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Hand sanitizers are developed as alcohol-based liquid gel formulations, generally used to decrease the amount of infectious agents on human hands. Verdegen, LLC proposed to prepare an arthropod repellent gel for public use when the recent outbreaks of Zika infection vectored through Aedes mosquitoes in the American continents prompted multi-faceted emergency measures. Four different gel formulations were developed, comprising two of the most efficacious commercial arthropod repellent active ingredients, N,N-diethyl-3-methyl benzamide (deet) and 2-(2-hydroxyethyl)-1-piperidinecarboxylic acid 1-methylpropyl ester (picaridin), each at different concentrations (20 and 33% deet, or 20 and 33% picaridin). Compliance with the use of topical arthropod repellents remains an issue among military personnel. One of the most common complaints by Soldiers is that they do not like how the repellents applied on their skin leave behind an oily or greasy residue. These new gel formulations offer a user-friendly alternative for commonly used arthropod repellents formulations for the military and civilian personnel. We tested the efficacy and protection time of these new gel formulations in comparison with the commercially available cream formulations of deet and picaridin at similar concentrations. Our data show that gel formulations have better topical attributes, and offer equal or better biting protection for up to 48 h against host-seeking Aedes aegypti (L.) (Diptera: Culicidae) female mosquitoes.

A study was conducted to evaluate mosquito repellents against Asian citrus psyllid (ACP), Diaphorina citri Kuwayama (Hemiptera: Liviidae) and to expand our knowledge of the potential of essential plant oils as deterrents of ACP infestations. The psyllid vectors a bacterium, ‘Candidatus Liberibacter asiaticus,’ presumed causal agent of a serious disease of citrus, huanglongbing (also known as citrus greening disease). Twenty-two candidate deterrents were tested as 20% solutions in methanol using a laboratory assay. Adults were free to enter and settle in one of three vials containing orange jasmine flush, one vial treated with a candidate deterrent, one vial treated with water or one treated with methanol. Seven mosquito repellents (CisPMD, DEET, DHS220, Icaridin, IR-3535, S-220, and TransPMD) and four essential oils (citronella, lavender, lemon eucalyptus, and a commercial mixture of oils from orange, clove, cinnamon, eucalyptus and rosemary) reduced ACP infestations on flush in the vials. Following a 24-h assay period, an average of 75% (range 58–88%) fewer psyllids were found in vials treated with these deterrents as compared to the combined number found in the control vials. Greenhouse evaluations were conducted on phytotoxicity of 5 or 25% solutions of eight deterrents and on ACP colonization of citrus seedlings sprayed with these deterrents. Few ACP colonized seedlings sprayed with 25% solutions, but this was attributed to phytotoxicity. Infestations were reduced on seedlings treated with 5% solutions, but these reductions also were largely attributed to phytotoxicity. Although unsprayed seedlings were in close proximity, adults found these plants and laid relatively large numbers of eggs. While some of the mosquito repellents and essential plant oils deterred infestations, none was completely effective and 5–25% solutions were too phytotoxic to be feasible as direct plant sprays. These results indicated the deterrents as tested hold little potential as a major tactic for reducing ACP infestations in citrus. Alternative application approaches to avoid phytotoxicity could be explored, and individual constituents of the more promising essential plant oils could be investigated.

Cat thyme is an important medicinal plant used for treating many diseases. With renewed interest as arthropod deterrent and repellents, there is immediate need to cultivate cat thyme on large scale in the laboratory. To improve cat thyme seed germination, obstacles involved in its seed dormancy must be investigated. To address such challenges, mechanical abrasion and chemical treatments were used to enhance the rate of seed germination. The application of mechanical abrasion with low speed grinding using walnut husk to improve the germination of cat thyme seeds was studied. In addition, to improve the seed germination percentage, the seeds were further treated with different concentrations of hydrogen peroxide (2.5, 5, 10 and 15%). The results show that the treatment of 5% hydrogen peroxide concentration promoted the seed germination rate. After the aforementioned different treatments, Baggy method was used and it achieved 50% germination rate within 30 days. In conclusion, the germination tests showed that cat thyme seed germination improved with combination of mechanical abrasion and 5% hydrogen peroxide treatments. Key words: Cat thyme, seed germination percentage, hydrogen peroxide.

The invasive Argentine ant (Linepithema humile) has become established worldwide in regions with Mediterranean or subtropical climates. The species typically disrupts the balance of natural ecosystems by competitively displacing some native ant species via strong exploitation and interference competition. Here we report that Argentine ants utilize glandular secretions for inter and intra-specific communications during aggressive interactions with a heterospecific competitor, California harvester ant (Pogonomyrmex californicus). Chemical analyses indicated that Argentine ants deploy glandular secretions containing two major volatile iridoids, dolichodial and iridomyrmecin, on the competitor’s cuticular surface during aggressive interactions. Bioassays indicated that the glandular secretions function as a defensive allomone, causing high levels of irritation in the heterospecific. Furthermore, the same glandular secretions elicited alarm and attraction of conspecific nestmates, potentially enabling more rapid/coordinated defense by the Argentine ants. Two major volatile constituents of the glandular secretion, dolichodial and iridomyrmecin, were sufficient to elicit these responses in conspecifics (as a mixture or individual compounds). The current study suggests that invasive Argentine ants’ superior exploitation and interference competition may rely on the species’ effective semiochemical parsimony.

