Flight behavior of Musca domestica and Stomoxys calcitrans (Diptera: Muscidae) in a Kansas dairy barn

Aerial density, flight thresholds, and periodicity were estimated for the house fly, Musca domestica L., and the stable fly, Stomoxys calcitrans (L.), from data collected by suction traps located in a dairy barn in Kansas between 1 July and 31 October 1970. M. domestica catches increased from July to August, declining to near zero by the end of October. S. calcitrans catches peaked in July and September with a major decline in August. Both species exhibited a diel periodicity in flight with maximal activity during the early afternoon. Secondary peaks were detected in the late afternoon or early evening. M. domestica activity peaked about two hours after S. calcitrans. Male and female S. calcitrans flight activity patterns were slightly different, but peaked at the same time. Both species flew at temperatures between 20 and 38 degrees C. At temperatures over 33 degrees C, stable fly activity decreased rapidly. No upper threshold for flight by M. domestica was detected. The median temperature-flight thresholds of male and female S. calcitrans were significantly different, with females flying at lower temperatures than males. The threshold for M. domestica flight was lower than for S. calcitrans. The shape of the temperature-flight relationship indicated that the flight threshold was determined by heat accumulation.     

The distribution of Stomoxys calcitrans (Diptera, Muscidae) in stables

Cowsheds and pigsties were studied for infestation with the stable fly. 81.5% of the cowsheds, but only 20% of the pigsties were found to be infested. Both people working in the sheds and sties and villagers felt molested. The control of the stable fly proved to be not difficult.     

Impact of house fly salivary gland hypertrophy virus (MdSGHV) on a heterologous host, Stomoxys calcitrans

The effect of Musca domestica salivary gland hypertrophy virus (MdSGHV) on selected fitness parameters of stable flies, Stomoxys calcitrans (L.), was examined in the laboratory. Virus-injected stable flies of both genders suffered substantially higher mortality than control flies. By day 9, female mortality was 59.3 +/- 10.1% in the virus group compared with 23.7 +/- 3.7% in the controls; mortality in virus-injected males was 78.1 +/- 3.1% compared with 33.3 +/- 9.3% for controls. Fecundity of control flies on days 6-9 was 49-54 eggs deposited per live female per day (total, 8,996 eggs deposited), whereas virus-injected flies produced four to five eggs per female on days 6-7 and less then one egg per female per day thereafter (total, 251 eggs). Fecal spot deposition by virus-injected flies was comparable to controls initially but decreased to approximately 50% of control levels by day 4 after injection; infected flies produced only 26% as many fecal spots as healthy flies on days 6 and 7. None of the virus-injected stable flies developed symptoms of salivary gland hypertrophy. Quantitative real-time polymerase chain reaction demonstrated virus replication in injected stable flies, with increasing titers of virus genome copies from one to four days after injection. MdSGHV in stable flies displayed tissue tropism similar to that observed in house fly hosts, with higher viral copy numbers in fat body and salivary glands compared with ovaries. Virus titers were approximately 2 orders of magnitude higher in house fly than in stable fly hosts, and this difference was probably due to the absence of salivary gland hypertrophy in the latter species.     

Attractiveness of beach ball decoys to adult Stomoxys calcitrans (Diptera: Muscidae)

The attractiveness of inflated beach balls covered with adhesive and used as decoys to trap adult stable flies was investigated on Florida panhandle beaches. Decoys were painted either solid black, solid white, or a mixed pattern that consisted of three equally spaced white circles (20 cm diameter) on a solid black background. Another set of decoys (referred to as plain) were unpainted and retained the manufacturer's original color scheme. The plain decoy consisted of a separate blue, yellow, and red diamond-shaped panel. Each color panel was separated by a white panel of similar size and orientation. Plain decoys collected significantly (<0.05) more stable flies than other treatments but no significant difference was noted between colored panels. The mixed pattern decoy captured significantly fewer flies than the plain decoy but significantly more flies (nearly twice) when compared with solid white or black decoys. No difference in preference was observed when fly abundance on the black background was compared with that on white circles and total abundance from both areas appeared to be additive compared with either area alone. No significant differences were found in the number of flies trapped on solid white versus black decoys. When trapping efficiency was compared with Alsynite translucent fiberglass cylinders covered with adhesive-treated cellophane sheets, the decoy trap caught significantly more (>10 times) flies per square centimeter. Alsynite cylinders are considered standard tools when sampling fly populations. Adhesive-treated beach ball decoys may be an alternative method for luring stable flies away from human hosts in recreation areas, or from animals, thereby reducing biting annoyance from these pests.     

