Low Volume Spraying of Sheep to Control the Sheep Ked1,2 J. E. LLOYD,E. J.

OLSON,and R. E. PFADT

Entomology Section, University of Wyoming, Laramie

82071

ABSTRACT pressurized CO2, Diazinon AG500 and Korlan 2 provided 100% control of MeloPhagus ovinus (L.) at nozzle delivery rates of 4.8 and 9.0 mlfsec, respectively. The sheep passed through the chute at a rate of ca. 60 sheepf min. No adverse effects on the sheep were noticed.

Undiluted Diazinon® AG500 (48% diazinon) and Kor· lan® 2 (24.5% ronnel) were applied to flocks of sheep by driving the animals through a narrow chute and directly over a single spray nozzle that was directed toward their undersides. The sprayer was powered by

Until 1973, eradication of the sheep ked, Melophagus ovinus (L.), from range flocks in Wyoming was achieved by treating entire flocks in spring with 1.5% dieldrin dust applied by means of a power duster (Pfadt and DeFoliart 1957). The use of 1.5% dieldrin dust for sheep ked control was cancelled by the United States Environmental Protection Agency (EP A), and is no longer included in the EPA Compendium of Registered Pesticides." One percent dust formulations of ronnel, coumaphos, and diazinon have been demonstrated to eradicate sheep keds when applied at 1.l-1.4 kg/min to flocks by means of a power duster (Pfadt and Lavigne 1965, Pfadt et al. 1975, 1976); .these products are not listed in the EPA Compendium and are not approved for use. The only product currently approved for power dusting of sheep is 0.5% coumaphos which does not provide eradication of keds (Pfadt and Lavigne 1965, Pfadt et al. 1975). Because of the lack of an effective dust for ked control on large range flocks and partly because of the unavailability of commercially produced power dusters, efforts are underway in Wyoming to deter· mine alternative treatment methods. An effective treatment for sheep 'ked control described by Lloyd et al. (1977) is the "spot-on" method, which is a dermal application of a few ml of concentrated insecticide formulation to a single spot on the back, usually by means of a syringe. An advantage that this method shares with power dusting is that animals treated with a low volume of insecticide formulation do not become wet and therefore, subject to chilling as they might when dipped or sprayed. Because the spot-on method is time consuming, it may be impractical for treatment of large range flocks. The objectives of this study were to develop a technique of rapid treatment of large numbers of animals by utilizing a low volume, i.e., a few ml per animal of liquid insecticide and to provide eradication of sheep keds with insecticide formulations that are commercially available. MATERIALSAND METHODs.-The components of the 1 Diptera:

Hippoboscidae. Approved by the Director of the Wyoming Agric. Exp. Stn. for publication as journal Article No. jA-954. Received for pub· lication Jan. 16, ]978. The authors gratefully acknowledge the help of: G. D. johnson, R. Kumar, J. W. Lavigne, S. H. Tyndall, and M. Ullah. (\ E. P. A. Compendium of Registered Pesticides, Vol. III, Suppl. No. 16, 7-31-75, Technical Services Division, Ollice of Pesticide Programs, U. S. Environmental Protection Agency, Washington, D. C. 2

