The toxicity of 102 plant essential oils against third instars of cecidomyiid gall midge, Camptomyia corticalis, was examined using a vapor-phase mortality bioassay. Results were compared with that of a conventional insecticide dichlorvos. Based on 24 h LC50 values, all essential oils were less toxic than dichlorvos (LC50, 0.027 mg/cm3). The LC50 of caraway seed, armoise, sage (Clary), oreganum, lemongrass, niaouli, spearmint, cassia special, sage (Dalmatian), thyme red, bay, garlic, and pennyroyal essential oil is between 0.55–0.60 mg/cm3. The LC50 of cassia pure, thyme white, cassia redistilled, star anise, peppermint, wintergreen, cinnamon bark, majoram, chamomile romon, eucalyptus, rosemary, cedar wood, pimento berry, savory (summer), lavender, and coriander oil is between 0.61–0.99 mg/cm3. All other essential oils tested exhibited low toxicity to the cecidomyiid larvae (LC50,>0.99 mg/cm3). The active principles of active essential oils were identified by GC-MS analysis. The major active principles are such as pulegone, thujone, camphor, 1,8-cineole, a-pinene, thymol, menthol. At a rate of 5 mg/cm3, pulegone, and thujone, exhibited 100% morality whereas camphor, 1,8-cineole, α-pinene, thymol and menthol showed 90% mortality at 15 mg/cm3. 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 described as potential insecticides for the control of the mushroom fly as fumigants with contact action.

The larvicidal activity of 104 plant essential oils and their major constituents against third instar larvae of mushroom fly Camptomyia corticalis was examined using a vapor-phase mortality bioassay. Results were compared with those of the conventional insecticides dichlorvos. Over ten plant essential oils exhibited showed more than 90% mortality. At a rate of 0.2 mg/cm3 air, pulegone, and thujone, exhibited 100% morality whereas camphor, 1,8-cineole, α-pinene, thymol and menthol showed 90% mortality at 0.6 mg/cm3 air. 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 described as potential insecticides for the control of the mushroom fly as fumigants with contact action.

The repellency of 104 plant essential oils to female Aedes aegypti was examined using a cage-distribution assay. Results were compared with those of the conventional mosquito repellent N,N-diethyl-m-toluamide (DEET). Coriander, oreganum, pennyroyal, lemoneucalyptus, and spearmint exhibited high repellency effect (>60 minutes at 50 mg/filter paper), followed by sage, leavander, tarragon, bergamot, and neroli oils which showed moderate effective (< 40 minutes at 50 mg/filter paper (5 cm diameter)). In the light of global efforts to reduce the level of highly toxic synthetic repellents, essential oils described merit further study as potential repellents for the control of mosquito populations.

The American house dust mite, Dermatophagoides farinae Hughes, is the most important factor of allergic diseases, such as atopic dermatitis, rhinitis, and asthma. The protein-denaturing activity of nerolidol (1), chrysin (2), and spathulenol (3) identified in the Brazilian propolis against D. farinae was evaluated using SDS-PAGE and dot-blot immunoassay. Results were compared with those of the currently available dust mite protein-denaturing agent tannic acid. SDS-PAGE showed that application of test compounds and tannic acid (100 μg each) caused complete disappearance of D. farinae protein bands. In a dot-blot immunoassay, test compounds and tannic acid (100 μg each) strongly inhibited the IgE-binding reactivity to D. farinae protein of a highly mite-sensitive asthmatic patient. The Brazilian propolis constituents described merit further study as potential dust mite-allergen denaturants for protection from humans from various diseases caused by house dust mites.

The toxicity of imperatorin (1) and osthol (2) identified in Cnidium monnieri seed and four structurally related compounds to third instar larvae of insecticidesusceptible (KS-CP strain) and field-collected (DJ-CP colony) of Culex pipiens pallens was examined. Results were compared with those of to conventional mosquito larvicide, fenitrothion and temephos. Based on 24-h LC50 values, imperatorin was 1.9, 3.7, 4.2, 12.4, and 15.1 times more toxic than isopimpinellin, isoimperatorin, osthole, xanthotoxin, and bergapten against KS-CP larvae, respectively. Overall, these compounds were less toxic than either fenitrothion or temephos. However, these compounds did not differ in toxicity against larvae from the two Culex strains, even though the DJ-CP larvae exhibited high levels of resistance α-cypermethrin, deltamethrin, chlorpyrifos, fenthion, and chlorfenapyr (resistance ratio, 94-1179). This finding indicates that the isolated compounds and the pyrethroid, organophosphorus, and pyrrole insecticides do not share a common mode of action or elicit cross-resistance.

