NOTES
A case of traumatic dermal myiasis in Quebec caused by Phormia regina (Meigen) (Diptera: Calliphoridae) F. E. A. ALI-KHAN Department of Entomology, Macdonald College of McGill University, Ste Anne-de-Bellevue, Quebec AND
Can. J. Zool. Downloaded from www.nrcresearchpress.com by University of P.E.I. on 11/24/14 For personal use only.
Z. ALI-KHAN Department of Microbiology and Immunology, McGill University, Montreal, Quebec Received April 1, 1975 ALI-KHAN,F. E. A . , and 2. ALI-KHAN.1975. A case of traumatic dermal myiasis in Quebec caused by Phormia regina (Meigen) (Diptera: Calliphoridae). Can. J. Zool. 53: 1472-1476. A case of human myiasis due to Phormia regina (Meigen) is reported from Montreal, Quebec. Large numbers of larvae were removed from a necrotic hip wound in a 44-year-old male. Larvae were reared to the adult stage; larval and pupal measurements and development times are given. ALI-KHAN, F. E. A . , et 2. ALI-KHAN.1975. A case of traumatic dermal myiasis in Quebec caused by Phormia regina (Meigen) (Diptera: Calliphoridae). Can. J. Zool. 53: 1472-1476. On a rencontre un cas de myiase humaine causee par Phormia regina (Meigen) B Montreal, Quebec. On a trouve un grand nombre de lames dans la blessure necrosique de la hanche, chez un individu mile Lge de 44 ans. Les larves Blevees sont parvenues au stade adulte; on donne les mesures des larves et des pupes ainsi que le temps ecoule entre les phases du dtveloppement. [Traduit par le journal]
Phormia regina (Meigen), the black blowfly, is a common fly in the United States but not abundant in Canada. It is known as a coolweather blowfly, being active in the southern states throughout winter except for a few days during cold periods, but may disappear during a hot dry summer. In the northern United States it is absent only during the coldest weather but found in large numbers in spring and fall. In Ontario it has been found to occur from midApril to early November, being most abundant towards the end of July (Judd 1956). Most probably, in northern latitudes it passes the winter in the soil in either the pupal or prepupal stage (Bishopp and Laake 1915). The larvae are normally saprophagous, feeding in large numbers in carcasses of animals but may also infest wounds and feed on both dead and living tissue. They are one of the most troublesome of sheep maggots especially in the south-western United States, infesting the rumps of ewes following lambing, old festering sores following dehorning, or soiled wool near the
anus where they may eventually work into the flesh. Reported cases of human myiasis involving larvae of this species of fly are very rare. Stewart (1929) describes infestation of pussy scalp sores of a 25-year-old woman in Texas. A great quantity of larvae of Phormia regina were removed after treatment of the area with a supersaturated sulfur wash. In Mississippi, Dove (1937) reports a case where 15-20 small larvae of this species were removed from the ear of a 4-year-old boy. Scott (1964), in recording cases of human myiasis not previously published, mentions the possible involvement of P . regina in furuncular myiasis in Idaho in 1959. No further information is given. James (1948) notes that larvae of P. regina have been reported in enteric mviasis but also that the record needs substantiation. The following appears to be the first reported case of human myiasis due to P. regina in Canada. Adults were reared from larvae isolated from a wound. In addition to this, two published -
-
-
1473
NOTES
Can. J. Zool. Downloaded from www.nrcresearchpress.com by University of P.E.I. on 11/24/14 For personal use only.
