Stable Fly Populations Research Articles

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.

Intra- and interspecific competition and host race formation in the apple maggot fly, Rhagoletis pomonella (Diptera: Tephritidae).

Intra- and interspecific resource competition are potentially important factors affecting host plant use by phytophagous insects. In particular, escape from competitors could mediate a successful host shift by compensating for decreased feeding performance on a new plant. Here, we examine the question of host plant-dependent competition for apple (Malus pumila)- and hawthorn (Crataegus mollis)-infesting larvae of the apple maggot fly, Rhagoletis pomonella (Diptera: Tephritidae) at a field site near Grant, Michigan, USA. Interspecific competition from tortricid (Cydia pomonella, Grapholita prunivora, and Grapholita packardi) and agonoxenid (subfamily Blastodacninae) caterpillars and a curculionid weevil (Conotrachelus crataegi) was much stronger for R. pomonella larvae infesting the ancestral host hawthorn than the derived host apple. Egg to pupal survivorship was estimated as 52.8% for fly larvae infesting hawthorn fruit without caterpillars and weevils compared to only 27.3% for larvae in harthorns with interspecific insects. Survivorship was essentially the same between fly larvae infesting apples in the presence (44.8%) or absence (42.6%) of interspecific insects. Intraspecific competition among maggots was also stronger in hawthorns than apples. The order or time that a larva exited a hawthorn fruit was a significant determinant of its pupal mass, with earlier emerging larvae being heavier than later emerging larvae. This was not the case for larvae in apples, as the order or time that a larva exited an apple fruit had relatively little influence on its pupal mass. Our findings suggest that decreased performance related to host plant chemistry/nutrition may restrict host range expansion and race formation in R. pomonella to those plants where biotic/ecological factors (i.e. escape from competitors and parasitoids) adequately balance the survivorship equation. This balance permits stable fly populations to persist on novel plants, setting the stage for the evolution of host specialization under certain mitigating conditions (e.g. when mating is host specific and host-associated fitness trade-offs exist).

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.

ADULT AGE AND REPRODUCTIVE SUCCESS IN STABLE FLY POPULATIONS (DIPTERA: MUSCIDAE)

AbstractThe pterin age-grading method was applied to natural populations of stable flies sampled for 3 years from diverse locations in Minnesota and Iowa. Significant differences were detected among years in mean degree-day ages per fly. Fly ages, in degree-day units, were exponentially distributed. A two-parameter Weibull distribution closely fit the fly survival distributions. Mean expectations of life did not differ significantly between males and females and were estimated to be 86.6 degree-days above a 6.5 °C threshold. Conventional age-grading techniques based on ovarian morphology applied to Iowa females showed that large fractions of the populations experienced delays in vitellogenesis. The reproductive rate, in terms of lifetime ovipositions, was less than the maximum sustainable rate suggested by ambient temperatures.

Seasonal Abundance of Stable Flies and House Flies (Diptera: Muscidae) in Dairies in Alberta, Canada

Seasonal abundance of stable flies and house flies was studied at four dairies in southern Alberta, Canada, from May to October in 1989, 1990, and 1991. Stable flies were active from May to October in all years and showed population peaks in August and September. The weekly rate of change of stable fly populations was influenced by temperature and accumulated degree-days above 10 degrees C. The weekly rate of change of stable fly populations showed four peaks which were attributed to the emergence of an initial generation which had overwintered, followed by an additional three generations. Stable fly attacks on dairy cows occurred mainly from July through October, corresponding with the last two generations. House fly population abundance was much lower than stable fly populations and showed peaks in June, July, and September. Weekly changes in house fly abundance were not influenced by temperature and only weakly influenced by accumulated degree-days above 10 degrees C. Peaks in the weekly rate of change were associated with emergence of an initial, overwintering generation followed by four generations produced throughout the summer.

Allozyme variation in stable flies (Diptera: Muscidae)

Polyacrylamide gel electrophoresis was used to resolve allozymes in the cosmopolitan blood-feeding stable fly, Stomoxys calcitrans (L.). Nineteen of 38 loci were polymorphic (53%). Mean heterozygosities among all loci and among only polymorphic loci were 0.096 and 0.182, respectively. These gene diversity measures are about half those among other muscid Diptera. Variation in gene frequencies was examined in 10 natural stable fly populations from Iowa and Minnesota. Gene frequencies were homogeneous at five of eight loci among six populations in 1990 and eight of eight loci among four populations in 1992. Wright's F statistics showed no significant departure from random mating among stable flies. It was concluded that gene flow compensates for any local differentiation in stable fly populations.

