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The antimicrobial activity of the mandibular gland secretion of a formicine ant, Calomyrmex sp. (Hymenoptera: Formicidae)
JOURNAL
OF INVERTEBRATE
PATHOLOGY
42, 306-311 (1983)
The Antimicrobial Activity of the Mandibular Gland Secretion of a Formicine Ant, Calomyrmex sp. (Hymenoptera: Formicidae) ELAINE
Department
of
J.
BROUGH'
Zoology, Monash University, Clayton, Victoria, Australia
Received May 17, 1982; accepted February 23, 1983 The mandibular gland secretion from mature workers of the formicine ant Calomyrmex sp. exhibits strong antimicrobial activity when tested against selected soil microorganisms, The activity against bacteria is both inhibitory and bacteriocidal while that against fungi is inhibitory. The white secretion from young workers appears to be much weaker in its antibiotic effects. KEY WORDS: Calomyrmex; mandibular gland: antibiotic.
INTRODUCTION
The mandibular gland secretion of an Australian formicine ant, Calomyrmex sp. (ANIC No. 1 splendidus ?) has been found to be important as an alarm defense system (Brough, 1976, 1978). The secretion is produced in large quantities by a glandular epithelium which degenerates after production (Brough, 1977). As the secretion gradually accumulates in the hypertrophied glandular reservoir after eclosion of the adult worker, it changes in color from white through cream and yellow to the deep orange of the U-week-old worker. The secretion has alarm-promoting properties, is repellent to other ant species, and is highly repugnant to a variety of insectivorous mammals (Brough, 1978). While investigating the pheromonal properties of the secretion, it was noticed that Calomyrmex colonies, which were kept in artificial nests in the laboratory, gradually built sizeable heaps of cadavers and nest debris in unoccupied corners but fungi were not apparent and the material did not appear to decay. This suggested that bacterial and fungal growth was prevented in some way and it was thought that this could be another function of the mandibular gland secretion. A series of tests was therefore t Present address: Biology Department, University, Papua New Guinea.
BOX
320 306
0022-2011/83 $1.50 Copyright
0 1983 by Academic
Press, Inc.
conducted to study the effect of the secretion on the growth of soil microorganisms. MATERIALS
AND METHODS
Soil samples were taken from a Calomyrmex nest and from surrounding soil in a semidesert area, 110 km south of Broken Hill, New South Wales, Australia, which is the habitat of the ant. Sample A was taken from the surface galleries of a nest; sample B from surface soil distant to the nest; and sample C from an area distant to a nest and 0.3 m from the surface. To test the effects of mandibular gland secretion of the soilmicrobes, three sets of plates were prepared as follows. Ten grams of each soil sample were shaken with 90 ml of sterile water and lo-fold serial dilutions were prepared. Dilutions IO-*, 10-3, and lop4 for soil samples B and C were plated together with (1) twofold dilutions of mandibular gland secretion, and (2) lo-fold dilutions of streptomycin. The twofold dilutions of mandibular gland secretion were made from an initial dilution of six glands in 1 ml of sterile water. As the secretion was almost insoluble in water, these dilutions were essentially suspensions of differing concentrations. Tenfold streptomycin dilutions were prepared from an initial solution of 1 million units of streptomycin sulfate (equivalent 1 g streptomycin base) in 1 ml of sterile water.
