House and Stable Fly Seasonal Abundance, Larval Development Substrates, and Natural Parasitism on Small Equine Farms in Florida.

House flies, Musca domestica Linnaeus, and stable flies, Stomoxys calcitrans (L.) (Diptera: Muscidae), are common pests on horse farms. The successful use of pupal parasitoids for management of these pests requires knowledge of seasonal fluctuations and biology of the flies as well as natural parasitism levels. However, these dynamics have not been investigated on small equine farms. A 1-year field study began in July 2010, in north central Florida, to determine adult fly population levels and breeding areas on four small equine farms. Weekly surveillance showed that pest flies were present year-round, though there were differences in adult population levels among farms and seasons. Fly development was not confirmed on two of the four small farms, suggesting that subtle differences in husbandry may adversely affect the development of immature flies. In six substrates previously identified as the most common among the farms, stable fly puparia were found overwhelmingly in hay mixed with equine manure and house fly puparia were found in fresh pine shavings mixed with equine manure. Natural parasitism was minimal as expected, but greatest numbers of natural parasitoids collected were of the genus Spalangia. Differences in adult and immature fly numbers recovered emphasizes the need for farm owners to confirm on-site fly development prior to purchase and release of biological control agents. Additionally, due to the low natural parasitism levels and domination of parasitism by Spalangia cameroni, augmentative releases using this species may be the most effective.

Experimental transmission of Corynebacterium pseudotuberculosis biovar equi in horses by house flies.

BACKGROUND: The route of Corynebacterium pseudotuberculosis infection in horses remains undetermined, but transmission by insects is suspected. OBJECTIVES: To investigate house flies (Musca domestica L.) as vectors of C. pseudotuberculosis transmission in horses. ANIMALS: Eight healthy, adult ponies. METHODS: Randomized, controlled, blinded prospective study. Ten wounds were created in the pectoral region where cages for flies were attached. Three ponies were directly inoculated with C. pseudotuberculosis. Four ponies were exposed for 24 hours to 20 hours C. pseudotuberculosis-inoculated flies. One negative control pony was exposed to noninoculated flies. Ponies were examined daily for swelling, heat, pain, and drainage at the inoculation site. Blood was collected weekly for CBC and biochemical analysis, and twice weekly for synergistic hemolysis inhibition titers. RESULTS: Clinical signs of local infection and positive cultures were observed in 7/7 exposed ponies and were absent in the negative control. In exposed ponies, peak serologic titers (1:512 to 1:2,048) were obtained between days 17 and 21. Seroconversion was not observed in the negative control. Neutrophil counts were higher in the positive and fly-exposed groups than in the negative control (P = .002 and P = .005) on day 3 postinoculation. Serum amyloid A concentrations were higher in the positive control than in the negative control and fly-exposed ponies on days 3 (P < .0001) and 7 (P = .0004 and P = .0001). No differences were detected for other biochemical variables. CONCLUSIONS AND CLINICAL IMPORTANCE: House flies can serve as mechanical vectors of C. pseudotuberculosis and can transmit the bacterium to ponies.

Development and Oviposition Preference of House Flies and Stable Flies (Diptera: Muscidae) in Six Substrates From Florida Equine Facilities.

House flies, Musca domestica L., and stable flies, Stomoxys calcitrans (L.), (Diptera: Muscidae), common pests on equine facilities, were studied in the laboratory to determine the success and duration of larval development and oviposition preferences on six substrates commonly found on equine facilities. Substrates tested were hay soiled with urine and manure, fresh horse manure, pine shaving bedding soiled with urine and manure (<12 h old), pine shaving bedding soiled with urine and manure (aged >72 h in a manure pile), builders sand bedding soiled with urine and manure aged 3 d, and soil from an overgrazed pasture mixed with urine and manure of variable age. House fly larvae failed to develop into adults in hay, soil, and sand substrates. Stable flies preferred to oviposit on substrates with plant material and not on fresh manure. However, when eggs were added to the substrates, pupariation was maximal in fresh manure and the fresh pine shaving substrate. Stable flies developed in all six equine substrates, but development was less successful on the substrates with soil. In choice tests, fresh manure and the fresh pine shaving substrates were the most attractive for house fly oviposition. These substrates also yielded the greatest number of house fly puparia from artificially added eggs. An understanding of oviposition preferences and differential larval development of house flies and stable flies on these substrates may help develop options for reducing pest populations by effectively managing equine waste and selecting appropriate bedding materials.

