Common Cattle Grub Research Articles

Anatomie et Histologie du Tube Digestif de la Larve d'Hypoderma Bovis [Diptère Œstriforme

SUMMARYThe microscopical study of the cells and the contents of the alimentary canal of common cattle grub, Hypoderma bovis, during its 3 larval stages shows the following:The first instar grub feeds upon connective tissue of the host owing to enzymes of its salivary glands. The gut content is of a fluid nature without any cell and stored into the mid-gut, this one being a closed-bag. Collagenolytic activity of the mid gut is more important than in salivary glands but evidences are given that the mid gut doesn't produce this enzyme. The hind-gut appears to be used only for the excretion of the Malpighian tubules.The second and third larvae are different. The structure of the cells of the salivary glands and gut appear to be more differentiated. A continuity could be noted between the lumen of the hind and mid gut. During these stages the maggot is feeding upon pus only and its collagenolytic activity decreases.

Transplantation of Common Cattle Grub Larvae into Horses1

Transplantation of Common Cattle Grub Larvae into Horses1

Evaluation of Shell SD 8447, SD 8448, and SD 8436 as candidate systemic insecticides for control of common and northern cattle grubs.

Three materials of low mammalian toxicity from the Shell Development Company, SD 8447 (2-chloro-1-(2,4,5-trichlorophenyl) vinyl dimethyl phosphate), SD 8448 (2-chloro-1-(2,4,5-trichlorophenyl) vinyl diethyl phosphate), and SD 8436 (2-chloro-1-(2,4-dibromophenyl) vinyl dimethyl phosphate) showed moderate systemic activity against the northern cattle grub Hypoderma bovis (L.), and the common cattle grub H. lineatum (de Villers), when they were applied to calves by the pour-on procedure. Although early tests indicated 89-100% control with these materials, later tests produced 41 and 60% control on animals treated with SD 8447 at 30 g/head and 46 and 73% control on animals treated with SD 8436 at 20 g/head. SD 8448 was not included in the later tests. The materials produced no significant cholinesterase depression, no indication of toxicity, and no significant differentials in weight gain.

Efficacy, Cholinesterase Inhibition, and Residue Persistence of Imidan® for the Control of Cattle Grubs1234

Spray and pour-on trials with Imidan®, ( N- (mercaptomethyl) phthalimide S -( O,O -dimethyl phosphorodithioate) for the control of the common cattle grub, Hypoderma lineatum (de Villers), and the northern cattle grub, H. bovis (L.), were conducted in Oregon in 1964-65 and 1965-66. The 1st year, when 2 herds of 50 calves each were sprayed, Imidan at 0.25 and 0.10% reduced infestations by 75-100%, but at 0.05% it was ineffective (0-31%). In contrast, a pour-on of Ruelene® (4- tert -butyl-2-chlorophenyl methyl methylphosphoramidate), at the then currently recommended rate of application (9.2 g/calf), was 98-100% effective. No demonstrable weight differences occurred because of the chemical treatment, either in the week after the applications or in the 3 to 5 months thereafter. No toxic reactions were observed in either herd. In 1965-66, Imidan sprays on a group of 101 calves gave good control (97%) at a concentration of 0.375%, but a 0.25% spray gave only 67% control, and a 0.08% spray produced no effect. In contrast, Ruelene sprayed at 0.375% provided 99% grub control. However, pour-on treatments of Imidan in 2 herds (at a 4.9 g/head rate of application) yielded 98 and 90% control, respectively. No toxic reactions were observed. Cholinesterase activity was determined in whole blood taken from 50 calves treated with Imidan or with Ruelene in 1964-65 and in a group of 20 calves treated with Imidan pour-on or left as controls in 1965-66. In the 1st year, when blood was withdrawn at 0, 1, 3, 7, and 28 days posttreatment, the maximum mean apparent inhibition (15%, compared with the control group) was found in the group treated with 0.25% Imidan at day 3 and day 7. The maximum mean apparent inhibition in the group treated with Ruelene was 3% in the day 7 samples. In 1965-66, blood was withdrawn at 0, 2, 7, and 14 days posttreatment. The maximum mean apparent inhibition (28%) was found in the Imidan pour-on treated group at day 7. In 1964-65, Imidan residues were determined in 5 steers sprayed at a concentration of 0.25% Imidan and slaughtered on days 3, 7, 14, 28, and 59 posttreatment. On day 3, significant residues were found in omental, perirenal, and subcutaneous fat, and in muscle, but not in liver. Residues were below detection limits in all tissue samples on and subsequent to day 7.

