Plant essential oils have been reported to show repellent, insecticidal and growth-reducing effect on many insect herbivores. Recently, it has been reported that plants synthesize secondary metabolites regulating insect juvenile hormone (JH) receptor complex as a part of their defense mechanisms. We tested 180 plant essential oil compounds using a yeast two-hybrid system transformed with the Aedes aegypti JH receptor as a reporter system. Among them, we identified 17 compounds that showing high JH agonist (JHA) or antagonist (JHAN) activities. They were grouped into 4 groups by their structural similarity and their insecticidal activity was tested against larvae of Aedes albopictus, Plutella xylostella, Plodia interpunctella and Laodelphax striatellus. These results could provide insights on the plant-insect coevolution and may be useful for the development of insect specific and safe pesticides.

The effects of some essential oils and Sopophora extract on Frankliniella occidentalis adults, Myzus persicae adults, Plutella xylostella larvae, and Spodoptera exigua larvae were investigated. Insecticidal and phytotoxicity activities of emulsion in water formulations containing the active essential oils as active ingredients under laboratory and pot conditions were also tested. Based on these results, NRS-13 and NRS-24 formulations were selected to further assess as follows; the GC and GC-MS analysis on the active essential oils, the quantity analysis of the major components contained in the formulations, their insecticidal activities under pot and field conditions, and their oral, dermal, skin and eye irritation, and fish toxicities. Thus, the NRS-13 (BaechooSaferTM) and NRS-24 (JindiOutTM) formulations could be considered as insecticides for pest control.

본 연구에서는 계피 정유 3종의 구성성분을 분석하였고, 미국선녀벌레에 대한 살충활성을 검정하였다. (E)-Cinnamaldehyde을 포함한 9종의 계피 정유 구성성분과 21종의 유사 물질을 미국선녀벌레 약충에 대해 살충활성을 검정한 결과, hydro-cinnamic acid가 반수치사농도 1.55 mg/cm 2로 가장 좋은 살충활성을 보였으며, geranic acid도 1.59 mg/cm 2로 높은 살충 활성을 보였다. Cinnamaldehyde를 포함한 hydro-cinnamaldehyde, (E)-cinnamaldehyde, cinnamdyl alcohol, cinnamyl acetate, dibutyl phtalate, anethole, a-cyano cinnamic acid, (s)-perillyl alcohol, methyl cinnamaldehyde, bonyl acetate 12종이 중간정도의 활성(1.60 - 4.94 mg/cm 2 )을 보였으며, 다른 물질들은 살충활성이 낮거나 없었다. 미국선녀벌레 성충에 대해서는 eugenol 이 반수치사 농도 10.81 mg로 가장 높은 살충활성을 보였으며, geranic acid (30.68 mg)도 높은 살충력을 보였다. Cinnamaldehyde 등 9종이 반수 치사 농도 105.44~255.76 mg의 살충활성을 보였다. 다른 18종의 물질은 활성이 낮거나 없었다. 실제 포장인 인삼포장에 발생하는 미국선녀벌레에 대한 적용시험에서 cinnamon bark 정유와 cinnamon green leaf 정유가 각각 82.3%와 82.9%의 높 은 살충활성을 보였다. 농업환경에서 고독성 합성살충제의 사용을 줄일 수 있는 방안으로 본 논문에서 선발한 계피정유가 미국선녀벌레의 약충 및 성충 방제에 유용한 수단으로 이용될 수 있을 것으로 사료된다.

