Seasonal abundance of stable flies and house flies (Diptera: Muscidae) in dairies in Alberta, Canada

Seasonal dynamics of Diptera in individual biotopes in the center of the European part of Russia

In a changing climate, phenological observations are gaining new importance. They can tell what changes are taking place in certain environmental conditions. The studies were conducted in 2019 within the territory of the Republic of Mordovia (the center of the European part of Russia). Beer traps (beer as a bait) were used to collect Diptera. The material was collected in the period from April to October in different forest biotopes (pine forest, lime forest, aspen forest, birch forest and oak forest) and the air temperature was recorded at the same time. In total, more than 14.000 specimens of Diptera were recorded. Overall, 29 families were recorded. The largest number of families was observed for birch (23 families) and pine (24 families) forests, the smallest number – in aspen forest (16 families). The families Muscidae, Drosophilidae, Calliphoridae had the largest number of captured individuals (44.5%, 35.2%, 7.6% of the total number of individuals respectively). The highest number of individuals was captured in oak forest. The dynamics of abundance in all biotopes were similar and were characterized by the same number of declines and rises. The first small significant peak in the number of Diptera occurred in the first half of summer. A slight increase in the number of specimenі occurred in mid-June. In the second half of September, there was a gradual increase in the number and the maximum peak was recorded in mid-October, then there was a decline. The autumn increase in the number of Diptera in all five biotopes exceeded the summer peak by several times. This dynamic was typical for most families. However, species from the family Lonchaeidae had the peak in July. For our better understanding of the changes in the seasonal dynamics of the number of Diptera, long-term observations in different climatic zones are needed.

Seasonal dynamics of Diptera in individual biotopes in the center of the European part of Russia

In a changing climate, phenological observations are gaining new importance. They can tell what changes are taking place in certain environmental conditions. The studies were conducted in 2019 within the territory of the Republic of Mordovia (the center of the European part of Russia). Beer traps (beer as a bait) were used to collect Diptera. The material was collected in the period from April to October in different forest biotopes (pine forest, lime forest, aspen forest, birch forest and oak forest) and the air temperature was recorded at the same time. In total, more than 14.000 specimens of Diptera were recorded. Overall, 29 families were recorded. The largest number of families was observed for birch (23 families) and pine (24 families) forests, the smallest number – in aspen forest (16 families). The families Muscidae, Drosophilidae, Calliphoridae had the largest number of captured individuals (44.5%, 35.2%, 7.6% of the total number of individuals respectively). The highest number of individuals was captured in oak forest. The dynamics of abundance in all biotopes were similar and were characterized by the same number of declines and rises. The first small significant peak in the number of Diptera occurred in the first half of summer. A slight increase in the number of specimenі occurred in mid-June. In the second half of September, there was a gradual increase in the number and the maximum peak was recorded in mid-October, then there was a decline. The autumn increase in the number of Diptera in all five biotopes exceeded the summer peak by several times. This dynamic was typical for most families. However, species from the family Lonchaeidae had the peak in July. For our better understanding of the changes in the seasonal dynamics of the number of Diptera, long-term observations in different climatic zones are needed.

Stable fly activity is associated with dairy management practices and seasonal weather conditions

Stable flies (Stomoxys calcitrans) are blood-sucking insects commonly associated with cattle production systems worldwide and are known to cause severe irritation to cattle due to painful bites. Cattle react to biting stable flies with an aggregating behavior known as bunching. Bunching behavior reduces grazing or feed consumption and thus reduces cattle productivity and welfare. Cattle’s fly-repelling behaviors include foot stomping, head tossing, tail switching and skin twitching. A longitudinal study was conducted in 2017 on 20 California dairies (average lactating herd size = 2,466 (SE±28.392)) during the stable fly season from April to July. The study objectives were to estimate the association between environmental factors and dairy characteristics including facility design, feed and manure management, total mixed ration (TMR) components fed to cattle, and operational pest management procedures and the outcome stable fly activity on California dairies. Stable fly activity was measured by counting stable flies on cow forelimbs (leg count) and on Alsynite traps (trap count) over the 13-week study period. Weekly leg counts were performed for cattle in lactating cow pens (31 pens from 10 study dairies) with counts made during the morning (AM) and again during the afternoon (PM). Trap counts were performed on all 20 study dairies. Data were analyzed using linear mixed models which revealed temporal variation in the average leg and trap counts with stable fly activity increasing from May to June and then decreasing to the lowest activity in July. Leg counts were higher during the afternoon compared to morning. Ambient temperatures ≤30⁰C and relative humidity (RH) measurements <50% were associated with higher leg and trap counts. Traps located at the periphery of study dairies had higher stable fly counts compared to traps located in the interior of the dairy. Cow pens with trees on the periphery had higher leg counts in comparison to pens away from trees. Specific TMR components were associated with both leg and trap counts. Dairies feeding by-products including almond hulls, wet distillers’ grain, fruits, and vegetables had higher trap counts compared to dairies that did not feed these ingredients. At the pen level, pens with rations that contained straw had lower average leg counts compared to pens fed with rations that did not contain straw. A similar association was observed for pens with rations that contained wheat silage when ambient temperatures were ≤30⁰C. In contrast, pens with water added to the TMR while the RH was ≥50% had higher average leg counts compared to pens without water added to the TMR. Dairies that applied insecticides for fly control to their entire facility had lower trap counts compared to dairies that did not apply insecticides. Stable fly activity measured on California dairies using leg and trap counts varied according to the month, environmental factors, pen surroundings, trap location, TMR components, and insecticide use.

The combined effects of temperature and relative humidity parameters on the reproduction of Stomoxys species in a laboratory setting

In this study, Stomoxys species (S. calcitrans, S. sitiens and S. indica) were examined to improve on the current technique for mass rearing using a method of combined incubation parameters. Moreover, the reproductive potential of immature forms at various stages of development was defined. Immature forms of stable flies were incubated according to species. There was no significant difference in the number of immature forms obtained among species incubated under the same conditions. Six incubation parameters were used in combination, at temperatures (T) of 32°C, 27°C and 22°C and relative humidity (RH) of 90% and 70% RH. The combined method resulted in a higher number of eggs hatching at 32°C and 90% humidity as well as an increase in the number of larva pupated and emergence of imago at 27°C and 70% humidity.

