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Fatty acids derived from natural oils are considered as perspective products for adoption as repellents. Fatty acids derived from coconut oil have shown promise as repellents. This study consisted of an olfactometer evaluation of new formulations containing medium-chain fatty acids for spatial repellency and an in laboratory arm-in cage study for contact repellency against Aedes aegypti L. mosquitoes. Six formulations each of capric acid and lauric acid were evaluated for spatial repellency. These formulations contained 0.28-10% of either capric acid or lauric acid as the active ingredients in a consumer friendly skin care formulation. Base formula without fatty acids was evaluated as control in spatial repellency evaluation. For the arm-in cage evaluations, six formulations of capric acid, one base formulation, and a 7% N,N-diethyl-m-toluamide (DEET) product were tested for contact repellency. For contact repellency, United States Department of Agriculture (USDA) standard repellent test cages were used to determine the complete protection time (CPT) of the different formulated repellents. Among all capric acid formulations tested, the concentration of 2.25% (wt) indicated the best level of spatial repellency, but not significantly different from other concentrations. None of the lauric acid concentrations showed any level of spatial repellency. In the arm-in-cage evaluations, the highest contact repellency resulted from 4.5% capric acid, which was significantly higher than 7% DEET and base formula., (© The Author(s) 2022. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Thirteen botanical product repellent compounds such as 2-undecanone, capric, lauric, coconut fatty acids (and their methyl ester derivatives), and catnip oil were formulated in either Coppertone or Aroma Land lotions and evaluated against laboratory-reared Aedes aegypti L. (Diptera: Culicidae) mosquitoes. These formulations contained 7-15 wt/wt of the botanical repellent as the major active ingredient either pure or as mixtures. USDA standard repellent test cages were used to determine the complete protection time (CPT) of the different formulated repellents. Two of the evaluated formulations, a 7% capric acid in Coppertone (CPT 2.7 ± 0.6 h) and 7% coconut fatty acids containing carrylic acid, capric acid, and lauric acid in Coppertone (CPT 2.3 ± 2.0 h), provided strong repellency against mosquitoes up to 3 h, which was equivalent to the (N,N-diethyl-m-toluamide) DEET control (CPT 2.7 ± 0.6 h). This work suggests future potential for these botanical product-based repellents as alternatives to commercial DEET-containing products., (© The Author(s) 2020. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

The present research aimed to evaluate the larvicidal activity of several recently discovered natural repellents formulated in lotions against larvae of Aedes aegypti. We used a modified larval bioassay method by the World Health Organization standards in evaluating larval mortality at 24-, 48-, and 72-h exposure. Among the test repellents, 2-undecanone showed 100% mortality of Ae. aegypti larvae, followed by catnip oil, capric acid, coconut oil fatty acids, methyl caprate, methyl laurate, and coconut oil methyl esters. The repellent, 2-undecanone showed median lethal concentration (LC50) values of 73.07, 26.45, and 15.68 ppm at 24-, 48-, and 72-h exposure, respectively. Larvicidal activity varied among the other repellents tested., (Copyright © 2020 by The American Mosquito Control Association, Inc.)

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., (Copyright © 2013 Elsevier B.V. All rights reserved.)

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., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Changes in the time to first bite (TFB) and the bloodfeeding behavior of adult female Aedes aegypti (L.) mosquitoes following dissemination of Sindbis virus (SINV) were observed after exposure to repellents with the active ingredients (AI) DEET, picaridin, 2-undecanone (2-U), and oil of lemon eucalyptus. Dissemination of SINV significantly decreased (P<0.0001) the TFB of DEET (15%) and picaridin (15%) by 46% and 37%, respectively. Significant (P<0.0001) changes in activation, probing, and engorgement times were observed in SINV infected mosquitoes after exposure to the four repellents compared to uninfected mosquitoes. Taken together, a decrease in TFB and time to complete the four bloodfeeding stages will lessen the prey-status, and enhance both the chances of mosquito survival and arbovirus transmission., (Published by Elsevier B.V.)