Although many synthetic pesticides have played important roles in pest management in agriculture, forest, housings, gardens, and managed landscapes for several decades, increased concerns to human health and environmental contamination have limited their usages and application in integrated pest management (IPM). Many plant essential oils have a variety of biological activities including adulticidal, acaricidal, larvicidal, ovicidal, repellent, antifeedant, and oviposition deterrent ones against insect pests. These oils and major terpenoid constituents show neurotoxic effects by interference with the cockroach octopamine and nematode SER-2 tyramine receptors. Most plant volatile oils contain plentiful phenylpropanoids, mono and sequiterpenes, and related phenols. They have been widely used in the flavor, fragrance, aroma therapy, food additives, and cosmetic industries. Some volatile plant essential oils have traditionally been used as stored product protectors and mosquito repellents, while their successful cases in commerce have been recently applied. Especially, these essential oils have not only been treated against house and garden pests, but these oils also have higher potential to be employed as “green pesticides” in the field of stored products, green house, and medical insect pests due to their fumigant action. Eventually, considering resistance development to many synthetic pesticides, it is likely that plant volatile or essential oil-based pesticides would play an essential role as an alternatives since they typically consist of the complex mixtures of constituents responsible for slow resistant development. In addition, the mixtures of these oils with conventional insecticides and the application of their capability to to enhance the efficacy of conventional products remains a main market niche. In this presentation, several cases of test evidences under laboratory and field conditions will be discussed. Ultimately, plant volatile-based pesticides and repellents would play an important role in future IPM programs due to their relative safety to non-target organisms and the environment.

Electroantennogram techniques (EAGs) were employed to record olfactory responses in the antennae of the adult female stable fly, Stomoxys calcitrans (Diptera: Muscidae), to Zanthoxylum piperitum pericarp steam distillate (ZP-SD), Z. armatum seed oil (ZA-SO) and their 29 volatile constituents alone as well as binary mixture of the ZP-SD and ZA-SO with 1-octen-3-ol. The electrophysiological responses of the test materials were compared with those of DEET and 1-octen-3-ol. At concentration of 10-1 (v/v) in mineral oil, ZP-SD, ZA-SO, and all volatiles elicited EAG responses in the fly antennae except for DEET, which is extremely low volatile. ZP-SD, ZA-SO, and some of the test volatiles elicited EAG responses rather lower than 1-octen-3-ol, which showed vapor phase repellency and toxicity to the fly in our previous behavioral research. This suggests that the stable fly possesses olfactory receptor neurons responding to given repellent compounds per se. In binary mixture with 1-octen-3-ol at concentration of 10-1, ZP-SD and ZA-SO elicited 16±0.55 and 18±0.63 mV while ZP-SD, ZA-SO, and 1-octen-3-ol alone elicited responses of 14±0.45, 15.8±0.37 and 16.2±0.58 mV, respectively. Among the volatile compounds, terpinen- 4-ol, β-myrcene, α-phellanderene, citronellal, and limonene oxide elicited 80 – 96% relative EAG amplitude compared to 1-octen-3-ol as a reference (100%). Based on structure-activity relationships, constituents having aldehyde moiety elicited bigger EAG responses than those of alcohol or ether one. The perception in the fly antenna to plant volatile compounds exhibited complicated patterns of olfactory responses. Current and future directions of this study on sensory processing mechanisms underlying repellent behaviors will be discussed.

Origanum essential oil [Origanum acutidens (Hand.-Mazz.)] showing insecticidal activity and repellency against red flour beetle, Tribolium castaneum (Coleoptera: Tenebrionidae) adults was analysed by GC-MS. All constituents of the oil were identified, and the main components were carvacrol (67.2%), p-cymene (16.2%), γ-terpinene (5.5%), thymol (4.9%),and linalool(2.1%). In vapor phase fumigant assay, the origanum oil was more effective in closed condition (LD50 = 0.555 mg/cm3) than in open one (LD50 = 0.353 mg/cm3).This result suggests that the toxicity of the oil to red flour beetle is exerted largely by vapor phase. Based on 24-h LD50 values, the toxicity of caryophyllene oxide (0.00018 mg/cm3) was comparable with that of dichlorvos (0.00007mg/cm3) as a positive insecticide. In addition, thymol, camphene, α-pinene, p-cymene, and γ-terpinene gave good insecticidal activity (LD50 = 0.012 - 0.195 mg/cm3). In repellent test using 9 constituents of origanum oil, caryophyllene oxide showed 100% repellent activity at 0.0158 and 0.0032 mg/cm2. These results indicate that the origanum oil and its some components could be potential candidates as a fumigant and repellent for managing T. castaneum adults. Potential molecular target of repellents will be discussed.