Cattle Grub Control with Feed Additives (Coumaphos and Fenthion) and Pour-ons (Fenthion and Trichlorfon)1

The effectiveness of 3 organic phosphorus compounds (coumaphos, fenthion, trichlorfon) against the common cattle grub. Hypoderma lineatum (de Villers), and the cattle grub, H. bovis (L.), was investigated. A 133-day feedlot trial consisted of 216 calves used in 6 feed-additive treatment groups, 1 pour-on treatment group, and a control group. Forty-four additional calves received 3 pour-on treatments in a separate 133-day trial. The control group (48 animals) averaged 20 grubs per head. All 6 feed additive treatments and the 4 pour-on treatments significantly (P < 0.05) reduced the number of grubs present, as compared with an average of the peak grub count of individual animals in the control group. The reductions of grub counts by the feed additive treatments were: 3 mg per kg and 4 mg per kg coumaphos daily. 6 days-56%, 90%; 1 mg per kg and 1.5 mg per kg fenthion daily, 6 days-92 %, 98%; and 2 mg per kg and 3 mg per kg fenthion daily, 3 days-86%, 90%. The pour-on treatments, applied once at a rate of Y2 fl oz per 100 lb, gave results as follows: 8% and 12% trichlorfon—96%, 95%; and 1 % and 2% fenthion—77%, 85%. When the percent control by the various treatments is considered in conjunction with the number of animals free of grubs throughout the trial and those with a peak count of fewer than 5 grubs per head, it appears that fenthion feed additives at 1.0 mg per kg and 1.5 mg per kg per day for 6 days and trichlorfon pour-ons (8%, 12%) were the most satisfactory treatments. No significant differences in total weight gain or overall feed efficiency existed among the treatment groups and the control group. The usual better performance by steers as compared with heifers was observed, but sex of animal had no effect on grub counts.

Systemic Insecticides and Late-Season Application for Cattle Grub Control In Western Nebraska1

Two systemic insecticides, trichlorfon and fenthion, were tested for control of Hypoderma bovis (L.), northern cattle grub; and H. lineatum (dc Villers), common cattle grub, through 2 grub seasons, 1964-65, 1965-66. Trichlorfon was tested as 8% and 12% pour-on in the 1964-65 test. Only the 8% pour-on was tested in 1965-66. Fenthion was tested as a 1% feed premix in 1964-65 and 1965-66, and as a 2% pour-on formulation in 1965-66. All treatments in both tests provided excellent control. Applications were approximately I month later than the currently recommended cut-off date, October 31. The late application caused no side effects in the animals.

