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LABORATORY EVALUATION OF 21 INSECT REPELLENTS AS LARVICIDES AND AS OVIPOSITION DETERRENTS OF AEDES ALBOPICTUS (DIPTERA: CULICIDAE)

ABSTRACT Twenty-one commercial insect repellent products, including 12 botanical, 6 DEET-based, and 3 synthetic organics, were evaluated as larvicides and as oviposition deterrents of Aedes albopictus. Ten of the 12 botanical products at 0.1% concentration provided 57–100% mortality of laboratory-reared 4th-stage Ae. albopictus larvae at 24 h after treatment. Five of the 6 DEET-based products and 3 synthetic organic repellents at 0.1% concentration induced 88–100% larval mortality at 24 h after treatment. All 12 botanical products proved highly effective oviposition deterrents of Ae. albopictus, resulting in 76–100% effective repellency at 24 h after exposure. The 6 DEET-based repellents and the 3 synthetic organic repellents caused 84–100% effective oviposition repellency of Ae. albopictus at 24 h after exposure. Several botanical repellents previously shown to have minimal protection from mosquito bites proved effective oviposition deterrents. Some commercial topical repellents have good potential for development and use in management of container-inhabiting mosquitoes because they deter oviposition and kill larvae.

Laboratory Evaluation of Mosquito Repellents Against Aedes albopictus, Culex nigripalpus, and Ochlerotatus triseriatus (Diptera: Culicidae)

Abstract Four synthetic mosquito repellents (Autan [10% KBR3023], IR3535 [7.5%], Off! [15% deet], Skinsations [7% deet]) and eight natural (primarily plant extracts and/or essential oils) product-based repellents (Bite Blocker [2% soybean oil], ByGone, GonE!, Natrapel [10% citronella], Neem Aura, Sunswat, MosquitoSafe [25% geraniol], and Repel [26% p-menthane-3,8-diol]) were tested in the laboratory against Aedes albopictus Skuse, Culex nigripalpus Theobald, and Ochlerotatus triseriatus (Say). When estimated mean protection time (eMPT) responses for each repellent were averaged for all three mosquito species, Autan, Bite Blocker, Off!, and Repel prevented biting for ≥7.2 h; IR3535, MosquitoSafe, and Skinsations for 3.2–4.8 h; and ByGone, Natrapel, GonE, NeemAura, and SunSwat for 0.9–2.3 h. Against Ae. albopictus, the eMPT for Off! and Repel exceeded 7.0 h and ranged from 5.0 to 5.7 h for Autan, Bite Blocker, and Skinsations. Bygone, GonE, NeemAura, and SunSwat provided 0.2 h protection against Ae. albopictus and Oc. triseriatus, whereas Autan, Bite Blocker, Off!, and Repel prevented bites by Oc. triseriatus for ≥7.3 h. All 12 repellents provided an eMPT ≥2.8 h against Cx. nigripalpus (maximum: 8.5 h for Bite Blocker). When the average eMPT for each repellent (for all species) was divided by the eMPT for 7% deet (Skinsations), the order of repellent effectiveness and the corresponding repellency index (Ri) was Repel (1.7) > Bite Blocker (1.5) = Autan (1.5) = Off! (1.5) > Skinsations (1.0) > IR3535 (0.8) > MosquitoSafe (0.6) > Natrapel (0.5) > Neem Aura (0.3) = SunSwat (0.3) = Bygone (0.3) > GonE (0.2).

Repellency of IR3535, KBR3023, para-menthane-3,8-diol, and deet to black salt marsh mosquitoes (Diptera: Culicidae) in the Everglades National Park.

Abstract IR3535, KBR3023, para-menthane-3,8-diol (PMD), and deet were evaluated in controlled studies with human subjects (n = 5) for repellency to black salt marsh mosquitoes (Ochlerotatus taeniorhynchus Wiedemann), in the Everglades National Park, FL. In tests of 6-h duration, with an average mosquito biting pressure on exposed forearm skin of 19.5 (±13.7) bites per minute, the mean percent repellencies (SE) for IR3535, KBR3023, PMD, and deet was 88.6 (3.2), 97.5 (1.7), 89.2 (2.9), and 94.8 (2.5), respectively. Mean complete protection times (SE) for IR3535, KBR3023, PMD, and deet were 3.0 (1.0), 5.4 (0.6), 3.8 (1.4), and 5.6 (0.5) h, respectively. Untreated (ethanol) controls provided 0% repellency. When mosquito biting rates on the untreated forearm skin of repellent-treated subjects were compared with biting rates on the forearm skin of control subjects, the former were 23%–40% lower early in tests and as much as 22% higher late in tests. These differences cast doubt on the technical merit of test designs comprising evaluation of more than one repellent at a time on the same human subject while underscoring the importance of untreated subjects as negative controls in field repellent bioassays.