Larval Distribution and Behavior of Chrysomya rufifacies (Macquart) (Diptera: Calliphoridae) Relative to Other Species on Florida Black Bear (Carnivora: Ursidae) Decomposing Carcasses.

Larval interactions of dipteran species, blow flies in particular, were observed and documented daily over time and location on five black bear carcasses in Gainesville, FL, USA, from June 2002 - September 2004. Cochliomyia macellaria (Fabricius) or Chrysomya megacephala (Fabricius) larvae were collected first, after which Chrysomya rufifacies (Macquart) oviposited on the carcasses in multiple locations (i.e., neck, anus, and exposed flesh) not inhabited already by the other blow fly larvae. Within the first week of decomposition, C. rufifacies larvae grew to ≥12 mm, filling the carcasses with thousands of larvae and replacing the other calliphorid larvae either through successful food source competition or by predation. As a result, C. macellaria and C. megacephala were not collected past their third instar feeding stage. The blow fly species, C. megacephala, C. macellaria, Lucilia caeruleiviridis (Macquart), Phormia regina (Meigen), Lucilia sericata (Meigen), and C. rufifacies, completed two developmental cycles in the 88.5-kg carcass. This phenomenon might serve to complicate or prevent the calculation of an accurate postmortem interval.

Attraction of Stomoxys sp. to various fruits and flowers in Mali.

The attraction of three Stomoxys species to 26 fruits and 26 flowers of different plant species was investigated in two different sites in Mali during 2008. Stomoxys niger bilineatus Grunberg (Diptera: Muscidae) was attracted to a wider spectrum of species, significantly attracted by four fruits and eight flowers compared with control traps, whereas S. sitiens Rondani (Diptera: Muscidae) was attracted to six fruits and seven flowers of different plants, and S. calcitrans L. (Diptera: Muscidae) was only attracted to one fruit and three flowers. Cold anthrone assays showed a significantly higher prevalence of sugar feeding amongst all three species at the lagoon site than at the site near Mopti. The rhythm of activity study shows temporally separated blood- and sugar-feeding periods for S. niger bilineatus and S. sitiens, but not for S. calcitrans. A comparison between blood and sugar feeding throughout the day shows that sugar feeding activity is as frequent as blood feeding activity. Because not much is known about the preferred sugar sources for Stomoxys species in their natural habitats, the present study provides valuable information regarding the attraction capability of several plants with possible future implication for Stomoxys control strategies.

Nuisance flies on Australian cattle feedlots: immature populations.

Species composition, seasonality and distribution of immature fly populations on a southern Queensland feedlot during 2001-2003 were determined. Similar data were collected on feedlots in central New South Wales and central Queensland. The fly species recovered in the highest numbers were Musca domestica L. (Diptera: Muscidae), Stomoxys calcitrans L. (Diptera: Muscidae) and Physiphora clausa Macquart (Diptera: Ulidiidae). Houseflies were the dominant species at all feedlots. Houseflies preferred the warmer months from October to June, but stable flies preferred the cooler months and peaked in spring (September-November) and autumn (March-May). Larval abundance ratings recorded in the feedlot and numbers of larvae extracted in the laboratory from corresponding samples followed similar trends. Larvae of M. domestica were most abundant in the hospital and induction area and least abundant in horse stables and yards. Pupae of M. domestica were abundant in the hospital and induction area and drains, but least abundant in horse stables and yards. Larvae of S. calcitrans were most abundant in drains and least abundant in horse stables and yards. Pupae of S. calcitrans were most numerous in drains and least numerous in old cattle pens. Feedlot design and management had little effect on fly reduction.

Efficacy of commercial mosquito traps in capturing phlebotomine sand flies (Diptera: Psychodidae) in Egypt.

