Edita E. Revay

Efficacy of the botanical repellents geraniol, linalool, and citronella against mosquitoes

ABSTRACT: We determined the degree of personal protection provided by citronella, linalool, and geraniol in the form of commercially available candles or diffusers, both indoors and outdoors. Under the uniform conditions of the experiments, all substances repelled significantly more mosquitoes than the unprotected control. Furthermore, the repellents tested were more active when in the form of a continuous release diffuser than in candle form. All candles were 88g containing 5% of the active ingredient and all diffusers contained 20g of 100% active ingredient. Indoors, the repellency rate of citronella candles was only 14% while the repellency rate of citronella diffusers was 68%. The repellency of geraniol candles was 50% while the diffusers provided a repellency rate of 97%. No linalool candles were available for study but linalool diffusers repelled mosquitoes by 93%. Outdoors, citronella diffusers placed 6 m from mosquito traps repelled female mosquitoes by 22%, linalool repelled females by 58%, and geraniol repelled females by 75%. Trap catches were significantly reduced again when diffusers were placed 3 m from the traps. We concluded that geraniol had significantly more repellent activity than citronella or linalool in both indoor and outdoor settings.

INDOOR PROTECTION AGAINST MOSQUITO AND SAND FLY BITES : A COMPARISON BETWEEN CITRONELLA, LINALOOL, AND GERANIOL CANDLES

ABSTRACT The repellent effect of 3 essential-oil-based candles was evaluated in a high biting pressure environment in Israel. In human landing assays, the repellency rate of 5% citronella candles against mosquitoes was 29.0%, of 5% linalool candles was 71.1%, and of 5% geraniol candles was 85.4%. The candles with geraniol were about twice as effective as those with linalool and were about 5 times as effective as citronella candles in protecting a person from being bitten indoors by mosquitoes. The repellency rate of 5% citronella candles towards sand flies was 24.7%, of 5% linalool candles was 55.2%, and of 5% geraniol candles was 79.7%. A geraniol candle was almost 5 times as effective as a citronella candle and about twice as effective as a linalool candle in protecting a person from being bitten indoors by sand flies.

Control of Culex quinquefasciatus in a storm drain system in Florida using attractive toxic sugar baits.

Attractive toxic sugar baits (ATSBs) were used to control mosquitoes in the storm drains of a residential area on the outskirts of St Augustine, Florida. The drainage system was newly constructed and no mosquitoes were breeding inside it. The area covered by the storm drains was divided in half; 10 drains served as control drains and 16 drains served as experimental drains. The baits, which consisted of a mixture of brown sugar, fruit juice, green dye marker and boric acid, were presented at the entrances of the treated drains and exit traps were positioned over the drain openings and the connecting tubes leading to retention ponds. Similar baits with orange dye and without toxin were presented at the entrances of control drains. A total of 220 pupae of Culex quinquefasciatus (Diptera: Culicidae) were released in each control and toxin‐treated drain, and the numbers of recovered mosquitoes were examined to determine the effectiveness of ATSBs in the storm drain system. An average of 178.2 mosquitoes exited each drain in the control area; 87.0% of these had fed on the baits and were stained orange, whereas 13.0% were unstained. In the toxin‐treated drains, 83.7% of hatched females and 86.6% of hatched males were controlled by the baits.

Evaluation of attractive toxic sugar bait (ATSB)—Barrier for control of vector and nuisance mosquitoes and its effect on non-target organisms in sub-tropical environments in Florida

The efficacy of attractive toxic sugar baits (ATSB) with the active ingredient eugenol, an Environmental Protection Agency exempt compound, was evaluated against vector and nuisance mosquitoes in both laboratory and field studies. In the laboratory, eugenol combined in attractive sugar bait (ASB) solution provided high levels of mortality for Aedes aegypti, Culex quinquefasciatus, and Anopheles quadrimaculatus. Field studies demonstrated significant control: >70% reduction for Aedes atlanticus, Aedes. infirmatus, and Culex nigripalpus and >50% reduction for Anopheles crucians, Uranotaenia sapphirina, Culiseta melanura, and Culex erraticus three weeks post ATSB application. Furthermore, non-target feeding of six insect orders, Hymenoptera, Lepidoptera, Coleoptera, Diptera, Hemiptera, and Orthoptera, was evaluated in the field after application of a dyed-ASB to flowering and non-flowering vegetation. ASB feeding (staining) was determined by dissecting the guts and searching for food dye with a dissecting microscope. The potential impact of ATSB on non-targets, applied on green non-flowering vegetation was low for all non-target groups (0.9%). However, application of the ASB to flowering vegetation resulted in significant staining of the non-target insect orders. This highlights the need for application guidelines to reduce non-target effects. No mortality was observed in laboratory studies with predatory non-targets, spiders, praying mantis, or ground beetles, after feeding for three days on mosquitoes engorged on ATSB. Overall, our laboratory and field studies support the use of eugenol as an active ingredient for controlling important vector and nuisance mosquitoes when used as an ATSB toxin. This is the first study demonstrating effective control of anophelines in non-arid environments which suggest that even in highly competitive sugar rich environments this method could be used for control of malaria in Latin American countries.