Seasonal abundance of the stable fly Stomoxys calcitrans in southwest England

The stable fly Stomoxys calcitrans (L.) is a cosmopolitan biting fly of both economic and welfare concern, primarily as a result of its painful bite, which can cause blood loss, discomfort and loss of productivity in livestock. Between June and November in 2016 and May and December in 2017, Alsynite sticky-traps were deployed at four Donkey Sanctuary sites in southwest England, which experience recurrent seasonal biting fly problems. The aim was to evaluate the seasonal dynamics of the stable fly populations and the risk factors associated with abundance. In total, 19 835 S. calcitrans were trapped during the study period. In both years, abundance increased gradually over summer months, peaking in late August/September. There were no relationships between seasonally detrended abundance and any climatic factors. Fly abundance was significantly different between sites and population size was consistent between years at three of the four sites. The median chronological age, as determined by pteridine analysis of flies caught live when blood-feeding, was 4.67 days (interquartile range 3.8-6.2 days) in males and 6.79 days (interquartile range 4.8-10.4 days) in females; there was no significant, consistent change in age or age structure over time, suggesting that adult flies emerge continuously over the summer, rather than in discrete age-related cohorts. The data suggest that flies are more abundant in the vicinity of active animal facilities, although the strong behavioural association between flies and their hosts means that they are less likely to be caught on traps where host availability is high. The implications of these results for fly management are discussed.

Effects of Diet Quality and Temperature on Stable Fly (Diptera: Muscidae) Development

The effects of diet quality and temperature on the development time and size of stable flies, Stomoxys calcitrans (L.), was evaluated. Both development time and size varied relative to diet quality and temperature, and their effects were additive. Diet quality and temperature made similar contributions to the variance in size whereas temperature was responsible for >97% of the variance in development time. Regression analysis predicted the shortest development time, egg to adult, to be 12.7 days at 32 °C and 70% nutrients. Egg to adult development varied curvilinearly relative to diet quality and temperature on the degree day 10 (DD10) scale taking 261 DD10 at 30 °C and 50% nutrients. The thermal threshold was 11.5 °C with a thermal constant of 248. Very few stable flies developed to adult on the poorest diet (12.5% nutrients) and adults emerged from fewer than 1% of the puparia at 35 °C. The heaviest pupae (15.4 mg) were produced with the 100% diet at 15 °C and adults had a higher probability of emerging successfully from heavier puparia. The length of the discal-medial cell of adult wings had a cubic relationship with puparia weight and peaked at 21 °C. Egg to pupariation survival was predicted to peak at 27 °C and 71% diet whereas puparia to adult survival peaked at 24 °C and 100% diet. Diet quality and temperature had no effect on sex ratio and the rate of development did not differ between the sexes. Female stable flies were ≈5% larger than males. Composite metrics for egg to pupariation and egg to adult fitness were developed. The optimum for puparia fitness was 29 °C and 78% diet quality and for adult fitness 25 °C and 83% diet quality. Diet accounted for 31% of the variance in pupal fitness and 24% of the variance in adult fitness whereas temperature accounted for 17% and 20%, respectively.

The Factors Influencing Seasonal Dynamics and Spatial Distribution of Stable Fly Stomoxys calcitrans (Diptera, Muscidae) within Stables

The biology of the stable fly is fairly well known, but factors influencing the distribution of adult stable flies within stables are still inadequately investigated. The four experimental stables were located in south western Slovakia. Within each stable, five sticky traps were localized along the stable, and the flies were weekly counted during the flight season of years 2015–2017. Seasonal activity and stable fly abundance in relation to temperature, rainfall, light conditions, relative air humidity, and cows per stable were evaluated. The seasonal activity of the stable fly shows one large peak at the end of summer and a second smaller peak just before the end of the flight season. The spatial distribution of stable flies was unique for each stable. All of the environmental variables had significant and mostly positive effect on stable fly abundance. The strongest and most positive effect on stable fly counts was temperature and rainfall five weeks prior to collecting session. Within the stable, cow number, air humidity, and light conditions are the strongest candidates to influence their distribution.

Predicting nuisance fly outbreaks on cattle feedlots in subtropical Australia

Flies are important arthropod pests in intensive animal facilities such as cattle feedlots, with the potential to cause production loss, transmit disease and cause nuisance to surrounding communities. In the present study, seasonal population dynamics of three important nuisance flies, namely house flies (Musca domestica L.), bush flies (M. vetustissima Walker) and stable flies (Stomoxys calcitrans L.) (Diptera: Muscidae), were monitored on cattle feedlots in south-eastern Queensland, Australia, over 7 years. Musca domestica was by far the dominant species, comprising 67% of the total flies trapped. Models were developed to assess the relationship between weather parameters and fly abundance and to determine whether population trends could be predicted to improve the timing of control measures. For all three species, there were two main effects, namely time-of-year (mainly reflected by minimum temperatures and solar radiation) and rainfall. The abundance of all three species increased with increasing temperature and rainfall, reaching a peak in summer, before decreasing again. Rainfall events resulted in significantly elevated numbers of M. domestica for up to 5 weeks, and for 1 week for M. vetustissima. Peak fly numbers were predicted by the model to occur in spring and summer, following 85–90-mm weekly rainfall. The population dynamics of S. calcitrans were least influenced by rainfall and it was concluded that weather variables were of limited use for forecasting stable fly numbers in this environment and production system. The models provide a useful tool for optimising the timing of fly-control measures, such as insecticide or biopesticide applications, adding to the efficiency of integrated control programs.

Evidence for Sticky-Trap Avoidance by Stable Fly, Stomoxys calcitrans (Diptera: Muscidae), in Response to Trapped Flies

Populations of stable flies, Stomoxys calcitrans, and other filth flies are often sampled using sticky traps. We wanted to know whether flies already caught on sticky traps might inhibit to some extent subsequent flies from being caught. To test this, we recorded the number of stable flies landing on white plastic corrugated panels (Coroplast®), which were prepared according to 4 treatments: 12 live stable flies glued to the surface, 12 live house flies (Musca domestica) glued to the surface, 12 black dots, and no treatment. From 160 observations, we found that fewer stable flies landed on panels with either attached stable flies (129) or house flies (133) compared with the number landing on panels with black dots (259) and/or with no treatment (210). This apparent inhibitory effect of trapped flies may explain published trap-catch patterns from field studies.