Four types of commercial mosquito control traps, the Mosquito Magnet Pro (MMP), the Sentinel 360 (S360), the BG-Sentinel (BGS), and the Mega-Catch Ultra (MCU), were compared with a standard Centers for Disease Control and Prevention (CDC) light trap for efficacy in collecting phlebotomine sand flies (Diptera: Psychodidae) in a small farming village in the Nile River Valley 10 km north of Aswan, Egypt. Each trap was baited with either carbon dioxide (CO2) from combustion of butane gas (MMP), dry ice (CDC and BGS traps), light (MCU and S360), or dry ice and light (CDC). Traps were rotated through five sites in a5 x 5 Latin square design, repeated four times during the height of the sand fly season (June, August, and September 2007) at a site where 94% of sand flies in past collections were Phlebotomus papatasi (Scopoli). A total of 6,440 sand flies was collected, of which 6,037 (93.7%) were P. papatasi. Of the CO2-baited traps, the BGS trap collected twice as many P. papatasi as the MMP and CDC light traps, and at least three times more P. papatasi than the light-only MCU and S360 traps (P < 0.05). Mean numbers (+/- SE) of P. papatasi captured per trap night were as follows: BGS 142.1 (+/- 45.8) > MMP 56.8 (+/- 9.0) > CDC 52.3 (+/- 6.1) > MCU 38.2 (+/- 6.4) > S360 12.6 (+/- 1.8). Results indicate that several types of commercial traps are suitable substitutes for the CDC light trap in sand fly surveillance programs.

Dispersal of stable flies (Diptera: Muscidae) from larval development sites in a Nebraska landscape.

Seven mark-recapture studies were conducted over 3 yr to assess dispersal of newly emerging adult stable flies, Stomoxys calcitrans L., from larval development sites in a mixed agricultural environment in northeastern Nebraska. Infested hay debris piles were marked by dusting their surfaces with fluorescent pigments, adults were captured with surrounding grids of Alsynite sticky traps, and specimens were dissected to determine feeding histories and reproductive age. Distances and directions of 3,889 marked specimens indicated males and females dispersed equally and in all directions. Midguts of males and females were equally likely to contain blood-meal remnants. Percentage with blood remnants and percentage of females with yolk increased with distance from mark origin, indicating survival and spread were positively associated with host finding success. A time-integrated diffusion model fit to results from the seven studies indicated 50% of stable fly adults had dispersed beyond 1.6 km of their natal site, but only 5% had dispersed beyond 5.1 km. These results indicate that stable fly adults on cattle in a given area are most likely to have originated from larval development sites within an ≈ 5 km radius of the subject cattle.

Evaluation of two commercial traps for the collection of Culicoides (Diptera: Ceratopogonidae).

Two types of commercial propane-powered traps, mosquito magnet (MM) (American Biophysics Corporation) MM-Freedom (Freedom) and MM-Liberty Plus (Liberty Plus), were evaluated for the collection of Culicoides. Trap preference and seasonal characteristics for the 3 major species, Culicoides furens, Culicoides barbosai, and Culicoides mississippiensis, were recorded from July 7, 2005, to July 24, 2006. Over 35 million Culicoides were captured during our study. When species were evaluated separately, analysis of overall mean trap collections yielded 5 months (February, March, June, September, and October) with significant trap effects. The Freedom trap captured more C. furens in June and October; the Liberty Plus trap captured more C. mississippiensis in February, March, and April, and more C. barbosai in September. The high numbers of Culicoides captured during our study suggest that the number of host-seeking Culicoides could potentially be reduced by continuous trapping during times when they are prevalent. Results of these investigations will be used to guide future control efforts.

Flybrella: a device to attract and kill house flies.

Flybrella is a lightweight inexpensive trap that can be suspended like an upside-down umbrella in prominent locations where house flies, Musca domestica L., rest. It consists of a solid, cylindrical backbone to which is attached a perforated transparent tube, or baffle, with a commercial sugar/toxicant strip affixed inside. Centered directly beneath the tube and also attached to the backbone is a 10-cm-diameter inverted opaque plastic cone. House flies readily enter the tube, feed on the fast-acting toxicant, and then fall directly down the tube where they are collected in and concealed by the cone. The cone may be emptied easily through a capped opening in the bottom. In paired indoor tests, the efficacy of the commercial sugar/toxicant strip was increased significantly by the individual addition of several other attractant materials. Variants of the original design were tested, including a more efficient design featuring two concentric tubes with offset perforations. The toxicant strip may be easily removed and/or replaced when desired.