Chemical investigation of the fungal strain Gymnoascus reessii za-130, which was previously isolated from the rhizosphere of tomato plants infected by the root-knot nematode Meloidogyne incognita, led to the isolation and identification of a new indoloditerpenoid metabolite designated gymnoascole acetate. Its structure was established by spectroscopic methods including 1D- and 2D-NMR and MS analyses. Gymnoascole acetate demonstrated strong adverse effects on M. incognita second-stage juvenile (J2) viability; exposure to 36 μg/mL for 24 h induced 100% paralysis of J2 (EC50 = 47.5 μg/mL). Gymnoascole acetate suppressed M. incognita egg hatch relative to controls by >90% at 133 μg/mL after 7 days of exposure. The numbers of root galls and J2 in both soil and roots were significantly reduced (p = 0.05) by treatment with 2–200 μg/mL gymnoascole acetate/kg soil, compared to untreated control plants; nematode suppression increased with gymnoascole acetate concentration. This study demonstrated the nematotoxicity...

Invasive species have major impacts on biodiversity and are one of the primary causes of amphibian decline and extinction. Unlike other top ant invaders that negatively affect larger fauna via chemical defensive compounds, the Argentine ant (Linepithema humile) does not have a functional sting. Nonetheless, it deploys defensive compounds against competitors and adversaries. We estimated levels of ant aggression toward 3 native terrestrial amphibians by challenging juveniles in field ant trails and in lab ant foraging arenas. We measured the composition and quantities of toxin in L. humile by analyzing pygidial glands and whole-body contents. We examined the mechanisms of toxicity in juvenile amphibians by quantifying the toxin in amphibian tissues, searching for histological damages, and calculating toxic doses for each amphibian species. To determine the potential scope of the threat to amphibians, we used global databases to estimate the number, ranges, and conservation status of terrestrial amphibian species with ranges that overlap those of L. humile. Juvenile amphibians co-occurring spatially and temporally with L. humile die when they encounter L. humile on an ant trail. In the lab, when a juvenile amphibian came in contact with L. humile the ants reacted quickly to spray pygidial-gland venom onto the juveniles. Iridomyrmecin was the toxic compound in the spray. Following absorption, it accumulated in brain, kidney, and liver tissue. Toxic dose for amphibian was species dependent. Worldwide, an estimated 817 terrestrial amphibian species overlap in range with L. humile, and 6.2% of them are classified as threatened. Our findings highlight the high potential of L. humile venom to negatively affect amphibian juveniles and provide a basis for exploring the largely overlooked impacts this ant has in its wide invasive range.Efectos del Veneno de la Hormiga Argentina sobre los Anfibios Terrestres Resumen Las especies invasoras tienen un impacto importante sobre la biodiversidad y son una de las causas principales del declive y extinción de los anfibios. A diferencia de otras hormigas super-invasoras que afectan negativamente a animales más grandes por medio de compuestos químicos de defensa, la hormiga argentina (Linepithema humile) no tiene unaguijón funcional. Sin embargo, esta hormiga despliega compuestos defensivos contra sus competidores y adversarios. Estimamos los niveles de agresión de las hormigas hacia tres anfibios terrestres nativos exponiendo a los anfibios juveniles en pistas de hormigas en el campo y en las arenas de forrajeo de las hormigas en el laboratorio. Medimos la composición y las cantidades de toxina que presenta L. humile por medio del análisis de las glándulas pigidiales y el contenido en el cuerpo completo. Examinamos los mecanismos de la toxicidad en los anfibios juveniles cuantificando la toxina en el tejido del anfibio, buscando daños histológicos y calculando las dosis tóxicas para cada especie de anfibio. Para determinar el alcance potencial de la amenaza para los anfibios usamos bases de datos mundiales para estimar el número, distribución y estado de conservación de las especies terrestres de anfibios con distribuciones que se solapan con la de L. humile. Los anfibios juveniles que co-ocurren temporal y espacialmente con L. humile mueren al encontrarse con esta especie de hormiga en sus pistas. En el laboratorio, cuando un anfibio juvenil entró en contacto con L. humile, las hormigas reaccionaron rápidamente rociando a estos juveniles con veneno proveniente de las glándulas pigidiales. La iridomyrmecina fue el compuesto tóxico que encontramos en las glándulas pigidiales. Después de ser absorbida por la piel del anfibio, se acumuló en el cerebro, los riñones y el hígado. La dosis tóxica para los anfibios depende de la especie. A nivel mundial, se estima que 817 especies de anfibios terrestres tienen una distribución que se solapa con la de L. humile, y el 6.2% de estas especies se encuentran clasificadas como amenazadas. Nuestros hallazgos resaltan el potencial alto del veneno de L. humile para tener efectos negativos sobre los anfibios juveniles y también proporcionan una base para la exploración de los impactos de esta hormiga en su amplio rango invasivo, los cuales generalmente son ignorados.生物入侵对生物多样性有着重要影响, 同时也是导致两栖动物数量减少和灭绝的主要原因之一。不同于其它通过化学防御物质对大型动物产生负面影响的入侵蚁类, 阿根廷蚁 (Linepithema humile) 不具备功能性的刺, 但它还是可以利用防御化合物来对付竞争者和攻击者。我们通过在野外蚁道和实验室的蚂蚁觅食场所观察蚂蚁如何挑战三种本土陆生两栖动物的幼体, 估计了蚂蚁的攻击性强度。通过分析阿根廷蚁臀板腺体和全身的物质组成, 我们测定了其毒素的成分和含量。通过定量两栖动物幼体组织中的毒素, 寻找组织损伤, 并计算毒素对每种两栖动物的毒性剂量, 我们分析了蚂蚁毒素对两栖动物幼体的毒性机制。接下来, 为了确定两栖动物面临潜在威胁的范围, 我们利用全球数据库分析了与阿根廷蚁分布范围重合的陆生两栖动物的数量、范围和濒危情况。在野外, 与阿根廷蚁时空上共存的两栖动物幼体在蚁道上遇到阿根廷蚂蚁时会发生死亡。在实验室中, 当两栖动物幼体接触到阿根廷蚁时, 蚂蚁会迅速做出反应, 向其喷射臀板腺体毒液。喷射液体中的有毒化合物为阿根廷虹臭蚁素, 动物吸收后会在脑、肾和肝组织中积累, 毒素对两栖动物的毒性剂量取决于物种。在世界范围内, 估计有 817 种陆生两栖动物的分布区与阿根廷蚁分布区重叠, 其中有 6.2% 为濒危物种。本研究的发现强调了阿根廷蚁的毒液对两栖动物幼体潜在的巨大负面影响, 并为探索阿根廷蚁在其广大的入侵范围内尚未得到重视的影响提供了基础。【翻译: 胡怡思; 审校: 聂永刚】 阿根廷蚁毒液对陆生两栖动物的影响.