Behavioral response of Stomoxys calcitrans (Diptera: Muscidae) to conspecific feces and feces extracts

The attraction response of Stomoxys calcitrans (L.) to its own feces was evaluated in a triple cage olfactometer. Both time- and concentration-response relationships were obtained for female S. calcitrans exposed to cellulose sponges impregnated with fresh fly feces or filter papers treated with chloroform:methanol extracts of fresh fly feces in 6-min tests. Attraction to feces collected on cellulose sponges decreased as the air flow increased. Feces collected on cellulose sponges and held for 28-31 retained attractive activity. More female flies were attracted than males to feces on sponges or to polar solvent extracts of feces-contaminated cages. The activity of feces extract on filter paper decreased rapidly. Chemical identification of the active compounds present could lead to useful baits for traps.     

Attempted transmission of Ehrlichia risticii (Rickettsiaceae) with Stomoxys calcitrans (Diptera: Muscidae)

Experimental transmission of Ehrlichia risticii, the causal agent of Potomac horse fever, was attempted with adult stable flies, Stomoxys calcitrans, (L.) using two feeding schedules. In schedule A, a set of 140 flies was allowed to feed once on an experimentally infected donor pony and once 24 h later on a recipient pony. A different set of flies was used each day for a 12-d period. In schedule B, 240 flies were allowed to feed once daily for 12 consecutive d on the donor pony followed by five consecutive daily feedings on the recipient pony. E. risticii was isolated from the blood of the experimentally infected pony during the entire fly-feeding schedule. The recipient pony did not develop clinical signs of Potomac horse fever and remained seronegative to E. risticii up to 60 d after the last stable fly feeding. Mice injected intraperitoneally with emulsions of schedule A and B stable flies were seronegative for E. risticii 30 d after inoculation, and ehrlichial organisms were not demonstrated in impression smears from the digestive tracts of the flies. The stable fly did not transmit E. risticii under these experimental conditions.     

Assessment of Stomoxys calcitrans (Diptera: Muscidae) as a vector of porcine reproductive and respiratory syndrome virus

Porcine Reproductive and respiratory syndrome (PRRS) is a globally significant swine disease caused by an arterivirus. The virus replicates in alveolar macrophages of infected pigs, resulting in pneumonia in growing pigs and late-term abortions in sows. Outbreaks occur on disparate farms within an area despite biosecurity measures, suggesting mechanical transport by arthropods. We investigated the vector potential of stable flies, Stomoxys calcitrans (L.) (Diptera: Muscidae), in the transmission of porcine reproductive and respiratory syndrome virus (family Arteriviridae, genus Arterivirus, PRRSV) under laboratory conditions. Stable flies were collected around PRRS-negative boar stud barns in North Carolina and tested for presence of the virus. Stable flies were collected on alsynite traps placed near the exhaust fan of the close-sided tunnel-ventilated buildings, suggesting blood seeking flies are attracted by olfactory cues. No flies were positive for PRRSV. We assessed transmission of the virus through an infective bite by feeding laboratory reared stable flies on blood containing virus and transferring them to naive pigs for subsequent bloodmeals. Transmission of the virus to naive pigs by infective bites failed in all attempts. The volume of blood contained within the closed mouthparts of the stable fly seems to be insufficient to deliver an infective dose of the virus. Stable flies are unlikely to transmit PRRSV from one pig to another while blood feeding. The fate of the virus after a bloodmeal remains to be determined.     