The toxicity of cypress (Cupressus sempervirens) and howood (Cinnamomum camphora) essential oils, and its constituents to adult western flower thrips, Frankliniella occidentalis using leaf-dipping bioassay and vapour-phase toxicity bioassays. Both cypress and howood essential oils were toxic to western flower thrips. The most active principles were determined to be linalool, linalool oxide, cis-linalool oxide, trans-linalool oxide, camphor, and 1,8-cineole from cypress and howood essential oils. Linalool (24h LC50, 0.030 µg/cm2), linalool oxide (24h LC50, 0.036 µg/cm2), cis-linalool oxide (24h LC50, 0.043 µg/cm2), trans-linalool oxide (24h LC50, 0.045 µg/cm2), and camphor (24h LC50, 0.10 µg/cm2) were the most toxic. Potent toxicity was also observed with 1,8-cineole, a-pinene, d-limonene, a-terpinene, cinnamaldehyde, b-pinene, 3-carene a-terpineol, camphene, and terpineol (24h LC50, 0.33–0.65 µg/cm2). The spray bioassy of cypress and howood oil formulation (500 ppm) resulted in > 80% mortality toward western flower thrips population. Global efforts to reduce the level of toxic synthetic insecticides in the agricultural environment justify further studies on cypress and howood essential oil-derived materials as potential contact-action fumigants for the control of western flower thrips populations.

Polydnavirus (PDV) is a group of double-stranded DNA insect viruses. PDV is mutualistic with some ichneumonid and braconid wasps to parasitize specific lepidopteran hosts. The viral genome is located on the wasp chromosome(s) as a proviral form and replicates only at the female reproductive organ during late pupal stage. The viral particles are accumulated in the oviduct lumen and delivered to the parasitized host along with wasp eggs during parasitization. The viral particles enter target tissues in the parasitized larvae and alter host physiological processes for the wasp development by suppressing immune responses and extending larval period. Cotesia plutellae bracovirus (CpBV) is a PDV symbiotic to C. plutellae parasitizing young larvae of the diamondback moth, Plutella xylostella. The viral particles of CpBV encode 157 open reading frames classified into different gene families. CpBV-PTP family is the largest and comprises of at least 40 gene members. CpBV-BEN, CpBV-ELP, and CpBV-IkB families also share common motifs in each gene group. In addition, two homologous genes of CpBV15α and CpBV15β are encoded in a viral genome segment. To apply these viral genes to enhance an alpha-baculovirus in insecticidal activity, they were recombined with AcNPV under a PDV promoter. As a control, under the same promoter, the recombinant baculovirus expressed an enhanced green fluorescence protein (EGFP). Upon injection or oral feeding tests, three different recombinant baculoviruses (AcNPV-ELP1, AcNPV-CpBV15α, AcNPPV-CpBV15β) enhanced the insecticidal activity compared to a control recombinant (AcNPV-EGFP). However, there was a variation in the up-regulation of the insecticidal activities among the recombinants. AcNPV-ELP1 showed the greatest potency in the insecticidal activity against the beet armyworm, Spodoptera exigua, larvae. AcNPV-ELP1 exhibited a significant variation in insecticidal activity among different larval stages of S. exigua. In the fifth instar, 1.435x107 PIB treatment of AcNPV-ELP1 showed a median lethal time at 112.7 h. ELP1 protein was detected in the hemolymph at 24 h after the viral treatment. Foliar spray of AcNPV-ELP1 was performed in pot assay and resulted in 88% control efficacy against S. exigua, while control efficacies of AcNPV-EGFP and bifenthrin (a pyrethroid insecticide) resulted in 65% and 96%, respectively. These results suggest that a PDV gene, ELP1, may be applied to develop a novel control agent by ameliorating commercial microbial insecticides or by generating transgenic crops.