Thymol, the key component of the thyme oil and its derivatives were evaluated for their structure activity relationship as fungicide against Rhizoctonia solani. Since plant-based chemicals are considered as “Generally Recognized as Safe” (GRAS) chemicals, there is great potential to use those and synthetic derivatives against R. solani and other fungal pathogens, in vitro, and in the greenhouse or field conditions. Among the six thymol derivatives evaluated, thymol acetate was considered as the most suitable commercially viable plant-based fungicide due to its superior efficacy as well as lowest residue.

Southern rootworm (Diabrotica undecimpunctata howardi) affects several plants such as soybean, sorghum, wheat, cucumber, alfalfa, cucurbits and it is most damaging to corn and peanuts. The pheromone based “attract and kill” strategy is one of the powerful ways to control pest population. To address our key objective of the practical utility of the synthetic pheromone, we have developed a simple synthetic strategy to produce gram scale southern corn rootworm pheromone in nine simple steps starting from S-Citronellol. The present strategy takes advantage of the existing chiral center of commercially available S-Citronellol. To get the basic carbon skeleton of the pheromone, the main step in the synthetic strategy is coupling of aliphatic units through Wittig reaction. The phosphonium salt from a non-functionalized aliphatic bromide followed by Wittig reaction improved the overall yield in the multistep synthesis of this pheromone. The large-scale production of pheromone enabled us to test it in the field.

Significance Surveillance of mosquito populations is essential for determining the best timing for intervention as well as for monitoring circulation of new and previously detected pathogens. Trapping gravid females is more effective because they are more likely to be infected than nongravid females. However, better gravid trap attractants are sorely needed to replace fermentation recipes, which are cumbersome, have poor quality control, generate an offensive smell, and do not provide a long-term and consistent source of attractants. By using a reverse chemical ecology approach based on odorant receptors from the southern house mosquito, we have identified that acetaldehyde in a wide range of doses both attracts gravid female mosquitoes and stimulates them to lay eggs in oviposition trays., Pheromones and other semiochemicals play a crucial role in today’s integrated pest and vector management strategies. These semiochemicals are typically discovered by bioassay-guided approaches. Here, we applied a reverse chemical ecology approach; that is, we used olfactory proteins to lead us to putative semiochemicals. Specifically, we used 7 of the top 10 odorant receptors (ORs) most expressed in the antennae of the southern house mosquito, Culex quinquefasciatus, and which are yet to be deorphanized. We expressed these receptors in the Xenopus oocyte recording system and challenged them with a panel of 230 odorants, including physiologically and behaviorally active compounds. Six of the ORs were silent either because they are not functional or a key odorant was missing. CquiOR36, which showed the highest transcript levels of all OR genes in female antennae, was also silent to all odorants in the tested panel, but yielded robust responses when it was accidentally challenged with an old sample of nonanal in ethanol. After confirming that fresh samples were inactive and through a careful investigation of all possible “contaminants” in the old nonanal samples, we identified the active ligand as acetaldehyde. That acetaldehyde is activating CquiOR36 was further confirmed by electroantennogram recordings from antennae of fruit flies engineered to carry CquiOR36. Antennae of female mosquitoes also responded to acetaldehyde. Cage oviposition and dual-choice assays demonstrated that acetaldehyde is an oviposition attractant in a wide range of concentrations and thus of potential practical applications.