The Organophosphorus pesticides are widely used for agricultural and domestic purposes due to their relatively low persistence in the environment. Chlorpyrifos-methyl (CM) is used at a rate of over 14 million pounds per year in US agriculture, ranking it as the second most heavily used pesticide. This study aimed at isolating bacteria from soil and determining their ability to degrade CM and identify the intermediates in culture broth. Bacteria capable of degrading CM was isolated by enrichment culture. Chryseobacterium sp. strain KR200 degraded CM up to 91.58% in 7days. Studies with CM in liquid culture of Chryseobacterium sp. strain KR200 demonstrated that the isolate hydrolyzed CM to 3,5,6-trichloro-2-pyridinol, and utilized this compound for growth and energy. We performed SDS-PAGE and two-dimensional gel electrophoresis and identified proteins whose expression pattern is affected by CM using mass spectrometry. The results revealed various proteins that can be grouped according to their respective cellular function. These results highlight the potential of this bacterium to be used in the clean up of contaminated pesticide waste in the environment.

The toxicity of materials derived from seed of Pongamia pinnata Pierre toward to third instar larvae of Aedes aegypti and Culex pipiens pallens was examined using direct contact bioassay. Results were compared with those of the currently used insecticides: fenthion and temephos. The active principles of Pongamia pinnata were identified as the karanjin (1), pongamone (2), palmitic acid (3) and karanjachromene (4), by spectroscopic analysis. Based on 24h LC50 values, karanjin (14.61 and 16.13 ppm) was the most toxic compound but less effective than fenthion (0.0031 and 0.068 ppm) and temephos (0.016 and 0.056 ppm) against Ae. aegypti and Cx p. pallens. Moderate toxicity was produced by pongamone (34.50 and 39.53 ppm), palmitic acid (36.93 and 42.96 ppm), and karanjachromene (43.05 and 48.95 ppm). P. pinnata seed derived materials, particularly karanjin, merit further study as potential mosquito larvicides for the control of mosquito populations in light of global efforts to reduce the level of highly toxic synthetic larvicides in the aquatic environment

The vapor phase repellency and toxicity of Zanthoxylum piperitum pericarp steam distillate (ZP-SD), Z. armatum seed oil (ZA-SO), and their 29 constituents to the adult female stable fly, Stomoxys calcitrans (Diptera: Muscidae), were examined using filter paper fumigation bioassay. Results were compared with those of the currently used repellent: DEET. Both of ZP-SD and ZA-SO exhibited vapor phase repellency and toxicity to female flies at 5 to 40 mg/filter paper (0.23 to 1.82 mg/cm3 air) during a 120-min exposure, whereas DEET exhibited neither repellency nor toxicity to the stable fly. At 5 mg/filter paper, vapor phase of ZP-SD and ZA-SO repelled 50 to 67% and 61 to 51% flies, respectively, to control area during 30 to 120 min. At 40 mg/filter paper, vapor phase of ZP-SD and ZA-SO caused 100% and 81% mortality, respectively, after 120 min of exposure. Among the tested volatile constituents, cuminaldehyde was the strongest repellent and toxic compound to the fly and was four times more toxic than ZP-SD and ZA-SO. Cuminaldehyde vapor phase repelled 62% flies to control area after 30 min at 2.5 mg/filter paper and caused 100% mortality after 120 min at 10 mg/filter paper. Based on the structure-activity relationships, the toxicity and repellency of constituents having aldehyde moiety were better than those of alcohol or ether one. Overall, ZP-SD, ZA-SO, and their bioactive constituents could be useful as potential vapor repellents to control stable fly population.

The toxicity of materials derived from rhizome of Cnidium officinale Makino to adults from B and Q biotype of Bemisia tabaci was examined using a leaf-dipping bioassay. Results were compared with those of two currently used insecticides: acetamiprid and thiamethoxam. The active principles of C. officinale rhizome were identified as butylidenephthalide (1), ligustilide (2), and 3-butylphthalide (3) by spectroscopic analysis. These compounds exhibited 100% mortality against both B and Q biotype adults at 2.5 mg/ml. At a concentration of 1.25 mg/ml, butylidenephthalide produced 88 and 92% mortality against B and Q biotype adults, respectively. 3-butylphthalide showed 100 and 89% mortality against B and Q type adults, respectively. Ligustilide exhibited 97 and 100% mortality against B and Q type adults, respectively. The toxicity of these compounds to B type adults was almost equal to that of thiamethoxam and acetamiprid, whereas two insecticides exhibited 40% mortality to Q biotype. C. officinale rhizome-derived materials merit further study as potential insecticides for the control of B. tabaci populations due to global efforts to reduce the level of highly toxic synthetic pesticides.

