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Residues of Stirofos (Rabon®) in Eggs of Laying Hens Treated for Northern Fowl Mite Control by Dipping1,2
Residues of Stirofos (Rabon®) in Eggs of Laying Hens Treated for Northern Fowl Mite Control by Dipping1,2 M. C. IVEY, JOYCE A. DEVANEY, G. WAYNE IVIE, and KENNETH R. BEERWINKLE Veterinary Toxicology and Entomology Research Laboratory\ Agricultural Research Service, US Department of Agriculture, College Station, Texas 77841 (Received for publication May 18, 1981)
dipping (Furman, 1952; Woods, 1920), most
1
Acari: Macronyssidae. This paper reports the results of research only. Mention of a pesticide does not constitute a recommendation for use by the USDA, nor does it imply registration under FIFRA as amended. Also, mention of a proprietary product does not constitute an endorsement by the USDA. 2
Stirofos (Rabon®) is currently registered as a spray formulation for the control of certain ectoparasites, including the NFM, on poultry, but this procedure is subject to the limitations elaborated above. Recent studies in this laboratory have shown that dipping birds in aqueous suspensions of stirofos controls the NFM on laying hens for several weeks. Thus, dipping offers promise as an effective NFM control procedure that might be adapted
443
Downloaded from http://ps.oxfordjournals.org/ at Northern Arizona University on June 12, 2015
ABSTRACT Laying hens were treated with a wettable powder formulation of stirofos [Rabon®, 2-chloro-l-(2,4,5-trichlorophenyl) vinyl dimethylphosphate] by dipping in a .5 or 1.0% actual ingredient (AI) water suspension of a 50% wettable powder (WP) stirofos formulation. Stirofos residues were detected in eggs within 1 day after treatment and reached maximum levels 3 days after dipping (.021 and .035 ppm in the low- and high-dose birds, respectively). After that time, levels of residues in eggs declined rapidly and no sample contained detectable quantities (<.004 ppm) of stirofos after 21 days. Dipping may be a practical control method for the northern fowl mite on chickens, because stirofos dips effectively control this mite on laying hens for at least 6 weeks and because resulting residues in eggs are well below established tolerances. (Key words.- eggs, residue, dipping, control, northern fowl mite, stirofos (Rabon), hens, 2-chIorol-(2,4,5-trichlorophenyl) vinyl dimethylphosphate) 1982 Poultry Science 61:443-446 commercial poultrymen now use either an INTRODUCTION acaricidal spray or dust to control mites on Since its introduction into the United States, infested chickens. However, effective NFM the northern fowl mite (NFM), Ornithonyssus control can be very difficult to obtain due to sylviarum (Canestrini and Fanzago), has spread dramatic increases in the size of layer and throughout the United States and is now the breeder flocks, labor costs, and current manmost important external parasite of caged agement practices in which 10 or more birds poultry (DeVaney, 1978; Woods, 1920). This may be caged together (Loomis et al., 1979). hematophagus mite is a parasite that usually The NFM is especially difficult to control in spends its entire life cycle on the host. The large breeder flocks on litter where roosters NFM can build up large populations on infested birds in a matter of weeks (DeVaney et al, normally carry heavier mite populations than hens. In addition, the NFM appears to be 1980) and may adversely affect egg production, acquiring resistance to some chemicals used for male reproductive potential, and overall bird performance (DeVaney et al, 1977; DeVaney, its control, particularly malathion and carbaryl (Foulk and Matthysse, 1964; Furman and Lee, 1979, DeLoach and DeVaney, 1981). It has 1969; Nelson and Bertun, 1965; Reid et al, potential as a reservoir and/or vector of the 1956; Rodriguez and Riehl, 1963). However, virus causing western equine encephalomyelitis some researchers believe that what is considered (Reeves et al, 1947) and is a source of an"resistance" by many producers may be the noyance to poultrymen (Hall, 1979; Miller and result of insufficient acaricide coverage (and Price, 1977). Therefore, efforts to control the thus inefficient control) by the spraying or NFM are necessary for both economic and dusting procedures currently used (Loomis et practical reasons. Although early recommenal, 1979). dations for control of the NFM included
444
IVEY ET AL.