Control of Cattle Grubs with Organic Phosphorus Compounds Administered in Feed1

Three organic phosphorus compounds were evaluated as feed additives for cattle grub control using 200 Hereford steers in a 119-day feedlot trial. Coumaphos was fed at 3 rates, fenthion at 2 rates and Marctin® ( N -hydroxy-naphthalimide diethyl phosphate) at 1 rate. Each treatment group consisted of 5 pens of 5 cattle each, and the control group of 10 pens of 5 animals. Grubs identified as the common cattle grub, Hypoderma lineatum (de Villers), and the northern cattle grub, H. bovis (L.), were collected during the trial. Fenthion in feed for 6 days (1 and 2.5 mg/kg per day) gave 96% and 99% control of cattle grubs. Daily administration of coumaphos at 7.5 mg/kg for 3days and 5 mg/kg for 6 days gave 92% and 87% grub control. Two treatments, 33 ppm coumaphos in feed for 119 day and 20 mg/kg Maretin daily for 6 days, were completely ineffective against grubs. Cattle that were fed fenthion (1 and 2.5 mg/kg) and coumaphos (5 mg/kg) daily for 6 days, or coumaphos (7.5 mg/kg) daily for 3 days, had significantly (P<0.05) fewer grubs and significantly (P<0.05) more were grub-free than in similar groups of untreated cattle or those that received coumaphos at 33 ppm in feed daily for 119 days or Maretin at 20 mg/kg per day for 6 days. Based on the ratio of grub-free to total number of animals per group, the 2.5 mg/kg fenthion treatment was significantly (P<0.05) better than all other treatments except 7.5 mg/kg coumaphos. Medicated feed containing fenthion, Maretin, or 33 ppm coumaphos was readily consumed and did not produce anorexia or signs of toxicity. Anorexia and signs of organic phosphorus compound toxicity were observed in animals treated with coumaphos at 7.5 mg/kg daily for 3 days, while mild anorexia and soft feces resulted from treatment with 5 mg/kg coumaphos daily for 6 days. The weight gain and feed conversion by steers in the various treatment groups did not differ significantly from each other or from the control group.

The Common Cattle Grub in Cattle in Southwestern Texas1

Common cattle grubs, Hypoderma lineaturn (de Villers), were observed in the backs of a small herd of Hereford cattle for 2 years at Camp Bullis, Texas, and for 4 years after the herd was moved to Kerrville, Texas. In both locations, grubs were present in the backs of cattle in the fall-winter season: at Camp Bullis, grubs were found first in November; at Kerrville, grubs were found first in September and in peak numbers in November-December. The average number of grubs in the herd varied from year to year, a reflection of the differences in activity and/or populations of common cattle grub adults and in the susceptibility of the cattle. At Camp Bullis, most of the herd were older cows; at Kerrville, most were 1-4 years old. The average number of grubs in cattle was related to age as follows: calves 19.8, yearlings 27.5, 2- to 5-year-olds 14.0-15.1, and cows (estimated 4-15 years old) found 5.2. No significant decrease or increase in susceptibility of cattle to infestation by cattle grubs occurred the year following the year in which grubs were controlled in cattle with systemic insecticides.

Dermal application of ten systemic insecticides to cattle for the control of the common cattle grub.

In small-scale field tests in Texas, the following systemic treatments gave >80% control of the common cattle grub, Hypoderma lincatum (de Villers), in cattle: Bayer 37342 (O, O-dimethyl O-[4-(methylthio)-3,5-xylyl] phosphorothioate) as a pour-on of 1 oz per hundredweight (cwt) of a 15.5% water emulsion; coumaphos as a pour-on of ½ oz per cwt of a 4% commercial pour-on formulation; fenthion as a spray of 1 gallon (gal) per animal of a 0.25% suspension or 2½ gal per animal of a 0,25% emulsion; runnel as a pour-on of 2 oz per cwt of a 10.2% oil suspension or 10% water emulsion; Ruclene® (4-tert-butyl-2-chlorophenyl methyl methylphosphoramidate) as a pour-on of 1oz per cwt of 4-8% water suspensions, water emulsions, or oil suspensions or an 8% commercial pour-on formulation. and as sprays of 1 quart per animal of a 2% emulsion or 1-1½ gal per animal of a 0.5% suspension or emulsion; Shell Compound 4072 [2-chloro-l-(2.4-dichlorophenyl) vinyl diethyl phosphate] as a spray of 1 gal per animal of a 0.25% suspension; and trichlorfon as a pour-on of 1 oz per cwt of 7.75-15.5% water solutions or as a spray of 1 quart per animal of 4% water solution and 1-1½ gal per animal of 1.5% water solution. Treatments giving <80% control were fentllion used as a pour-on of ½ oz per cwt of a 1% commercial pour-on formulation; Imidan® (O, O-dimethyl S-phthalimidomethyl phosphorodithioate) as a spray of 1 gal per animal of a 0.25% suspension; Nemacide® [O-(2,4-dichlorophenyl) O, O-diethyl phosphorothioate) as a pour-on of 1 oz per cwt of a 15.5% oil or water emulsion; ronnel as a pour-on of 2 oz per CWI of a 10.2% water suspension; and Stauffer R-2371 [S-bis (p-chlorophenyl) methyl O, O-diethyl phosphorodithioate) as a pour-on of 1 oz per cwt of a 15.5% water emulsion.

