Stable Fly Populations Research Articles

Distribution and abundance of natural parasitoid (Hymenoptera: Pteromalidae) populations of house flies and stable flies (Diptera: Muscidae) at the University of Florida Dairy Research Unit

From September 2001 through September 2002, house fly and stable fly pupae were collected weekly from three fly habitats at the University of Florida Research dairy in northcentral Florida and evaluated for parasitism. Varying parasitism percentages were observed throughout the study but they were not affected by temperature, precipitation or fly abundance. Of the 6,222 house fly pupae and 1,660 stable fly pupae that produced either a host fly or a parasitoid, 26.9% and 26.7% were parasitized, respectively. Ten parasitoid species were recovered, with the genus Spalangia accounting for 85.7% of the total; the most common parasitoids attacking house fly and stable fly pupae were Spalangia endius Walker (33.9% and 27.3%), S. cameroni Perkins (27.9% and 40.6%), and S. nigroaenea Curtis (21.0% and 24.8%), respectively. Other parasitoids included one specimen of S. erythromera Förster and four specimens of Phygadeuon fumator Gravenhörst (Ichneumonidae). The percentage parasitism of pupae collected from bunker silos was higher than that of pupae from calf pens and open pastures. Spalangia cameroni was consistently recovered through the entire year. Spalangia nigroaenea was predominant in July, August, and September. Spalangia endius was most active from October to May with a peak of relative abundance in January.

Assessing pest control using changes in instantaneous rate of population increase: Treated targets and stable fly populations case study

The instantaneous rate of population increase was used to assess the ability of attractive targets coated with permethrin to control stable fly populations on 3 dairy farms in south central Ontario, Canada. Two attractive targets were deployed over 10 wk in 2001 at each of 6 dairy farms. Three farms were outfitted with 2 untreated targets and 3 were outfitted with 2 targets treated with permethrin [Ectiban-impregnated Coroplast (Ectiban: Schering-Plough Canada Inc., Pointe-Claire, Québec, Canada; Coroplast: Great Pacific Enterprises Inc., Granby, Québec, Canada)]. Population growth rate was measured in terms of degree-days above a 10°C developmental threshold (rDD10). The rDD10 at the 3 treated dairy farms were significantly lower than rDD10 at the 3 neighboring untreated dairy farms (mean rDD10: treated=0.0088, untreated=0.013), but not in the previous year when targets were not installed (mean rDD10: treated=0.012, untreated=0.015). This supports a long-term approach to management that lowers population growth rates in those regions where stable fly numbers increase exponentially from spring until winter, by shortening the period of economic impact of this pest.

The effect of <i>Macrocheles muscaedomesticae</i> and <i>M. subbadius</i> (Acarina: Macrochelidae) phoresy on the dispersal of <i>Stomoxys calcitrans</i> (Diptera: Muscidae)

In south-central Ontario, the stable flies disperse from their overwintering farms and re-establish populations at neighbouring dairy and beef farms each spring. Two species of phoretic macrochelid mites commonly found on stable flies are Macrocheles muscaedomesticae and M. subbadius. We tested the hypothesis that mite phoresy affects the dispersal of their stable fly phorionts. At a beef farm we found a higher proportion of parous stable flies with mite scars than expected, based on the proportion of nulliparous females carrying mites. These results were consistent with our hypothesis, indicating that stable flies without mites may be emigrating more than flies carrying mites. We further tested our hypothesis by comparing the mite load on dispersing stable flies sampled with a vehicle-mounted truck trap to the mite load on resident stable flies sampled from three dairy farms and one beef farm (May to October, 2001). Significantly, no stable flies caught in the truck trap were carrying mites, compared to the seasonal means of 10% and 5% of female and male stable flies with mites at the four farms. This effect of mite phoresy on stable fly populations is discussed.

Local Infestation or Long-Distance Migration? The Seasonal Recolonization of Dairy Farms by <I>Stomoxys calcitrans</I> (Diptera: Muscidae) in South Central Ontario, Canada

Stable fly (Diptera: Muscidae) populations in south central Ontario, Canada, first occur on dairy farms in late spring, grow exponentially throughout the summer, and are frozen back each autumn. We examined the extent of overwinter persistence on 22 dairy farms in a 55- by 60-km region north of Lake Ontario that spans four climatic zones. Our overwintering sampling of larval habitat identified three farms located in the southern section of the study region as potential overwintering refugia. Using sticky trap catches to identify the timing of first spring appearance at each farm, we then tested two models of how local farm populations are reestablished annually: 1) stable flies disperse from local climatic refuges and colonize neighboring farms (the local source model); and 2) stable flies are carried into the study region by frontal weather systems (the distant source model). The timing of when stable flies first occurred at these farms supported a local source of dispersing colonists from a small proportion of local refuge farms. We discuss our results in terms of how yearly fluctuation in climate would affect refuge farm density in the region and how this, in turn, would shift the recolonization dynamic. Implications for controlling stable flies also are discussed.