to current poultry management practices. The current studies were undertaken to determine the levels of stirofos residues that might be expected to occur in eggs of laying hens treated for NFM control by dipping in either a .5 or 1.0% stirofos formulation. METHODS AND MATERIALS
All eggs laid by each group were collected daily and recorded. Eggs for residue analysis were collected at 0, 1, 3, 5, 7, 10, 14, 21, and 28 days posttreatment. All eggs from a given group on each sampling day were broken into a large beaker, homogenized with a Willems® Polytron homogenizer (PT-20 generator), transferred to Dow Ziploc® quart
Chemical Analysis of Eggs for
Stirofos
Extraction. Twenty gram samples of homogenized eggs were blended in a Waring® blender with 100 ml of acetonitrile. The contents were transferred to a 600 ml beaker, heated on a hot plate to near boiling, and filtered through a 250 ml fritted glass Buchner funnel (containing a disc of No. 40 filter paper and ca. 30 g of anhydrous sodium sulfate) into a 500 ml Erlenmeyer flask. The blender, beaker, and funnel were washed with ca. 150 to 200 ml of acetonitrile, which was combined with the original filtrate. A Snyder column was attached to the flask, and the extract was concentrated by distillation to ca. 50 ml, cooled to room temperature, and transferred to a 500 ml separatory funnel containing 50 ml of hexane. An additional 100 ml of hexane was used to make the transfer. The funnel was shaken for ca. 2 min, the phases were allowed to separate, and the acetonitrile was drained into a second separatory funnel that contained 100 ml hexane. After the second funnel was shaken, the acetonitrile was drained into a 250-ml Erlenmeyer flask. Two additional 50-ml portions of acetonitrile were used to partition, in sequence, the hexane in the first and second funnels. The combined acetonitrile extracts, containing the stirofos, were then concentrated to ca. 5 to 10 ml by distillation through a Snyder column. Hexane (3 5 ml) was added to the extract through the Snyder column, the column was removed, and the solvent was removed using low heat of a hot plate and finally a mild jet of nitrogen at ambient temperature. The residue was dissolved in 2 ml of hexane, stoppered, and die contents held for subsequent chromatographic cleanup. Cleanup of Extracts. Glass cleanup columns (Kontes No. 11416-B, 24/40 joints) were prepared by adding, in order, a plug of glass wool, 1 cm of anhydrous sodium sulfate, 10 g of silicic acid (heated 16 hr at 225 C, cooled, 14% water added, and allowed to equilibrate), 1 cm of sodium sulfate, and a plug of glass wool. The silicic acid was packed by attaching an aspirator to the elution end of the column and tapping the column gently on a table top until no additional settling occurred. The column was then prewashed with 50 ml of 1:1 dichloromethane-hexane, the sample was trans-
Downloaded from http://ps.oxfordjournals.org/ at Northern Arizona University on June 12, 2015
The chickens used for this study were 55-week-old White Leghorn hens (Hi-Lay) in good egg production. Records of the birds showed no exposure to pesticides of any type during an 8-month period prior to initiation of the current study. The hens were individually identified by numbered leg bands and were housed in individual laying cages. For 2 weeks prior to initiation of die study, they were monitored for health problems and egg production. Only birds in apparent good health and with >50% egg production were selected for the study. Two days prior to treatment, the hens were individually weighed and randomly assigned to three groups of 6 birds each. The hens were dipped in a stainless steel vat (122 X 76 X 76 cm) containing 50 gal of either water (control) or a .5 or 1.0% AI aqueous suspension of Rabon® 50% WP [stirofos, 2-chloro-l-(2,4,5-trichlorophenyl) vinyl dimethylphosphate]. The temperature of the dipping suspension was ca. 23 to 25 C, and the suspension was thoroughly agitated with a wooden paddle just prior to dipping to assure homogeneity. For dipping, the birds (groups of 6) were placed in commercial plastic coops (86 X 56 X 22 cm), the entire coop and birds were completely submerged in the vat for 5 sec, lifted out for 20 sec, and resubmerged again for 5 sec. This double dipping procedure was used to assure maximum wetting of the chickens. After dipping, the birds (still inside the dipping coops) were allowed to drain for several minutes before being transferred back to their laying cages. The control and stirofos-treated hens were housed in two separate rooms and were observed periodically for any signs of illness.
size plastic bags, frozen, and held at —18 C until analyzed.