Baculovirus expression system has been used to produce functional proteins of various eukaryotic genes. A polydnaviral gene, CpBV-ELP1, was cloned in an alpha-baculovirus, Autographa californica multiple nuclear polyhedral virus (AcNPV), and expressed in Sf9 cells. CpBV-ELP1 protein was released into the culture medium due to its signal peptide. The culture broth containing CpBV-ELP1 was collected and fractionated with different concentrations of ammonium sulfate. Most CpBV-ELP1 was precipitated in 25-100% ammonium sulfate. The precipitate proteins were separated with a size exclusion chromatography sieving 100 kDa size. CpBV-ELP1 was eluted after relatively high molecular weight protein peaks. The fractions rich in CpBV-ELP1 were collected and further fractionated with an anion exchange chromatography. The purified CpBV-ELP1 was toxic to both larvae of Plutella xylostella and Spodoptera exigua by oral test used as leaf dipping method. A lethal median concentrations (LC50) were 7.5 ㎍/mL (95% CI: 1.2-24.3 ㎍/mL) for 2nd instar larvae of P. xylostella and 4.4 ㎍/mL (95% CI: 1.9-8.4 ㎍/mL) for 3rd instar larvae of S. exigua. These results suggest that CpBV-ELP1 may be applied to develop novel transgenic crops.

Essential oils or phytochemicals that are naturally synthesized by plants have received much attention as alternative pest control strategy. They are composed of highly volatile compounds which are less toxic to human but highly toxic to pests such as insects, microorganisms and nematodes. Until now, many researchers have evaluated the toxicities of essential oils and phytochemicals in Korea. Among them some of essential oils are formulated as repellents against mosquitoes. However, even such a broad research, the mode of action of essential oils is still unclear. To develop more effective and environmental friendly natural pesticides and to help understand the mode of action of essential oils, we have investigated the structureactivity relationship (SAR) between the chemical components of bio-active essential oils and nematode as well as insect pests. SAR of short-chain aliphatic compounds and ester analogues and pine wood nematode, Brusaphelenchus xylophilus; and salicylate analogues and adzuki been weevil, Callosobruchus chinensis are discussed here.

The cry gene from Bacillus thuringiensis (Bt), encoding the Cry protein, has been recently introduced into crops to generate transgenic plants that are resistant to pest insects. In this study, through the 3D structure prediction and accompanying mutagenesis study for the Mod-Cry1Ac, 7 and 16 amino acid residues from domain I and II, respectively, responsible for its insecticidal activity against larvae of Spodoptera exigua and Ostrinia furnacalis were identified. We used site-directed mutagenesis to improve the insecticidal activity of Mod-Cry1Ac, resulted 31 mutant cry genes. These mutant cry genes were expressed, as a polyhedrin fusion form, using a baculovirus expression system. The expressed proteins were 95 kDa and SDS-PAGE analysis of the recombinant polyhedra revealed that expressed Cry proteins was occluded into polyhedra and activated stably to 65 kDa by trypsin. When the insecticidal activities of these mutant Cry proteins against to larvae of P. xylostella, S. exigua and O. furnacalis were assayed, they showed higher or similar insecticidal activity compared to those of Cry1Ac and Cry1C. Especially, Mutant-N16 is considered to have the potential for the efficacious biological insecticide since it showed the highest insecticidal activity.

In the present study, lichen(Parmelia sp.) extract showed insecticidal activity against Aedes albopictus, and the effect of growth inhibiting activity was investigated. Acetone and methanol extracts of the lichen against larvae of Aedes albopictus were showed high insecticidal activities in low lethal concentration. 50% lethal concentration of the acetone extractof the lichen is 0.13% and the 50% lethal concentration of methanol extract of lichen is 0.15% respectively. This experiment that used acetone and methanol extracts of the lichen were observed for 24, 48 and 72 hours. As a result, the higher concentration and the longer exposure time is increased mortality against Aedes albopictus. Pupation time took more time as the higher concentration of acetone extract of lichen. Consequently, the lichen extract is effect in inhibiting the growth of Aedes albopictus larvae. In this experiment indicates that lichen extract has activity against Aedes albopictus and is available as the natural insecticide.