Furuncular Dermal Myiasis From Dermatobia hominis

To the Editor:— Dermal or cutaneous myiasis is caused by invasion of the skin by larvae of flies of several genera which are commonly known as bot, warble, and screwworm flies. The usual hosts are livestock and various domestic animals. Dermal myiasis has been reported in many parts of the world, including the United States. Furuncular dermal myiasis is caused by species of Hypoderma and Wohlfahrtia and by Dermatobia hominis . The larva penetrates the skin through a hair follicle and forms a furuncle at or near the site of penetration. Hypoderma migrates extensively within the body first. Cases in the United States have been caused by species of Wohlfahrtia , particularly in children (J. R. Audy, personal communication, September 1965) 1 and by H lineatum (a common cattle grub). 2 The first case caused by D hominis was reported in 1962. 3 The gravid Wohlfahrtia fly lays its eggs on the

A Study of the Dermal Treatment of a Steer with C14-Labeled Imidan

Absorption, excretion, and metabolism of radiolabeled (C14) Imidan® ( O,O -dimethyl S -phthalimidomethyl phosphorodithioate) were studied in a steer after dermal application. Imidan was moderately absorbed by the skin of the steer, since 9.6% of the applied dose was recovered in the excreta within 7 days. The compound was rapidly broken down in the blood system, as indicated by the small percentage of radioactivity which could be extracted with chloroform (less than 2%). The principal route of elimination of absorbed material was through the urine, in which nearly 8% of the applied dose was found within 7 days. Paper chromatography and electrophoresis of urine samples indicated that the primary degradation of Imidan in the steer occurred at the nitrogen atom, resulting in the almost exclusive production of phthalic and phthalamic acids. The presence of benzoic acid as a metabolite was not conclusively proved. The systemic action against common cattle grubs, Hypoderma lineatum (de Villers), is evidently the result of very low concentrations of Imidan or the oxygen analogue.

Area Population Control of Heel Flies by Ruelene Pour-on Application Annually to Cattle1

The study was conducted on the Vail and Vickers Ranch, Santa Rosa Island, a grazing range of 54,000 acres off the California coast about 30 miles southwest of Santa Barbara. For more than 20 years, heel fly gadding was extremely inconvenient to the spring round-up and caused a serious extra labor cost. The record suggests that both the common cattle grub, Hypoderma Uneatum (de Villers), and the northern cattle grub, H. bovis (L.), were present. Each spring the herd on the island is sorted, and some of the animals remain until the following spring; in the fall, calves purchased on the mainland are brought to the island. It is likely the large heel fly population was supported by either or both sources of cattle. Control treatments started in August 1960. A single annual treatment of pour-on of one part Ruelene® 25 E (4- tert -butyl-2-chlorophenyl methyl methylphosphoramidate) mixed with 2 parts of water and applied at 1 oz of the mixture per 100 lb of body weight was selected, but in the fall of 1960 it was necessary to spray some of the cattle with wettable powder. In 1961–63 cattle on the island were treated in September; the new calves were treated on the mainland before shipment to the island. Each year a representative lot of cattle on the island was left untreated, taken to a feedlot on the mainland before November, and examined in January for cattle grubs by palpation of the back. The average number of cattle grubs found each year in the untreated cattle decreased progressively from 22.6 in 1960 to zero in 1963; however, 1 grub was found in 977 treated cattle in 1963. In contrast to the situation prior to the control program, the spring round-up work of 1962 and of 1963 was completely free of inconvenience from gadding by heel flies.

AGGREGATION SITES OF MALES OF THE COMMON CATTLE GRUB, HYPODERMA LINEATUM (DEVILLERS) (DIPTERA: OESTRIDAE).