Infectivity of Serratia marcescens (Eubacteriales: Enterobacteriaceae) in Stomoxys calcitrans (Diptera: Muscidae)

Serratia marcescens Bizio, a facultative pathogen of insects, was isolated from stable flies, Stomoxys calcitrans (L.), collected from Nebraska beef cattle feedlots and dairies. Infection rates in laboratory-reared stable flies infected by topical exposures to the bacterium were 57 and 64% in two experiments. Per os exposures to sucrose and water solutions, and bovine blood inoculated with S. marcescens, produced mortality rates of about 45 and 10%, respectively.     

Geographic distribution of stomoxyine flies (Diptera: Muscidae) and diurnal activity of Stomoxys calcitrans in Thailand

Stomoxyine flies (Stomoxys spp.) were collected in 10 localities of Thailand using the Vavoua traps. These localities represented four major ecological settings, as follows: small local dairy farms, large industrial dairy farms, a national park, and one elephant conservation area. Three species of stable flies were identified in the following proportions: Stomoxys calcitrans (91.5%), Stomoxys indicus (7.9%), and Stomoxys sitiens (0.6%). The number of flies collected differed significantly among collection sites (chi2 = 360.15, df=3, P < 0.05). The greatest number of stomoxyine flies was captured in dairy farms. Seasonal and daily activity of S. calcitrans was observed during a 1-yr period at two selected locations (Dairy Farming Promotion Organization of Thailand and Khao Kheow Open Zoo). S. calcitrans was more abundant during the rainy season (March-September), but was not associated with the total rainfall (r2 = 0.0002, P > 0.05). Peak of daily flight activity of males S. calcitrans was at 1000 and 1600 h, whereas females showed an increase of activity all along the day until 1600 h. A better understanding of stomoxyine fly behavior related to patterns of daily activity will facilitate and improve the efficiency of fly control measures in private and government sectors.     

Phenotypic susceptibility to pyrethroids and organophosphate of wild Stomoxys calcitrans (Diptera: Muscidae) populations in southwestern France

Parasitology Research - Stomoxys calcitrans (Diptera: Muscidae), is an important vector of lumpy skin disease and bovine besnoitiosis in Europe. Control of this biting fly could represent a...     

Evaluation of various substances to increase adult Stomoxys calcitrans (Diptera: Muscidae) collections on alsynite cylinder traps in north Florida.

During 1993-1995, field studies evaluated various volatile substances to increase the catch of adult stable flies, Stomoxys calcitrans L., on adhesive-coated translucent fiberglass (Alsynite) cylinder traps. Dry ice, 1-octen-3-ol (referred to as octenol), acetone, 4:1:8 mixture of 1 octen-3-ol: 3-n-propylphenol: 4-methylphenol, and an eye gnat (Hippelates) attractant were tested. Using dry ice as a baseline, the latter 4 treatments also were considered as possible alternatives to carbon dioxide. Dry ice significantly increased fly collections on cylinders as much as 25-fold compared with cylinders with no odor. Although trap collections increased by approximately 4% with addition of octenol (release rate approximately 18.0 mg/h), it was not significantly different when compared with dry ice alone. Fly collections on cylinders baited with octenol only were significantly lower than dry ice and not significantly different from cylinders with no odor. Collections from Alsynite cylinders baited with either acetone released at approximately 62.0 mg/h or eye gnat bait plus sand caught significantly more stable flies than no odor. However, neither substance increased fly collections as much as dry ice. The 4:1:8 phenolic mixture (released at either 0.7 mg/h or 20.0 mg/h) significantly increased fly collection on cylinders nearly 6-fold compared with no odor and warrants further investigation as an alternative to carbon dioxide for sampling stable flies.     