cases of intestinal and subungual myiasis (Ali-Khan and Ali-Khan 1974) and one unpublished case of vaginal myiasis, identified in section, caused by other species of Diptera have been seen recently in the Montreal area. Case History The patient was a 44-year-old male resident of Verdun, a suburb of Montreal. He entered hospital with chronic renal, and congestive heart failure. He was paraplegic and had had a necrotic hip wound for a number of years. The extent of the lesion was severe, extending from the hip area through a subcutaneous sinus tract as far as the scrotum, and also involving necrosis of bone. The wound was washed with hydrogen peroxide and on several occasions bunches of larvae of the size of a golf ball involving 'hundreds' of specimens were found on the gauze covering the wounds. Six live larvae were sent to one of us (Z. A-K.) for identification on August 2, having been removed from the patient on August 1. The larvae were examined under a stereoscopic microscope, and one larva, morphologically similar to the others, was preserved in formalin and the rest were placed on raw ground beef in a container covered with cheesecloth. At first they were very active, and as a result one larva was lost when it penetrated the cheesecloth, but within a day and a half the remainder had become contracted and immobile. By the morning of the 3rd day all four larvae were found to have pupated and were removed to dryish soil. One pupa was preserved in formalin. Adults from two pupae emerged on August 11 and the third on August 12. These were identified as two males and a female of Phormia regina. Dimensions and Development of the Larvae and Pupae First-, second-, and third-larval instars, the puparium, and adults of Phormia regina have been described by Ha11 (1948), but measurements are not given for the cephalopharyngeal sclerites, nor the posterior spiracles, which are specific features of the larva. We include these measurements and overall dimensions of our larva and puparium and development times for comparison with those from more southern localities. Our one preserved larva (Fig. 1) was appar-
FIG.1 . Third-instar larva of Phormia regina.
ently third instar. It had one posterior spiracle with three slits and the other with two and an imperfectly formed third. The larva measured 14.5 by 3.0 mm which agrees with the dimensions, length 9-17, diameter 3-4 mm given by Hall (1948) for third-instar larvae of this species, and the cephalopharyngeal sclerites were of the form for third-instar larvae. Measurements in microns (p) of the posterior spiracles (Fig. 2) and cephalopharyngeal sclerites (Fig.
Can. J. Zool. Downloaded from www.nrcresearchpress.com by University of P.E.I. on 11/24/14 For personal use only.
1474 CAN. J. ZOOL. VOL. 53, 1975
TABLE 1 Measurements in microns (p) of the posterior spiracles and cephalopharyngeal sclerites following the convention of Sanjean (1957) Posterior spiracle Length left
right
Middle spiracular slit
Width left
Length
right
left
right
Width left
right
Can. J. Zool. Downloaded from www.nrcresearchpress.com by University of P.E.I. on 11/24/14 For personal use only.
Cevhalovharyngeal sclerites Tip of mouth hook to farthest point of posterodorsal process 368
Anterodorsal process to tip of dorsal cornu 1008
3), following the convention of Sanjean (1957), are shown in Table 1. The width of the right posterior spiracle was somewhat less than that of the left because of the aberrant third slit. The two spiracles were separated by a distance of about two-thirds that of the left spiracle. The puparium was 9.0 by 3.0 mm. Hall (1948) gives length 9.0-9.5, diameter 3-4 mm. Development times of this species depend on the temperature. According to Bishopp et al. (1917), eggs hatch in from less than 24 h to 4 days in carcasses but he notes that on living animals the rate of development is probably faster. Melvin (1934) found these eggs complete incubation in 8.13 h at 99 "F (ca. 37 "C). Total length of the larval stage ranges from 4 to 15 days (Bishopp 1915). Our larvae pupated 3 days after they were removed from the patient's wound. Our pupal stage lasted 7-8 days. The average rearing temperature was 70°F (ca. 21 "C). Bishopp (1915) gives 3-13 days for the pupal stage in Texas and Kamal (1958) 4-9 days under controlled temperature of 80 f 2 OF (ca. 27 f 1 "C) and relative humidity 50 f 2%.