Males of Hypoderma lineatum (DeVillers) were discovered aggregating along the open margins of streams coursing through pasture-land ravines in California. These bot flies positioned themselves in a “ waiting attitude” which appeared correlated with mating behavior. Daily flight activity lasted from mid-morning to mid-afternoon, but its continuance depended upon limited masking of the sun by clouds. Marked males tended to remain at the aggregation site and were seen as much as 8 days after their release. Further study of such aggregation behavior as a potential avenue for developing additional control measures against the common cattle grub is necessary.

Survival of First-Instar Common Cattle Grubs under Anaerobic Conditions in vitro12

In the field of physiology, no study is more important than that of respiration. Most animals require oxygen to complete the respiratory cycle. Surprisingly, however, a considerable number of multicelled animals live either in the complete absence of oxygen or at levels so low as to be not measurable; for example, those insects that live in deep lakes and in the intestines of larger animals. Therefore, in order to advance knowledge of the biology of insects that live in tissues of large animals, it was desirable to determine whether such an insect, taken from its natural habitat, could survive in vitro under conditions of low levels or complete absence of oxygen. The common cattle grub, Hypoderma lineatum (de Villers), was selected as a test insect, since in previous experiments the uptake of oxygen by first instars of this species was so low that it could not be measured with the Warburg^ apparatus, even when 5 or 6 larvae were placed in a single vessel and the apparatus operated for 24 hr. Further, in this insect's natural habitat in the subcutaneous tissues of bovines, oxygen is available in only very minute quantities.

Chromosome Studies in Three Species of Diptera (Muscidae and Hypodermatidae)

Studies on the chromosome number and chromosome morphology of three species of Diptera are reported. The squash technique was used on larval “brains” and testes from pupae and newly emerged males. Both the horn fly, Haematobia irritans (L.), and the stable fly, Stomoxys calcitrans (L.), have a diploid number of 10 chromosomes, and the common cattle grub, Hypoderma lineatum (de Villers), has a diploid number of 12.

Small-Scale Field Tests in Texas with Six Systemic Insecticides for the Control of Cattle Grubs

Groups of 12 to 46 cattle on seven ranches near Spur in north Texas and Kerrville in southwestern Texas were treated. One spraying with 0.25% General Chemical 4072 (2-chloro-1-(2,4-dichlorophenyl)vinyl diethyl phosphate) and two sprayings separated by 2 months were 67% and 81% effective in preventing encystment of common cattle grubs ( Hypoderma linea tum (deVillers)). Bayer 37342( O,O -dimethyl O -4-(methylthio)-3,5-xylyl phosphorothioate) afforded 99% control as a 0.5% spray, but only 38% or 58% control as a 2% pour-on in oil or water at 6 oz. per heard. A pour-on of 6 oz. per head of 8% Dipterex® (dimethyl 2,2,2-triehloro-1-hydroxyethylphosphonate) in oil was only 70% effective. Famophos® ( O-p -(dimethylsulfamoyl)phenyl O,O -dimethyl phosphorothioate) afforded 94% control when calves were each injected intramuscularly with dosages of approximately 15 mg./kg. Bayer 29493 ( O,O -dimethyl O -[4-(methylthio)- m -tolyl] phosphorothioate) was 98% effective when applied as a pour-on of 1% in oil at 6 oz. per head. A dip of O.5% Ruelene® ( O -4- tert -buty1-2-chlorophenyl O -methyl methylphosphoramidate) afforded 100% control, and 0.25% afforded 86% control.

Field Tests with Low-Level Feeding of Ronnel for Control of Cattle Grubs and Horn Flies

Four groups of Hereford cattle were offered ronnel in a mineral supplement in feed at the recommended level of 7.8 mg./kg./day for 14 days and/or in mineral blocks in pastures. The effects on populations of horn flies ( Haematobia irritans (L.)) and numbers of common cattle grubs ( Hypoderma lineatum (de Villers)) appearing in the animals’ backs were recorded. Group 1 was offered mineral supplement plus mineral blocks, group 2 mineral supplement only, and groups 3 and 4 mineral blocks only. When the mineral supplement containing ronnel was offered, populations of horn flies were reduced throughout the feeding period and for about 1 week thereafter. Consumption of ronnel in mineral block form varied considerably from group to group and from week to week within a group. A level of 3.5 mg/kg/day of ronnel was inadequate to prevent a buildup in the number of horn flies, but some apparent control was obtained with levels as low as 4 mg./kg./day when maintained for periods longer than 1 week. With group 2 only 40% cattle grub control was obtained; with groups 1, 3, and 4, 78-98% control was obtained.