Laboratory and field evaluation of insect repellents as oviposition deterrents against the mosquito Aedes albopictus.

Abstract. Three experimental approaches were used to evaluate the oviposition deterrency of three insect repellents, AI3‐35765, AI3‐37220 (piperidine compounds), and the standard N,N‐diethyl‐3‐methylbenzamide (deet) to the mosquito Aedes albopictus Skuse (Diptera: Culicidae). Against laboratory‐reared Ae. albopictus gravid females, the EC50 values of AI3‐37220, AI3‐35765 and deet were 0.004%, 0.008% and 0.011% in laboratory cages and 0.004%, 0.01% and 0.009% in an outdoor screened cage. For a natural population of Ae. albopictus tested in the field, the EC50 values were determined as 0.004%, 0.008% and 0.001%, respectively. Ageing concentrations of 0.1% of each repellent provided > 50% effective oviposition deterrency against the laboratory population of Ae. albopictus for 13 days in laboratory cages, for 15 days in the outdoor cage, and for 21 days against field population of Ae. albopictus in Florida. These topical skin repellents are effective oviposition deterrents for Ae. albopictus when employed at relatively low application rates.

Laboratory and field evaluation of insect repellents as larvicides against the mosquitoes Aedes albopictus and Anopheles albimanus.

Abstract. Acute toxicity and persistence of three insect repellents, deet and two piperidines (AI3‐35765 and AI3‐37220), were evaluated against mosquito larvae of Aedes albopictus (Skuse) and Anopheles albimanus Wiedemann (Diptera: Culicidae) in the laboratory, and against natural populations of Ae. albopictus in the field. In laboratory studies, the LC50 values of the repellents for first instars ranged between 0.005 and 0.021% (Ae. albopictus) and between 0.01 and 0.014% (An. albimanus) and, for fourth instars, between 0.019 and 0.034% (Ae. albopictus) and between 0.015 and 0.024% (An. albimanus). A 0.1% concentration of deet caused 90–100% mortality in first‐instar Ae. albopictus for 4 weeks, whereas AI3‐35765 and AI3‐37220 at the same concentration killed 95–100% of larvae for 12 weeks and 98–100% of larvae for 33 weeks post‐treatment, respectively. Deet and AI3‐35765 at 0.1% concentration resulted in complete mortality of first‐instar An. albimanus for 3 weeks post‐treatment, whereas AI3‐37220 resulted in 91–99% larval mortalities for 35 weeks post‐treatment. A 0.1% concentration of AI3‐37220 provided 77–98% larval mortality for 20 weeks and 63–97% larval mortality for 12 weeks post‐treatment, respectively, against fourth‐instar Ae. albopictus and An. albimanus.

Laboratory Toxicity of Three Mosquito Oviposition Repellents to Six Nontarget Aquatic Invertebrates

Abstract Toxicity of three mosquito oviposition repellents, N,N-diethyl-3-methylbenzamide (AI3-22542 or deet), AI3-35765, and AI3-37220 to 6 aquatic nontarget invertebrates, was evaluated in the laboratory. The 24-h LC50 values for Cypricercus sp. (Ostracoda), Moina sp. (Cladocera), Eucyclops agilis Koch (Copepoda), Strelkovimermis spiculatus Poinar & Camino (Nematoda), first- and fourth-instar Toxorhynchites amboinensis Doleschall larvae (Diptera), and fourth-instar Chironomus decorus Johannsen larvae (Diptera) ranged from 0.012 to 0.127% or 120 to 1,270 ppm. Cypricercus sp., Moina sp., E. agilis, first-instar Tx. amboinensis and fourth-instar C. decorus were generally more sensitive to the test repellents than male and female S. spiculatus and fourth-instar Tx. amboinensis. Male S. spiculatus was more sensitive to the repellents than its female and this was probably because of the smaller body size of the male. All invertebrates were generally more sensitive to AI3-37220 than to deet and AI3-35765. The experimental repellents were considered safe to the aquatic nontarget organisms when employed as oviposition repellents for Aedes albopicus (Skuse) mosquitoes.

Attraction, feeding, and repellency responses in mutant strains of Aedes aegypti.

ABSTRACT In a laboratory olfactometer, 12% of female Aedes aegypti with a marker gene for red eye (re), 0.7% of females with a marker gene for white eye (we), and 54.1% of females with normal (norm) eye color were attracted to odor from a human hand. When a synthetic attractant blend was used in place of the hand, the attraction rate was 7%, 0.3%, and 35.4%, respectively. On average, re females required significantly less time (76.8 sec) than we (189.6 sec) or norm (176.7 sec) females to locate, land on, and probe human skin but no difference was found between mosquito strains in the time required for females to bloodfeed to repletion on a restrained guinea pig. Differences among mosquito strains in the repellency of 15% diethyltoluamide (deet), 6.65% deet, and 10% citronella were not significant.