Precipitation and Temperature Effects on Stable Fly (Diptera: Muscidae) Population Dynamics

The dynamics of stable fly, Stomoxys calcitrans (L.), populations relative to temperature and precipitation were evaluated in a 13-yr study in eastern Nebraska. During the course of the study, >1.7 million stable flies were collected on an array of 25 sticky traps. A log-normal model using degree-days with a 15 °C threshold and weekly lags 0-4 for temperature and 2-7 for precipitation provided the best fit with the observed data. The relationships of temperature and precipitation to stable fly trap catches were both curvilinear, with maxima at 6.6 degree-day-15 (≈22 °C) and 7.4 mm precipitation per day, respectively. The temperature and precipitation model accounted for 72% of the variance in seasonal trap catches.

House Flies in the Confined Cattle Environment Carry Non-O157 Shiga Toxin-Producing Escherichia coli

Cattle manure is one of the primary larval developmental habitats of house flies, Musca domestica (L.). Cattle serve as asymptomatic reservoirs of Shiga toxin-producing Escherichia coli (STEC), and bacteria are released into the environment in cattle feces. The USDA-FSIS declared seven STEC serogroups (O157, O26, O45, O103, O145, O121, and O111) as adulterants in beef products. In addition, the serogroup O104 was a culprit of a large outbreak in Germany in 2011. Our study aimed to assess the prevalence of seven non-O157 STEC (O26, O45, O145, O103, O121, O111, and O104) serogroups in adult house flies. Flies (n = 463) were collected from nine feedlots and three dairy farms in six states in the United States and individually processed. This involved a culturing approach with immunomagnetic separation followed by multiplex polymerase chain reactions for detection of individual serogroups and virulence traits. The concentration of bacteria on modified Possé agar ranged between 1.0 × 101 and 7.0 × 107 (mean: 1.5 ± 0.3 × 106) CFU/fly. Out of 463 house flies, 159 (34.3%) carried one or more of six E. coli serogroups of interest. However, STEC was found in 1.5% of house flies from feedlots only. These were E. coli O103 and O104 harboring stx1 and ehxA and E. coli O45 with stx1, eae, and ehxA. This is the first study reporting the isolation of non-O157 STEC in house flies from the confined cattle environment and indicating a potential role of this insect as a vector and reservoir of non-O157 STEC in confined beef cattle.

Biology and trapping of stable flies (Diptera: Muscidae) developing in pineapple residues (Ananas comosus) in Costa Rica

Pineapple production in Costa Rica increased nearly 300-fold during the last 30 yr, and >40,000 hectares of land are currently dedicated to this crop. At the end of the pineapple cropping cycle, plants are chopped and residues incorporated into the soil in preparation for replanting. Associated with increased pineapple production has been a large increase in stable fly, Stomoxys calcitrans (L.), populations. Stable flies are attracted to, and oviposit in, the decomposing, chopped pineapple residues. In conjunction with chemical control of developing larvae, adult trapping is an important control strategy. In this study, four blue-black fabric traps, Nzi, Vavoua, Model H, and Ngu, were compared with a white sticky trap currently used for stable fly control in Costa Rica. Overall, the white sticky trap caught the highest number of stable flies, followed by the Nzi, Vavoua, Model H, and Ngu. Collections on the white sticky trap increased 16 d after residues were chopped; coinciding with the expected emergence of flies developing in the pineapple residues. During this same time period, collections in the blue-black fabric traps decreased. Sex ratio decreased from >7:1 (females:males) 3-7 d after chopping to 1:1 at 24-28 d. White sticky, Nzi and Vavoua traps collected similar numbers of colonizing flies 3-7 d after residues were chopped. However, white sticky traps collected more flies once emergence from the pineapple residues began. Although white sticky traps collected more flies than fabric traps, they remain labor intensive and environmentally unsound because of their disposable and nonbiodegradable nature.

Stable Fly, Stomoxys calcitrans (L.), Dispersal and Governing Factors

Although the movement of stable fly, Stomoxys calcitrans (L.), has been studied, its extent and significance has been uncertain. On a local scale (<13 km), fly movement occurs between host animals and resting sites to feed and mate, mainly at on-farm locations where herbivorous livestock regularly congregate. Small numbers emigrate from livestock congregation sites in search of other hosts and oviposition substrate, mostly within <1.6 km. Such local movement occurs by flight ~90 cm above ground, or with moving livestock. While stable flies are active year-round in warm latitudes, cold winters in temperate areas result in substantial population and activity declines, limiting movement of any sort to warmer seasons. Long-distance dispersal (>13 km) is mainly wind-driven by weather fronts that carry stable flies from inland farm areas for up to 225 km to beaches of northwestern Florida and Lake Superior. Stable flies can reproduce for a short time each year in washed-up sea grass, but the beaches are not conducive to establishment. Such movement is passive and does not appear to be advantageous to stable fly's survival. On a regional scale, stable flies exhibit little genetic differentiation, and on the global scale, while there might be more than one "lineage", the species is nevertheless considered to be panmictic. Population expansion across much of the globe likely occurred from the late Pleistocene to the early Holocene in association with the spread of domesticated nomad livestock and particularly with more sedentary, penned livestock.

Repellent effectiveness of seven plant essential oils, sunflower oil and natural insecticides against horn flies on pastured dairy cows and heifers

Plant essential oils (basil, geranium, balsam fir, lavender, lemongrass, peppermint, pine and tea tree), mixed with either sunflower oil or ethyl alcohol, were applied at 5% concentrations to the sides of Holstein cattle. Pastured cattle treated with essential oils diluted in sunflower oil had less flies than the untreated control for a 24-h period. However, the essential oil treatments were not significantly different than the carrier oil alone. Barn-held heifers treated with essential oils and sunflower oil alone had significantly less flies than the untreated control for up to 8 h after treatment. Basil, geranium, lavender, lemongrass and peppermint repelled more flies than sunflower oil alone for a period ranging from 1.5 to 4 h after treatments applied to heifers. All essential oils repelled > 75% of the flies on the treated area for 6 and 8 h on pastured cows and indoor heifers, respectively. Geranium, lemongrass and peppermint stayed effective for a longer duration. Essential oils mixed with ethyl alcohol demonstrated less repellence than when mixed with the carrier oil. Safer's soap, natural pyrethrins without piperonyl butoxide and ethyl alcohol alone were not efficient at repelling flies. Essential oils could be formulated for use as fly repellents in livestock production.