The development of resistance by mosquitoes to current synthetic compounds has resulted in reduced effectiveness of prevention and control methods worldwide. An alternative nonchemical based control tools are needed to be evaluated particularly plant-derived essential oils. Several components of vetiver oil have been documented as insect repellents. However, detailed knowledge of those components action against insect remains unknown. In this study, behavioral response of Anopheles minimus to four constituents of vetiver oil (valencene, terpinen-4-ol, isolongifolene, vetiverol) was evaluated by using the high-throughput screening assay system. Vetiverol and isolongifolene exhibited strong contact irritancy action at 1.0% (80.2% escaping) and 5.0% (81.7% escaping) concentration, respectively, while moderate action was found in both valencene and terpinen-4-ol at 5.0% (57.6% escaping). Only at 1.0% (0.7 spatial activity index [SAI]) and 5.0% (1.0 SAI) of valencene and 0.5% (0.7 SAI) of isolongifolene showed spatial repellency activity. High mortality (58.9-98.2%) was recorded in all concentration of vetiverol and isolongifolene. Meanwhile, valencene exhibited high mortality only at 5.0%, terpinen-4-ol showed very low toxic action (0-4.3%) in all concentration. These proved that valencene in vetiver oil is the promising constituent that can be developed as an alternative mosquito control mean in efforts to prevent disease transmission.

Preparation of a complete stereoisomeric library of 1,10-bisaboladien-3-ols and selected 10,11-epoxy-1-bisabolen-3-ols was pivotal for the identification of the aggregation pheromone of the brown marmorated stink bug, Halyomorpha halys. Herein, we describe syntheses of the remaining 10,11-epoxy-1-bisabolen-3-ols, and provide additional evidence on the assignment of relative and absolute configurations of these compounds by single-crystal X-ray crystallography of an intermediate, (3S,6R,7R,10S)-1-bisabolen-3,10,11-triol. To demonstrate the utility of this stereoisomeric library, we revisited the aggregation pheromone of the harlequin bug, Murgantia histrionica, and showed that the male-produced pheromone consists of two stereoisomers of 10,11-epoxy-1-bisabolen-3-ol. Employment of eight cis-10,11-epoxy-1-bisabolen-3-ol stereoisomeric standards, two enantioselective GC columns, and NMR spectroscopy enabled the identification of these compounds as (3S,6S,7R,10S)-10,11-epoxy-1-bisabolen-3-ol and (3S,6S,7R,10R)-10,11-epoxy-1-bisabolen-3-ol, which are produced by M. histrionica males in 1.4:1 ratio.

Wheel bugs (Heteroptera: Reduviidae: Harpactorinae: Arilus) are general predators, the females of which have reddish-orange subrectal glands (SGs) that are eversible like the osmeteria in some caterpillars. The rancid odor of Arilus and other reduviids actually comes from Brindley's glands, which in the North (A. cristatus) and South (A. carinatus) American wheel bugs studied emit similar blends of 2-methylpropanoic, butanoic, 3-methylbutanoic, and 2-methylbutanoic acids. The Arilus SG secretions studied here are absolutely species specific. The volatile SG components of A. carinatus include (E)-2-octenal, (E)-2-nonenal, (E)-2-decenal, (E,E)-2,4-nonadienal, (E)-2-undecenal, hexanoic acid, 4-oxo-nonanal, (E,E)-2,4-decadienal, (E,Z)-2,4- or (Z,E)-2,4-decadienal, and 4-oxo-(E)-2-nonenal; whereas in A. cristatus the SG secretion contains β-pinene, limonene, terpinolene, terpinen-4-ol, thymol methyl ether, α-terpineol, bornyl acetate, methyl eugenol, β-caryophyllene, caryophyllene oxide, and farnesol. Arilus spp. SG secretions may be sex pheromones, but verification of this hypothesis requires further testing.

A field bioassay evaluating candidate chemicals as aerial repellents was developed and evaluated against natural mosquito populations in Beltsville, MD. The bioassay consisted of an attractive source surrounded by a grid of 16 septa containing a volatile candidate aerial repellent, compared with an attractive source without such a grid. The attractive source was a Centers for Disease Control and Prevention light trap supplemented with carbon dioxide. Significant sources of variation included weather, position, and the differential response of mosquito species. Despite these sources of variation, significant repellent responses were obtained for catnip oil, E,Z-dihydronepetalactone, and DEET.

Dried male inflorescences of breadfruit ( Artocarpus altilis , Moraceae) are burned in communities throughout Oceania to repel flying insects, including mosquitoes. This study was conducted to identify chemicals responsible for mosquito deterrence. Various crude extracts were evaluated, and the most active, the hydrodistillate, was used for bioassay-guided fractionation. The hydrodistillate and all fractions displayed significant deterrent activity. Exploratory GC-MS analysis revealed more than 100 distinctive peaks, and more than 30 compounds were putatively identified, including a mixture of terpenes, aldehydes, fatty acids, and aromatics. A systematic bioassay-directed study using adult Aedes aegypti females identified capric, undecanoic, and lauric acid as primary deterrent constituents. A synthetic mixture of fatty acids present in the most active fraction and individual fatty acids were all significantly more active than N,N-diethyl-m-toluamide (DEET). These results provide support for this traditional practice and indicate the potential of male breadfruit flowers and fatty acids as mosquito repellents.