STIROFOS RESIDUE IN EGGS
Gas Chromatography of Stirofos A Tracor 222 gas chromatograph equipped with a Tracor Flame Photometric Detector operating in the phosphorus mode was used. The column was borosilicate glass (4 mm id X 1.22 m) filled with 5% DC-200 coated Gas Chrom Q (80 to 100 mesh). Carrier gas was prepurified nitrogen adjusted to a flow rate of 120 ml/min (exhaust). The column was heated isothermally to 213 C, die injector to 210 C, and the detector to 190 C. Hydrogen and air flowing to the detector were adjusted to 60 and 120 ml/min, respectively. At these conditions, the retention time for stirofos was ca. 2.0 min. Samples (20 g) of control eggs were fortified at levels of 0, .005, .025, .05, .10, and .20 ppm of stirofos before extraction. Recoveries ranged from 88 to 96%. With the sample size and
dilutions used, levels of stirofos in eggs as low as .004 ppm were detectable. RESULTS AND DISCUSSION Stirofos residues were detected in eggs of laying hens within 1 day after dipping the birds in a .5 or 1.0% aqueous suspension of stirofos (Table 1). Residues reached their maximum levels in eggs collected 3 days after dipping (.021 and .035 ppm in the low- and high-dose birds, respectively), but after that time residues declined so rapidly that no samples contained detectable quantities of stirofos after 21 days (Table 1). In samples collected during the first 7 days posttreatment, stirofos residues were higher in the eggs from birds treated at the higher dosage rate (with the exception of day 1), but this difference was not apparent in eggs collected after day 7. Residues in the 10-and 14-day egg samples, regardless of treatment group, were very low and only slightly above the detection limit of the method. Dipping these hens in aqueous suspensions of stirofos did not result in any bird mortality or significant effects on health, egg production, or body weight. Egg production averaged >70% in each of the 3 groups during the study. Our studies have shown that dipping laying hens in a .5 or 1.0% wettable powder suspension of stirofos will not result in persistent residues in the eggs. Although stirofos residues are readily detectable in eggs within 1 day after dipping, residues are in all cases less than the established .1 ppm tolerance (Anonymous, 1970). Within 7 days after dipping, levels of stirofos residues are at or below .01 ppm, and residues are marginally detectable or nondetectable by 14 to 21 days after treatment. Because stirofos dips give effective
TABLE 1. Stirofos residues in eggs of chickens dipped in .5% or 1% suspensions of stirofos Stirofos3'3 (ppm) Days posttreatment Treatment Control .5% 1.0%
10 0 0 0
0
0 .017 .012
.021 .035
0 = <.004 ppm stirofos. Uncorrected for percentage recoveries.
.011 .019
14
21
28
.005
0 0 0
0 0 0
0 .004 .012
.008 .007
0
Downloaded from http://ps.oxfordjournals.org/ at Northern Arizona University on June 12, 2015
ferred to the column by using 25 ml of die 1:1 dichloromethane-hexane solvent mixture (in 4 to 6 ml aliquots) to complete the transfer, and the column was then washed with 125 ml more of the same solvent mixture. The receiver was changed and the stirofos was eluted with 195 ml of the solvent mixture at a flow rate of ca. 130 ml/h. The receiver was attached to a Buchii® Rotovapor and the volume of solvent was reduced to ca. 3 ml in a 45 to 50 C water bath. The residue was then transferred to a 50 ml glass-stoppered flask with hexane and evaporated to dryness by warming on a hot plate and using a mild jet of nitrogen, except that the last 1 to 2 ml of solvent were removed at room temperature. Hexane (2 ml) was used to dissolve the residue and a 10 /il aliquot was injected into the gas chromatograph. Stirofos residues were quantitated by comparing peak heights with those of standards of known concentration.
445
446
IVEY ET AL.
control of the northern fowl mite on laying hens for at least 6 weeks when challenged with the NFM on a weekly basis (DeVaney and Beerwinkle, 1981, unpublished data), this treatment may be practical, economical, and acceptable.