Distinctive hydrocarbons of the black dump fly, Hydrotaea aenescens (Diptera: Muscidae).

Hydrotaea aenescens (Wiedemann), the black dump fly, is a potential biological control agent originally from the western hemisphere, now found in many parts of the Palearctic region except for the United Kingdom, where it cannot be imported for any reason. A complication of classical biological control is the problem of strain identification, as one must be able to somehow mark or follow a particular strain that has been introduced into the field or is contemplated for release. Gas chromatographic analysis of the surface hydrocarbons of pooled and individual dump fly adults resulted in reproducible hydrocarbon patterns that differentiated widely distributed strains of H. aenescens and showed similarities between strains that were related. Sexual dimorphism was observed in the surface hydrocarbons. Conspecific similarities included identities of the hydrocarbons found in colony material collected worldwide, with differences being found in the quantities of compounds present.

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.

Failure of Hydrotaea aenescens, a larval predator of the housefly, Musca domestica, to establish in wet poultry manure on a commercial farm in Florida, USA.

Hydrotaea aenescens (Weidemann) (Diptera: Muscidae) larvae and pupae were released in high-rise pullet houses in Pascoe County, Florida, U.S.A., for biological control of houseflies, Musca domestica L. (Diptera: Muscidae), in three separate tests during a 14-month period (April 1994-May 1995) and did not become established. However, H. aenescens believed to be from our releases did become established at a caged-layer farm 0.3 km from the release farm. Moisture in pullet house manure generally exceeded 80%, which is above the level at which H. aenescens is reared in colony. Caged-layer manure was also very wet, but crusted areas provided sites for H. aenescens larval development. Results demonstrate that H. aenescens adults will disperse from release sites and populate preferred sites without becoming a nuisance.

Effect of airflow on house fly (Diptera: Muscidae) distribution in poultry houses.

Numbers of fecal and vomit spots deposited by house flies, Musca domestica L., on spot cards were about twice as high on cards placed on the downwind sides as on the upwind sides of building support posts in caged-layer poultry houses with tunnel ventilation in Brooksville, FL. This trend was stronger at the ends of the houses where airflow is faster than in the relatively still-air center of the houses. A similar evaluation conducted in a pullet house (Zephyrhills, FL) with an evaporative cooling ventilation system revealed significantly higher fly counts on spot cards and sticky cards in downwind compared with upwind orientations. Flies in the pullet house were concentrated in both ends of the house and in the center, with comparatively fewer flies in the intermediate regions. There was a high degree of correlation between spot card and sticky card counts in the pullet house.

Effects on commercial broiler chicks of constant exposure to ultraviolet light from insect traps.

Constant exposure of newly hatched Avian x Avian broilers to ultraviolet light from insect traps for 42 d resulted in no significant differences in mortality, weight gain, feed consumption, or feed conversion. Birds were exposed to greater intensities of ultraviolet light for longer periods than could be expected under commercial conditions. Although house flies are rarely a problem in broiler houses, our results indicate that insect traps with ultraviolet light as an attractant would not be detrimental to production of broilers. The need for additional testing of light traps for nuisance fly control in commercial broiler houses is discussed.

Management of ectoparasites with biological control organisms.

Biological control is not a new concept, but for many reasons it is gaining interest for control of livestock ectoparasites. These reasons will be discussed, both from a political view and from environmental and economic views. The US government has vowed to reduce pesticide use by the year 2000, but other forces may drive this change even faster. Pesticide costs are high, and efficacy against some pests is questionable. Also, many producers are concerned about the environment, and are anxious to do their part to reduce chemical pollution. Specialised training is required to reduce on-the-farm difficulties involved with the use of biological-control organisms. Otherwise, how do producers or veterinarians purchase and use biocontrol organisms, and how do they critique what has been purchased? Included is a short summary of the three most common ectoparasites of livestock, and the type of biological-control strategies being developed to combat them. Much of the classical work has been done on filth fly control, most likely because of the nuisance status of flies, and because of the availability of candidate beneficial organisms, particularly parasitic wasps. And finally, two fly-control success stories will be briefly described. Tremendous strides have been made in house-fly and stable-fly control with parasitic wasps on feedlots, but more work is needed to better understand the habits of immature fly populations. A predaceous fly is being tested for pest fly control in dairies. Larvae of this fly can kill 15-20 house-fly larvae daily, and the adults do not become pestiferous on farms or around homes. Biological control will be an important part of livestock pest control in the future, but its implementation will require a corps of educated producers who are confident that biological control can work for them.