Several lines of evidence suggest that insect repellent molecules reduce mosquito-host contacts by interacting with odorants and odorant receptors (ORs), thereby ultimately affecting olfactory-driven behaviours. We describe the molecular effects of 10 insect repellents and a pyrethroid insecticide with known repellent activity on two highly specific Aedes aegypti (Diptera: Culicidae) ORs, AaOR2 + AaOR7 and AaOR8 + AaOR7, exquisitely sensitive to key mosquito attractants indole and (R)-(-)-1-octen-3-ol, expressed in oocytes of Xenopus (Anura: Pipidae). Our study demonstrates that insect repellents can both inhibit odorant-evoked currents mediated by ORs and independently elicit currents in the absence of odorants. All of the repellents had effects on one or both ORs; most of these compounds were selective inhibitors and showed a high degree of specificity in their capacity to activate the two ORs. These results show that a range of insect repellents belonging to structurally diverse chemical classes modulate the function of mosquito ORs through multiple molecular mechanisms.

4S,4aS,7S,7aR; 4R,4aS,7S,7aR; 4S,4aS,7S,7aS, and 4R,4aS,7S,7aS diastereomers of iridomyrmecin have been prepared in 5 steps from 4aS,7S,7aR and 4aS,7S,7aS-nepetalactones, major components of catnip oil. 4S,4aS,7S,7aR and 4R,4aS,7S,7aR-iridomyrmecin have been identified as defensive compounds from Iridomyrmex ants.

Vetiver, a nonhost grass for certain nematodes, was studied for the production of compounds active against the southern root-knot nematode, Meloidogyne incognita. In laboratory assays studying the effects on second-stage juvenile (J2) activity and viability, crude vetiver root and shoot extracts were nematotoxic, resulting in 40% to 70% J2 mortality, and were also repellent to J2. Vetiver oil did not exhibit activity against J2 in these assays. Gas chromatography-mass spectrometry analyses of three crude vetiver root ethanol extracts and a commercial vetiver oil determined that two of the major components in each sample were the sesquiterpene acid 3,3,8,8-tetramethyltricyclo[5.1.0.0(2,4)]oct-5-ene-5-propanoic acid and the sesquiterpene alcohol 6-isopropenyl-4,8a-dimethyl-1,2,3,5,6,7,8,8a-octahydronaphthalen-2-ol. The acid was present in higher amounts in the extracts than in the oil. These studies demonstrating nematotoxicity and repellency of vetiver-derived compounds to M. incognita suggest that plant chemistry plays a role in the nonhost status of vetiver to root-knot nematodes, and that the chemical constituents of vetiver may be useful for suppressing nematode populations in the soil.

A previously described modular high-throughput screening system was used to characterize the spatial repellent, contact irritant, and toxicant chemical actions of 14 compounds historically used or under investigation for vector control. The response of F1-F4 Aedes aegypti (Thailand strain) to various concentrations of 4 organochlorines (chlordane, DDT, dieldrin, methoxychlor); 4 pyrethroids (alphacypermethrin, cypermethrin, deltamethrin, permethrin); 3 organophosphates (chlorpyrophos methyl, fenitrothion, malathion); 2 carbamates (bendiocarb, propoxur); and 1 pyrazole (chlorfenapyr) were evaluated. Results show chemicals exert different combinations of contact irritant, spatial repellent, and toxic actions. This is true even within the same chemical class. These actions can be ordered for each chemical based on the testing dose at which the specific response is elicited. Data also indicate that behavioral responses to spatial repellent and contact irritant actions are separate (or independent) from the toxic action of a compound. Results from pyrethroid and DDT assays also show chemicals can induce behavior-modifying actions, such as contact irritancy and spatial repellency, which will reduce man-vector contact, despite evidence of insecticide resistance within the test population. These findings support previous laboratory and field studies showing man-vector contact and disease transmission are routinely interrupted by spatial repellent and contact irritant actions of common public health insecticides. Studies similar to that presented here can be used as baseline evidence for expected vector responses and support best approaches for more detailed behavioral research.

Gas chromatographic-electroantennographic detection (GC-EAD) analysis showed that male antennae of the green lacewing, Chrysopa nigricornis Burmeister, the most common lacewing species in the U.S. Pacific Northwest, consistently responded to two compounds in thoracic extracts of conspecific males: 1-tridecene and (1R,2S,5R,8R)-iridodial. These compounds were not detected in extracts of the abdominal cuticle, and no other antennally active compounds were found in the abdominal samples. In field-trapping experiments, traps baited with iridodial significantly attracted large numbers of C. nigricornis males (both western and eastern forms) during summer and early fall, plus a few individuals of conspecific females only in early fall. Iridodial also attracted males of the goldeneyed lacewing, C. oculata Say, and, to a lesser extent, C. coloradensis Banks males. Methyl salicylate (MS), reported as an attractant for both sexes of C. nigricornis and C. oculata, was inactive by itself at the concentration tested in our study, but in a few instances slightly enhanced the responses of Chrysopa spp. to iridodial. However, MS alone and its binary blend with iridodial seemed to attract the hoverfly, Metasyrphus americanus (Weidemann). 2-Phenylethanol, a reported attractant for another lacewing, Chrysoperla plorabunda (Fitch) [=carnea (Say)], did not capture any lacewings. Our assays indicated that the lacewing pheromone, iridodial, loaded onto either rubber septa or as a binary blend with MS in polyethylene bags could last at least 5 wk in the field during the summer season. Based on this study, a new attractant system for green lacewings is being developed for both domestic and international markets.