The insecticidal activities of materialsderived from Dryopteris crassirhizoma Nakai against third instar larvae of three species mosquitoes (Culex pipiens, Aedes albopictus and Anopheles sinnensis) were evaluated using a direct contact mortality bioassay. The methanol extracts of D. crassirhizoma showed 100%, 87.8% and 100% larvicidal activity at 1,000 ppm against Cx. pipiens, Ae. albopictus and An. sinensis, respectively. Hexane fraction showed 100% larvicidal activity three species mosquitoes at 500 ppm after 24 hrs. Purification of the biologically active constituents from the hexane extraction with larvicidal activity was done using silica gel column chromatography. H1 and H3 fractions gave 100% mortality to Cx. pipiens, Ae. albopictus and An. sinensis at 100 ppm. H1 fraction separated with methanol to give a H111 through centrifugation. Fraction of the biologically active constituents from the H3 fraction with larvicidal activity was done using methanol. H31 fraction was determined 100% mortality to Cx. Pipiens, Ae. albopictus and An. sinensis at 50 ppm, respectively. Two fractions were analyzed C14H22O (H111, MW206.0) and C11H14O4 (H31, MW210.08) by GC and GC-MS. D. crassirhizoma derived compounds described herein could be useful for managing filed populations as larvicide of Cx. pipiens, Ae. albopictus and An. sinensis.

곤충병원성세균 Xenorhabdus nematophila (Xn)의 일부 대사물질은 대상 곤충의 phospholipase A2 (PLA2)를 억제하여 아이코사노이드 생합성 활성을 저해시킨다. 그러나 이들 세균 대사물질이 억제하는 곤충의 PLA2에 대해서는 알려져 있지 않다. Xn의 배양액에서 화학구조가 동정된 8 가지 대사물질들은 두 종의 나비목 배추좀나방(Plutella xylostella)과 파밤나방(Spodoptera exigua)의 유충에 대하여 살충 활성을 보유했다.특별히 이들 물질은 모두 Bacillus thuringiensis (비티)의 살충력을 크게 향상시켰다. 파밤나방의 세포성 인지질 분해효소(SecPLA2)를 클로닝하고 대장균에서 과발현시켰다. 분리된 SecPLA2를 지방체에서 얻은 인지질과 반응시켰을 때 여러 다가불포화지방산을 해리시켰다. 이 효소활성이 Xn 유래 대사물질들에 의해 뚜렷이 억제되었다. 또한 SecPLA2에 대한 억제효과와 비티 살충력 상승효과 사이에 정의 상관관계를 보였다. 본 연구는 SecPLA2가 Xn 대사물질의 억제 대상 분자 종말점 가운데 하나라고 제시하고 있다.

In the midst of environments with crop-mixing, there were more preferred the fruit trees by brown-winged green (Plautia stali (Scott)), and yellow-brown stink bug (Halyomorpha halys (Stål) and vegetables by Far eastern green stink bug (Nezara antennata Scott) and Bean bug (Riptortus pedestris (Thurnberg)). The major dominant species was identified as P. stali, infesting fruit trees over 99.4% among tested insects. It is severely damaged on peach of middle and late ripening, crab apple, pear and wild fruit of Actinidia arguta. In an investigation for the seasonal occurrence using aggregation pheromone trap, P. stali was peaked with three times at late-May ~ early-June, mid- and late-July, and mid-Sept. ~ Oct. And H. halys slightly peaked at mid-June, and mid- and late-July and increased the occurrence at mid-Sept. ~ mid-Oct. Using seven insecticides - dinotefuran WP, flonicamid WP, etofenprox WP, chlorpyrifos WP, cabaryl WP, chlothianidin SC, and bifenthrin WP - registered on apple, contact and residual toxicity was tested on both male and female of P. stali and H. halys. Contact toxicity of dinotefuran WP was excellent on P. stali but the others had low effect. While all insecticides except flonicamid, residual toxicity were all effective on P. stali. Dinotefuran have a excellent contact toxicity and chlorpyrifos and bifenthrin have good residual toxicity against both male and female of H. halys.