REFERENCES CITED
Downloaded from http://ps.oxfordjournals.org/ at Northern Arizona University on June 12, 2015
Anonymous, 1970. Tolerances and exemptions from tolerance for pesticide chemicals in or on raw agricultural commodities. Fed. Reg. 35:10517. DeLoach, J. R., and J. A. DeVaney, 1981. Northern fowl mite, Omithonyssus sylviarum (Canestrini and Fanzago), ingests large quantities of blood from White-Leghorn hens. J. Med. Entomol. 18:374-377. DeVaney, J. A., 1978. A survey of poultry ectoparasite problems and their research in the United States. Poultry Sci. 57:1217-1220. DeVaney, J. A., 1979. The effects of the northern fowl mite, Omithonyssus sylviarum, on egg production and body weight of caged white Leghorn hens. Poultry. Sci. 58:191-194. DeVaney, J. A., M. H. Elissalde, E. G. Steel, B. F. Hogan, and H. D. Petersen, 1977. Effects of the northern fowl mite, Omithonyssus sylviarum (Canestrini and Fanzago) on White Leghorn roosters. Poultry Sci. 56:1585—1590. DeVaney, J. A., J. H. Quisenberry, B. H. Doran, and J. W. Bradley, 1980. Dispersal of the northern fowl mite, Omithonyssus sylviarum (Canestrini and Fanzago), and the chicken body louse, Menacanthus stramineus (Nitzsch), among thirty
strains of egg-type hens in a caged laying house. Poultry Sci. 59:1745-1749. Foulk, J. D., and J. G. Matthysse, 1964. A new toxicological test method for hematophagous mites. J. Econ. Entomol. 57:602—604. Furman, D. P., 1952. Control of the northern fowl mite. J. Econ. Entomol. 45:926-930. Furman, D. P., and D. Lee, 1969. Experimental control of the northern fowl mite. J. Econ. Entomol. 62:1246. Hall, R. D., 1979. The northern fowl mite . . . poultry's most damaging external parasite. Poultry Dig. 38:430-438. Loomis, E. C , E. H. Bramhall, and L. L. Dunning, 1979. Comparative effectiveness of Fenvalerate and Carbaryl sprays against the northern fowl mite. J. Econ. Entomol. 72:856-859. Miller, W. V., and F. C. Price, 1977. The avian mite, Omithonyssus sylviarum. on mammalian hosts with references to transmission to poultry. J. Parasitol. 63:417. Nelson, T. E., and K. M. Bertun, 1965. Synergism of malathion against the northern fowl mite. J. Econ. Entomol. 58:1117-1118. Reeves, W. C , W. McD. Hammon, D. P. Furman, H. E. McClure, and B. Brookman, 1947. Recovery of western equine encephalomyelitis virus from wild bird mites (Liponyssus sylviarum) in Kern County, California. Science 105:411-412. Reid, W. M., R. L. Linkfield, and G. Lewis, 1956. Limitations of malathion in northern fowl mite and louse control. Poultry Sci. 35:1397-1398. Rodriguez, J. L., and L. A. Riehl, 1963. Northern fowl mites tolerant to malathion. J. Econ. Entomol. 56:509-511. Woods, H. P., 1920. Tropical fowl mite in the United States with notes on the life history and control. US Dept. Agr. Circ. 79.