A modular and novel assay system for rapid mass screening of chemical compounds for contact irritant and spatial repellent actions against adult mosquitoes is described. The responses of Aedes aegypti to various concentrations of 3 topical repellents, deet, Bayrepel, and SS220, were evaluated. At treatment concentrations > or = 25 nmol/cm2 of SS220, mosquitoes exhibited significant contact irritant (escape) and spatial repellent (movement away from the chemical source) responses, whereas, a 10-fold increase in the treatment concentration of deet and Bayrepel was required to produce similar responses. The novel bioassay system detected contact irritancy and spatial repellency activity with reproducible results and provided baseline data for determining minimum effective concentrations for other chemicals. The system is compact in size, easy to decontaminate, and requires only a minute quantity of chemical compound.

Recently, catnip, Nepeta cataria L. (Lamiaceae), essential oil has been formulated and marketed as an alternative repellent for protection against biting arthropods by several vendors. We isolated the major active components of catnip oil, E,Z- and Z,E-nepetalactone, and quantitatively measured their antibiting efficacy compared with the repellents N,N-diethyl-3-methylbenzamide (deet) and chiral (1S,2′S)-2-methylpiperidinyl-3-cyclohexene-1-carboxamide (SS220) against the yellowfever mosquito, Aedes aegypti (L.), by using an in vitro assay and human volunteers at 24 nmol compound/cm2 (cloth or skin). Of all compounds tested in an in vitro assay, SS220 ranked as the most effective, whereas catnip oil and the nepetalactone compounds did not differ significantly from each other or from deet. However, in human volunteer bioassays, neither E,Z and Z,E-nepetalactone nor racemic nepetalactone deterred mosquito biting as effectively as SS220 or deet. All compounds differed significantly from the control. ...

Four diastereomers of the insecticide iridomyrmecin are prepared in five steps from naturally occurring nepetalactones, which are isolated from catnip oil.

ortho-Substituted polychlorinated biphenyls (PCBs) make up a large part of the PCB residue found in the environment and human tissues. Our laboratory as well as others have demonstrated that ortho-substituted congeners exhibit important biological activities by aryl hydrocarbon (Ah) receptor-independent mechanisms, including changes in second messenger systems necessary for normal cell function and growth. Previous structure-activity relationship (SAR) studies on second messengers and transthyretin (TTR; prealbumin) binding focused little attention on the ortho-substituted PCBs. Disruption of thyroid hormone (TH) transport is one potentially important mechanism by which PCBs can alter TH homeostasis. A more systematic study of PCB binding to TTR, a major TH transport protein, was undertaken, in which the role of ortho-substitution was more thoroughly investigated. Results from this study indicated that the ortho-only substituted series showed significant binding activity and the relative affinities were 2,2′,6 > 2,2′ = 2,6 ⪢ 2 = 2,2′,6,6′. As anticipated on the basis of steric considerations, bromine was shown to be more active as an ortho-substituent where the relative affinity of 2,2′-Br was equivalent to 2,2′,6-Cl. The congener patterns (di-meta-substitution in one or both rings) most closely resembling the diiodophenolic ring of thyroxine (T4) showed the highest binding activity. Multiple ortho-substituents were shown to decrease binding activity in such patterns. Congener patterns (single meta-substitution in one or both rings) more closely resembling the monoiodophenolic ring of T3 showed significantly lower binding activity, consistent with the relatively low binding activity of T3 and smaller size of chlorine compared to iodine. The addition of ortho-substitution to such patterns gave variable results depending on the substituent relationship (adjacency or nonadjacency) to the pattern. Some patterns such as 2,2′,4,4′,5,5′ showed good binding activity and represent common congeners in the commercial Aroclor mixtures and in the environment. The binding potencies of ortho-PCBs to TTR may represent a signature SAR that predicts specific biologic/toxic effects. In this regard, the binding potencies were consistent with measured biological activities of these PCBs, including effects on cell dopamine content, Ca2+ homeostasis, and protein kinase C translocation in neuronal cells and brain homogenate preparations.

Biphenyl 4 and vinyldibromide 8 were prepared on a multigram scale and shown to be comparatively specific arachidonic acid epoxygenase and ω-hydroxylase inhibitors, respectively, in rat kidney microsomal fractions.