sprayer (Fig. I) were the CO2 cylinder with pressure regulator, insecticide tank, line pressure gauge, shutoff valve, nozzle, and frame. The insecticide tank was a 9.5-liter stainless steel Challenger' equipped with quick. disconnect fittings. U nlik.e most insecticide sprayers that can be adapted to CO2 pressurization, the Challenger has several safety features in the event of accidental overpressurization of the tank (Grow et al. 1973). A line pressure gauge and a globe shut-off valve were placed in the line between insecticide tank. and nozzle. The shut-off valve and nozzle were connected by a 50-cm section of 9.375-mm stainless steel tubing with compression fittings. A single J;4 T TeeJet5 spray nozzle with flat spray tip was located in the bottom of a 50 cm wide wooden frame. The wooden frame protected and supported the nozzle, and guided each animal directly over the spray (Fig. 2). Rates of delivery of 2.3, 4.8, and 9.0 ml/sec were achieved by using line pressures of 2.1, 1.05 and 3.5 kg/cm2 and TeeJet flat spray tips, nos. 730039, 8001, and 730116, respectively. Hose connections were made with 9.375-mm hydraulic hose and 15.625-mm cable clamps. Two organophosphorus insecticides were applied as undiluted sprays, Diazinon® AG500 (48% diazinon)· at delivery rates of 2.3 and 4.8 ml/sec and Korlan® 2 (24.5% ronnel) 7 at 4.8 and 9.0 ml/sec. All sheep in a flock were treated with a single insecticide at one rate of application. Each rate was evaluated on 2 flocks. Ewes and 4- to 5-month-old lambs passed through the spray at rates between 60 and 73 animals/min (based on 5 flocks). Bucks passed through with similar ease (one group timed at 73/min). The flocks used in this experiment were on farms in southeast Wyoming. The breeds included Columbia, Corriedale, Hampshire, Rambouillet, Southdown, Suffolk, and several crosses. Total number of sheep (ewes, lambs and bucks) in flocks ranged from 73722, and averaged 218. Fleece length of lambs at time of spraying averaged 4.4 cm and ranged from 1.3-7.5 cm; fleece length of ewes averaged 2.1 cm and ranged from 0.3-3.8 cm. Ked density was determined by a total count of adult keds on 5 lambs and 5 ewes from each flock 'Firestone Steel Products Co., Spartanburg, SC, 29301. 5 Spraying Systems Co., Wheaton, IL, 60187. o Ciba-Geigy Corp., Greensboro. NC, 27409. 'The Dow Chemical Co., Midland, MI, 48640.

548

©1978 Entomological Society of America

0022-0493/78/0071-0548$00.75/0

June 19i8

LLOYD ET AL.: Low

VOLUME

549

SPRAYING OF SHEEP

FIG. I.-The spraying system: A, CO, cylinder; B, insecticide tank; C, line pressure gauge; D, \'ah'e; F, frame; E,lIozzle.

FIG. 2.-Sheep passing through sprayer in operation. The liquid insecticide coming from the nozzle is barely visible.

immediately before treatment, on the 5 lambs I wk posttreatment, and on the same 5 ewes and 5 lambs (j wk posttreatment (Pfadt and Lavigne 1965)_ The fi-wk interval provided sufficient time for adult emergence of all pupae present at the time of spraying_ An untreated flock was examined in the same manner at the pretreatment time and 6 wk posttreatment time. Percentage reduction of keds was computed from the pre- and posttreatment counts of each treated flock_ RESULTSANDDISCUsStoN.-Both 48% diazinon (Diazinon AG500) and 24.5% ronnel (Korlan 2) appeared to be excellent insecticides for low volume

spraying of sheep for ked control. Eradication was achieved with the diazinon and ronnel formulations at 4.8 and 9.0 mljsec, respectively (Table I). and neither formulation caused any apparent ill effects to the sheep. Both insecticides currently have residue tolerances established in sheep, and both are available commercially. Eradication of keels due to treatment was evident at the time of the 6 wk examination. Apparently, both eliazinon and ronnel were effecting mortality I wk after treatment since all live keels present on lambs at the I wk examination were tenera!. Presumably, insecticide remained for suf· ficient time to kiII those keds as well.

Table I.-Efficacy o( 48% diazinon (Diazinon@ AG500) and 24.5% ronnel (Korlan®2) (or sheep ked control. --

rllsect icicle Diazillon 48%

-

Before trealmellt

% reduction

6 wk after treatment

% reo duction

13.0 0.4

91 98

0

100

0 0

100 100

0

100

0 0

100 100

0.2

99

0 0

100 100

40.2 2.8

1.2

97

0 0

100 100

2.9 0.6

139.2 4.0

0.2

99

2.0 0

98 100

lambs ewes

ii.1 3.8

117.8 18.6

1.2

99

0 0

100 100

lambs ewes

5.1 1.0

133.8 1.0

0

100

0 0

100 100

lambs ewes

4.8 1.3

45.0 3.0

lambs ewes

1.8 0.7

140.6 23.6

2.3

lambs ewes

4.1 I.H

10.6 1.0

lambs ewes

3.8 2.2

66.2 19.6

lambs ewes

5.1 l.l

124.0 3.8

lambs ewes

5.4 1.7

4.8

lambs ewes

9.0 9.0

4.8

I wk after treatment

94

2.3

4.8

Ulltrcated

Fleece lcllgth (em)