Comments It is apparent that the adult fly was attracted to the patient's suppurating lesion. This species shows a marked tendency to deposit its eggs in large masses (Bishopp and Laate 1915) which accounts for the large numbers of larvae found both in the case reported by Stewart (1929) and in the present case where the many 'hundreds'
Length of dorsal cornu 584
Length of ventral cornu 41 7
could well have resulted from eggs of a single female fly. The larvae were apparently actively feeding on necrotic tissue in the wound and could possibly have had beneficial effects since larvae of this species have been used in the past for treatment of deep pus-discharging human wounds (Horsfall 1962) and osteomyelitis (Robinson 1933). However, Hall (1948) notes that they may destroy healthy tissue as well since in cases of animal myiasis there is sometimes a bloody discharge.
Acknowledgments We are grateful to Dr. M. T. James of Washington State University, U.S.A., who confirmed our identification of the adult flies. ALI-KHAN,F. E. A., and Z. ALI-KHAN.1974. Two cases of human Sarcophaga (Diptera: Sarcophagidae) myiasis in Quebec, with descriptions of the larvae. Can. J. Zool: 52: 643-647. BISHOPP,F. C. 1915. Flies which cause myiasis in man and some aspects of the problem. J. Econ. Enanimals tomol. 8: 317-329. BISHOPP,F. C., and E. W. LAAKE.1915. A preliminary statement regarding wool maggots of sheep in the United States. J. Econ. Entomol. 8: 466-474. BISHOPP,F. C., J. D. MITCHELL, and D. C. PARMAN. 1917. Screw-worms and other maggots affecting animals. U .S. Dep. Agric. Farmers' Bull. NO. 857. DOVE,W. E. 1937. Myiasis of man. J. Econ. Entomol. 30: 29-39. HALL,D. G . 1948. The blowflies of North America. Vol. IV. Thomas Say Foundation, LaFayette, Indiana. HOR~FALL, W. R. 1962. Medicalentomology. The Ronald Ress Co., N.Y, JAM,,, M. T. 1948. The flies that cause myiasis in man. U.S. Dep. Agric. Misc. Publ. No. 631.
-
1476
CAN. J. ZOOL.
JUDD, W. W. 1956. Resultsofa survey ofcalyptrate fliesof
medical importance conducted at London, Ontario during 1953. Am. Midl. Nat. 56: 388-405. KAMAL, A. S. 1958. Comparative study of thirteen species of sarcosaprophagous Calliphoridae and Sarcophagidae (Diptera). I. Bionomics. Ann. Entomol. Soc. Am. 51: 261-271.
Can. J. Zool. Downloaded from www.nrcresearchpress.com by University of P.E.I. on 11/24/14 For personal use only.
MELVIN,R. 1934. Incubation period of eggs of certain muscoid flies at different constant temperatures. Ann. Entomol. Soc. Am. 27: 406-410.
VOL. 53,
1975
ROBINSON, W. 1933. The use of blowfly larvae in the treatment of infected wounds. Ann. Entomol. Soc. Am. 26: 270-276.
SANJEAN, J. 1957. Taxonomic studies of Sarcophaga larvae of New York with notes on the adults. Cornell Univ., Agric. Exp. Stn. Mem. No. 349. SCOTT, H. G. 1964. Human myiasis in North America (1952-1962 inclusive). FI. Entomol. 47: 255-261. STEWART, M. A. 1929. A case of dermal myiasis caused by Phormia regina Meig. J . Am. Med. Assoc. 92: 798-799.
Reduced activity in transmitter-carryingvoles J. M. HAMLEY AND J. B. FALLS Department o f z o o l o g y , Universiry of Toronto, Toronto, Ontario M5S IAI Received June 4, 1975 HAMLEY, J. M., and J. B. FALLS.1975. Reduced activity in transmitter-carrying voles. Can. J. 2001.53: 1476-1478. Transmitter-carrying meadow voles (Microtuspennsylvanicus) behaved normally asjudged by casual observation and live-trapping, but showed reduced activity in exercise wheels for several days.