Development of a novel walk-through fly trap for the control of horn flies and other pests on pastured dairy cows

A prototype walk-through fly vacuum system, designed to remove horn flies Haematobia irritans (L.) (Diptera: Muscidae) from cattle, was developed and tested for efficacy. The study was conducted during 4 fly seasons over 17 consecutive weeks each year within the months of May through September at 1 dairy research herd in the coastal plain of North Carolina. Additional data on horn flies, as well as face flies (Musca autumnalis) and stable flies (Stomoxys calcitrans), were collected during 1 yr from 7 commercial pasture-based and organic dairy farms in the piedmont region of North Carolina. The number of flies observed on animals in the pasture was compared with the number of flies collected in the trap. Studies were initiated after horn fly densities had met or exceeded a threshold of 200 flies per animal. The vacuum trap removed between 1.3 and 2.5 million flies annually from the research station cattle. Most fly removal occurred during the first few weeks of operation and maintained densities below threshold thereafter. Cattle using the fly trap at the research farm had only about 28% the number of horn flies as untreated cattle, and reductions ranged from 67.5 to 74.5% across the 4-yr study. In addition to large numbers of horn flies, traps placed on commercial dairies during 1 yr collected stable flies, face flies, and house flies, all species with differing behavior and larger in size than horn flies. The estimated cost of running the trap is $72 per season at commercial rates of $0.12 per hour and an expected 4h of daily operation during the time of milking. Use of a vacuum system as described herein has potential as a cost-effective method in reducing populations of parasitic flies in pasture-based dairy production systems without the use of insecticides.

Spatial distribution, seasonality and trap preference of stable fly, Stomoxys calcitrans L. (Diptera: Muscidae), adults on a 12-hectare zoological park

Although this study was originally designed to compare the efficacy of two different stable fly traps within 10 sites at a 12-ha zoological park, seasonal and spatial population distribution data were simultaneously collected. The two traps included an Alsynite fiberglass cylindrical trap (AFT) and a blue-black cloth target modified into a cylindrical trap (BCT). Both traps were covered with sticky sleeves to retain the attracted flies. Paired trap types were placed at sites that were 20–100 m apart. Distance between trap pairs within sites ranged from 1 to 2 m, and was limited by exhibit design and geography. Both trap types reflect/refract ultraviolet (UV) light which attracts adult S. calcitrans. During this 15-week study, AFTs captured significantly more stable flies than the BCTs at 8 of the 10 sites. Of the 12,557 stable flies found on the traps, 80% and 20% were captured by AFTs and BCTs, respectively. The most attractive trap site at the zoo was at the goat exhibit where most stable flies were consistently captured throughout the study. This exhibit was 100 m from the other exhibits, next to a small lake, and adjacent to a field containing pastured exotic ungulates, rhea and ostrich. Stable fly populations peaked in early June then slowly decreased as the last trapping date approached. We believe this to be the first seasonality data collected at a zoological park. Results demonstrate the use of urban zoos by stable flies and the need to develop environmentally friendly stable fly management systems for zoos. Zoo Biol. 33:228–233, 2014. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

Spatial-temporal dynamics of stable fly (Diptera: Muscidae) trap catches in Eastern Nebraska

Spatial and temporal relationships among catches of adult stable flies, Stomoxys calcitrans (L.), on sticky traps in eastern Nebraska were evaluated. Twenty-five alsynite sticky traps were placed in a 5 by 5 grid with ≍1.6-km intervals in a mixed agricultural environment from 2003 to 2011. Denser grids of 45-90 traps were implemented for varying lengths of time during the course of the study. More than two million stable flies were collected over 9 yr. Seasonal abundances based upon total collections from the primary grid of 25 traps were bimodal most years with population peaks in June and September or October. Individual trap catches varied greatly, both spatially and temporally. Trap catches were spatially aggregated with autocorrelation extending to ≍2 km. Synchrony among trap catches declined linearly with respect to distance between traps and differences in seasonal distribution increased asymptotically relative to distance between traps. Proximity to confined livestock facilities increased catch and proportion of catch collected later in the season. Fifteen to 20 traps were adequate for estimating stable fly populations with the standard error of the mean equal to 30% of the mean for most of the stable fly season. Early and late in the season, when mean trap catches were low, between 100 and 135 traps would be needed to maintain that level of confidence. Seasonal collection distributions from permutations of subsets of the data with fewer than 24 traps differed significantly from those of the complete grid of 25 traps, indicating that 20 or more traps may be needed to evaluate the seasonal dynamics of a stable fly population.

Seasonality and daily flight activity of stable flies (Diptera: Muscidae) on dairy farms in Saraburi Province, Thailand

Knowledge of seasonal abundance and flight activity patterns are required to design effective management programs for insect pests of humans and livestock. In this study, the seasonality and daily flight activity of Stomoxys species were observed on two dairy farms in Saraburi Province, Thailand. Data were assessed throughout 1 year using Vavoua traps from September 2010 to August 2011. A total of 2,520 individuals belonging to four species were collected. Most Stomoxys species peaked in September (rainy season) and gradually decreased in number toward February (dry season); a second peak occurred between March and April (hot season). Stomoxys calcitrans was caught throughout the year and was the most abundant species in this study. The total number of males and females of S. calcitrans differed significantly among seasons and time intervals. The weather parameters of relative humidity and light intensity were significantly correlated with S. calcitrans abundance.

