and red (625 nm). The complex wavelengths was combined with two single wavelengths, such as blue-green, blue-yellow, blue-red, green-yellow, green-red and yellow-red. When the optimal light condition was investigated, the all light treatments attracted the highest number of S. exigua at 40 lux intensity and 60 min duration. Based on the single wavelengths under optimal light condition, the green LED exhibited the highest attraction rate (88.9%), followed by blue (81.1%), yellow (63.3%) and red (56.7%), respectively. In case of complex wavelengths under same conditions, the bluegreen complex (93.3%) had the significantly highest attractive activity, whereas blue-yellow, blue-red, green-yellow, green-red and yellow-red wavelengths were slightly decreased in comparison with single wavelengths. These data clearly show that blue-green complex had the greatest attraction against S. exigua.

Sweet potato whitefly, Bemisia tabaci, is one of the most common and critical green house pests in the world. The object of this study was to evaluate the attraction effect of various colored high power light emitting diodes (HPLEDs) against B. tabaci. These insects with diverse HPLEDs were examined by LED equipped chamber in the dark room at 27±0.5℃ and 60±5% relative humidity. Evaluated light-sources were blue (470±10 nm), green (520±5 nm), yellow (590±5 nm) and red (625±10 nm) HPLEDs, and tested with various illuminance intensity at 20, 40, 60, 80 and 100 lux. Base on the attraction rates, the green (94.4%) HPLED was the most effective against B. tabaci, followed by yellow (78.9%), blue (71.1%) and red (60%) HPLEDs. Furthermore, these data show that both the 80 lux intensity and 40 min light-exposure time using the green HPLED was the most suitable for attraction of B. tabaci. Putting all results, our data will provide the useful information for eco-friendly pest control against B. tabaci.

The two-spotted spider mite, Tetranychus urticae Koch is the most harmful pest among many cropping systems, particularly vegetables and other annual crops. In this study, the methanol extract from the inner bark of Tabebuia impetiginosa was evaluated for acaricidal activity against T. urticae by using a leaf disk method and were compared with commercial acaricide, abamectin. A crude methanol extract of T. impetiginosa had strongly acaricidal activity at 2,000 ppm against the T. urticae. Methanol extract of T. impetiginosa was partitioned with hexane, chloroform, ethyl acetate, butanol and water fraction, successively. In this result, the chloroform fraction showed a strong acaricidal activity at 1,000 ppm. Therefore, active fraction of T. impetiginosa extract was purified by using silica gel column chromatography and high performance liquid chromatography. The structure of acaricidal component was analyzed by EI-MS, 1H-NMR and 13C-NMR spectra, and was identified as TI-3123. Based on the LC50 values of TI-3123 and abamectin against T. urticae were resulted in 0.011 mg/l and 0.340 mg/l, respectively. These results showed that acaricidal activity of the T. impetiginosa can be mostly attributed to TI-3123. Furthermore, TI-3123 was approximately 30.91 times more toxic than abamectin against T. urticae. All these results suggested that active component in T. impetiginosa derived materials could be use for biological control for T. urticae. Further studies should be performed to the structure activity relationship of TI-3123 and compared with its derivatives.

To response evaluation of high power light emitting diodes (HPLEDs) as potential attractants to the Spodoptera exigua adults, we investigated the attractiveness of specific wavelength, illuminance intensity and light-exposure time, and compared them to the fluorescent. The all light treatments with the 40 lux intensity attracted the significantly highest number of S. exigua. The optimal light-exposure time exhibited the highest attraction rate at the 60 min. When the attraction and repellent rate in the optimal conditions to the S. exigua was surveyed, the white HPLED exhibited the highest attraction rate (91.1%), whereas the red HPLED exhibited the most repellent rate (33.3%). When evatuated of illuminance efficiency with fluorescent as control, white and red HPLED were found to be 9.14 and 10.34 times more efficient than fluorescent. These data clearly show that both the 40 lux intensity and the 60 min light-exposure time by using the white HPLED was the most suitable for attraction of the S. exigua.