ACTIVITY
OF Calomyrmex SECRETION
307
One milliliter of the respective dilutions whose secretion is cream in color. As the was added to the dish which was subse- glandular reservoirs from these young ants appear to be incompletely filled, the initial quently poured with 20 ml of cornmeal agar. Control plates received 1 ml of the dilution was made with 12 glands per ml. A 0.05-ml sample of each dilution was tested respective soil dilutions only. After incubaof each bacterial tion at 25°C for 3 days, counts were made of against suspensions isolate as previously described. the bacterial and fungal colonies. The activity of the mandibular gland seThe activity of the secretion was also cretion was also tested against five bac- tested against three soil fungi. Three isoterial isolates (bacteria A-4, A-5, B-6, C-3, lates of Rhizopus sp., Fusarium sp., and and C-8) which had been selected from the Trichoderma sp. were innoculated on the initial soil dilutions. Suspensions of each edge of cornmeal agar plates. Incubation bacterium were poured with 20 ml of Lilly at 25°C for 3 days established growth. and Barnett’s (1951) agar. Duplicate plates Three wells were then cut into the agar. were prepared and 7 wells were cut in each: One well received 0.05 ml of a secretion a single drop of agar sealed the bottom of dilution (six glands/ml), the central well was left as a control, and the third received each well. For each bacterial suspension, plate I received 0.05 ml of six twofold man0.05 ml of streptomycin (10,000 units/ml). dibular gland dilutions (i.e., six glands/ml, The plates were incubated for a further 3 three glands/ml, etc.) administered sepa- days and then photographed. rately to each of the six wells. The central well remained as a control. Plate 11 reRESULTS ceived 0.05 ml of six IO-fold streptomycin dilutions (10,000 units/ml to 0.1 units/ml) in Table 1 gives the results of plating the the same manner. After 36 hr incubation at soil dilutions with mandibular gland secre25”C, the plates were photographed and the tion and streptomycin. The numbers of orzones of inhibition measured. For each bac- ganism units for each dilution tested may be terial suspension these measurements were compared with those of the control plates. graphed and the levels of activity for manAs can be seen in each series, at the highest dibular gland secretion were then deterconcentration of six glands/ml, the manmined from the graph by comparison with dibular gland secretion almost completely the activity of streptomycin. This experiinhibited microbial growth and proved to be ment was repeated using the secretion of more effective than 1000 units of strepglands dissected from 4-week-old ants tomycin. Even at low concentrations (0.75 TABLE NUMBERS
OF MICROORGANISM MANDIBULAR
UNITS EXHIBITING GI.AND SECRETION
Mandibular gland dilution (glands/ml) Soil dilution Sample B IO-’ IO-3 10-4
Sample C IO-’ I o-3 I O-4
6
3
2 0 0
II
0 0
367 I
0
0
1 0
I
GROWTH IN EACH PLATE AFTER AND STREPTOMYCIN SLII.FATF
Streptomycin dilution (units/ml)
TREATMENT
Control (no additive)
0.75
IO00
100
IO
81 14
580 70
57 1
0
I
3 2 0
0
420 48 4
1100 152 24
42 43 8
1061 I25 II
31 2 0
173 35 3
82 103 6
3100 312 55
I.5
WITH
ELAINE
J. BROUGH
FIG. 1. Inhibition ofgrowth for bacterium A-5 by mandibular gland secretion. Wells 1 to 6 received 6, 3, 1.5, 0.75, 0.375, and 0.187 glands/ml, respectively: c = control well.
glands/ml) growth was halved when compared to the control plates. When tested against individual bacteria, the secretion showed strong antibiotic activity in four out of the five cases. Two of the plates produced in the experiments are shown in Figures 1 and 2. Two zones of activity are apparent; the outer zone representing inhibitory activity and the inner zone showing the bacteriocidal activity, with the area between the two measurable zones representing the bacteriostatic level of activity. At the highest concentration of six glands/ml, the inhibitory activity was equivalent to 51 units of streptomycin for bacterium A-4, 154 units for bacterium A5, 378 units for bacterium B-6, and 154 for bacterium C-8. The fifth bacterium, C-3, showed weak inhibition by streptomycin but appeared to be resistant to mandibular gland secretion. Tests using secretion from
the young ants showed that inhibition was weak and zones could only be measured for the two most concentrated dilutions. Only one zone of activity was apparent in each case, with no evidence of bacteriocidal action. Bacterium C-3 appeared unaffected by this secretion of young ants. Figure 3 shows the result of the test against the fungus Trichodermu sp. Inhibition of mycelial growth by mandibular gland secretion was shown for each fungus and appeared to be stronger than streptomycin in its effect. Streptomycin is known, however, to have low activity against soil fungi. DISCUSSION
From these experiments it is apparent that Calomyrmex mandibular gland secre-
ACTIVITY
OF Cnlomyrmex SECRETION
309
FIG. 2. Inhibition of growth for bacterium A-5 by streptomycin. Wells 1 to 6 received 10.000. 1000. 100, 10. I, and 0.1 units/ml, respectively; c = control well.