Stable fly phenology in a mixed agricultural--wildlife ecosystem in northeast Montana

The stable fly, Stomoxys calcitrans (L.), is a cosmopolitan species of blood-feeding Muscidae and an important pest of cattle. Although the cattle industry is the largest commodity in Montana, no research has been conducted on the abundance, distribution, or impact of stable flies in the state. Observations of stable flies attacking West Nile virus (family Flaviviridae, genus Flavivirus, WNV) -infected pelicans on a refuge in close proximity to pastured and confined cattle provided an opportunity to describe stable fly phenology in a mixed agricultural-wildlife ecosystem. Coroplast cards used to monitor and compare adult populations in three habitats (peninsula, pasture, confinement lot) located within 1.5-4.5 km of each other revealed that temporal dynamics differed by site. Adult abundance was generally lowest at the confinement lot, the only location where larval development was identified. Stable flies were collected on all traps placed in pasture, with traps adjacent to pastured cattle consistently collecting the most. Adults also were collected on the peninsula supporting the pelicans' nesting site, but whether the potential hosts or physical landscape served as an attractant is unclear. At all three sites, data indicated that overwintering was not successful and that a transition occurred from early season immigrating adults that used suitable local larval development substrates to subsequent autochthonous populations.

Effects of temperature on mortality of larval stable fly (Diptera: Muscidae) caused by five isolates of Bacillus thuringiensis

We examined the effects of temperature on mortality of larval stable fly [Stomoxys calcitrans (L.)] caused by Bacillus thuringiensis tolworthi 4L3, B. t. darmastedensis 4M1, B. t. thompsoni 401, B. t. thuringiensis HD2, and B. t. kurstaki HD945. At moderate doses, mortality caused by all isolates ranged from 87 to 99% at 15 degrees C and declined to 29-63% as temperature increased to 30 degrees C. A similar pattern was seen when a higher dose was used, except that the reduction in mortality at warmer temperatures was not as great as was seen with the moderate doses. Insecticidal activity of each isolate against first-instar larvae was reduced by only 5-15% after 5 d in the medium. Mortality of second- and third-instar larvae ranged from 2 to 21%, suggesting the isolates were less effective against larger larvae.

Arthropod Surveillance Programs: Basic Components, Strategies, and Analysis

Effective entomological surveillance planning stresses a careful consideration of methodology, trapping technologies, and analysis techniques. Herein, the basic principles and technological components of arthropod surveillance plans are described, as promoted in the symposium "Advancements in arthropod monitoring technology, techniques, and analysis" presented at the 58th annual meeting of the Entomological Society of America in San Diego, CA. Interdisciplinary examples of arthropod monitoring for urban, medical, and veterinary applications are reviewed. Arthropod surveillance consists of the three components: 1) sampling method, 2) trap technology, and 3) analysis technique. A sampling method consists of selecting the best device or collection technique for a specific location and sampling at the proper spatial distribution, optimal duration, and frequency to achieve the surveillance objective. Optimized sampling methods are discussed for several mosquito species (Diptera: Culicidae) and ticks (Acari: Ixodidae). The advantages and limitations of novel terrestrial and aerial insect traps, artificial pheromones and kairomones are presented for the capture of red flour beetle (Coleoptera: Tenebrionidae), small hive beetle (Coleoptera: Nitidulidae), bed bugs (Hemiptera: Cimicidae), and Culicoides (Diptera: Ceratopogonidae) respectively. After sampling, extrapolating real world population numbers from trap capture data are possible with the appropriate analysis techniques. Examples of this extrapolation and action thresholds are given for termites (Isoptera: Rhinotermitidae) and red flour beetles.

Dewatered sewage biosolids provide a productive larval habitat for stable flies and house flies (Diptera: Muscidae)

Species diversity and seasonal abundance of muscoid flies (Diptera: Muscidae) developing in biosolid cake (dewatered biosolids) stored at a wastewater treatment facility in northeastern Kansas were evaluated. Emergence traps were deployed 19 May through 20 October 2009 (22 wk) and 27 May through 18 November 2010 (25 wk). In total, 11,349 muscoid flies were collected emerging from the biosolid cake. Stable flies (Stomoxys calcitrans (L.)) and house flies (Musca domestica (L.)), represented 80 and 18% of the muscoid flies, respectively. An estimated 550 stable flies and 220 house flies per square-meter of surface area developed in the biosolid cake annually producing 450,000 stable flies and 175,000 house flies. Stable fly emergence was seasonally bimodal with a primary peak in mid-July and a secondary peak in late August. House fly emergence peaked with the first stable fly emergence peak and then declined gradually for the remainder of the year. House flies tended to emerge from the biosolid cake sooner after its deposition than did stable flies. In addition, house fly emergence was concentrated around midsummer whereas stable fly emergence began earlier in the spring and continued later into the fall. Biosolid age and temperature were the most important parameters affecting emergence for house flies and stable flies, whereas precipitation was not important for either species. This study highlights the importance of biosolid cake as a larval developmental habitat for stable flies and house flies.

Population dynamics of stable flies Stomoxys calcitrans (Diptera: Muscidae) at an organic dairy farm in Denmark based on mark-recapture with destructive sub-sampling

A population of stable flies, Stomoxys calcitrans (L.), was studied on a Danish cattle farm in two successive years. Flies were captured monthly by sweep nettings and marked with fluorescent dust. Absolute population size, dilution rate, loss rate, and adult longevity were estimated by means of a modified version of Bailey's triple catch method. In both years, the abundance of flies peaked in July. Using a statistical model, we were able to explain 86.6% of the variation in the per capita growth rate r as a function of current temperature, precipitation, and population size. Omitting precipitation from the model, it still explained 69.3%. The model predicts that stable flies have a temperature optimum at 21.8°C, and that no development will take place when temperatures inside the stable are below 10.2°C or above 33.5°C. At the optimal temperature the intrinsic rate of natural increase is 0.070 d(-1). The per capita dilution rate increased with temperature and decreased with population size, whereas no effect of these factors on the per capita loss rate could be shown. Mean adult survival time was estimated to 6.3 d with 95% CL ranging from 4.3 to 11.1 d. The study points at the possibility of developing predictive models as tools for achieving better, and more environmentally sound, control of stable flies.