Repellent efficacy of the Off! Clip-on Mosquito Repellent device (S. C. Johnson and Son, Inc., Racine, WI) containing Metofluthrin was evaluated on six human volunteers against the container-breeding mosquito Aedes albopictus (Skuse) and the salt marsh mosquito Aedes taeniorhynchus (Wiedemann) at two field locations in northeastern Florida. The device repelled mosquitoes by releasing a vaporized form of the pyrethroid insecticide metofluthrin ([AI] 31.2%) and provided 70% protection from Ae. albopictus bites for > 3 h. For the second field trial, a repellent device that was used in the first trial was tested after being open for >1 wk. This device provided 79% protection from Ae. taeniorhynchus bites for 3 h. Our field results showed that the repellent device was 70 and 79% effective at repelling Ae. albopictus and Ae. taeniorhynchus from human test subjects in both field locations in northeastern Florida.

Aedes aegypti (L.) (Diptera: Culicidae) female mosquitoes infected systemically with Sindbis virus (SINV) took longer than uninfected mosquitoes to locate and fully engorge on blood. On days 7 and 14 postexposure, blood feeding took 1.3 and 1.5 times longer in mosquitoes with a disseminated SINV infection, respectively. SINV dissemination did not affect the average weight of unfed Ae. aegypti, but did result in a 10 and 12% increase in blood imbibed compared with mosquitoes without a positive SINV dissemination and non-SINV-exposed mosquitoes, respectively. Ae. aegypti mosquitoes with a disseminated SINV infection fed an average of 4 h sooner than uninfected mosquitoes when offered a bloodmeal contained inside a DEET (N,N-diethyl-3-methylbenzamide) saturated (30%) bovine sausage casing. Together, these results indicate that behavioral changes in mosquito host-seeking, blood feeding and sensitivity to DEET occurred in mosquitoes after SINV infection and dissemination.

Three plant-based repellents-REPEL LEMON Eucalyptus Insect Repellent Lotion (active ingredient [AI] 30% oil of eucalyptus), Bite Blocker Xtreme Sportsman Organic Insect Repellent ([AI] 3% soybean oil, 6% geranium oil, and 8% castor oil), and Bite Blocker BioUD Insect Repellent ([AI] 7.75% 2-undecanone)--were evaluated against OFF! ([AI] 15% N,N-diethyl-m-toluamide or N,N-diethyl-3-methyl-benzamide, also called DEET) at a field site in Elkton, FL, to determine the mean protection time provided against Psorophora columbiae (Dyar & Knab). These products provided different protection times against biting Ps. columbiae. REPEL provided the longest protection time (330 min) followed by Bite Blocker Xtreme Sportsman (163 min), Bite Blocker BioUD (140 min), and OFF! (130 min). This study provides the first information about plant-based insect repellent protection times against Ps. columbiae.

To determine whether a Sindbis virus (family Togaviridae, genus Alphavirus, SINV) infection in Aedes aegypti (L.) (Diptera: Culicidae) affected its response to the repellent DEET, we orally exposed Ae. aegypti to an artificial bloodmeal containing SINV or diluent and then allowed to feed on a 10% sucrose suspension containing 3% DEET. When tested seven or more days after the initial bloodmeal, although none of the diluent-exposed mosquitoes fed on the DEET-sucrose suspension, at least 60% of the SINV-exposed mosquitoes fed on the suspension. When legs from the SINV-exposed mosquitoes were tested to determine dissemination status, 89% of those that fed on the DEET-sucrose suspension contained virus. In contrast, only 34% of the nonfeeders had a disseminated infection. When offered a choice between sucrose with or without DEET, a significantly higher percentage of the SINV-exposed mosquitoes than the control mosquitoes fed on the sucrose containing 3% DEET. Together, these results indicate that mosquitoes with a disseminated SINV infection may be less responsive to DEET than uninfected mosquitoes. Therefore, repellent use may be less effective in deterring infected mosquitoes from biting than previously believed.

Three botanical natural repellents, Swamp Buddy Bug Chaser (AI 12% plant-based essential oils), All Sport (AI plant-based essential oils, benzophenone-3, octinoxate, and octisalate), and Geraniol (AI 25% geraniol oil and lemongrass extract) were evaluated at a field site in Elkton, Florida, to determine the protection time provided against Psorophora ferox, Aedes atlanticus, and Ae. mitchellae. These three products provided different protection times against biting mosquitoes. Geraniol provided the longest protection time from mosquito bites (4 h), followed by All Sport (1.5 h) and Swamp Buddy Bug Chaser (1 h). This study provides the first information about botanical insect repellents against these floodwater mosquito species.