Delayed-type hypersensitivity (DTH) reactions are initiated by sensitized T cells. Their progression is dependent upon the local release of various autacoids, including cytokines and eicosanoids, by T cells, infiltrating inflammatory cells, and resident tissue cells. 12(R)-hydroxy-5,8,14-eicosatrienoic acid [12(R)-HETrE], an cicosanoid produced by skin and cornea, possesses potent proinflammatory properties at picomolar concentrations including vasodilation, increase in membrane permeability, neutrophil chemotaxis, and angiogenesis. Because DTH reactions are associated with many of these same phenomena, we examined the effect of 12(R)-HETrE and related 12-hydroxyeicosanoids on the expression of DTH to purified protein derivative of tuberculin in sensitized guinea pigs. In the absence of purified protein derivative of tuberculin, none of the eicosanoids evoked erythema or edema after intradermal injection at doses up to 100 pmol. When injected together with purified protein derivative of tuberculin, 12(R)-hydroxy-5,8,10,14-eicosatetraenoic acid [12(R)-HETE], but not its enantiomer 12(S)-HETE, significantly inhibited macroscopic expression of delayed reactivity (erythema) only at the highest dose tested, 10 pmol. In contrast, 12(R)-HETrE significantly enhanced expression of DTH at doses between 1 fmol and 1 pmol (50% and 30% increases above control, respectively). Its stereoisomer, 12(S)-HETrE, did not enhance DTH at any tested dose, but was able to block the activity of 12 (R)-HETrE when injected simultaneously. Enhancement or inhibition of visible skin responses was not associated with qualitative or quantitative changes in cellular infiltrates at the reaction site. 12(R)-HETrE had no effect on the nonimmunologic inflammatory skin reaction induced by phorbol myristate acetate, suggesting selectivity toward DTH. We conclude that 12(R)-HETrE enhances DTH via a yet to be determined mechanism and that its stereo-isomer, 12(S)-HETrE, may be a useful antagonist for studying the inflammatory actions of this eicosanoid.

A differentiated, six-carbon vicinal -diol chiron was prepared from D -glucurono-6,3-lactone and exploited in the asymmetric synthesis of the erythro/threo -isomers of the title eicosanoids.

The type IIB eicosanoids, 12(R),20- and 12(S),20-dihydroxyeicosatetraenoic acid (DiHETE), were conveniently synthesized utilizing a carbohydrate-derived bis-lactol as a differentiated 4-hydroxyhex-2(E)-enedial chiron. 12(S),20-DiHETE, but not the 12(R)-isomer, induced vasodilation in precontracted canine arteries.

3(S)-Hydroxy-Leukotriene B 4 ( 1a ), its 3(R)-epimer 1b , and a 14,15-acetylenic analogue were efficiently prepared via chelation-controlled reduction of ketone 12 , obtained by acetylide addition to chiral β-hydroxylactones 7/9 .

3(S)-Hydroxy-Leukotriene B 4 ( 1a ), its 3(R)-epimer 1b , and a 14,15-acetylenic analogue were efficiently prepared via chelation-controlled reduction of ketone 12 , obtained by acetylide addition to chiral β-hydroxylactones 7/9 .

The type IIB eicosanoids, 12(R),20- and 12(S),20-dihydroxyeicosatetraenoic acid (DiHETE), were conveniently synthesized utilizing a carbohydrate-derived bis-lactol as a differentiated 4-hydroxyhex-2(E)-enedial chiron. 12(S),20-DiHETE, but not the 12(R)-isomer, induced vasodilation in precontracted canine arteries.

A differentiated, six-carbon vicinal -diol chiron was prepared from D -glucurono-6,3-lactone and exploited in the asymmetric synthesis of the erythro/threo -isomers of the title eicosanoids.

20-hydroxyeicosatetraenoic acid, a major renal P-450 metabolite of arachidonic acid, has been quantified in human urine using capillary gas chromatography/electron capture negative ion chemical ionization mass spectrometry. The urinary excretion of 20-hydroxyeicosatetraenoic acid was in the low pg/ml range. However, treatment of urine with beta-glucuronidase resulted in a 13- to 28-fold increase in its concentration. This suggests 20-hydroxyeicosatetraenoic acid differs from other eicosanoids in that it is excreted primarily as a glucuronide conjugate.

Davanone, a key sesquiterpene component of davana oil, has been synthesized in five convenient steps. Oxygenated sesquiterpenes have been linked to insect deterrent properties. Based on initial screening of davana oil, davanone and its hydroxy precursors have been generated and are being evaluated as arthropod deterrents against disease vectors.

The lacewing Chrysopa septempunctata Wesmael is an important, common predator of several insects in China, Japan, Russia, and many parts of Europe. Our field trapping experiments in northeast China showed that males of this green lacewing are strongly attracted to the lacewing pheromone of Chrysopa oculata Say, (1R,2S,5R,8R)-iridodial. The induced plant volatile, methyl salicylate, was unattractive to C. septempunctata by itself at the concentration tested, but synergistic when combined with iridodial where the lacewing population was high. (1R,4aS,7S,7aR)-Nepetalactol and (4aS,7S,7aR)-nepetalactone (aphid sex pheromone components) caught significantly more males of C. septempunctata than did blank control traps, but were inferior to iridodial dispensers, which remained strongly attractive to C. septempunctata males for at least 2.5 months. These results indicate that (1R,2S,5R,8R)-iridodial is a powerful attractant for C. septempunctata, and may have great potential for enhanced biological control of garden, agricultural, and forest insect pests.