Economic impact of stable flies (Diptera: Muscidae) on dairy and beef cattle production

Stable flies, Stomoxys calcitrans (L.), are among the most damaging arthropod pests of cattle worldwide. The last estimate of their economic impact on United States cattle production was published 20 yr ago and placed losses at $608 million. Subsequently, several studies of effects of stable flies on beef cattle weight gain and feed efficiency have been published, and stable flies have become increasingly recognized as pests of cattle on pasture and range. We analyzed published studies and developed yield-loss functions to relate stable fly infestation levels to cattle productivity, and then estimated the economic impact of stable flies on cattle production in the United States. Four industry sectors were considered: dairy, cow-calf, pastured stockers, and feeder cattle. In studies reporting stable fly infestation levels of individual herds, median annual per animal production losses were estimated to be 139 kg of milk for dairy cows, and 6, 26, and 9 kg body weight for preweanling calves, pastured stockers, and feeder cattle, respectively. The 200,000 stable flies emerging from an average sized winter hay feeding site reduce annual milk production of 50 dairy cows by an estimated 890 kg and weight gain of 50 preweanling calves, stockers, or feeder cattle by 58, 680, or 84 kg. In 2009 dollars, the value of these losses would be $254, $132, $1,279, or $154, respectively. Using cattle inventories and average prices for 2005-2009, and median monthly infestation levels, national losses are estimated to be $360 million for dairy cattle, $358 million for cow-calf herds, $1,268 million for pastured cattle, and $226 million for cattle on feed, for a total impact to U.S. cattle industries of $2,211 million per year. Excluded from these estimates are effects of stable flies on feed conversion efficiency, animal breeding success, and effects of infested cattle on pasture and water quality. Additional research on the effects of stable flies on high-production dairy cows and nursing beef calves is needed to increase the reliability of the estimates.

Seasonal abundance of stable flies and filth fly pupal parasitoids (Hymenoptera: Pteromalidae) at Florida equine facilities

Beginning in November 2007 and continuing until December 2009, weekly stable fly, Stomoxys calcitrans (L.), surveillance was conducted at four equine facilities near Ocala, FL, by using alsynite sticky traps for adults and by searching immature developmental sites for pupae. Adult stable fly trap captures were highly variable throughout the year, ranging from 0 to 1,400 flies per trap per farm. The greatest adult stable fly activity was observed during the spring months of March and April, with weekly three-trap means of 121 and 136 flies per farm, respectively. The importance of cultural control measures was most apparent on the only farm with no reported insecticide use and the lowest stable fly trap captures, where an intense daily sanitation and composting program was conducted. A survey of on-site filth fly pupae revealed that 99.9% of all parasitoids recovered were Spalangia spp., consisting of Spalangia cameroni Perkins (56.5%), Spalangia nigroaenea Curtis (34.0%), Spalangia endius Walker (5.8%), and Spalangia nigra Latreille (3.7%). The implications of these findings are discussed.

Do climatic and physical factors affect populations of the blow fly Chrysomya megacephala and house fly Musca domestica?

The blow fly, Chrysomya megacephala (Fabricius), and house fly, Musca domestica L., are medically and forensically important flies. The population dynamic of these flies is essential for both control and forensical aspects. The aim of this study was to investigate the climatic and physical factors affecting the population trend of both species in Chiang Mai province, northern Thailand, using the Geographic Information System (GIS). Based on systematic random sampling, 18 study sites were selected in three districts (Mueang Chiang Mai, Mae Rim, and Hang Dong). Six land use types were involved in the study sites, i.e., disturbed mixed deciduous, mixed deciduous forest, mixed orchard, lowland village, city, and paddy field. Adult flies were sampled every 2 weeks using an in-house prototype reconstructable funnel trap. Two types of bait were used--one with fresh beef viscera for luring M. domestica and the other with 1-day tainted beef viscera for luring C. megacephala. Collections were conducted from May 2009 to May 2010, and analysis of climatic factors (temperature, relative humidity, and light intensity) was carried out. Correlation bivariate analysis was performed initially to determine the relationship between climatic factors and the number of flies. Consequently, an ordinary co-kriging approach, in ArcGIS 9.2, was performed to predict the spatial distribution of flies with land use and climatic factors as co-variables. A total of 63,158 flies were captured, with C. megacephala being the most common species collected (68.37%), while only 1.3% were M. domestica, thus proving that C. megacephala was the most abundant species in several land use types. A significantly higher number of females than males was found in both species. Fly populations can be collected throughout most of the year with a peak in late summer, which shows a positive relation to temperature but negative correlation with relative humidity. C. megacephala was predicted to be abundant in every land use type, from lowland to forested areas, while the density of house fly was association with altitude and land use types.

A longitudinal study of Besnoitia besnoiti infections and seasonal abundance of Stomoxys calcitrans in a dairy cattle farm of southwest France

Bovine besnoitiosis, caused by the cyst-forming apicomplexan Besnoitia besnoiti, is commonly reported in some restricted regions of South-Western Europe, and in larger regions of Africa and Asia. This infection is thought to be transmitted by blood feeding insects and is responsible for major economic losses in cattle production. A recent emergence in Europe, notified in the Centre of France, Spain and Germany, has attracted more attention to this disease. Clinical signs could appear in some animals; however, many infected cattle remain asymptomatic or show scleral-conjunctival cysts (SCC) only. Recent development of serological methods allows carrying out seroepidemiological field studies. In this respect, a long-term investigation was performed in a dairy cattle farm localized in an enzootic area of besnoitiosis of South-western France between March 2008 and May 2009. The objective was to estimate the seasonal pattern of B. besnoiti infections based on the presence of SCC and serology (ELISA and Western blot). In parallel, an entomological survey was conducted to describe population dynamics of Stomoxys calcitrans and Tabanidae species. The seroprevalence determined by Western blot in a cohort of 57 animals continuously present during the whole survey increased from 30% in March 2008 to 89.5% in May 2009 and was always higher than the prevalence based on clinically assessed SCC. New positive B. besnoitia seroconversions occurred throughout the year with the highest number in spring. In addition, many seroconversions were reported in the two months before turn-out and could be associated with a high indoors activity of S. calcitrans during this period.