Rate (ml/sec)

4.8

Ronnel 24.5%

~~--Mean no. keds per allimal and % reduction

--------

8.6

50.4 6.0

550

JOURNAL

OF ECONOMIC

At the lower rates of application, both insecticide formulations failed to eradicate keds from heavily infested flocks, i.e., those with ca. 140 keds{lamb. Results, however, indicated that the lower rates provided eradication of light infestations of 10-40 keds{ lamb. Although this study was not designed to measure effect of fleece length on insecticide effectiveness, it should be noted that at the higher rates of application, eradication was achieved with both insecticides on lambs with a fleece length of ca. 5 em. When applied as concentrated sprays, neither the Diazinon AG500 formulation of diazinon nor the Korlan 2 formulation of ronnel produced apparent adverse effects. The animals evinced no discomfort due to the formulation; nursing lambs fed immediately following treatment; and there were no notice· able skin reactions. When applied as a spot-on, Korlan 2 causes an immediate, often intense discomfort, and during posttreatment examinations, a scab is found attached to the fleece in the area where the formulation was applied (Lloyd et a1. 1977). Spraying the insecticide over a larger area of the body appears to eliminate discomfort and skin damage. It was apparent during the spray operation that not all liquid was deposited on the sheep. We attempted to estimate the volume of liquid deposited as well as the uniformity of coverage by applying an aqueous ameranth dye solution. A large (36 kg) lamb with petri dishes strapped across its belly was placed in a small flock and run through the spray several· times. Most of the spray adhered to the center of the

ENTOMOLOGY

Vol. 71, no.;

belly, and coverage appeared to be uniform. Aplication of insecticide to areas where most keds are located may be an advantage of this method. The volume of liquid that was collected in the petri dishes each time the lamb was run through the spray was variable. The estimated deposit per lamb at the 4.8 ml{sec delivery rate varied between 0.30 and 0.51 ml, and at 9.0 ml{sec, between 0.64 and 1.89 ml. If these volumes represented the amount of insecticide formulation that was deposited on the fleece, then the amounts of actual insecticide deposited were well below those that would be applied according to label direction, e.g., 2.4 ml of Diazinon AG500 (based on Diazinon® 50 W label) and 4.8 ml of Korlan 2. REFERENCES CITED Grow, R. R., J. E. Lloyd, and R. Kumar. 1973. An economical COo-powered insecticide sprayer for small experimental plots. J. Econ. Entomol. 66: 252-3. Lloyd, J. E., R. E. Pfadt, and E. J. Olson. 1977. Sheep ked control with pour-on insecticides. Insecticide Acaricide Tests 2: I45-{j. Pfadt, R. E., and G. R. DeFoliart. 1957. Power dusting to control the sheep ked. J. Econ. Entomol. 50: 190-4. Pfadt, R. E., and R. J. Lavigne. 1965. Further tests with power dusting to control the sheep ked. Ibid. 58: 37-38. Pfadt, R. E., J. E. Lloyd, and G. Sharafi. 1976. Sheep ked control with 1% diazinon dust. Insecticide Acaricide Tests 1: 118. Pfdat, R. E., J. E. Lloyd, and E. W. Spackman. 1975. Power dusting with organophosphorus insecticides to control the sheep ked. J. Econ. Entomol. 68: 468-70.

Low volume spraying of sheep to control the sheep ked.

Low Volume Spraying of Sheep to Control the Sheep Ked1,2 J. E. LLOYD,E. J. OLSON,and R. E. PFADT Entomology Section, University of Wyoming, Laramie...
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