The toxicity of Cyperus rotundus rhizome steam distillate constituents and their related compounds to adult females and males of the susceptible KS-BG strain and field-collected SR-BG and DR-BG colonies of Blattella germanica (L.) was examined using residual contact + fumigant and vapor-phase mortality bioassays. Results were compared with those of three organophosphorus (chlorpyrifos, dichlorvos, and fenitrothion), three carbamate (bendiocarb, dioxacarb, and propoxur), and three pyrethroid insecticides (bifenthrin, cypermethrin, and deltamethrin). In contact + fumigant mortality bioassay, p-cymene (LC50, 0.33 mg/cm2) was the most toxic terpenoid, followed by o-cymene, m-cymene, β-pinene, 1,8-cineole, and α-pinene, (LC50, 0.44–0.92 mg/cm2) against female B. germanica. These terpenoids were less toxic than the insecticides tested. Females were 3.1–3.6 times more tolerant than males to three cymene compounds. The toxicity of these monoterpenoids were almost identical against females from either of the three strains, even though the SR-BG and DR-BG females exhibited resistance to bifenthrin [resistance ratio (RR), 96 and 17], cypermethrin (RR, 67), deltamethrin (97 and 66), dioxacarb (19 and 22), and propoxur (24 and 32). In vapor-phase mortality bioassay, these monoterpenoids were effective in closed but not in open containers, indicating that the effect of these compounds was largely a result of vapor action. C. rotundus rhizome steam distillate and its constituents merit further study as potential insecticides for the control of insecticide-resistant B. germanica populations as fumigants with contact action.

The toxicity of 10 plant essential oils to adults of acaricide-susceptible, chlorfenapyr-resistant (CRT-53), fenpropathrin-resistant (FRT-53), pyridaben-resistant (PRT-53), and abamectin-resistant (ART-53) strains of Tetranychus urticae Koch and to female Neoseiulus californicus McGregor was examined using spray or vapor-phase mortality bioassays. In bioassay with the susceptible adults, strong toxicity was produced by lemon eucalyptus, peppermint, citronella Java, thyme red, caraway seed, pennyroyal, and clove leaf essential oils (LC50, 0.0193-0.0327 mg/cm3). The toxicity of these essential oils was almost identical against adults from either of the susceptible and resistant strains, even though CRT-53, FRT-53, PRT-53, and ART-53 adults exhibited high levels of resistance to chlorfenapyr [resistanc ratio (RR), >9140], fenpropathrin (RR, 94), pyridaben (RR, >390), and abamectin (RR,85), respectively. Against female N. californicus was 1.0 to 1.9 times more tolerant than T. urticae to the test essential oils. Thus, these essential oils merit further study as potential acaricides for the control of acaricide-resistant T. urticae populations as fumigants because of their lower toxicity to N. californicus.

The toxicity of materials derived from root of Asiasarum heterotropoides against early third instar larvae from susceptible Culex pipiens pallens, Aedes aegypti, and Ochlerotatus togoi was examined using direct contact mortality bioassays. Results were compared with those following the treatment with two currently used mosquito larvicides, temephos and fenthion. The bioactive principles of A. heterotropoides root were identified as asarinin, asarone, methyleugenol, pellitorine, and pentadecane by spectroscopic analysis. As judged by 24 h LC50 values, pellitorine (2.08-2.38 ppm) was the most toxic compound, followed by asarinin (10.49-16.49 ppm) and asarone (22.38-26.99 ppm). These compounds were less toxic than either temephos (0.16-0.20) or fenthion (LC50, 0.23-0.29). Weak activity was produced by methyleugenol (53.30-58.52 ppm) and pentadecane (96.71-99.19 ppm). A. heterotropoides root-derived materials, particularly pellitorine, merit further study as potential mosquito larvicides for protection from humans and domestic animals from vector-borne diseases and nuisance caused by mosquitoes.

