Jerry F. Butler

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.

Haemogregarine specificity in two communities of Florida snakes, with descriptions of six new species of Hepatozoon (Apicomplexa : Hepatozoidae) and a possible species of Haemogregarina (Apicomplexa : Haemogregarinidae)

Five species of snakes in Florida, from Palm Beach County in the south and Alachua County 450 km to the north, occur in similar habitat but have distinctive Hepatozoon species characteristic of each host species. In Palm Beach County, Diadophis punctatus is host to Hepatozoon punctatus n. sp., Thamnophis sauritus sackenii to Hepatozoon sauritus n. sp., and Nerodia fasciata pictiventris to Hepatozoon pictiventris n. sp. In Alachua County, N. fasciata pictiventris is parasitized by Hepatozoon fasciatae n. sp., Seminatrix p. pygaea by Hepatozoon seminatrici n. sp., and Thamnophis s. sirtalis by Hepatozoon sirtalis n. sp. Each Hepatozoon sp. has distinctive gamonts and sporogonic characters and, in the 4 species where known, meronts. Nerodia floridana is host to Haemogregarina floridana n. sp. in both localities, with generic identification tentative, based upon presence of erythrocytic meronts. The presence of sporocysts in the proboscis of 31% of Aedes aegypti infected by H. pictiventris is the first report of infective stages of a reptilian Hepatozoon species within the mouthparts of a dipteran vector. This study suggests that in Florida, at least, the diversity of the Hepatozoon community not only equals but probably exceeds the diversity of the snake communities present, and that host specificity in nature may be much greater than that postulated from previous studies.

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.

WILD FLORIDA HOUSE FLIES (MUSCA DOMESTICA) AS CARRIERS OF PATHOGENIC BACTERIA

ABSTRACT Bacteria carried by wild house flies (Musca domestica L.) collected near the rear entrances and dumpsters of 4 restaurants in north central Florida were identified. Live house flies were collected and individually transferred to blood agar plates for 1 h. After removing the flies, the plates were incubated overnight at 37C. Bacterial colonies that were morphologically distinct were isolated from other colonies by streaking onto new plates. The bacteria were identified by fatty acid analysis and sequence of their 16S rRNA gene. The bacterial isolates included 5 new bacterial records for house flies: Acinetobacter baumanni, Bacillus pumilus, Cronobacter sakazakii, Methylobacterium persicinum, and Staphylococcus sciuri. Other bacteria identified have been associated previously with house flies, including Bacillus cereus, B. thuringiensis, Escherichia coli 0157:H7, Shigella dysenteriae, Staphylococcus saprophyticus, and Staphylococcus xylosus. Most of the organisms recovered from the house fly are serious pathogens, known to produce diseases such as meningitis, food poisoning, diarrhea, abscesses, bloodstream infections, and hemorrhagic colitis. The possible exception is Bacillus thuringiensis, a known pathogen for insects that only occasionally produces allergic reactions in humans. If these organisms are not prevented from entering the food preparation and consumption areas, they could become a serious risk in the transmission of diseases.

Stable fly sex attractant and mating pheromones found in female body hydrocarbons

Investigation into the nature and function of stable fly pheromones indicated that both male sex attractant and mating pheromones are present. Polyolefin fraction of female body hydrocarbons attracted virgin males while thetrans andcis olefins were found to be responsible for mating stimulation. Characterization of the attractive components is under way.

LABORATORY EVALUATION OF COLORED LIGHT AS AN ATTRACTANT FOR FEMALE AEDES AEGYPTI, AEDES ALBOPICTUS, ANOPHELES QUADRIMACULATUS, AND CULEX NIGRIPALPUS

Abstract Mosquito feeding activity was monitored in an electronic apparatus (visualometer), having ten ports, illuminated from below with narrow bandwidths of light (700, 650, 600, 550, 500, 450, 400, or 350 nm). Responses of adult female Aedes albopictus Skuse, Ae. aegypti (L.), Anopheles quadrimaculatus, Say and Culex nigripalpus Theobald to feeding stations (blood containers) over each light port. No-light and broad spectrum white light were used as controls. Color preferences were based on electronic detection of feeding times. Aedes aegypti showed no significant feeding preferences over any of the colors. Conversely, Ae. albopictus, An. quadrimaculatus, and Cx. nigripalpus showed preferences for several of the wavelengths of light. In decreasing order, Aedes albopictus fed significantly longer at 600 nm, 500 nm, white, 450 nm, 400 nm, and black. For An. quadrimaculatus, significantly longer feeding durations were found over the black or white controls and all other individual wavelengths had significantly longer feeding durations than 350 nm. Finally, in decreasing order, significantly greater feeding times were recorded for Cx. nigripalpus over 500 nm, 600 nm, 450 nm, white, 650 nm, and 550 nm compared to the other wavelengths tested.