Predators and Parasitoids of House Flies and Stable Flies (Diptera: Muscidae) in Cattle Confinements in West Central Nebraska

In Lincoln County, NE, cattle confinements were sampled weekly during the summers of 1983 ( n = 5) and 1984 ( n = 4) for pupal parasitoids and arthropod predators of house fly, Musca domestica (L.), and stable fly, Stomoxys calcitrans (L.). Parasitism of these flies increased through the field season, peaking in August and September. The overall rate of parasitism was significantly influenced by specific fly breeding habitats but was not Significantly influenced by confinement type or waste management efforts. In addition, parasitism of house flies was significantly different between years. The pteromalids Muscidifurax zaraptor Kogan & Legner and Spalangia nigroaenea Curtis accounted for most of the parasitism of house fly pupae. Aleochara lacertina Sharp and S. nigroaenea were the most abundant stable fly pupal parasitoids. Grass clippings, used as an artificial breeding habitat for stable flies, influenced the occurrence of parasitoids and increased the rate of stable fly parasitism. Adult stable fly populations peaked in late July 1983 and in late August 1984. House fly populations generally increased throughout the summer. Confinement type and waste management efforts influenced adult fly population trends. The staphylinids Philonthus americanus Erichson and Oxytelus sculptus Gravenhorst were the most abundant insect predators found in this study.

Stable flies ( Stomoxys calcitrans L.) and the behavior of grazing beef cattle

A change-over design with complete balance for first residual effects was used with a tethered grazing technique to evaluate the effects of arthropod ectoparasites on the behavior of adult Angus beef cows ( Bos taurus) (body weight (BW), 465 ± 30 kg) grazing vegetative tall fescue ( Festuca arundinacea Schreb. cultivar ‘Kentucky 31’). The three treatments were: T 1, open grazing plots with exposure to natural ectoparasite populations; T 2, grazing plots with exclosures (5 m × 5 m × 2 m) to minimize natural ectoparasite populations; T 3, similar enclosures containing 2500 laboratory-reared adult stable flies ( Stomoxys calcitrans L.). At the start of grazing, herbage dry matter (DM) mass (> 5 cm) of the 25 cm sward was 2882 kg ha −1 and the herbage DM allowance (> 5 cm) was 1.0 kg (100 kg BW) −1 h −1. Nine flies alighted on cows in open plots (T 1), very few (< 1) on cows grazing in the exclosures (T 2) and 108 stable flies alighted on cows in the enclosures (T 3). Of the latter, there were 67 on front legs, 30 on hind legs and seven on the trunk. Stable fly populations on the body surfaces of cows declined logarithmically during grazing meals. During the first part of grazing meals, stable flies induced cows (in T 3) to move their heads (8 times per minute), and to lift their front legs (8 times per minute) and hind legs (3 times per minute). Stable flies also induced ear movements (12 per minute), tail movements (69 per minute) and skin twitches (25 per minute). Rates of stable fly-induced behavior declined logarithmically during grazing meals. Cows in T 1, T 2 and T 3 visited 4.2, 3.9 and 3.1 feeding stations per minute, respectively, but rates of herbage DM intake were not affected by the presence of stable flies ( P > 0.05) and averaged 0.35 kg (100 kg BW) −1 h −1. In the absence of stable flies (T 2), rates of biting of cows declined logarithmically from 46 to 30 bites min −1. Cows subjected to stable flies (T 3), however, started grazing at 19 bites min −1 and ended grazing meals at 26 bites min −1. Mean herbage DM intakes per bite were 833, 694 and 1011 mg for T 1, T 2 and T 3, respectively.

Management of stable flies in cattle feedlots with releases of parasitic wasps (1993)

During 1992, adult stable fly populations were sampled in 25 Kansas feedlots. A native stable fly parasitic wasp, Spalangia nigroaenea, was released in 19 of these feedlots. Stable fly populations were reduced up to 48% and parasite emergence was increased 21% when compared with feedlots where S. nigroaenea was not released. The percentage of total parasites that were S. nigroaenea nearly doubled in the release feedlots, compared to the nonrelease feedlots. This parasitic wasp has shown considerable promise for stable fly control in cattle feedlots. Overall, sampling and parasite costs averaged 32 cents per animal for the season.

Origin of Stable Flies (Diptera: Muscidae) on West Florida Beaches: Electrophoretic Analysis of Dispersal

Stable fly adults were collected from 16 locations within the state of Florida and from locations in six other states in an attempt to determine the source of stable fly populations along Florida beaches on the Gulf of Mexico. Electrophoretic analyses were made of a minimum of 10 enzymes in each of 37 separate populations. Extremely low heterozygosity resulted in an inability to use standard genetic identity and distance procedures for determining the divergence of allopatric populations to establish the source of flies captured from beach areas where reproduction was unlikely. Comparisons of rare alleles in populations grouped geographically, computations of number of possible migrants, and analysis of conditional average frequency of alleles led to the conclusion that flies captured on Florida beaches come from a variety of sites, with locations northwest of the beaches contributing the majority of flies in outbreaks.