tion is toxic to microorganisms. Tests against isolated bacteria demonstrate that the material is not only inhibitory but has definite bacteriocidal activity. The toxicity extends to the fungi but in this case the range of activity so far investigated only shows an inhibition of growth with no evidence of definite fungicidal activity. A large array of substances from a variety of arthropods have been shown to possess antibacterial activity (Valcurone and Baggini, 1957; Maschwitz, 1967). Many of these substances are produced by glands which are effective in defense but the utilization of the antimicrobial properties in nature has not been substantiated, although Maschwitz (1967) concluded that the secretion of the pygidial gland of certain dytiscids is used to prevent bacterial infection and the settling of epizooic organisms from the water onto the insects’ exoskeleton. Within the formicidae, Pavan ( 1958) reported the antibacterial activity of the
mandibular gland secretion of Lasius fuliginosus and that this secretion is used as an adhesive substance during nest formation but does not conclude that the secretion is important in the control of microbial growth. It has been proposed, however, that the metapleural glands of certain myrmicine species produce an antiseptic for protection against microorganisms (Maschwitz et al., 1970). More recently, geraniol and citral, contained in the Nassanoff gland secretions of worker honey bees, Apis mellifera, have been shown to inhibit the growth of the fungus Ascosphaera apis which causes chalkbrood disease (Gochnauer et al., 1979). Analysis of the major volatile components extracted from the heads of Calomyrmex workers and presumed to derive from the mandibular glands, has also shown the presence of geraniol as the (E) isomer of another component, nerol (Brown and Moore, 1979). In this case, however, gera-
310
ELAINE
(2)
J. BROUGH
sp. by (I) mandibular gland secretion (six gland FIG. 3. Inhibition of the growth of Trichoderma stn zptomycin (10.000 units/ml): c = control well.
niol is present as only a small proportion of the volatile components which include two ketones, two aldehydes, and three pyrazines (Brown and Moore, 1979). All of these components could act as alkylating agents and, if able to disrupt the cellular mechanism of mitotic division, would display antibiotic activity. The pyrazines, with their pyrimidine-like structure, could be considered prime candidates, and it is interesting that Brown and Moore (1979) reported that these compounds increase in proportion with the increasing age of the ants from which the extract was made. This would be in accord with the increased antibiotic properties of the secretion of mature ants. Identification of the active component(s), however, will require the availability of significant amounts of each of the known volatiles and may also require further analysis of the secretion which is known to contain a number of nonvolatile components (Moore, pers. commun.).
As in the case of geraniol and citral produced by the honey bee, the value of the antibiotic properties for the ant is unclear. Careful observations of worker activity in the nest failed to provide any evidence of direct use. It has been previously noted, however, that any secretion expelled from the glands but which is not drawn back into the reservoir is cleaned away into the infrabuccal pocket, the contents of which are later discarded (Brough, 1976). In this way the secretion could become incorporated into the collective debris of the nest and so cause the observed lack of fungal and bacterial decay. The lower level of antibiotic activity of the white- to cream-colored secretion from young adults also suggests that this property is not primarily for use within the nest since it is these younger ants which care for the larvae and do the majority of the “household” duties. These observations tend to indicate that the antibiotic properties of the secretion may simply be a corol-
ACTIVITY
OF
lary of the other biological properties (pheromonal, repellent, repugnant) already demonstrated and as such, have no direct usage in the life of the colony.
ant, Calomyrmcx Tierpsychol.,
I wish to thank Dr. A. A. Holland for allowing me the use of his microbiology laboratory and for his advice.
REFERENCES E. J. 1976. Notes on the ecology of an Australian desert species of Calomyrmex (Hymenoptera: Formicidae). J. Austrul. Ent. Sot., 15,
BROUGH,
(Hymenoptera:
Formicidae).
Z.
46, 279-297.
M. W., AND MOORE, B. P. 1979. Volatile secretory products of an Australian formicine ant of the genus Calomyrmex (Hymenoptera: Formicidae).
BROWN,
Insect
ACKNOWLEDGMENT
311
SECRETION
Calomyrmex
Biochem.,
9, 45 I-460.
T. A., BOCH, R., AND MARGETTS. V. J. 1979. Inhibition of Ascosphaeru upis by citral and geraniol. .I. Invertebr. Pathol., 34, 57-61. LILLY, V. G.. AND BARNETT. H. L. 1951. “Physiology of Fungi.” McGraw-Hill, New York.