The insecticidal activities of materials derived from the rhizomes of turmeric, Curcuma longa L., against third instar larva of Culex pipiens and Aedes albopictus were evaluated using a direct contact mortality bioassay. Curcuma longa L. hexane extraction showed 100% larvicidal activity both two mosquitoes species at 1,000 ppm after treated 24 h. Purification of the biologically active constituents from the hexane extraction with larvicidal activity was done using silica gel column chromatography. H1 fraction gave 100% mortality to C. pipiens and A. albopictus at 100 ppm. H12 fraction was determined 100% and 87.8% larvicidal activity to C. pipiens and A. albopictus at 50 ppm, respectively. H12 fraction was analyzed as the sesquiterpene, ar-turmerone (C15H20O) and turmerone(C15H22O) by GC and GC-MS.

In the midst of environments with crop-mixing, there were more preferred the fruit trees by brown-winged green (Plautia stali (Scott)), and yellow-brown stink bug (Halyomorpha halys (Stål)) and vegetables by Far eastern green stink bug (Nezara antennata Scott) and Bean bug (Riptortus pedestris (Thurnberg)). The major dominant species was identified as P. stali, infesting fruit trees over 99.4% among tested insects. It is severely damaged on peach of middle and late ripening, crab apple, pear and wild fruit of Actinidia arguta. In an investigation for the seasonal occurrence using aggregation pheromone trap, P. stali was peaked with three times at late-May∼early-June, mid- and late-July, and mid-Sept. ∼Oct. And H. halys slightly peaked at mid-June, and mid- and late-July and increased the occurrence at mid-Sept. ∼mid-Oct. Using seven insecticides - dinotefuran WP, flonicamid WP, etofenprox WP, chlorpyrifos WP, cabaryl WP, chlothianidin SC, and bifenthrin WP - registered on apple, contact and residual toxicity was tested on both male and female of P. stali and H. halys. Contact toxicity of dinotefuran WP was excellent on P. stali but the others had low effect. While all insecticides except flonicamid, residual toxicity were all effective on P. stali. Dinotefuran have a excellent contact toxicity and chlorpyrifos and bifenthrin have good residual toxicity against both male and female of H. halys.

Insecticidal and repellent activity of sandalwood oil (Santalum austrocaledonium) and its components was tested against cotton aphid , Aphis gossypii in laboratory and field. The activity was estimated by calculating survival rate of aphid after application of sandalwood oil and its components. Analysis by gas chromatography-mass spectrometry led to identification of 5 compounds, alpha-santatol, bergamotol, epi-beta-santalol, and beta-satalol. The components of sandalwood oil was isolated by column chromatography for testing insecticidal and repellent activity. Santalol showed strong insecticidal and repellent activity as a commercial insecticide, imidachloprid. Sandalwood oil and isolated alpha-santatol and beta-santatol also showed strong insecticidal and repellent activity, however there was no significant difference among them.

Insecticidal susceptibilities of 16 registered insecticides on each developmental stages of Phthorimaea operculella were investigated and further examined the contact, oral and residual toxicities after chosen from insecticides showing good effect. Mortality, longevity and effect on reproduction of 16 insecticides to P. operculella adults were also investigated. To the eggs and pupae, only spinosad showed 71.1% inhibition rate of egg hatch and 66.7% inhibition rate of emergence. To the 3rd nymphs, fenitrothion (LC50 336.6 ppm), esfenvalerate (LC50 8.6 ppm), ethofenprox (LC50 35.7 ppm), and emamectin benzoate (LC50 0.05 ppm) showed oral toxicity over 90% and esfenvalerate (LC50 0.87 ppm), ethofenprox (LC50 16.5 ppm), emamectin benzoate (LC50 0.53 ppm), and spinosad (LC50 2.48 ppm) showed the contact toxicity over 90%. To the adults, mortalities of insecticides were showed as below: deltamethrin and spinosad showed perfect mortality 48 h after treatment; esfenvalerate, ethofenprox, and thiamethoxam showed 40 - 60% mortalities; but the others are not showed any effect. Fecundities of female adults were inhibited by esfenvalerate, emamectin benzoate, and dinotefuran, compare to that of the control, but there were no statistical differences to that of ethofenprox, benfuracarb, thiamethoxam, clothianidin, and diflubenzuron. Adult longevity was showed no difference compare to that of the control. Residual effect of emamectin benzoate showed perfect insecticidal activity at 14 days after treatment and the next ethofenprox showed over 90% at 7 days after treatment.