Effects on white Leghorn hens of constant exposure to ultraviolet light from insect traps.

Constant exposure of Hy-Line W-36 White Leghorn hens to ultraviolet light from insect traps resulted in no significant differences in egg production, fertility, hatchability of fertile eggs, or total hatchability. Also, there were no apparent effects on the eyes of the birds. Results were the same when either blacklight or blacklight blue tubes were used. The need for additional testing of light traps for nuisance fly control in commercial caged layer houses is discussed.

Development of house flies (Diptera:Muscidae) in sand containing varying amounts of manure solids and moisture.

House flies, Musca domestica L., developed in 200 cm3 of coarse sand containing just 1 ml (0.47%) of dairy manure solids and 10 ml (4.74%) of moisture. At these levels, development was slow (21.5 d from 1st instar to adult), adult survival was low (7.5%), but successful development did occur. At higher manure and moisture levels, rates of development and survival were similar to those reported previously. All soil samples collected from a feedlot dairy contained higher levels of manure solids than the highest level tested in the laboratory. The implications for fly control in soil/manure mixtures and the need for additional studies are discussed.

Biology and control of tabanids, stable flies and horn flies.

Tabanids are among the most free-living adult flies which play a role as livestock pests. A single blood meal is used as a source of energy for egg production (100-1,000 eggs per meal), and females of certain species can oviposit before a blood meal is obtained (autogeny). Therefore, the maintenance of annual populations requires successful oviposition by only 2% of females. Wild animal blood sources are usually available to maintain annual tabanid populations. Larval habitats are also independent of domestic livestock. Thus, the use of repellents or partial repellents is the only effective chemical strategy to reduce the incidence of tabanids on livestock. Permanent traps (and possibly treated silhouette traps) can be employed to intercept flies. Selective grazing or confinement can also reduce the impact of tabanids. Stable fly adults are dependent on vertebrate blood for survival and reproduction, but the amount of time spent in contact with the host is relatively small. Stable fly larvae develop in manure, spilled feed and decaying vegetation. Management of larval habitats by sanitation is the key to stable fly control. Treatment of animals with residual insecticides can aid in control; thorough application to the lower body parts of livestock is important. Proper use of modified traps, using either treated targets or solar-powered electrocution grids, can be effective in reducing stable fly populations. Adult horn flies spend the major part of their time on the host, and the larvae are confined to bovid manure. Therefore, almost any form of topical insecticide application for livestock is effective against horn flies, in the absence of insecticide resistance. Treatments should be applied when economic benefit is possible; economic gains are associated with increased weaning weights and weight gains of yearling and growing cattle. Oral chemical treatments (insect growth regulators or insecticides) administered at appropriate rates via bolus, water, food or mineral mixtures can inhibit horn fly larval development. However, adult horn fly movement among cattle herds limits the use of larval control for horn fly population management. The augmentation of native parasites, predators and competitors has been attempted and even promoted for horn fly and stable fly control, but evidence for the success of such programmes is equivocal.

New diets for production of house flies and stable flies (Diptera: Muscidae) in the laboratory.

A diet for rearing the house fly, Musca domestica (L.), was developed from feed constituents available on a year-round basis in Gainesville, FL. The diet, called the Gainesville House Fly Diet, performed as well or better than the Chemical Specialties Manufacturers' Association fly larval medium (CSMA) and can be mixed, bagged, and delivered by a local feed mill within 3 d. By adding pelleted peanut hulls 1:1 by volume, the house fly diet becomes suitable for rearing the stable fly, Stomoxys calcitrans (L.). Use of these diets and the economics involved are discussed further.