Lutzomyia spp. (Diptera: Psychodidae) Response to Olfactory Attractant- and Light Emitting Diode-Modified Mosquito Magnet X (MM-X) Traps

ABSTRACT Mosquito Magnet-X traps were modified for use with blue, green, red, and blue-green-red light-emitting diodes and olfactory attractants to determine the response of Lutzomyia shannoni (Dyar) and Lutzomyia vexator (Coquillett) (Diptera: Psychodidae) field populations to these attractants. Red and blue-green-red-baited traps captured the highest numbers of Lu. shannoni and Lu. vexator, respectively, although, there were no significant differences between the colors. Baiting the traps with CO2 attracted significantly higher numbers of Lu. shannoni but showed no effect on Lu. vexator capture. In comparison with CO2 alone, Lu. shannoni preferred 1-octen-3-ol and 1-hexen-3-ol (0.05 g per trap) in combination with CO2.

Susceptibility of Aedes aegypti and Aedes albopictus larvae to Ascogregarina culicis and Ascogregarina taiwanensis (Apicomplexa: Lecudinidae) from Florida

The susceptibility of Aedes aegypti to Ascogregarina culicis and Aedes albopictus to Ascogregarina taiwanensis was examined with mosquito and parasite strains from Tampa, FL. When each host was bioassayed with its natural gregarine, the infection intensity indicated that Ae. aegypti was 59% more susceptible to A. culicis (87 gamonts/larva) than Ae. albopictus to A. taiwanensis (47 gamonts/larva). Infections in single and mixed host populations exposed to 100 oocysts/larva of one and both parasites demonstrated that Ae. aegypti harbors higher A. culicis gamont loads than Ae. albopictus of A. taiwanensis. In dual gregarine exposures of single host populations, the A. culicis infection intensity in Ae. aegypti was reduced by approximately 50%. A. taiwanensis exhibited the same capability of infecting Ae. albopictus in single and dual exposures. In mixed host populations there were no cross infections, but A. taiwanensis in Ae. albopictus produced an infection intensity of approximately 70% lower than that of A. culicis in Ae. aegypti.

First isolation of Trypanosoma cruzi from a wild-caught Triatoma sanguisuga (LeConte) (Hemiptera: Triatominae) in Florida, U.S.A.

An adult female Triatoma sanguisuga was found to be naturally infected with Trypanosoma cruzi. This is the first report of a T. cruzi infection in this bug in Florida and suggests that a study of trypanosomiasis in reservoirs and vectors in north Florida is warranted.

Evaluation of semiochemical toxicity to Aedes aegypti, Ae. albopictus and Anopheles quadrimaculatus (Diptera: Culicidae).

BACKGROUND Mosquitoes are the most important vectors of human pathogens. Wide-scale use of pesticides has led to the development of resistance to most common insecticide groups. The need to develop novel products that have a low impact on human health and the environment is well established. The toxicity of selected semiochemicals with molecular structures indicative of insecticidal activity was determined against adult Aedes aegypti (L.) and Anopheles quadrimaculatus (Say). The two most active insecticides against Ae. aegypti were also evaluated against Ae. albopictus (Skuse). RESULTS Fifteen semiochemicals classified as terpenoid alcohols, ketones or carboxylic esters showed toxicity to both mosquito species. Geranyl acetone (LC(50) = 38.51 microg cm(-2)) followed by citronellol (LC(50) = 48.55 microg cm(-2)) were the most toxic compounds to Ae. aegypti, while geraniol and lavonax, with LC(50) values of 31.88 and 43.40 microg cm(-2), showed the highest toxicity to An. quadrimaculatus. Both geranyl acetone and citronellol were highly toxic to Ae. albopioctus. No semiochemical showed fumigation activity against either species. All semiochemicals persisted for less than 24 h when tested on filter paper. CONCLUSION Quantification of LC(50) values of several semiochemicals against Ae. Aegypti, An. quadrimaculatus and Ae. albopioctus showed that semiochemicals not only modify insect behaviors but also hold potential as potent insecticides for mosquito control programs.