Maize weevil is one of the most common and critical storage pest in the world. In this study, the insecticidal activity of the methanol extracts derived from Caesalpinia sappan was evaluated against adults of maize weevil, using by direct contact and fumigant methods. Based on the two methods, ethyl acetate fraction of the C. sappan extracts had 100% mortality against Maize weevil adults at 10 mg. The biological constituent of C. sappan extract was isolated by various chromatographic techniques and identified as juglone. On the basis of 72 h LD50 values, in the direct contact bioassay, the insecticidal activity of juglone (0.010 mg/cm2) was the most effective, followed by 1,4-NQ (0.018 mg/cm2) and menadione (0.087 mg/cm2). In a fumigant bioassay, the insecticidal activity of juglone (0.014 mg/cm2) was the most effective, followed by 1,4-NQ (0.015 mg/cm2) against maize weevil adults. On the other hand, menadione, lawsone, and 2-methoxy-1,4-NQ observed no insecticidal activity or weak. These results suggested that active compound of C. sappan materials could be used as biological control agent against maize weevil. Therefore, further research should be performed to the structure activity relationship of juglone and compared with its derivatives.

We evaluated insecticidal and acetylcholine esterase inhibition activity of 11 Apiaceae plant essential oils and their constituents against male and female adults of Blattella germanica. Of 11 Apiaceae plant essential oils tested, dill (Anethum graveolens), carvi (Carum carvi), and cumin (Cuminum cyminum) essential oils demonstrated > 90 % fumigant toxicity against male adults of German cockroach at 5 mg/filter paper. In contact toxicity test, dill (Anethum graveolens), carvi (Carum carvi), cumin (Cuminum cyminum), and ajowan (Trachyspermum ammi) essential oils produced strong insecticidal activity against male and female adults of German cockroach. Among test compounds, carvone, 1,8-cineole, trans-dihydrocarvone, cuminaldehyde, trans-anethole, p-cymene, and γ-terpinene demonstrated strong fumigant toxicity against male and female adults of B. germanica. In a contact toxicity test, carveol, cuminaldehyde, (S)-(+)-carvone, trans-anethole, thymol, and p-cymene showed the strong contact toxicity against B. germanica male and female adults. IC50 values of α-pinene, carvacrol, and dihydrocarvone against female acetylcholine esterase were 0.28, 0.17, and 0.78 mg/mL, respectively. The toxicity of blends of constituents identified in 4 active oils indicated that carvone, cuminaldehyde, and thymol were major contributors to the fumigant or contact toxicity of the artificial blend.

We evaluated insecticidal activity of 11 Apiaceae plant essential oils and their constituents against rice weevil, Sitophilus oryzae.. Of 11 Apiaceae plant essential oils tested, dill (Anethum graveolens), carvi (Carum carvi), caraway seed (Carum carvi) and cumin (Cuminum cyminum) essential oils demonstrated strong fumigant toxicity against adults of rice weevil. Components of 4 active compounds were analyzed by GC and GC-MS, and fumigant toxicity of individual compound was also tested. Among test compounds, carvone, dihydrocarvone, carveol, linalool oxide, neral, cuminaldehyde, and anethole demonstrated the strong insecticidal activity. The toxicity of blends of constituents identified in 4 active oils indicated that carvone, and cuminaldehyde were major contributors to the fumigant toxicity of the artificial blend.

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.