J . M., et J . B. FALLS.1975. Reducedactivity in transmitter-carryingvoles. Can. J. Zool. HAMLEY, 53: 1476-1478. Des emetteurs installts sur des campagnols des champs (Microtus pennsylvanicus) ne semblent pas nuire 1 leur comportement normal, si on en juge par la simple observation et par les resultats des captures; I'activite de ces animaux dans les roues d'exercice se trouve cependant reduite pour plusieurs jours. [Traduit par le journal]
Portable radio transmitters are often used to track small mammals in the wild, usually assuming that the burden does not seriously affect their behavior (Brooks and Banks 1971; Corner and Pearson 1972). The animals continue their usual activities, yet their behavior may be altered in less obvious but measurable ways. Gilmer et al. (1 974) reported a long-lasting increase in comfort movements of ducks. Tester (1971) found no published reports of adverse behavioral effects on mammals, but, on the basis of his own experience, would expect transmitter-carrying animals to behave abnormally for at least 2 days. Our data show a decrease in running activity of meadow voles (Microtus pennsylvanicus). We used inexpensive homemade FM-transmitters that measured 22 x 14 x 6 mm, had trailing 10-cm whip antennas, and weighed 3.0 g (Hamley 1966). The voles (mean weight, 38 g) were anesthetized with ether and the transmitters mounted dorsally with a string tied around the neck. The transmitters rode snugly
against the body and caused no apparent loss of balance or hindrance to movement except that occasionally, when a vole was running rapidly through thick grass, vegetation caught under the forward edge of the transmitter and momentarily snagged the animal. This was never observed in a runway, and some individuals moved freely even in the thickest vegetation. Although the transmitter-carrying voles appeared to behave normally, two experiments were done to determine if their activity was affected. One group was followed in the field by live-trapping; a different group was observed in cages connected to exercise wheels. In the trapping experiment, 45 Sherman-type traps (size, 7.5 x 7.5 x 30 cm) were set on a grid at 10-m intervals, baited with rolled oats, and provided with straw for nest-making. They were checked daily and all voles caught were tagged. Ten of the voles (five male, five female) caught on April 17 and 18, 1966, were given dummy transmitters and released. Trapping was
A case of traumatic dermal myiasis in Quebec caused by Phormia regina (Meigen) (Diptera: Calliphoridae) F. E. A. ALI-KHAN Department of Entomology, Macdonald College of McGill University, Ste Anne-de-Bellevue, Quebec AND
Can. J. Zool. Downloaded from www.nrcresearchpress.com by University of P.E.I. on 11/24/14 For personal use only.
Z. ALI-KHAN Department of Microbiology and Immunology, McGill University, Montreal, Quebec Received April 1, 1975 ALI-KHAN,F. E. A . , and 2. ALI-KHAN.1975. A case of traumatic dermal myiasis in Quebec caused by Phormia regina (Meigen) (Diptera: Calliphoridae). Can. J. Zool. 53: 1472-1476. A case of human myiasis due to Phormia regina (Meigen) is reported from Montreal, Quebec. Large numbers of larvae were removed from a necrotic hip wound in a 44-year-old male. Larvae were reared to the adult stage; larval and pupal measurements and development times are given. ALI-KHAN, F. E. A . , et 2. ALI-KHAN.1975. A case of traumatic dermal myiasis in Quebec caused by Phormia regina (Meigen) (Diptera: Calliphoridae). Can. J. Zool. 53: 1472-1476. On a rencontre un cas de myiase humaine causee par Phormia regina (Meigen) B Montreal, Quebec. On a trouve un grand nombre de lames dans la blessure necrosique de la hanche, chez un individu mile Lge de 44 ans. Les larves Blevees sont parvenues au stade adulte; on donne les mesures des larves et des pupes ainsi que le temps ecoule entre les phases du dtveloppement. [Traduit par le journal]