dipping (Furman, 1952; Woods, 1920), most
1
Acari: Macronyssidae. This paper reports the results of research only. Mention of a pesticide does not constitute a recommendation for use by the USDA, nor does it imply registration under FIFRA as amended. Also, mention of a proprietary product does not constitute an endorsement by the USDA. 2
Stirofos (Rabon®) is currently registered as a spray formulation for the control of certain ectoparasites, including the NFM, on poultry, but this procedure is subject to the limitations elaborated above. Recent studies in this laboratory have shown that dipping birds in aqueous suspensions of stirofos controls the NFM on laying hens for several weeks. Thus, dipping offers promise as an effective NFM control procedure that might be adapted
443
Downloaded from http://ps.oxfordjournals.org/ at Northern Arizona University on June 12, 2015
ABSTRACT Laying hens were treated with a wettable powder formulation of stirofos [Rabon®, 2-chloro-l-(2,4,5-trichlorophenyl) vinyl dimethylphosphate] by dipping in a .5 or 1.0% actual ingredient (AI) water suspension of a 50% wettable powder (WP) stirofos formulation. Stirofos residues were detected in eggs within 1 day after treatment and reached maximum levels 3 days after dipping (.021 and .035 ppm in the low- and high-dose birds, respectively). After that time, levels of residues in eggs declined rapidly and no sample contained detectable quantities (<.004 ppm) of stirofos after 21 days. Dipping may be a practical control method for the northern fowl mite on chickens, because stirofos dips effectively control this mite on laying hens for at least 6 weeks and because resulting residues in eggs are well below established tolerances. (Key words.- eggs, residue, dipping, control, northern fowl mite, stirofos (Rabon), hens, 2-chIorol-(2,4,5-trichlorophenyl) vinyl dimethylphosphate) 1982 Poultry Science 61:443-446 commercial poultrymen now use either an INTRODUCTION acaricidal spray or dust to control mites on Since its introduction into the United States, infested chickens. However, effective NFM the northern fowl mite (NFM), Ornithonyssus control can be very difficult to obtain due to sylviarum (Canestrini and Fanzago), has spread dramatic increases in the size of layer and throughout the United States and is now the breeder flocks, labor costs, and current manmost important external parasite of caged agement practices in which 10 or more birds poultry (DeVaney, 1978; Woods, 1920). This may be caged together (Loomis et al., 1979). hematophagus mite is a parasite that usually The NFM is especially difficult to control in spends its entire life cycle on the host. The large breeder flocks on litter where roosters NFM can build up large populations on infested birds in a matter of weeks (DeVaney et al, normally carry heavier mite populations than hens. In addition, the NFM appears to be 1980) and may adversely affect egg production, acquiring resistance to some chemicals used for male reproductive potential, and overall bird performance (DeVaney et al, 1977; DeVaney, its control, particularly malathion and carbaryl (Foulk and Matthysse, 1964; Furman and Lee, 1979, DeLoach and DeVaney, 1981). It has 1969; Nelson and Bertun, 1965; Reid et al, potential as a reservoir and/or vector of the 1956; Rodriguez and Riehl, 1963). However, virus causing western equine encephalomyelitis some researchers believe that what is considered (Reeves et al, 1947) and is a source of an"resistance" by many producers may be the noyance to poultrymen (Hall, 1979; Miller and result of insufficient acaricide coverage (and Price, 1977). Therefore, efforts to control the thus inefficient control) by the spraying or NFM are necessary for both economic and dusting procedures currently used (Loomis et practical reasons. Although early recommenal, 1979). dations for control of the NFM included
444
IVEY ET AL.
to current poultry management practices. The current studies were undertaken to determine the levels of stirofos residues that might be expected to occur in eggs of laying hens treated for NFM control by dipping in either a .5 or 1.0% stirofos formulation. METHODS AND MATERIALS
All eggs laid by each group were collected daily and recorded. Eggs for residue analysis were collected at 0, 1, 3, 5, 7, 10, 14, 21, and 28 days posttreatment. All eggs from a given group on each sampling day were broken into a large beaker, homogenized with a Willems® Polytron homogenizer (PT-20 generator), transferred to Dow Ziploc® quart
Chemical Analysis of Eggs for
Stirofos