Gas chromatographic-electroantennographic detection (GC-EAD) experiments showed that antennae of males and females of the goldeneyed lacewing, Chrysopa oculata Say (Co. = Chrysopa), consistently responded to four compounds extracted from the abdominal cuticle of males: nonanal, nonanol, nonanoic acid, and (1R*,2S*,5R*,8R*)-iridodial. These compounds were not detected from abdominal cuticle of females. Thoracic extracts of both sexes contained antennal-stimulatory 1-tridecene and EAD-inactive skatole. Chrysopa oculata adults were most sensitive to (1R,2S,5R,8R)-iridodial standard at an EAD-response threshold between 0.1 and 1 pg, which was 10–100 times lower than thresholds for nonanal and nonanoic acid, and up to 10,000 times lower than thresholds for other compounds tested. A similar EAD response pattern was also found in another Chrysopa sp. (Co. quadripunctata Burmeister). In field-trapping experiments, (1R,2S,5R,8R)-iridodial was the only male-specific compound that attracted Co. oculata males. Males also were weakly attracted to (1R,4aS,7S,7aR)-nepetalactol (an aphid sex pheromone component), probably due to the 5% (1R,2S,5R,8R)-iridodial present in the synthetic sample as an impurity. A herbivore-induced plant volatile, methyl salicylate, increased attraction of males to (1R,2S,5R,8R)-iridodial, whereas 1-tridecene was antagonistic. No females were caught in the entire study. Scanning electron micrographs revealed numerous male-specific, elliptical epidermal glands on the 3rd–8th abdominal sternites of Co. oculata, which are likely the pheromone glands. Another lacewing species, Chrysoperla rufilabris (Burmeister) (Cl. = Chrysoperla), did not produce male-specific volatiles or possess the type of gland presumed to produce pheromone in Co. oculata males, but (Z)-4-tridecene was identified as a major antennal-stimulatory compound from thoracic extracts of both sexes of Cl. rufilabris. Thus, (1R,2S,5R,8R)-iridodial (or its enantiomer) is now identified as a male-produced male aggregation pheromone for Co. oculata, the first pheromone identified for lacewings.

A three-step synthesis of enantiomerically pure ( R) and ( S)- trans nerolidol from commercially available E, E-fanesol is described. Trans nerolidol is an abundant sesquiterpene in many plant species, almost enantiomerically pure; however, the configuration of chirality is S. There is no natural resource for R-trans nerolidol, which has recently been identified as a pheromone component of the fruit spotting bug Amblypelta lutescens. The simple syntheses reported here will make enantiomerically pure R- and S-trans nerolidol and homologues available for further research and ultimately for use in integrated pest management strategies comprising pheromones.

The recent identification of a male-produced aggregation pheromone [( S )-3,7-dimethyl-2-oxo-6-octene-1,3-diol, ( S )-CPB] offers a new tool for Colorado potato beetle (CPB) management. We developed a novel synthetic approach to produce CPB pheromone in seven steps and 46.54% overall yield. Grignard reaction, oxidation, and stereoselective methylation using organometallic reagent are the key steps in the commercially viable total synthesis, generating CPB pheromone in 98.6% enantiomeric purity and gram quantity.

1R,2S,5R,8R; 1R,2S,5R,8S; 1S,2S,5R,8R; and 1S,2S,5R,8S-Iridodials have been prepared in five steps from 4aS,7S,7aR and 4aS,7S,7aS-nepetalactones, major components of catnip oil. 1R,2S,5R,8R-Iridodial has been identified as a male-produced male-aggregation pheromone for Chrysopa oculata, the first pheromone of any kind identified for lacewings.

Leukotriene B 4 (LTB4), a product of arachidonic acid metabolism by the 5-1ipoxygenase pathway, is a potent granulocyte activator proposed as an important mediator A. of inflammatory and immune responses. Catabolic processes inactivate LTB4, however, low levels of ethanol (2-10mM) interfere with normal B-oxidation of LTB4 ~ o.2oby hepatocytes resulting in the accumulation of a novel =~ metabolite, 3(S)-hydroxy-LTB 4 [3(S)-OH-LTB4] [1, 2]. This metabolite may well be the long-sought, ethanol-inducible ~ 0.15 chemotactic agent responsible for the recruitment of neutrophils into liver parenchyma and the subsequent ~ 0.10 tissue damage therein [3]. We assessed the ability of 3(S)OH-LTB4 to recruit granulocytes into the guinea pig skin by the dermal content of the neutrophil marker enzyme, ~ 0.0s myeloperoxidase (MPO), and by histology. SC-53228 {(+ )(S)-7-[3-[2-(cyclopropylmethyl)-3-methoxy-4 [(methylami.= no)carbonyl] phenoxy[proproxy]-3,4-dihydro-8-propyl~ o.oo 2H-l-benzopyran-2-propanoic acid} is a potent, orally active, second generation LTB~ receptor antagonist and B. we investigated its ability to antagonize the chemotactic activity of 3(S)-OH-LTB4 [4, 5].

The title autacoids and acetylenic analogs were conveniently prepared from 2-deoxy- D -ribose via Barton deoxygenation, cuprate coupling, and Wittig homologation. 12(R)-HETrE, but not the 12(S)-isomer, significantly stimulated microvessel endothelial cell proliferation and proto-oncogene mRNA levels at sub-nano to picomolar concentrations. A high affinity binding site for 12(R)-HETrE was detected on microvessle endothelial cells.