Phormia regina (Meigen), the black blowfly, is a common fly in the United States but not abundant in Canada. It is known as a coolweather blowfly, being active in the southern states throughout winter except for a few days during cold periods, but may disappear during a hot dry summer. In the northern United States it is absent only during the coldest weather but found in large numbers in spring and fall. In Ontario it has been found to occur from midApril to early November, being most abundant towards the end of July (Judd 1956). Most probably, in northern latitudes it passes the winter in the soil in either the pupal or prepupal stage (Bishopp and Laake 1915). The larvae are normally saprophagous, feeding in large numbers in carcasses of animals but may also infest wounds and feed on both dead and living tissue. They are one of the most troublesome of sheep maggots especially in the south-western United States, infesting the rumps of ewes following lambing, old festering sores following dehorning, or soiled wool near the
anus where they may eventually work into the flesh. Reported cases of human myiasis involving larvae of this species of fly are very rare. Stewart (1929) describes infestation of pussy scalp sores of a 25-year-old woman in Texas. A great quantity of larvae of Phormia regina were removed after treatment of the area with a supersaturated sulfur wash. In Mississippi, Dove (1937) reports a case where 15-20 small larvae of this species were removed from the ear of a 4-year-old boy. Scott (1964), in recording cases of human myiasis not previously published, mentions the possible involvement of P . regina in furuncular myiasis in Idaho in 1959. No further information is given. James (1948) notes that larvae of P. regina have been reported in enteric mviasis but also that the record needs substantiation. The following appears to be the first reported case of human myiasis due to P. regina in Canada. Adults were reared from larvae isolated from a wound. In addition to this, two published -
-
-
1473
NOTES
Can. J. Zool. Downloaded from www.nrcresearchpress.com by University of P.E.I. on 11/24/14 For personal use only.
cases of intestinal and subungual myiasis (Ali-Khan and Ali-Khan 1974) and one unpublished case of vaginal myiasis, identified in section, caused by other species of Diptera have been seen recently in the Montreal area. Case History The patient was a 44-year-old male resident of Verdun, a suburb of Montreal. He entered hospital with chronic renal, and congestive heart failure. He was paraplegic and had had a necrotic hip wound for a number of years. The extent of the lesion was severe, extending from the hip area through a subcutaneous sinus tract as far as the scrotum, and also involving necrosis of bone. The wound was washed with hydrogen peroxide and on several occasions bunches of larvae of the size of a golf ball involving 'hundreds' of specimens were found on the gauze covering the wounds. Six live larvae were sent to one of us (Z. A-K.) for identification on August 2, having been removed from the patient on August 1. The larvae were examined under a stereoscopic microscope, and one larva, morphologically similar to the others, was preserved in formalin and the rest were placed on raw ground beef in a container covered with cheesecloth. At first they were very active, and as a result one larva was lost when it penetrated the cheesecloth, but within a day and a half the remainder had become contracted and immobile. By the morning of the 3rd day all four larvae were found to have pupated and were removed to dryish soil. One pupa was preserved in formalin. Adults from two pupae emerged on August 11 and the third on August 12. These were identified as two males and a female of Phormia regina. Dimensions and Development of the Larvae and Pupae First-, second-, and third-larval instars, the puparium, and adults of Phormia regina have been described by Ha11 (1948), but measurements are not given for the cephalopharyngeal sclerites, nor the posterior spiracles, which are specific features of the larva. We include these measurements and overall dimensions of our larva and puparium and development times for comparison with those from more southern localities. Our one preserved larva (Fig. 1) was appar-
FIG.1 . Third-instar larva of Phormia regina.
ently third instar. It had one posterior spiracle with three slits and the other with two and an imperfectly formed third. The larva measured 14.5 by 3.0 mm which agrees with the dimensions, length 9-17, diameter 3-4 mm given by Hall (1948) for third-instar larvae of this species, and the cephalopharyngeal sclerites were of the form for third-instar larvae. Measurements in microns (p) of the posterior spiracles (Fig. 2) and cephalopharyngeal sclerites (Fig.
Can. J. Zool. Downloaded from www.nrcresearchpress.com by University of P.E.I. on 11/24/14 For personal use only.