Sampling designs of insect time series data: are they all irregularly spaced?

Time series data are commonly obtained by trapping over a standardized period of time, for example daily or weekly. In this paper we present evidence that such sampling designs are inherently irregularly spaced due to the varying developmental rates and population parameters caused by changing temperatures during a sampling season. We modeled an exponentially growing population based on stable fly population growth rates, and then compare different sampling regimes to determine which produces the best estimate of population growth rate. These results are then compared to field data based on weekly sampling at three dairy farms in Ontario over two summers. Transforming catch numbers (N) to ln(N)/(number of degree days within the sampling period) corrects for the irregular spaced sampling in these data. These results support the use of measuring population parameters such as population growth rates in terms of degree days.

Male stable fly (Stomoxys calcitrans) response to CO2changes 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 (Stomoxys calcitrans: Diptera, Muscidae) trap response to changes in effective trap height caused by growing vegetation

Stable flies (Stomoxys calcitrans L.) are blood-feeding pests of cattle, whose populations are often monitored using sticky traps. Trap responses at different heights were compared with: 1) a choice and no-choice test, with sticky cards set at 30 and 121 cm heights (above ground), and 2) tall (120 cm) traps placed in short (3 cm) and tall (40 cm) grass to assess how vegetation height affects trap catches. In the first experiment, the percentage of upper to lower trap catches were similar at choice (16%) and no-choice traps (15%). In the vegetation study, stable fly catch height data were fitted to gamma distributions to determine the most productive trap heights; 20 cm above short grass and 24 cm above tall grass (from lower edge of trap). The results indicate that traps used to monitor stable fly populations should be maintained at a constant distance above surrounding vegetation rather than ground surface, otherwise trap data can be misleading.

Potential impacts of climate change on stable flies, investigated along an altitudinal gradient

Adult populations of stable flies were sampled along an altitudinal transect in Reunion Island to determine whether higher temperatures were associated with: (a) higher numbers of flies; (b) a longer season of infestation, and/or (c) different responses to warming in the cosmopolitan Stomoxys calcitrans (L) and the tropical Stomoxys niger niger Macquart (Diptera: Muscidae). Flies of both species were trapped at seven farms situated at four altitudes (100-1600 m a.s.l.) over a 90-week period. For both species, there were no relationships between the maximum or mean fly abundance and altitude. Only minimum abundance in winter was significantly higher at lower altitudes. Maximum and mean abundances differed significantly between nearby farms under similar climatic conditions. Seasonal fluctuations in fly abundance changed along the gradient. At lower altitudes, population growth started earlier after the winter but abundance declined earlier in summer, which resulted in a shift of the season of infestation. Seasonal fluctuations of both species were strongly related to climate variables at high altitude, mainly temperature. However, climate variables explained a decreasing proportion of the variations in abundance at lower altitudes. Stomoxys calcitrans was the most abundant species overall, but the proportion of S. n. niger increased significantly at lower altitudes and this species became predominant at 100 m a.s.l. It is concluded that stable fly infestations are unlikely to worsen in response to global warming. Maximum abundance is limited by local factors, possibly larval resources, which suggests that adequate husbandry practices could override the impact of climate change. Because S. n. niger tends to be the predominant pest at elevated temperatures, it is recommended that this species should not be introduced in areas where climate is changing.

Stable Fly Population Dynamics in Eastern Nebraska in Relation to Climatic Variables

Stable Fly Population Dynamics in Eastern Nebraska in Relation to Climatic Variables

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.

B25 台湾のサシバエミトコンドリアDNAに認められる遺伝的差異(第59回日本衛生動物学会大会特集)

B25 台湾のサシバエミトコンドリアDNAに認められる遺伝的差異(第59回日本衛生動物学会大会特集)

Comparative Efficiency of Six Stable Fly (Diptera: Muscidae) Traps

Five adhesive traps and the Nzi cloth-target trap were compared to determine their trapping efficiency and biases for stable flies, Stomoxys calcitrans (L.) (Diptera: Muscidae). Two configurations of the BiteFree prototype trap, constructed of polyethylene terephthalate, were most efficient for trapping stable flies, whereas the EZ trap was least efficient. The two Alsynite traps, Broce and Olson, were intermediate to the BiteFree prototype and EZ traps. All adhesive traps collected a ratio of approximately two males for each female. Approximately 50% of the flies collected on the adhesive traps, both male and female, were blood fed, and 20% were vitellogenic. The Nzi trap collected an older component of the stable fly population, 81% blood fed and 62% vitellogenic, but it was much less efficient than the adhesive traps. The effectiveness of the BiteFree prototype trap indicates that materials other than Alsynite are attractive to stable flies.