Activity of Bacillus thuringiensis isolates against immature horn fly and stable fly (Diptera: Muscidae)

We screened 85 isolates of Bacillus thuringiensis (Berliner), making up 57 different subspecies, and two isolates of Bacillus sphaericus (Meyer and Neide) for activity against immature horn flies, Haematobia irritans (L.), and stable flies, Stomoxys calcitrans (L.). The majority of B. thuringiensis and the B. sphaericus isolates had little or no activity against horn fly and stable fly. Approximately 87% of the isolates caused < 50% mortality of horn fly larvae and 64% caused < 25% mortality. For stable fly, 95% of the isolates caused < 50% mortality, and 93% caused < 25% mortality. Five isolates were highly toxic to horn fly and stable fly immatures. These isolates were B. t. tolworthi 4L3, B. t. darmstadiensis 4M1, B. t. thompsoni 401, B. t. thuringiensis HD2, and B. t. kurstaki HD945. The LD50 values ranged from 2.2 to 7.9 x 10(6) spores per g manure for horn fly and from 6.3 to 35 x 10(6) spores per g media for stable fly. These were consistently more toxic compared with the B. t. israelensis isolates examined. All had DNA that hybridized with cry1Aa, cry1Ab, and cry1Ac toxin probes, three hybridized with a cry1B probe, and two hybridized with a cry2A probe. These may have potential for use in integrated management of pest flies.

Male stable fly (Stomoxys calcitrans) response to CO2 changes with age: evidence from wind tunnel experiments and field collections

Male stable flies require at least one or more blood meals to reach sexual maturity and are often caught in CO2-baited traps. We tested the hypothesis that young male stable flies (one to three days, one blood feeding session) would be more responsive to CO2 bait than older male stable flies by monitoring the upwind movement of different-aged male stable flies exposed to CO2 using a wind tunnel. The proportion of males moving upwind toward CO2 decreased with age (days), from 49% for males < or = 3 days old, to 4.5% for males > 3 days old. To further test this, we conducted daily sampling of stable fly populations at a beef farm using a CO2-baited cloth trap. We found that days on which a high proportion of males were caught, females were predominantly from early developmental stages, indicating that proportionately more males were caught from field populations made up of younger cohorts. These results were consistent with the wind tunnel experiment patterns.

Stable fly population dynamics in eastern Nebraska in relation to climatic variables

Stable flies, Stomoxys calcitrans (L.), are among the most economically important arthropod pests of livestock in North America. In this study, we monitored the seasonal dynamics of a stable fly population in eastern Nebraska for 5 yr. Models based upon temperature and precipitation were developed to determine the affects of these variables on population levels as well as to project population trends. Stable flies appear in eastern Nebraska in late March to early April, and they build to a peak population during the last week of June and first week of July. In most years, the population decreases in midsummer, and then it increases to a second peak in mid-September. Temperature 0 to 2 wk before collection and precipitation 3 to 6 wk before collection were the most important weather variables accounting for 63 and 11% of the variation, respectively. Temperature 7 wk before collection was also significant, accounting for 3% of the variation. Reduced precipitation levels explained the observed midsummer drop in the stable fly populations. Changes in stable fly population levels were positively correlated with precipitation 1 to 2 wk prior and temperature the week of the change. Population change was negatively correlated with precipitation 6-8 wk prior and temperature 6-15 wk prior. The addition of the previous weeks trap collections to the climate based model eliminated the significance of temperature 2 and 7 wk before collection. Temperature 0-1 wk before collection accounted for 60% of the variation, precipitation 3 to 6 wk prior 12% of the variation, and the previous weeks' trap collections accounted for 11% of the variation. Low temperatures during October through January were correlated with higher stable fly populations the following June and July.

A Note on the Effect of Controlling Stable Flies (Stomoxys Calcitrans) in the Resting Activity and Pen Distribution of Dairy Cows

This study investigated the effect of controlling stable flies (Stomoxys calcitrans) on the number of dairy cows lying down and their pen distribution. The study randomly assigned 80 Holstein cows to 1 of 2 groups. The treated group (T) included cows individually sprayed with insecticide when found with an average of 10 stable flies per cow; in the control group (C), cows received no application of insecticide. The pen had 4 equal-size areas: (a) feeding, (b) drinking and sunny, (c) covered, and (d) manure. The study recorded the number of cows lying and the area of the pen where the nonhuman animal was located. The study found no difference (p > .05) between the proportion of T and C cows lying. However, cows preferred to lie down in pen area 3 when fewer than 10 stable flies per cow were found. Area 4 was the most avoided section of the pen, except when a high incidence of flies was present. The study concluded that high populations of S. calcitrans (> 10 flies per cow) did not affect the number of dairy cows lying down. However, it modified site preferences for lying.

Relationship between rainfall and stable fly (Diptera: Muscidae) abundance on California dairies

Populations of adult stable flies, Stomoxys calcitrans (L.), were visually estimated by counting flies on the front legs of cattle on southern and central California confined dairy feedlots between late April and mid-June (encompassing the peak stable fly activity period). Fly counts on 45-90 animals (three to six dairies) per weekly sample date were conducted in 1985, 1986, 1993, 2002, and 2003. Average biting intensity (flies per front leg) for the peak fly season was not significantly related to early winter (December-January), late winter (February-March), or total period (December-March) rainfall, but it was strongly related (r2 = 0.726) to March rainfall. March rains probably moistened outside decaying manure habitats and similar substrates that are particularly suitable at that time for stable fly oviposition and larval development. Degree-day accumulations link the timing of significant (> or = 1.3 cm) late winter or early spring rains to peak adult stable fly activity two generations later in May and early June.