Developmental Sites and Relative Abundance of Immature Stages of the Stable Fly (Diptera: Muscidae) in Beef Cattle Feedlot Pens in Eastern Nebraska

A 3-yr study was done to determine where and at what relative frequency stable fly, Stomoxys calcitrans (L.), immatures develop in beef cattle feedlot pens and the relationship of stable fly immature versus adult sample densities. Pens within feedlots were divided into five areas (the feed apron, back fence, side fences, mound, and the general lot); from each area, three core samples were randomly taken weekly. In 1986 and 1987, the feed apron yielded the most immature stable flies (62.5%). The mound and side fences yielded a significant percentage of flies (24.6 and 8.4%, respectively). There was a strong correlation (overall r = 0.86) between numbers of immatures and numbers of adults 2 wk later. In 1988, a drought year, low numbers of immatures were collected, and only one correlation between numbers of immatures and adults was significant. In all 3 yr, sample densities of stable fly immatures peaked and began to decline by midseason. Waste management along the feed apron and mound areas could significantly reduce stable fly populations. Sampling immatures from these areas could permit prediction of adult numbers.

Seasonal Ovipositional Status of Field Populations of Female Stable Flies (Diptera: Muscidae) in Cattle Feedlots as Measured by Two Sampling Methods

The ovipositional status of field populations of adult stable flies, Stomoxys calcitrans (L.), in cattle feedlots was investigated for 3 yr in southeast Nebraska. The proportions of female flies in each of three ovipositional stages (nulliparous, uniparous, and biparous) collected by two sampling methods (a stanchioned-calf technique and Alsynite fiberglass traps) at three times of day at two cattle feedlots were compared. In 2 of the 3 yr of the study, location (Feedlots A, B, or C), time of sampling (0800, 1100, and 1400 hours), and method of collection did not affect significantly the proportions of female stable flies in each ovipositional stage. During the 3 yr of the study, nulliparity was the predominant ovipositional stage. At the time of population peaks of adult stable flies, the majority of female stable flies were nulliparous, which indicates that the population peaks are caused by young flies that had recently emerged. More than 97.0% of the female flies collected during this study had immature eggs. We concluded that both methods sampled the same population of female stable flies: each method has strengths for different types of ecological studies. Also, we feel that increasing stable fly populations at any feedlot develop on site and are not a result of immigration. Furthermore, at beef cattle feedlots, most adult female stable flies do not live much beyond one egg cycle.

Seasonal Abundance and Spatial Distribution Patterns of Three Adult Muscoid (Diptera: Muscidae) Species on Equine Premises

Adult face fly, Musca autumnalis De Geer, stable fly, Stomoxys calcitrans (L.), and horn fly, Haematobia irritans (L.), populations on four Kentucky horse farms were monitored weekly from late April to mid-October 1987 and 1988 using dry ice-baited canopy traps and visual counts of flies on pastured horses. Face flies were most abundant during May 1987 and June of both years followed by peak stable fly activity during mid-June, July, and August of both years and peak horn fly activity during mid-September of both years. Canopy trap collections of face flies were correlated with visual counts of face flies on pastured horses for 1987 and 1988. Horn flies were not collected in the canopy traps, and stable flies were not observed on pastured horses. Using visual count data to determine the degree of population aggregation, horn fly populations were found to be more contagious than face flies as populations increased on pastured horses. From the canopy trap data, face fly and stable fly populations had similar aggregation indices or similar distribution patterns as populations increased.

Comparison of Three Sampling Methods for Estimating Adult Stable Fly (Diptera: Muscidae) Populations

Sampling of adult stable flies, Stomoxys calcitrans (L.), in cattle feedlots was investigated for 3 yr in southeast Nebraska. Three methods of estimating stable fly populations (front leg counts on cattle, a stanchioned-calf technique, and Alsynite fiber glass traps) were compared at three times of day. Time of sampling significantly affected population estimates in 2 of the 3 yr of the study. The correlation between sampling methods was determined for each sampling time and is discussed.

INSECTICIDE RESISTANCE IN FLIES (DIPTERA: MUSCIDAE) FROM POULTRY FARMS

AbstractPopulations of the house fly, Musca domestica L., and the false stable fly, Muscina stabulans (Fallén), collected on poultry farms west of Sydney were tested against insecticides by topical application. House flies were resistant to the organophosphorus insecticides diazinon, azamethiphos, trichlorphon and malathion and to the carbamate, propoxur. No resistance was detected to the synthetic pyrethroid, permethrin. Resistance factors were generally low for azamethiphos (3x–10x) and somwhat higher for diazinon (8x–22x). A proportion of field flies could survive very high doses of malathion, trichlorphon and propoxur, and resistance factors could not be determined. No resistance to any of the above insecticides was detected in populations of false stable flies. M. stabulans was between 2 and 35 times more susceptible to these insecticides than susceptible house flies, except for permethrin which was equitoxic to both species.

