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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.

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.

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.

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.

Chemicals can protect humans from the bites of hemophagous arthropods through three different primary actions: irritancy (excitation), repellency, or toxicity, actions that can be evaluated using a laboratory-based assay system. In this study, the deterrent and toxic actions of three synthetic pyrethroids and DDT were characterized on six field strains of Aedes aegypti from Thailand under laboratory-controlled conditions using the high throughput screening system. All six strains showed significant contact irritant responses to the three synthetic pyrethroids, but significantly weaker irritant responses to DDT. Marked repellency responses were seen in all six Ae. aegypti test strains exposed to DDT, whereas the synthetic pyrethroids resulted in greater toxicity than DDT under similar test conditions. Although significantly different in actions, irritancy and repellency may reflect and be influenced by the background insecticide susceptibility status of a particular mosquito population. Results from this study can be used to guide decision making regarding more effective Ae. aegypti adult control in Thailand.

Analyses of the dorsal abdominal glands of fourth- and fifth-instar nymphs of the bed bud, Cimex lectularius L. (Hemiptera: Cimicidae), indicated the predominant constituents were (E)-2-hexenal and (E)-2-octenal, with lesser amounts of 4-oxo-(E)-2-hexenal and 4-oxo-(E)-2-octenal. The latter two compounds have not been reported previously as occurring in bed bugs. There were no differences in the chemical composition of the dorsal abdominal glands excised from exuviae left behind by either male or female adults, nor from glands excised from fourth-instar exuviae. Because the two oxo-aldehydes made up at least 16% of the gland contents, further study of the functional role of these chemicals seem advisable.

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.

An investigation of the biological effect of catnip oil (Nepeta cataria L.) on the behavioral response of field collected Aedes aegypti and Anopheles harrisoni was conducted using an automated excitorepellency test system. Aedes aegypti showed significantly higher escape rates from the contact chamber at 5% catnip oil compared to other concentrations (P < 0.05). With Anopheles harrisoni, a high escape response was seen at 2.5% catnip oil from the contact chamber, while in the noncontact chamber a higher escape response was observed at a concentration of 5%. Results showed that this compound exhibits both irritant and repellent actions.

Field-collected female goldeneyed lacewing (Chrysopa oculata) strongly avoided ovipositing on substrates exposed over 24 h to three of four lady beetle species tested, resulting in circa 3-fold higher egg deposition on control versus coccinellid-exposed substrates. The effect was stage-specific for Coleomegilla maculata; it was observed for adult and third-instar larvae but not for unfed first-instar larvae.

Hexyl and (E)-2-hexenyl butyrates and (E)-4-oxo-2-hexenal are major components of the metathoracic scent gland (MSG) secretion and aeration samples of many plant bugs (Miridae), including the tarnished plant bug, Lygus lineolaris (Palisot de Beauvois). Laboratory and field experiments were performed (1) to determine the extent to which MSG-produced compounds are detected by antennae of L. lineolaris males and females, and (2) to elucidate the behavioral activity associated with the antennally active MSG compounds. The three major MSG-produced compounds elicited strong antennal responses by both sexes. In Y-track olfactometer tests, attraction of males to virgin females was significantly reduced when a dispenser loaded with hexyl butyrate was placed with the virgin females. Hexyl butyrate tested alone against a blank control significantly repelled males. In the field, ternary and partial binary combinations of these three EAD-active compounds failed to attract either sex, whereas virgin females attracted a significant number of males. However, addition of hexyl butyrate and/or (E)-2-hexenyl butyrate to virgin female-baited traps significantly reduced the number of males caught compared with the level of the blank control traps. This might be due either to a negative effect on pheromone release by the females or direct repellency of males, or both. These MSG compounds may be useful for mating disruption and other pest management tactics against economically important plant bugs.

The newly invasive soybean aphid, Aphis glycines Matsumura, has seriously threatened soybean production in North America, after having spread to 20 states in the United States and several southern provinces of Canada. Control ofA.glycines has focused on applications of insecticides, which are not a long-term solution to soybean aphid pest management. In autumn, soybean aphids start producing alate females (gynoparae) that search for their overwintering host plants, the common buckthorn, Rhamnus cathartica. The gynoparae then produce pheromone-emitting wingless female offspring (oviparae) that attract male aphids. In this study, we report the chemical identiÞcation of the soybean aphid sex pheromone using gas chromatographyÐ electroantennogram, gas chromatog- raphyÐmass spectrometry, and nuclear magnetic resonance spectroscopy. Behavioral activities of males and gynoparous females in the Þeld were also characterized. The potential applications using formulations containing speciÞc soybean aphid pheromone compositions for reducing overwintering populations are discussed.

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. ...

The semiochemical cues used by geographically isolated strains of the parasitoid, Telenomus podisi (Ashmed), to find eggs of the stink bug Euschistus heros were investigated. Two strains of Te. podisi, maintained on eggs of a South American host (E. heros) were studied. One parasitoid strain originated from specimens collected near Brasilia, Brazil (SA strain), and a second strain originated from specimens collected at Beltsville, Maryland (NA strain). Cold tolerance tests of adults from the NA and SA Te. podisi strains, analyses of the cuticular hydrocarbons between the two strains, and crossing experiments between strains each indicated consistent differences between the NA and SA strains. Subsequent experiments using E. heros showed that SA Te. podisi females specifically recognize traces left on the substrate by walking E. heros females and then search intensively the area of the ‘footprints’, apparently looking for an egg mass to parasitize. By contrast, Te. podisi females of the NA strain are incapable of recognizing the footprints of E. heros females despite the fact that these parasitoids were reared from eggs of E. heros. The possibility that the two strains are actually different species is discussed.

The banana-spotting bug,Amblypelta lutescens lutescensDistant (Heteroptera: Coreidae), is one of the principal pests of tree fruits and nuts across northern and eastern Australia. Apart from visual damage assessment, there are currently no reliable methods for monitoring bug activity to aid management decisions. An attractant pheromone for this species that could be used as a trap lure could potentially fill this void. Earlier, two male-specific compounds were identified in airborne extracts fromA. lutescens lutescens, (E,E)-α-farnesene and (R,E)-nerolidol; an unknown compound with a molecular weight 220 was also detected. We now report the identification of this hitherto unknown compound as (R,E,E)-α-farnesene-10,11-oxide. Synthesis of this epoxide was conducted using a regioselective asymmetric dihydroxylation of a sulfolene. A blend mimicking the natural proportions of (E,E)-α-farnesene, (R,E)-nerolidol, and (R,E,E)-α-farnesene-10,11-oxide attracted male and femaleA. lutescens lutescensas well as nymphs in the field, verifying that the aggregation pheromone comprises or is contained within this group of compounds.