GOCHNAUER,
MASCHWITZ.
U.
1967. Eine
neuartige
wehr von Mikroorganismen wissenschaften,
Form
der
Ab-
bei Insekten. Nutur-
54, 649.
E. J. 1977. The morphology and histology of the mandibular gland of an Australian species of C’alomyrrnex (Hymenoptera: Formicidae). Zoomor-
U., KOOB, K., AND SCHILDKNECHT, H. 1970. Ein Beitrag sur Funktion der Metathoracald&e der Ameisen. /. Insect Physiol., 16, 387-404. PAVAN, M. 1958. Significato chimico e biologica di alcuni veleni di insetti. Inst. Anaf. Camp. Unit,. Pavia, l-75.
phologie.
VALCURONE,
339-346. BROUGH,
87, 73-86.
E. J. 1978. The multifunctional role of the mandibular gland secretion of an Australian desert
BROUGH,
MASCHWITZ,
M.
L.,
AND
sostanze antibatteriche Boll.
Inst.
Sieroter.
Milan.,
BAGGINI.
A.
1957.
Sulle
di origine entomologica. 36, 283-305.
OF INVERTEBRATE
PATHOLOGY
42, 306-311 (1983)
The Antimicrobial Activity of the Mandibular Gland Secretion of a Formicine Ant, Calomyrmex sp. (Hymenoptera: Formicidae) ELAINE
Department
of
J.
BROUGH'
Zoology, Monash University, Clayton, Victoria, Australia
Received May 17, 1982; accepted February 23, 1983 The mandibular gland secretion from mature workers of the formicine ant Calomyrmex sp. exhibits strong antimicrobial activity when tested against selected soil microorganisms, The activity against bacteria is both inhibitory and bacteriocidal while that against fungi is inhibitory. The white secretion from young workers appears to be much weaker in its antibiotic effects. KEY WORDS: Calomyrmex; mandibular gland: antibiotic.
INTRODUCTION
The mandibular gland secretion of an Australian formicine ant, Calomyrmex sp. (ANIC No. 1 splendidus ?) has been found to be important as an alarm defense system (Brough, 1976, 1978). The secretion is produced in large quantities by a glandular epithelium which degenerates after production (Brough, 1977). As the secretion gradually accumulates in the hypertrophied glandular reservoir after eclosion of the adult worker, it changes in color from white through cream and yellow to the deep orange of the U-week-old worker. The secretion has alarm-promoting properties, is repellent to other ant species, and is highly repugnant to a variety of insectivorous mammals (Brough, 1978). While investigating the pheromonal properties of the secretion, it was noticed that Calomyrmex colonies, which were kept in artificial nests in the laboratory, gradually built sizeable heaps of cadavers and nest debris in unoccupied corners but fungi were not apparent and the material did not appear to decay. This suggested that bacterial and fungal growth was prevented in some way and it was thought that this could be another function of the mandibular gland secretion. A series of tests was therefore t Present address: Biology Department, University, Papua New Guinea.
BOX
320 306
0022-2011/83 $1.50 Copyright
0 1983 by Academic
Press, Inc.
conducted to study the effect of the secretion on the growth of soil microorganisms. MATERIALS
AND METHODS
Soil samples were taken from a Calomyrmex nest and from surrounding soil in a semidesert area, 110 km south of Broken Hill, New South Wales, Australia, which is the habitat of the ant. Sample A was taken from the surface galleries of a nest; sample B from surface soil distant to the nest; and sample C from an area distant to a nest and 0.3 m from the surface. To test the effects of mandibular gland secretion of the soilmicrobes, three sets of plates were prepared as follows. Ten grams of each soil sample were shaken with 90 ml of sterile water and lo-fold serial dilutions were prepared. Dilutions IO-*, 10-3, and lop4 for soil samples B and C were plated together with (1) twofold dilutions of mandibular gland secretion, and (2) lo-fold dilutions of streptomycin. The twofold dilutions of mandibular gland secretion were made from an initial dilution of six glands in 1 ml of sterile water. As the secretion was almost insoluble in water, these dilutions were essentially suspensions of differing concentrations. Tenfold streptomycin dilutions were prepared from an initial solution of 1 million units of streptomycin sulfate (equivalent 1 g streptomycin base) in 1 ml of sterile water.