1474 CAN. J. ZOOL. VOL. 53, 1975
TABLE 1 Measurements in microns (p) of the posterior spiracles and cephalopharyngeal sclerites following the convention of Sanjean (1957) Posterior spiracle Length left
right
Middle spiracular slit
Width left
Length
right
left
right
Width left
right
Can. J. Zool. Downloaded from www.nrcresearchpress.com by University of P.E.I. on 11/24/14 For personal use only.
Cevhalovharyngeal sclerites Tip of mouth hook to farthest point of posterodorsal process 368
Anterodorsal process to tip of dorsal cornu 1008
3), following the convention of Sanjean (1957), are shown in Table 1. The width of the right posterior spiracle was somewhat less than that of the left because of the aberrant third slit. The two spiracles were separated by a distance of about two-thirds that of the left spiracle. The puparium was 9.0 by 3.0 mm. Hall (1948) gives length 9.0-9.5, diameter 3-4 mm. Development times of this species depend on the temperature. According to Bishopp et al. (1917), eggs hatch in from less than 24 h to 4 days in carcasses but he notes that on living animals the rate of development is probably faster. Melvin (1934) found these eggs complete incubation in 8.13 h at 99 "F (ca. 37 "C). Total length of the larval stage ranges from 4 to 15 days (Bishopp 1915). Our larvae pupated 3 days after they were removed from the patient's wound. Our pupal stage lasted 7-8 days. The average rearing temperature was 70°F (ca. 21 "C). Bishopp (1915) gives 3-13 days for the pupal stage in Texas and Kamal (1958) 4-9 days under controlled temperature of 80 f 2 OF (ca. 27 f 1 "C) and relative humidity 50 f 2%.
Comments It is apparent that the adult fly was attracted to the patient's suppurating lesion. This species shows a marked tendency to deposit its eggs in large masses (Bishopp and Laate 1915) which accounts for the large numbers of larvae found both in the case reported by Stewart (1929) and in the present case where the many 'hundreds'
Length of dorsal cornu 584
Length of ventral cornu 41 7
could well have resulted from eggs of a single female fly. The larvae were apparently actively feeding on necrotic tissue in the wound and could possibly have had beneficial effects since larvae of this species have been used in the past for treatment of deep pus-discharging human wounds (Horsfall 1962) and osteomyelitis (Robinson 1933). However, Hall (1948) notes that they may destroy healthy tissue as well since in cases of animal myiasis there is sometimes a bloody discharge.
Acknowledgments We are grateful to Dr. M. T. James of Washington State University, U.S.A., who confirmed our identification of the adult flies. ALI-KHAN,F. E. A., and Z. ALI-KHAN.1974. Two cases of human Sarcophaga (Diptera: Sarcophagidae) myiasis in Quebec, with descriptions of the larvae. Can. J. Zool: 52: 643-647. BISHOPP,F. C. 1915. Flies which cause myiasis in man and some aspects of the problem. J. Econ. Enanimals tomol. 8: 317-329. BISHOPP,F. C., and E. W. LAAKE.1915. A preliminary statement regarding wool maggots of sheep in the United States. J. Econ. Entomol. 8: 466-474. BISHOPP,F. C., J. D. MITCHELL, and D. C. PARMAN. 1917. Screw-worms and other maggots affecting animals. U .S. Dep. Agric. Farmers' Bull. NO. 857. DOVE,W. E. 1937. Myiasis of man. J. Econ. Entomol. 30: 29-39. HALL,D. G . 1948. The blowflies of North America. Vol. IV. Thomas Say Foundation, LaFayette, Indiana. HOR~FALL, W. R. 1962. Medicalentomology. The Ronald Ress Co., N.Y, JAM,,, M. T. 1948. The flies that cause myiasis in man. U.S. Dep. Agric. Misc. Publ. No. 631.
-
1476
CAN. J. ZOOL.
