De Villers Research Articles

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.

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.

Development of Cattle Grubs in Oklahoma Cattle Imported into Canada

Infested weanling heifer calves were imported into Alberta from Oklahoma in October of 1956. The subsequent seasonal incidence curve of their cattle grubs was characteristic of Oklahoma and not of Alberta infestations. Hypodermal grubs of Hypodermalineatum (de Villers) were found in these cattle earlier than in control Alberta cattle and the grubs dropped over a longer period of time. Grubs of H. bovis (L.) in the Oklahoma cattle formed a discrete second peak in the seasonal incidence curve. They occurred in the backs and dropped out at the same time as those in the Alberta cattle. Results of artificial infestations of Alberta cattle with H. lineatum eggs of Oklahoma origin indicated that the rate of development or grubs was not influenced by atmospheric temperatures. Published autecological results and soil temperature records suggested that only a small number or late-season Oklahoma puparia of H. lineatum would survive in Alberta, but that H. bovis would surive as well as the native ones. It is suggested that when northern cattle are imported into Oklahoma the relatively high temperatures would accelerate development of puparia, so their offspring would appear progressively earlier in subsequent years This would be particularly noticeable for H. bovis infestations. A group of late-born Oklahoma calves, imported into Alberta in 1961, carried grubs of H. bovis, which occurred in the backs earlier in the season than in the cattle examined in 1956-57. Apparently adaptation to the Oklahoma seasons had taken place in the intervening 5 years. H. bovis seems to be establishing itself in Oklahoma and adjusting to the seasons through adaptation in the puparial stage.

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.

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.

Effects of Topical Applications of Dibrom upon Cattle Lice and Cattle Grubs1

Dibrom®(1,2-dibromo-2,2-dichloroethyl dimethyl phosphate) sprays at a concentration of 0.5% produced useful levels of control in the cattle lice, Linognathus vituli (L.) and Solenoptes capillaus Enderlein. Control of populations of the cattle biting louse, Bovicola bovis (L.), was obtained with concentrations as low as 0.1%. The insecticide was applied to yearling beef cattle at a pressure of 400 p.s.i. at the rate of 1.5 gallons per animal. Marked mortality of larvae of Hypoderma lineatum (de Villers) and Hypoderma bovis (L.) in warbles in the backs of yearling cattle treated with Dibrom was noted. Animal systemic activity was not indicated. There was evidence of grub kill of both species for an extended period following treatment. This resulted in control for the balance of the warble season, which normally extends from December through May. Conccntrations of 0.25% to 0.5% Dibrom were considered effective. Application rates varied from 0,75 to 1.5 gallons per head at pressures of 400 p.s.i.

Control of Cattle Grubs by Pour-On, Injection, and Spray1

Four organophosphates were tested for efficacy against cattle grubs, Hypoderma lineatum (de Villers) and H. bovis (L.) using three methods of application: high-pressure, full-coverage spray; pour-on; or intramuscular injection. Ruelene® ( O -4- tert -butyl-2-chlorophenyl O -methyl methylphosphoramidate) showed grub reductions of 99.6% to 100% when used as a 0.25% spray or as a 10 or 7 gram/calf pour-on. Lesser reductions (90.0% to 96.3%) were noted with Ruelene as a 5 gram/calf pour-on. Co-ral® ( O,O -diethyl O -3-chloro-4-methyl-2-oxo-2 H -benzopyran-7-yl-phosphorothioate) was 91.1% effective as a 0.25% spray and 91.8% to 97.8% effective as a pour-on at the 5 gram/calf dosage. Bayer 29493 ( O,O -dimethyl O -[4-(methythio)- m -tolyl[ phosphorothioate) reduced grubs 100% as a 0.25% spray, a 2.5 gram/calf pour-on, or as a 7 mg./kg. injection. American Cyanamid 38023 (Famophos) ( O,O -dimethyl, O, p -(dimethylsulfamoyl) phenyl phosphorothioate) showed effectiveness against grubs of 94.8% using a 10 gram/calf pour-on and 99.6% as injections at either 15 or 7 mg./kg. Necessity of differential treatment of calves by the pour-on technique, accounting for dosage on a per unit weight basis, is not indicated. Cholinesterase activity and gains in weight were affected slightly in some of the treatments. Toxicity was encountered ill some of the treatments varying from mild to severe. Alfalfa hay appeared to have contributed to severe bloat in one group of treated calves.

Cattle Grub Control with Ruelene as a Dip and a Pour-on Treatment1

Ruelen®(O-4-tert-butyl-2-chlorophenyl O-methyl phosphoramidate) formulated as a 2 lb./gal. emulsifiable concentrate, was applied to cattle in large scale tests in Montana for the control of cattle grubs, Hypoderma lineatum (De Villers) and H. boris (L.). Dilution with 2 parts of water and administration by the pour-on method at dosages of 40, 55, and 70 mg./kg. to feed-lot calves resulted in grub reductions in excess of 99%. In rage cattle, dipped in concentrations of Ruelene of 0.125% and 0.25%, grub reductions were 75.7% and 99.3%, respectively. The 0.25% dip gave satisfactory control of cattle lice, Haematopinus eurysternus (Nitzseh) and Linognathus vituli (L.). Mild, transitory intoxication following treatment was noted in the feedlot calves, but not in the range cattle.

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.