Comparative Efficiency of Six Stable Fly (Diptera: Muscidae) Traps

Five adhesive traps and the Nzi cloth-target trap were compared to determine their trapping efficiency and biases for stable flies, Stomoxys calcitrans (L.) (Diptera: Muscidae). Two configurations of the BiteFree prototype trap, constructed of polyethylene terephthalate, were most efficient for trapping stable flies, whereas the EZ trap was least efficient. The two Alsynite traps, Broce and Olson, were intermediate to the BiteFree prototype and EZ traps. All adhesive traps collected a ratio of approximately two males for each female. Approximately 50% of the flies collected on the adhesive traps, both male and female, were blood fed, and 20% were vitellogenic. The Nzi trap collected an older component of the stable fly population, 81% blood fed and 62% vitellogenic, but it was much less efficient than the adhesive traps. The effectiveness of the BiteFree prototype trap indicates that materials other than Alsynite are attractive to stable flies.

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.

Large Sticky Traps for Capturing House Flies and Stable Flies in Dairy Calf Greenhouse Facilities

Large sticky traps were evaluated for stable fly, Stomoxys calcitrans (L.), and house fly, Musca domestica L., (Diptera: Muscidae) capture under field conditions in 5 dairy calf greenhouse facilities in New York. The farm with the highest stable fly capture had the highest house fly capture, and the farm with the lowest stable fly capture had the lowest house fly capture, suggesting that fly management practices greatly influenced trap captures. In general, stable fly populations, as reflected by increased trap capture, generally rose during the summer. Numbers of flies counted on calves did not increase, however, suggesting that the traps greatly reduced the potential stable fly pressure on the calves as the fly population increased. Estimated number of stable flies and house flies captured during this 10-wk study exceeded 142,000 and 900,000, respectively. Producers were generally pleased with the trap performance and most felt that these traps reduced flies in their calf greenhouses to acceptable levels.

Relationships between temperature and life-history parameters of Stomoxys calcitrans (Diptera: Muscidae).

Relationships between temperature and life history parameters were determined for the stable fly, Stomoxys calcitrans (L.). Median immature developmental times ranged from > 60 d at 15 degrees C to < 12 d at 30 degrees C, with minimum time at 30.6 degrees C. Egg survival decreased from 0.98 at 15 degrees C to 0.91 at 20 degrees C, then increased to 0.98 at 35 degrees C. Larval survival ranged from 0.83 at 20 degrees C to 0.65 at 35 degrees C, and pupal survival ranged from 0.93 at 20 degrees C to 0.42 at 35 degrees C with maxima at 22.1 degrees C and 19.9 degrees C for larvae and pupae, respectively. Median longevity of females and males were greatest at 17.3 degrees C. Time to 50% survival ranged from > 30 d at 15 degrees C to < 6 d at 35 degrees C. Daily fecundity averaged 1.07, 8.89, 14.88, 26.22, and 7.90 eggs per female per day at 15, 20, 25, 30, and 35 degrees C, respectively. Lifetime fecundity ranged from < 30 eggs per female at 15 and 35 degrees C to > 700 eggs per female at 25 degrees C and was greatest at 25.3 degrees C. Net reproductive rate, and the intrinsic rate of increase had maxima at 25.3 and 27.8 degrees C, and mean generation time was minimum at 33.4 degrees C. Proportional variation in the time of immature development and adult longevity were independent of temperature, but proportional variation in the time of oviposition was related inversely to temperature. Extreme temperatures appeared to lengthen the preoviposition period and reduce the duration of egg production. Relationships were compared with previous studies. Equations developed and presented in this article will be used to develop a temperature-dependent stable fly population model.