Temperature effects on development and survival of two stable flies, Stomoxys calcitrans and Stomoxys niger niger (Diptera: muscidae), in La Réunion Island

Two stable fly species, Stomoxys calcitrans (L., 1758) and Stomoxys niger niger Macquart, 1851, co-occur in La Reunion, where they are important pests of cattle. The survival and developmental rate of the immature stages were compared at five constant temperatures from 15 to 35 degrees C. In both species, immature survival was highest at 20-25 degrees C and markedly decreased at 15 and 35 degrees C. At the lower temperatures, mortality was observed mainly for S. calcitrans larvae and S. niger eggs. At the higher temperatures, mainly pupae of both species died. At all temperatures, S. calcitrans survived better than S. niger. Developmental time was highly similar in both species, decreasing from 71 d at 15 degrees C to 13 d at 30 degrees C in S. calcitrans and from 69 d at 15 degrees C to 14 d at 30 degrees C in S. niger. Developmental times increased slightly at 35 degrees C. Surprisingly, the tropical S. niger developed slightly faster than the cosmopolitan S. calcitrans at 15-20 degrees C; the reverse was found at higher temperatures. Temperature summation models confirmed that S. niger had a lower developmental threshold than S. calcitrans (11.3 versus 12.2 degrees C) and higher day-degree (DD) requirements to complete development (251 versus 225 DD). Overall, the results suggest that S. calcitrans is better adapted than S. niger, in terms of adult production from eggs, in the temperature range of La Reunion.

Retention of Escherichia coli by house fly and stable fly (Diptera: Muscidae) during pupal metamorphosis and eclosion

Populations of Escherichia coli obtained by feeding larval house flies, Musca domestica L. and stable flies, Stomoxys calcitrans (L.), persisted through the pupal stage. The abundance of E. coli in house fly pupae increased initially then declined before adult emergence. Abundance of E. coli in stable fly pupae increased through pupal development and remained high. Infected stable fly pupal cases typically contained more E. coli than house fly pupal cases. A greater proportion of emerging adult house flies were infected with E. coli compared with stable flies; however, the abundance of E. coli on infected flies was similar between species. Adult flies contained 0.04-0.19% of the E. coli in the pupal cases. The proportion of infected house fly adults and the amount of E. coli on the infected flies were related to the levels of E. coli in the pupal cases; however, these relationships did not occur with the stable fly. Results suggest that retention of E. coli from larval to adult house flies could play a role in the transmission and spread of E. coli, whereas stable fly adults probably play a minor role in E. coli spread. However, pupae of both species have potential to act as reservoirs for E. coli.

Persistence of Escherichia coli in immature house fly and stable fly (Diptera: Muscidae) in relation to larval growth and survival

The persistence of Escherichia coli in artificially fed larvae was examined for up to 48 h after ingestion by house flies, Musca domestica L., and stable flies, Stomoxys calcitrans (L.). The rate of change in the E. coli load was similar for both species for up to 5 h after ingestion. Up to 48 h after ingestion, abundance of E. coli declined in immature house flies but remained constant in immature stable flies. When different E. coli concentrations were fed to larvae, the abundance of E. coli increased in stable fly larvae regardless of the initial concentration. The E. coli load in house fly larvae increased when larvae were fed a low concentration of bacteria, but it declined when larvae were fed a high concentration of bacteria. Survival of house fly and stable fly larvae averaged 62 and 25%, respectively, when reared on pure E. coli cultures. These observations suggest that house fly larvae digest E. coli and use it as a food source but stable fly larvae do not.

Abundance of stable flies on heifers treated for control of horn flies with organophosphate impregnated ear tags

Ear tags containing 40% organophosphate insecticides (diazinon or diazinon plus chlorpyrifos-ethyl) were applied to control Haematobia irritans (L.) (Diptera: Muscidae) in treated (TG01 and TG02) and untreated (UG01 and UG02) groups of Holstein heifers born in 2001 and 2002, respectively. Control and treated groups were assessed for the abundance of Stomoxys calcitrans (L.) (Diptera: Muscidae) from August 2001 to April 2002 and again from August 2002 to April 2003. The treatment had a high efficacy for control of horn flies (maximum median number per heifer of TG01 and TG02 = 5) but a low effect on the abundance of stable flies. The total numbers of S. calcitrans were 1251 (42.9% of the total) and 1668 (57.1%) for TG01 and UG01, and 1423 (48.8%) and 1494 (51.2%) in TG02 and UG02, respectively. No significant difference in stable fly burden was found in 55 of the 76 weeks evaluated. A unimodal peak of abundance in the spring was found during the first fly season, and a bimodal abundance, with peaks in the spring and autumn, during the second season. No strong associations between horn fly and stable fly burdens was found in individuals of the CG01 (correlation coefficient = 0.13, P > 0.05) or CG02 (correlation coefficient = 0.538, P < 0.05, determination coefficient = 0.289).

Comparison of two methods (visual estimates and filming) for counts of horn flies (Haematobia irritans irritans) (L.) (Diptera: Muscidae)

Visual estimates are generally used for counts of horn flies, Haematobia irritans (L.) and play an important role as an instrument to quantify fly populations in scientific studies. In this study, horn fly counts were performed on 30 Nelore steers in the municipality of Araçatuba, SP Brazil, from January to December 1998. Flies were counted weekly by two methods: the estimate method whereby estimates of the number of flies on one side of the animal are obtained by visual observation, and the filming method whereby images of flies from both sides of the animal are recorded with a video camera. The tape was then played on a videotape recorder coupled to a television and the flies were counted on the screen. Both methods showed variations in horn fly population density during the period studied. However, significant differences (p < 0.05) were observed between the two methods with the filming method permitting the visualization of a larger number of flies than the estimate method. In addition, the filming method permitted safe and reliable counts hours after the images were taken, with the advantage that the tape can serve as an archive for random re-counts.

Comparison of sample units for estimating population abundance and rates of change of adult horn fly (Diptera: Muscidae)

This study compared the reliability of population estimates of adult horn fly, Haematobia irritans (L.), obtained using different sample units. Mean-variance relationships were similar for abundance estimates obtained by counting flies on the sunny sides of cattle, on the upper body, and on the whole animal. Precision varied among the sample units, and was lowest for estimates obtained using the sunny side. Abundance estimates obtained using the sunny side and upper body sample units were related to estimates obtained using the whole body sample unit. However, the proportion of flies in the upper body and sunny side sample units declined with increasing fly density. Seasonal movement toward the belly accounted for this decline. This movement resulted in bias in estimating rates of change based on counting flies on the sunny side and upper body sample units. Rates of change based on sampling the sunny side were more biased than estimates based on the upper body sampling unit. Bias in estimating rates of change was examined using an analytical model compared with field data, and resulted from changes in the proportion of flies occupying the sample unit. Bias also increased with increasing actual rates of change. The implication of these findings for studying horn fly populations are discussed.