Extraction. Twenty gram samples of homogenized eggs were blended in a Waring® blender with 100 ml of acetonitrile. The contents were transferred to a 600 ml beaker, heated on a hot plate to near boiling, and filtered through a 250 ml fritted glass Buchner funnel (containing a disc of No. 40 filter paper and ca. 30 g of anhydrous sodium sulfate) into a 500 ml Erlenmeyer flask. The blender, beaker, and funnel were washed with ca. 150 to 200 ml of acetonitrile, which was combined with the original filtrate. A Snyder column was attached to the flask, and the extract was concentrated by distillation to ca. 50 ml, cooled to room temperature, and transferred to a 500 ml separatory funnel containing 50 ml of hexane. An additional 100 ml of hexane was used to make the transfer. The funnel was shaken for ca. 2 min, the phases were allowed to separate, and the acetonitrile was drained into a second separatory funnel that contained 100 ml hexane. After the second funnel was shaken, the acetonitrile was drained into a 250-ml Erlenmeyer flask. Two additional 50-ml portions of acetonitrile were used to partition, in sequence, the hexane in the first and second funnels. The combined acetonitrile extracts, containing the stirofos, were then concentrated to ca. 5 to 10 ml by distillation through a Snyder column. Hexane (3 5 ml) was added to the extract through the Snyder column, the column was removed, and the solvent was removed using low heat of a hot plate and finally a mild jet of nitrogen at ambient temperature. The residue was dissolved in 2 ml of hexane, stoppered, and die contents held for subsequent chromatographic cleanup. Cleanup of Extracts. Glass cleanup columns (Kontes No. 11416-B, 24/40 joints) were prepared by adding, in order, a plug of glass wool, 1 cm of anhydrous sodium sulfate, 10 g of silicic acid (heated 16 hr at 225 C, cooled, 14% water added, and allowed to equilibrate), 1 cm of sodium sulfate, and a plug of glass wool. The silicic acid was packed by attaching an aspirator to the elution end of the column and tapping the column gently on a table top until no additional settling occurred. The column was then prewashed with 50 ml of 1:1 dichloromethane-hexane, the sample was trans-
Downloaded from http://ps.oxfordjournals.org/ at Northern Arizona University on June 12, 2015
The chickens used for this study were 55-week-old White Leghorn hens (Hi-Lay) in good egg production. Records of the birds showed no exposure to pesticides of any type during an 8-month period prior to initiation of the current study. The hens were individually identified by numbered leg bands and were housed in individual laying cages. For 2 weeks prior to initiation of die study, they were monitored for health problems and egg production. Only birds in apparent good health and with >50% egg production were selected for the study. Two days prior to treatment, the hens were individually weighed and randomly assigned to three groups of 6 birds each. The hens were dipped in a stainless steel vat (122 X 76 X 76 cm) containing 50 gal of either water (control) or a .5 or 1.0% AI aqueous suspension of Rabon® 50% WP [stirofos, 2-chloro-l-(2,4,5-trichlorophenyl) vinyl dimethylphosphate]. The temperature of the dipping suspension was ca. 23 to 25 C, and the suspension was thoroughly agitated with a wooden paddle just prior to dipping to assure homogeneity. For dipping, the birds (groups of 6) were placed in commercial plastic coops (86 X 56 X 22 cm), the entire coop and birds were completely submerged in the vat for 5 sec, lifted out for 20 sec, and resubmerged again for 5 sec. This double dipping procedure was used to assure maximum wetting of the chickens. After dipping, the birds (still inside the dipping coops) were allowed to drain for several minutes before being transferred back to their laying cages. The control and stirofos-treated hens were housed in two separate rooms and were observed periodically for any signs of illness.
size plastic bags, frozen, and held at —18 C until analyzed.
STIROFOS RESIDUE IN EGGS
Gas Chromatography of Stirofos A Tracor 222 gas chromatograph equipped with a Tracor Flame Photometric Detector operating in the phosphorus mode was used. The column was borosilicate glass (4 mm id X 1.22 m) filled with 5% DC-200 coated Gas Chrom Q (80 to 100 mesh). Carrier gas was prepurified nitrogen adjusted to a flow rate of 120 ml/min (exhaust). The column was heated isothermally to 213 C, die injector to 210 C, and the detector to 190 C. Hydrogen and air flowing to the detector were adjusted to 60 and 120 ml/min, respectively. At these conditions, the retention time for stirofos was ca. 2.0 min. Samples (20 g) of control eggs were fortified at levels of 0, .005, .025, .05, .10, and .20 ppm of stirofos before extraction. Recoveries ranged from 88 to 96%. With the sample size and