Systemic Insecticides Applied as a Topical Pour-On and as an Oral Drench for Cattle Grub Control

In south Mississippi during 1960-61 Ruelene® (O-4-tert-butyl-2-chlorophenyl O-methyl methylphosphoramidate) formulated as a 2 Ib/gal. emulsifiable concentrate, at dosages ranging from 38 to 120 mg./kg. and administered as a pour-on treatment resulted in 98.9% control of the common cattle grub, Hypoderma lineatum (de Villers). On nonweaned calves, using the pour-on method. Co-ral® (O, O-diethyl O-3-chloro-4-methyl-2-oxo-2H-1-benzopyran-7-yl phosphorothionte), 2% suspension in water, 250 ml. per animal, gave 84.7% control, and Ruelene, 50 mg./kg., gave 80.1% control. The average gains in weight of the Co-ral-treated group was significantly less than that of the other treatments indicating that this dosage of Co-ral to calves 4 to 6 months of age is too high. Differences in gains in weight of groups of mature Hereford heifers treated with pour-on applications of Ruelene (75 mg./kg.) and Co-ral (2% and 4% suspensions in mineral oil) were not significant. No grubs appeared in three groups of nonweaned Hereford calves treated as follows during 1961-62: pour-on applications-(1) Ruelene 60 mg./kg., (2) Co-ral. 2% suspension in mineral oil, 125 ml. per animal; oral drench-(3) Famophos® (O, O dimethyl, O, p-(dimethyl sulfamoyl) phenyl phosphorothioate) formulated as a 20% wettable powder and administered as a suspension in water at a dosage of 25 mg./kg. A second pour-on test gave grub control among several groups of nonweaned calves as follows: Bayer 29493 (O, O-dimethyl O-[4-(methylthio)-m-tolyl] phosphorothioate). 2% solution in mineral oil, 125 ml. per animal, 97.6% control; Ruelene, 50 mg./kg., 95.9% control; Co-ral, 2% suspension in mineral oil, 125 ml. per animal, 82.4% control. Differences in gains in weight in the 1961-62 tests were not significant, Co-ral (2%) administered at a rate of 125 ml. per animal in mineral oil (instead of 250 ml. in water as applied the previous year) did not affect gains in weight of nonweaned calves.

EFFECTS OF GAMMA RADIATION ON THE FERTILITY OF THE COMMON CATTLE GRUB, HYPODERMA LINEATUM (DE VILLERS).

SummaryAt 9–13 days after collection from the backs of cattle as larvae, or 6–8 days before heel flies emerged, pupae of the common cattle grub, Hypoderma lineatum (de Villers), were exposed to 1000, 2500, 5000, or 7500 roentgens of gamma radiation from a 60Co source. Flies from irradiated pupae were mated with those from non-irradiated pupae to determine fertility of the treated individuals. At 5000 and 7500 roentgens both sexes were completely sterilized; at 2500 r females were completely sterilized and males exhibited reduced fertility.

Low-Volume Dermal Applications and Injections of Co-Ral for Systemic Control of Cattle Grubs

Topical application and intramuscular injection of low volumes of the dermal systemic insecticide Co-Ral® ( O,O -diethy O -3-choloro-4-methyl-2-oxo-2H-1-benzoyran-7yl phosphorothioate) were shown to result in more efficient control of common cattle grubs ( Hypoderma lineatum (de Villers)) than the conventional application of 1 gallon per animal of a 0.5% spray, even though less active ingredient was used and less body area was involved. Injections as low as 5 mg./kg. and dermal applications of as little as 8 fl. Oz of 2% Co-Ral in oil suspension gave complete control; these dosages represent less than 25% of the active ingredient applied in the conventional spray. Apparently the direct application of a concentrate, particularly when formulated in liquid petrolatum, resulted in increased dermal absorption of the insecticide.