JUDD, W. W. 1956. Resultsofa survey ofcalyptrate fliesof
medical importance conducted at London, Ontario during 1953. Am. Midl. Nat. 56: 388-405. KAMAL, A. S. 1958. Comparative study of thirteen species of sarcosaprophagous Calliphoridae and Sarcophagidae (Diptera). I. Bionomics. Ann. Entomol. Soc. Am. 51: 261-271.
Can. J. Zool. Downloaded from www.nrcresearchpress.com by University of P.E.I. on 11/24/14 For personal use only.
MELVIN,R. 1934. Incubation period of eggs of certain muscoid flies at different constant temperatures. Ann. Entomol. Soc. Am. 27: 406-410.
VOL. 53,
1975
ROBINSON, W. 1933. The use of blowfly larvae in the treatment of infected wounds. Ann. Entomol. Soc. Am. 26: 270-276.
SANJEAN, J. 1957. Taxonomic studies of Sarcophaga larvae of New York with notes on the adults. Cornell Univ., Agric. Exp. Stn. Mem. No. 349. SCOTT, H. G. 1964. Human myiasis in North America (1952-1962 inclusive). FI. Entomol. 47: 255-261. STEWART, M. A. 1929. A case of dermal myiasis caused by Phormia regina Meig. J . Am. Med. Assoc. 92: 798-799.
Reduced activity in transmitter-carryingvoles J. M. HAMLEY AND J. B. FALLS Department o f z o o l o g y , Universiry of Toronto, Toronto, Ontario M5S IAI Received June 4, 1975 HAMLEY, J. M., and J. B. FALLS.1975. Reduced activity in transmitter-carrying voles. Can. J. 2001.53: 1476-1478. Transmitter-carrying meadow voles (Microtuspennsylvanicus) behaved normally asjudged by casual observation and live-trapping, but showed reduced activity in exercise wheels for several days.
J . M., et J . B. FALLS.1975. Reducedactivity in transmitter-carryingvoles. Can. J. Zool. HAMLEY, 53: 1476-1478. Des emetteurs installts sur des campagnols des champs (Microtus pennsylvanicus) ne semblent pas nuire 1 leur comportement normal, si on en juge par la simple observation et par les resultats des captures; I'activite de ces animaux dans les roues d'exercice se trouve cependant reduite pour plusieurs jours. [Traduit par le journal]
Portable radio transmitters are often used to track small mammals in the wild, usually assuming that the burden does not seriously affect their behavior (Brooks and Banks 1971; Corner and Pearson 1972). The animals continue their usual activities, yet their behavior may be altered in less obvious but measurable ways. Gilmer et al. (1 974) reported a long-lasting increase in comfort movements of ducks. Tester (1971) found no published reports of adverse behavioral effects on mammals, but, on the basis of his own experience, would expect transmitter-carrying animals to behave abnormally for at least 2 days. Our data show a decrease in running activity of meadow voles (Microtus pennsylvanicus). We used inexpensive homemade FM-transmitters that measured 22 x 14 x 6 mm, had trailing 10-cm whip antennas, and weighed 3.0 g (Hamley 1966). The voles (mean weight, 38 g) were anesthetized with ether and the transmitters mounted dorsally with a string tied around the neck. The transmitters rode snugly
against the body and caused no apparent loss of balance or hindrance to movement except that occasionally, when a vole was running rapidly through thick grass, vegetation caught under the forward edge of the transmitter and momentarily snagged the animal. This was never observed in a runway, and some individuals moved freely even in the thickest vegetation. Although the transmitter-carrying voles appeared to behave normally, two experiments were done to determine if their activity was affected. One group was followed in the field by live-trapping; a different group was observed in cages connected to exercise wheels. In the trapping experiment, 45 Sherman-type traps (size, 7.5 x 7.5 x 30 cm) were set on a grid at 10-m intervals, baited with rolled oats, and provided with straw for nest-making. They were checked daily and all voles caught were tagged. Ten of the voles (five male, five female) caught on April 17 and 18, 1966, were given dummy transmitters and released. Trapping was