Effects of stable flies (Diptera: Muscidae) on weight gain and feed efficiency of feedlot cattle.

Data pooled from three individual trials, with average stable fly populations of 2.58, 5.21, and 7.07 per leg, indicated a significant reduction in weight gains and a decrease in feed efficiency among feedlot cattle. Graphs of pooled data and previously reported data, converted to percentage loss on a per fly basis, indicated the economic threshold for stable flies (cost of treatment versus number of flies)is less than two stable flies per leg on feeder heifers.

Evaluation of Beef Cattle Feedlot Subsystems for Immature House Flies and Stable Flies

ABSTRACT INSECTS, have affected people and animals in various ways (King and Lenert, 1936). A blood-feeding fly, Stomoxys calcitrans (L.), commonly known as the stable fly, biting fly, or dog fly, can cause intense suffering to livestock. This fly is widely distributed and is an important pest of livestock in many countries (Hansens, 1951). Campbell et al. (1977) and Campbell and McNeal (1980) indicated that stable fly populations of 50/animal reduced weight gains by 0.09 kilograms/day (kg/d) and feed efficiencies by 12.9% for feeder cattle fed a growing ration. They further reported a reduction of 0.22 kd/d with a reduced feed efficiency of 10.9% when stable fly populations were 100/animal and they were fed a finishing ration. Therefore, control of stable flies in feedlots is critical to cattle performance. Flies normally breed within materials such as manure, silage, straw, lawn clippings, etc. that are high in organic matter and under various environmental conditions (King and Lenert, 1936; Hansens, 1951; Griffiths, 1962; Campbell et al., 1977; Berry and Kunz, 1978; Scholl et al., 1981; Betty et al., 1982; Meyer and Peterson, 1983) and all beef cattle feedlots use materials high in organic matter for feed and bedding. Producers use numerous methods for feedlot management. Any design or combination of subsystem designs can contribute to fly populations. However, producers have no specific format for evaluating their feedlot for fly-breeding potential. This study was initiated to determine the contribution of the feedlot subsystem facilities and of management practices to fly populations and to develop methods by which producers can evaluate specific feedlot subsystems that could lead to introducing fly control practices.

An Attractant Self-Marking Device for Marking Field Populations of Stable Flies with Fluorescent Dusts1

An attractant self-marking device for stable flies was developed using fluorescent dusts applied to the fiberglass panels of the Williams Trap. Flies that were attracted to the trap inadvertently marked themselves as they came in contact with the dusted surface of the trap panels. The fluorescent dust can be seen easily on flies by means of a long-wave ultraviolet light. Fluorescent dust was observed on flies a maximum of 14 days after marking. This marking technique had no discernible adverse effect on the survival or movement of the flies and provided an excellent means for studying natural movement and survival of wild flies in the field.

Evaluation of Sequential Releases of Spalangia endius (Hymenoptera: Pteromalidae) for Control of House Flies and Stable Flies (Diptera: Muscidae) Associated with Confined Livestock in Eastern Nebraska1

The pteromalid wasp Spalangia endius Walker was released for 13 weeks on two eastern Nebraska livestock feedlots for the control of house flies and stable flies. Parasitism of stable flies averaged 7.8 and 8.8% on nonrelease (control) lots and release lots, respectively: parasitism of house flies averaged 12.8 and 18.4% for the control and release lots, respectively. Spalangia cameroni Perkins, S. nigroaenea Curtis, S. nigra Latreille, and Muscidifurax spp. were native to the feedlots. S. endius was also recovered from the control lots in very low numbers. The strains of S. endius used in this study were ineffective in controlling house fly and stable fly populations under the conditions imposed and at the numbers released.

Populations and Economic Impacts of Stable Flies on Cattle

ABSTRACT POPULATIONS of stable flies, Stomoxys calcitrans (L.), were evaluated at 27 feedlots and 1 dairy in eastern Nebraska in 1980 and 1981. Stable flies occurred through the summers at all locations and the average population measurements at different locations varied by a ratio of more than 5 to 1. Seasonal variations were similar on most feedlots, increasing from low levels in May to maximum levels in July and fluctuating between medium and high levels until September/The population measures were used to estimate production losses of 2.30 kg and 3.51 kg per animal for the summers of 1980 and 1981, respectively