The toxicity of melissa and savory essential oil constituents against adult Bemisia tabaci was examined using vapor-phase toxicity bioassay. Results were compared with those following the treatment with currently used insecticide dichlorvos. As judged by 24 h LC50 values, thymol (0.59×10-3 mg/cm3) was the most toxic constituent, followed by cavacrol (0.60×10-3 mg/cm3). These compounds were slightly less toxic than dichlorvos (LC50, 0.20×10-3 mg/cm3). Strong activity was also obtained from borneol (LC50, 1.06×10-3 mg/cm3), α-terpineol (1.22×10-3 mg/cm3), geraniol (1.23×10-3 mg/cm3), linalool (1.33×10-3 mg/cm3), lavendulol (1.44×10-3 mg/cm3), nerol (1.52×10-3 mg/cm3), β-citronellol (1.81×10-3 mg/cm3), terpinene-4-ol (1.87×10-3 mg/cm3), 1-octen-3-ol (2.06×10-3 mg/cm3), and citral (2.34×10-3 mg/cm3). The melissa and savory essential oil-derived compounds, particularly thymol and carvacrol, merit further study as potential insecticides for the control of B. tabaci.

The toxicity of materials derived from dried fruit of Cnidium monnieri against early third instar larvae of Culex pipiens pallens was examined using direct contact mortality bioassay. Results were compared with those of currently used mosquito larvicide, temephos. The bioactive principle was identified as xanthotoxol by spectroscopic analysis. As judged by 24 h LD50 value, xanthotoxol was highly effective (4.40 ppm), although this compound was less toxic than temephos (0.16 ppm). C. monnieri fruit-derived materials, particularly xanthotoxol, merit further study as potential mosquito larvicides for protection from humans and domestic animals from vector-borne diseases and nuisance caused by mosquitoes.

One hundred seven plant essential oils were tested for insecticidal activities against Bemisia tabaci B and Q biotype adults, using the fumigation and direct spray methods. In the fumigation assay with the Q biotype adults, garlic oil was the most toxic (1.5×10-3 μl/cm3) on the basis of the LC50 value. Clove leaf, thyme, oregano (origanum), clove bud, savory, cinnamon bark, dabana, vetiver haiti and catnip essential oils also gave potent toxicity with the range of 1.7 to 4.5×10-3 μl/cm3 of LC50 values. These essential oils showed similar strong toxicity against B biotype. Based on the results obtained from fumigation test, nine plant essential oils were selected for the direct spray application at three concentrations (0.5, 0.1 and 0.02%). A litter difference was obtained between B and Q types in mortality to the tested oils. At the 0.5% concentration, they gave considerable mortality of 76 to 100%. At 0.1%, only garlic essential oil produced 96 to 100% mortality, but the others showed less than 76% mortality. Several plant essential oils appear to be candidates for the control of B. tabaci.

The acetylcholinesterase (AChE) inhibition of 12 plant-derived insecticidal compounds (anethol, anisaldehyde, 3-carene, 1,8-cineol, ethyl-cinnamate, linalool, magnolol, ethyl-p-methoxycinnamate, p-methoxycinamic acid, safrol, terpinen-4-ol, and α-terpineol) towards adult mosquitoes were examined by using Ellman method. Result were compared with those of dichlorvos, a potent AChE inhibitor. 3-Carene strongly inhibited AChE (IC50, 5.78×10-4 M), although the inhibition of the compound was lower than dichlorvos (IC50, 1.45×10-4 M). These results indicate that 3-carene acts as an AChE inhibitor, although an involvement of other insecticidal mechanism(s) might not be ruled out.

The toxicity of Kaempferia galanga rhizome-derived methanol extract (RME), powder (RP) and steam distillate (RSD) to Meloidogyne incognita second-stage juveniles (J2) and eggs and their effects on Lycopersicon esculentum germination and growth were examined in vitro and in pot experiments. Results were compared with those of three nematicides. In contact+fumigant bioassays with J2, RME applied at 1, 0.5 and 0.25mg/g soil exhibited 92, 88, and 73% mortality, respectively. The lethality of RME was almost similar to that of carbofuran but lower than that of either fosthiazate or metam-sodium. RSD and RP were less active than RME. In vapor-phase mortality bioassayswith J2, the test materials were effective in closed container than in open one, indicating that mode of delivery was, in part, a result of vapor action. RME, RSD, and fosthiazate treatments resulted in 91, 100, and 95% inhibition of egg hatch at 250μg/ml and 82, 88, and 81% inhibition of egg hatch at 100μg/ml, respectively. In filter-paper bioassays with L. esculentum seed at 8.8μg/cm2, RME and RP did not cause germination inhibition, while RSD and fosthiazate treatments resulted in 84 and 13% germination inhibition. In pot tests, RME and RSD applied at 8mg/g soil reduced galling caused by M. incognita significantly and fosthiazate at 0.02mg/g soil reduced galling completely. Rhizome materials did not cause any adverse effect on growth of L. esculentum, while fosthiazate application caused significantly reduced root weight. K. galanga rhizome-derived materials, particularly methanol extract, merit further study as potential nematicides and hatching inhibitors for the control of M. incognita populations as fumigants with contact action.