Evaluation of commercial products for personal protection against mosquitoes.

Human landing catch studies were conducted in a semi-field setting to determine the efficacy of seven commercial products used for personal protection against mosquitoes. Experiments were conducted in two empty, insecticide free, mesh-enclosed greenhouses, in Israel, with either 1500 Aedes albopictus or 1500 Culex pipiens released on consecutive study nights. The products tested in this study were the OFF!(®) Clip-On™ Mosquito Repellent (Metofluthrin 31.2%) and the Terminix(®) ALLCLEAR(®) Sidekick Mosquito Repeller (Cinnamon oil 10.5%; Eugenol 13%; Geranium oil 21%; Peppermint 5.3%; Lemongrass oil 2.6%), which are personal diffusers; Super Band™ Wristband (22% Citronella oil) and the PIC(®) Citronella Plus Wristband (Geraniol 15%; Lemongrass oil 5%, Citronella oil 1%); the Sonic Insect Repeller Keychain; the Mosquito Guard Patch (Oil of Lemon Eucalyptus 80mg), an adhesive-backed sticker for use on textiles; and the Mosquito Patch (vitamin B1 300mg), a transdermal patch. It was determined that the sticker, transdermal patch, wristbands and sonic device did not provide significant protection to volunteers compared with the mosquito attack rate on control volunteers who were not wearing a repellent device. The personal diffusers: - OFF!(®) Clip-On™ and Terminix(®) ALLCLEAR(®) Sidekick - provided superior protection compared with all other devices in this study. These diffusers reduced biting on the arms of volunteers by 96.28% and 95.26% respectively, for Ae. albopictus, and by 94.94% and 92.15% respectively, for Cx. pipiens. In a second trial conducted to compare these devices directly, biting was reduced by the OFF!(®) Clip-On™ and the Terminix(®) ALLCLEAR(®) by 87.55% and 92.83%, respectively, for Ae. albopictus, and by 97.22% and 94.14%, respectively, for Cx. pipiens. There was no significant difference between the performances of the two diffusers for each species.

Attractive Toxic Sugar Baits: Control of Mosquitoes With the Low-Risk Active Ingredient Dinotefuran and Potential Impacts on Nontarget Organisms in Morocco

ABSTRACT We evaluated the efficacy of attractive toxic sugar baits (ATSB) in the laboratory and field with the low-risk active ingredient dinotefuran against mosquito populations. Preliminary laboratory assays indicated that dinotefuran in solution with the sugar baits was ingested and resulted in high mortality of female Culex quinquefasciatus Say and Aedes aegypti Linnaeus. Field studies demonstrated >70% reduction of mosquito populations at 3 wk post-ATSB application. Nontarget feeding of seven insect orders—Hymenoptera, Lepidoptera, Coleoptera, Diptera, Hemiptera, Orthoptera, and Neuroptera—was evaluated in the field after application of attractive sugar baits (ASB) on vegetation by dissecting the guts and searching for food dye with a dissecting microscope. Nontargets were found stained with ASB 0.9% of the time when the application was applied on green nonflowering vegetation. Only two families were significantly impacted by the ASB application: Culicidae (mosquitoes) and Chironomidae (nonbiting midges) of the order Diptera. Pollinators of the other insect orders were not significantly impacted. No mortality was observed in the laboratory studies with predatory nontargets, wolf spiders or ground beetles, after feeding for 3 d on mosquitoes engorged on ATSB applied to vegetation. Overall, this novel control strategy had little impact on nontarget organisms, including pollinators and beneficial insects, and was effective at controlling mosquito populations, further supporting the development of ATSB for commercial use.