ACTIVITY
OF Calomyrmex SECRETION
307
One milliliter of the respective dilutions whose secretion is cream in color. As the was added to the dish which was subse- glandular reservoirs from these young ants appear to be incompletely filled, the initial quently poured with 20 ml of cornmeal agar. Control plates received 1 ml of the dilution was made with 12 glands per ml. A 0.05-ml sample of each dilution was tested respective soil dilutions only. After incubaof each bacterial tion at 25°C for 3 days, counts were made of against suspensions isolate as previously described. the bacterial and fungal colonies. The activity of the mandibular gland seThe activity of the secretion was also cretion was also tested against five bac- tested against three soil fungi. Three isoterial isolates (bacteria A-4, A-5, B-6, C-3, lates of Rhizopus sp., Fusarium sp., and and C-8) which had been selected from the Trichoderma sp. were innoculated on the initial soil dilutions. Suspensions of each edge of cornmeal agar plates. Incubation bacterium were poured with 20 ml of Lilly at 25°C for 3 days established growth. and Barnett’s (1951) agar. Duplicate plates Three wells were then cut into the agar. were prepared and 7 wells were cut in each: One well received 0.05 ml of a secretion a single drop of agar sealed the bottom of dilution (six glands/ml), the central well was left as a control, and the third received each well. For each bacterial suspension, plate I received 0.05 ml of six twofold man0.05 ml of streptomycin (10,000 units/ml). dibular gland dilutions (i.e., six glands/ml, The plates were incubated for a further 3 three glands/ml, etc.) administered sepa- days and then photographed. rately to each of the six wells. The central well remained as a control. Plate 11 reRESULTS ceived 0.05 ml of six IO-fold streptomycin dilutions (10,000 units/ml to 0.1 units/ml) in Table 1 gives the results of plating the the same manner. After 36 hr incubation at soil dilutions with mandibular gland secre25”C, the plates were photographed and the tion and streptomycin. The numbers of orzones of inhibition measured. For each bac- ganism units for each dilution tested may be terial suspension these measurements were compared with those of the control plates. graphed and the levels of activity for manAs can be seen in each series, at the highest dibular gland secretion were then deterconcentration of six glands/ml, the manmined from the graph by comparison with dibular gland secretion almost completely the activity of streptomycin. This experiinhibited microbial growth and proved to be ment was repeated using the secretion of more effective than 1000 units of strepglands dissected from 4-week-old ants tomycin. Even at low concentrations (0.75 TABLE NUMBERS
OF MICROORGANISM MANDIBULAR
UNITS EXHIBITING GI.AND SECRETION
Mandibular gland dilution (glands/ml) Soil dilution Sample B IO-’ IO-3 10-4
Sample C IO-’ I o-3 I O-4
6
3
2 0 0
II
0 0
367 I
0
0
1 0
I
GROWTH IN EACH PLATE AFTER AND STREPTOMYCIN SLII.FATF
Streptomycin dilution (units/ml)
TREATMENT
Control (no additive)
0.75
IO00
100
IO
81 14
580 70
57 1
0
I
3 2 0
0
420 48 4
1100 152 24
42 43 8
1061 I25 II
31 2 0
173 35 3
82 103 6
3100 312 55
I.5
WITH
ELAINE
J. BROUGH
FIG. 1. Inhibition ofgrowth for bacterium A-5 by mandibular gland secretion. Wells 1 to 6 received 6, 3, 1.5, 0.75, 0.375, and 0.187 glands/ml, respectively: c = control well.