dilutions used, levels of stirofos in eggs as low as .004 ppm were detectable. RESULTS AND DISCUSSION Stirofos residues were detected in eggs of laying hens within 1 day after dipping the birds in a .5 or 1.0% aqueous suspension of stirofos (Table 1). Residues reached their maximum levels in eggs collected 3 days after dipping (.021 and .035 ppm in the low- and high-dose birds, respectively), but after that time residues declined so rapidly that no samples contained detectable quantities of stirofos after 21 days (Table 1). In samples collected during the first 7 days posttreatment, stirofos residues were higher in the eggs from birds treated at the higher dosage rate (with the exception of day 1), but this difference was not apparent in eggs collected after day 7. Residues in the 10-and 14-day egg samples, regardless of treatment group, were very low and only slightly above the detection limit of the method. Dipping these hens in aqueous suspensions of stirofos did not result in any bird mortality or significant effects on health, egg production, or body weight. Egg production averaged >70% in each of the 3 groups during the study. Our studies have shown that dipping laying hens in a .5 or 1.0% wettable powder suspension of stirofos will not result in persistent residues in the eggs. Although stirofos residues are readily detectable in eggs within 1 day after dipping, residues are in all cases less than the established .1 ppm tolerance (Anonymous, 1970). Within 7 days after dipping, levels of stirofos residues are at or below .01 ppm, and residues are marginally detectable or nondetectable by 14 to 21 days after treatment. Because stirofos dips give effective
TABLE 1. Stirofos residues in eggs of chickens dipped in .5% or 1% suspensions of stirofos Stirofos3'3 (ppm) Days posttreatment Treatment Control .5% 1.0%
10 0 0 0
0
0 .017 .012
.021 .035
0 = <.004 ppm stirofos. Uncorrected for percentage recoveries.
.011 .019
14
21
28
.005
0 0 0
0 0 0
0 .004 .012
.008 .007
0
Downloaded from http://ps.oxfordjournals.org/ at Northern Arizona University on June 12, 2015
ferred to the column by using 25 ml of die 1:1 dichloromethane-hexane solvent mixture (in 4 to 6 ml aliquots) to complete the transfer, and the column was then washed with 125 ml more of the same solvent mixture. The receiver was changed and the stirofos was eluted with 195 ml of the solvent mixture at a flow rate of ca. 130 ml/h. The receiver was attached to a Buchii® Rotovapor and the volume of solvent was reduced to ca. 3 ml in a 45 to 50 C water bath. The residue was then transferred to a 50 ml glass-stoppered flask with hexane and evaporated to dryness by warming on a hot plate and using a mild jet of nitrogen, except that the last 1 to 2 ml of solvent were removed at room temperature. Hexane (2 ml) was used to dissolve the residue and a 10 /il aliquot was injected into the gas chromatograph. Stirofos residues were quantitated by comparing peak heights with those of standards of known concentration.
445
446
IVEY ET AL.
control of the northern fowl mite on laying hens for at least 6 weeks when challenged with the NFM on a weekly basis (DeVaney and Beerwinkle, 1981, unpublished data), this treatment may be practical, economical, and acceptable.
REFERENCES CITED
Downloaded from http://ps.oxfordjournals.org/ at Northern Arizona University on June 12, 2015
Anonymous, 1970. Tolerances and exemptions from tolerance for pesticide chemicals in or on raw agricultural commodities. Fed. Reg. 35:10517. DeLoach, J. R., and J. A. DeVaney, 1981. Northern fowl mite, Omithonyssus sylviarum (Canestrini and Fanzago), ingests large quantities of blood from White-Leghorn hens. J. Med. Entomol. 18:374-377. DeVaney, J. A., 1978. A survey of poultry ectoparasite problems and their research in the United States. Poultry Sci. 57:1217-1220. DeVaney, J. A., 1979. The effects of the northern fowl mite, Omithonyssus sylviarum, on egg production and body weight of caged white Leghorn hens. Poultry. Sci. 58:191-194. DeVaney, J. A., M. H. Elissalde, E. G. Steel, B. F. Hogan, and H. D. Petersen, 1977. Effects of the northern fowl mite, Omithonyssus sylviarum (Canestrini and Fanzago) on White Leghorn roosters. Poultry Sci. 56:1585—1590. DeVaney, J. A., J. H. Quisenberry, B. H. Doran, and J. W. Bradley, 1980. Dispersal of the northern fowl mite, Omithonyssus sylviarum (Canestrini and Fanzago), and the chicken body louse, Menacanthus stramineus (Nitzsch), among thirty
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