Evaluation of Stomoxys calcitrans (Diptera: Muscidae) behavioral response to human and related odors in a triple cage olfactometer with insect traps

A triple cage olfactometer provided with insect traps was used for evaluating behavioral responses of Stomoxys calcitrans (L.) females to human skin and breath, CO2, and L-lactic acid analogs. After demonstrating there were no significant differences caused by cage location or time of day, 3 sets of 3 olfactometer tests were performed in a day, every 2 h beginning at 0900 hours. When a human hand was used as attractant, the attraction (expressed as percentage of trapped flies) increased as a function of the time; an inverted U-shaped relationship between attractancy and air speed was observed; and variation in fly density in the range 25-75 per cage did not affect the attraction response. When human breath was used as attractant the attraction increased linearly as a function of time and it was exhalation frequency dependent; when air flow was absent the highest response was observed; and 24- to 38-h-old flies were more attracted than younger and older. When CO2 was tested, activation and orientation and probing behavior were concentration dependent with flows ranging between 0.0001 and 0.038 liter s(-1), but attraction was not. No attraction was observed with 10, 100, or 1,000 microg of compounds related to L-lactic acid and several synthetic human odors and related compounds, although orientation was often observed.     

Mechanical transmission of Bacillus anthracis by stable flies (Stomoxys calcitrans) and mosquitoes (Aedes aegypti and Aedes taeniorhynchus).

We evaluated the potential of stable flies, Stomoxys calcitrans, and two species of mosquitoes, Aedes aegypti and Aedes taeniorhynchus, to transmit Bacillus anthracis Vollum 1B mechanically. After probing on Hartley guinea pigs with a bacteremia of ca. 10(8.6) CFU of B. anthracis per ml of blood, individual or pools of two to four stable flies or mosquitoes were allowed to continue feeding on either uninfected guinea pigs or A/J mice. All three insect species transmitted lethal anthrax infections to both guinea pigs and mice. Both stable flies and mosquitoes transmitted anthrax, even when they were held at room temperature for 4 h after exposure to the bacteremic guinea pig before being allowed to continue feeding on the susceptible animals. This study confirms that blood-feeding insects can mechanically transmit anthrax and supports recent anecdotal reports of fly-bite-associated cutaneous human anthrax. The potential for flies to mechanically transmit anthrax suggests that fly control should be considered as part of a program for control of epizootic anthrax.     

Modulation of bovine lymphocyte response by salivary gland extracts of the stable fly,Stomoxys calcitrans (Diptera: Muscidae)

The effect of salivary gland extract of the stable fly, Stomoxys calcitrans (L), on bovine lymphocyte proliferation was determined, and antibody reactivity to salivary gland proteins was characterized in cattle exposed to stable flies. Salivary glands were dissected from male and female flies (4-8 d after eclosion), and protein extracts were made by freeze-thaw cycles. Salivary gland extract (SGE, 1 and 5 microg) significantly inhibited mitogen-driven proliferation of bovine lymphocytes, compared with 1 and 5 microg of identically prepared midgut extract (ANOVA, P < 0.05). Phytohemagglutinin A (PHA) stimulated lymphocyte responses were suppressed by 61.7 and 79.5% (mean values) with 1 and 5 microg of SCE, whereas concanvalin A (Con A) stimulated responses were suppressed by 62.9 and 77.1% (1 and 5 microg). In contrast, midgut extract (1 and 5 microg) minimally suppressed PHA (12.7% +/- 12.6 and 18.7% +/- 15.5) and Con A-driven responses (13.8% +/- 20.5 and 24.6% +/- 14.9), respectively. Viability studies using propidium iodide and flow cytometry demonstrated that SGE was not cytotoxic. Two-color immunofluorescence studies identified T and B lymphocytes as the nonviable cells in the cultures. Western blot analysis of serum collected from five dairy cows during periods of low and high fly exposure identified an immunodominant 27 kDa protein among the salivary gland proteins. These results indicate that exposure of cattle to stable fly saliva during blood feeding results in an antibody response to salivary proteins and that the saliva has a potential to modulate T lymphocyte function.