Reduction of mosquito biting-pressure: Spatial repellents or mosquito traps? A field comparison of seven commercially available products in Israel

The present study assessed the personal protection efficiency of seven commercially available mosquito control devices (MCD) under field conditions in Israel. Trials were performed in a high biting-pressure area inhabited by large populations of mosquito and biting midge species, using human volunteers as bait in landing catch experiments. Results show that under minimal air-movement, three spatial repellent based products (ThermaCELL(®) Patio Lantern, OFF!(®) PowerPad lamp, and Terminix(®) ALLCLEAR Tabletop Mosquito Repeller) significantly reduced the biting-pressure (t-test - P<0.01) when positioned at short distances from a volunteer (3, 7.5, and 10ft.), with the ThermaCELL unit being most effective (96.1, 89.9, and 76.66% reduction, respectively). No significant differences were seen between the three aforementioned devices at distances of 3 and 7.5ft., while at a distance of 10ft., only the ThermaCELL patio lantern repelled significantly more mosquitoes then the Terminix ALLCLEAR Tabletop Mosquito Repeller (t-test, P<0.05). In contrast, mosquito traps using attracting cues to bait mosquitoes (Dynatrap(®), Vortex(®) Electronic Insect Trap, Blue Rhino(®) SV3100) either significantly increased or had no effect on the biting-pressure at short distances compared with the unprotected control. Trials conducted over large areas showed that only the Blue Rhino trap was able to significantly reduce the biting-pressure (40.1% reduction), but this was only when operating four units at the corners of an intermediate sized area.

Ability of Essential Oil Candles to Repel Biting Insects in High and Low Biting Pressure Environments

ABSTRACT The first goal of this study was to compare the degree of personal protection against biting insects provided by geraniol, linalool, and citronella candle (5%) vapors outdoors, where such products are commonly used. At a distance of 1.0 m, citronella candles reduced the number of female mosquitoes caught in Centers for Disease Control and Prevention traps by 35.4% and sand flies by 15.4%, linalool candles reduced female mosquitoes by 64.9% and sand flies by 48.5%, while geraniol candles reduced female mosquitoes by 81.5% and sand flies by 69.8%. By increasing the distance to 2 m and 3 m, the repellency dropped significantly. The second goal was to compare the degree of personal protection provided by the best performing candle, geraniol, under conditions of high and low biting pressure. The introduction of geraniol candles to protect volunteers in a high biting pressure environment reduced the mosquito pressure by an average of 56% and the sand fly pressure by 62% over a distance of 1.0 m. In the low biting pressure environment, geraniol reduced the mosquito pressure by an average of 62%. No sand flies were present at this site.

Implications for operational control of adult mosquito production in cisterns and wells in St. Augustine, FL using attractive sugar baits

The aim of this study was to further investigate the use of attractive sugar baits as an effective, inexpensive, and environmentally friendly tool for integrated mosquito management programs. Mosquitoes were offered dyed sugar bait in wells and cisterns in an urban tourist area in St. Augustine, FL. Exit traps were constructed to cover the well and cistern openings so the number of resting and emerging mosquitoes stained by feeding on the sugar bait could be monitored. Four mosquito species were collected from these structures: Aedes albopictus (Skuse), Anopheles crucians (Wiedemann), Culex quinquefasciatus Say, and Toxorhynchites rutilus rutilus (Coquillett). Overall, 90% (1482/1644) of the mosquitoes trapped were stained. In general, the number of mosquitoes stained was significantly greater in wells (P<0.0001) and cisterns (P<0.0001) than the numbers that were not stained by the colored bait. Based on the number of mosquitoes stained, we would have expected considerable mosquito mortality had the sugar bait contained an oral toxin. The results of this study support the concept of using attractive toxic sugar baits as an effective tool for integrated mosquito management.

Simplified and Improved Monitoring Traps for Sampling Sand Flies

Simplified and improved monitoring traps for sampling sand flies Gunter C. Muller1, Edita, E. Revay2, and John C. Beier3 1Department of Microbiology and Molecular Genetics , IMRIC, Kuvin Centre for the Study of Infectious and Tropical Diseases, Faculty of Medicine, Hebrew University, Jerusalem 91120, Israel, guntercmuller@hotmail.com 2Department of Anatomy and Cell Biology, Bruce Rappaport Faculty of Medicine, Technion, Haifa, Israel 3Department of Epidemiology and Public Health, University of Miami Miller School of Medicine, Miami, FL 33136, U.S.A.