Population Genetics and Gene Variation of Stable Fly Populations (Diptera: Muscidae) in Nebraska

Genetic variation in stable fly, Stomoxys calcitrans (L.), populations from Nebraska, Canada, and Texas was sampled. Four of 12 allozyme loci were polymorphic, with an average of 1.7 alleles per locus. Observed and expected heterozygosities were 0.086 and 0.070, respectively. Nei's genetic distance between populations averaged 0.001 and ranged from 0.000 to 0.005. Wright's F statistics revealed greater variation within than among populations. Allele frequencies were homogeneous among temporal samples from a single population. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis of 6.4 kb of the mitochondrial DNA genome with 16 restriction enzymes revealed no variation in stable fly populations from Canada, Nebraska, and Texas. PCR-RFLP analysis of a 2.0-kb fragment of the nuclear ribosomal DNA internally transcribed spacer region also revealed no variation. The lack of genetic differentiation among stable fly populations indicates high levels of gene flow among populations. The low levels of variation observed with biochemical and molecular techniques are consistent with a genetic bottleneck during stable fly colonization of North America.

Scheduled sanitation to reduce stable fly (Diptera: Muscidae) populations in beef cattle feedlots.

Sanitation has been long recommended as a means of reducing stable fly, Stomoxys calcitrans (L.), populations at cattle feedlots, but there is little published research to support this recommendation. In each of the 2 yr of this study, 4 feedlots received complete sanitation and 4 feedlots received no cleaning. The objective was to have the initial cleaning done before 1 June and then to reclean as needed every 2 wk thereafter. The feedlots that were cleaned had significantly fewer flies than the uncleaned feedlots, with 50.9% fewer stable flies during the 1st yr and 36.2% fewer flies in the 2nd yr. These reductions were realized even though initial cleaning was not done by 1 June in either year: bad weather delayed completion until 20 June the 1st yr and 29 June the 2nd yr. Sanitation at cattle feedlots significantly reduces stable fly populations and sanitation may have been more effective if initial cleaning was done by 1 June.

Average Daily Gains of Brahman-Crossbred and English × Exotic Feeder Heifers During Long-Term Exposure to Stable Flies (Diptera: Muscidae)

Long-term exposure of Brahman-crossbred and English X Exotic heifers to a medium (approximately 14 stable flies per foreleg per minute at 1600 hours) stable fly, Stomoxys calcitrans (L.), population level caused a continuous decline in average daily gains of both breeds from day 1 to day 84 of exposure (that is, from 12 to 14 mo of age). Neither breed was affected by stable fly feeding from 85 d until 112 d exposure, when heifers were greater than or equal to 15 mo in age. At that age, heifers compensated for weight loss during the previous 84-d exposure to stable fly feeding. Overall reduction in average daily gain was approximately 0.15 kg/d or 9% for both breeds, indicating that Brahman-crossbred heifers were as susceptible to long-term exposure to a medium stable fly population as were English X Exotic heifers.

Behavior of grazing cattle exposed to small populations of stable flies ( Stomoxys calcitrans L.)

Cattle grazing in the presence of low-level infestations of stable flies ( Stomoxys calcitrans L.) may offset reductions of grazing time by increasing their rate of herbage intake, and this may contribute to the determination of economic threshold populations. On four consecutive days, we released four pulses of 50 or 100 laboratory-reared stable flies at 15 min intervals over 1 h in screened enclosures, according to a balanced change-over design. Within these enclosures, fasted, adult Angus cows ( Bos taurus L.) (body weight (BW) 465 ± 30 kg) grazed vegetative tall fescue ( Festuca arundinacea Schreb. cv. ‘Johnstone’) at herbage dry matter (DM) allowances of 1.4 kg (100 kg BW) −1 h −1. Alighted fly numbers on body surfaces of cows were similar during each quarter of grazing meals, and numbers of alighted flies increased linearly as more were released. Cows exposed to colonies of 100 stable flies had 16 alighted on fore legs, 5 on hind legs and 5 on trunks. Stable flies weighed 6.1 mg before and 17.7 mg after feeding. Fly-induced behavior of grazing cows did not vary significantly ( p > 0.05) within grazing meals, and releases of up to 100 stable flies caused linear increases in movements of heads (to 3.3 min −1), ears (to 3.7 min −1), skin twitches (to 14 min −1 side −1) and tail swishes (to 36 min −1), but had little effect on movements of fore and hind legs (< 1 min −1). Stable fly releases caused linear increases in herbage DM intake (0.43–0.53 kg (100 kg BW) −1 h −1) and bite DM mass (from 1.2 g to 1.5 g). Cows prehended 35, 38 and 31 bites min −1 when 0, 50 and 100 flies were released. The low levels of stable fly infestation used in this experiment had little direct negative interference on the mechanics of herbage ingestion, as indexed by fly-induced head and leg movements. Favorable conditions may increase the rate of stable fly feeding, shorten their feeding time and minimize interference with their grazing hosts. Faster rates of herbage intake of grazing cows in the presence of stable flies were attributed to annoyance.