glands/ml) growth was halved when compared to the control plates. When tested against individual bacteria, the secretion showed strong antibiotic activity in four out of the five cases. Two of the plates produced in the experiments are shown in Figures 1 and 2. Two zones of activity are apparent; the outer zone representing inhibitory activity and the inner zone showing the bacteriocidal activity, with the area between the two measurable zones representing the bacteriostatic level of activity. At the highest concentration of six glands/ml, the inhibitory activity was equivalent to 51 units of streptomycin for bacterium A-4, 154 units for bacterium A5, 378 units for bacterium B-6, and 154 for bacterium C-8. The fifth bacterium, C-3, showed weak inhibition by streptomycin but appeared to be resistant to mandibular gland secretion. Tests using secretion from
the young ants showed that inhibition was weak and zones could only be measured for the two most concentrated dilutions. Only one zone of activity was apparent in each case, with no evidence of bacteriocidal action. Bacterium C-3 appeared unaffected by this secretion of young ants. Figure 3 shows the result of the test against the fungus Trichodermu sp. Inhibition of mycelial growth by mandibular gland secretion was shown for each fungus and appeared to be stronger than streptomycin in its effect. Streptomycin is known, however, to have low activity against soil fungi. DISCUSSION
From these experiments it is apparent that Calomyrmex mandibular gland secre-
ACTIVITY
OF Cnlomyrmex SECRETION
309
FIG. 2. Inhibition of growth for bacterium A-5 by streptomycin. Wells 1 to 6 received 10.000. 1000. 100, 10. I, and 0.1 units/ml, respectively; c = control well.
tion is toxic to microorganisms. Tests against isolated bacteria demonstrate that the material is not only inhibitory but has definite bacteriocidal activity. The toxicity extends to the fungi but in this case the range of activity so far investigated only shows an inhibition of growth with no evidence of definite fungicidal activity. A large array of substances from a variety of arthropods have been shown to possess antibacterial activity (Valcurone and Baggini, 1957; Maschwitz, 1967). Many of these substances are produced by glands which are effective in defense but the utilization of the antimicrobial properties in nature has not been substantiated, although Maschwitz (1967) concluded that the secretion of the pygidial gland of certain dytiscids is used to prevent bacterial infection and the settling of epizooic organisms from the water onto the insects’ exoskeleton. Within the formicidae, Pavan ( 1958) reported the antibacterial activity of the
mandibular gland secretion of Lasius fuliginosus and that this secretion is used as an adhesive substance during nest formation but does not conclude that the secretion is important in the control of microbial growth. It has been proposed, however, that the metapleural glands of certain myrmicine species produce an antiseptic for protection against microorganisms (Maschwitz et al., 1970). More recently, geraniol and citral, contained in the Nassanoff gland secretions of worker honey bees, Apis mellifera, have been shown to inhibit the growth of the fungus Ascosphaera apis which causes chalkbrood disease (Gochnauer et al., 1979). Analysis of the major volatile components extracted from the heads of Calomyrmex workers and presumed to derive from the mandibular glands, has also shown the presence of geraniol as the (E) isomer of another component, nerol (Brown and Moore, 1979). In this case, however, gera-
310
ELAINE
(2)
J. BROUGH
sp. by (I) mandibular gland secretion (six gland FIG. 3. Inhibition of the growth of Trichoderma stn zptomycin (10.000 units/ml): c = control well.
niol is present as only a small proportion of the volatile components which include two ketones, two aldehydes, and three pyrazines (Brown and Moore, 1979). All of these components could act as alkylating agents and, if able to disrupt the cellular mechanism of mitotic division, would display antibiotic activity. The pyrazines, with their pyrimidine-like structure, could be considered prime candidates, and it is interesting that Brown and Moore (1979) reported that these compounds increase in proportion with the increasing age of the ants from which the extract was made. This would be in accord with the increased antibiotic properties of the secretion of mature ants. Identification of the active component(s), however, will require the availability of significant amounts of each of the known volatiles and may also require further analysis of the secretion which is known to contain a number of nonvolatile components (Moore, pers. commun.).
As in the case of geraniol and citral produced by the honey bee, the value of the antibiotic properties for the ant is unclear. Careful observations of worker activity in the nest failed to provide any evidence of direct use. It has been previously noted, however, that any secretion expelled from the glands but which is not drawn back into the reservoir is cleaned away into the infrabuccal pocket, the contents of which are later discarded (Brough, 1976). In this way the secretion could become incorporated into the collective debris of the nest and so cause the observed lack of fungal and bacterial decay. The lower level of antibiotic activity of the white- to cream-colored secretion from young adults also suggests that this property is not primarily for use within the nest since it is these younger ants which care for the larvae and do the majority of the “household” duties. These observations tend to indicate that the antibiotic properties of the secretion may simply be a corol-
ACTIVITY
OF
lary of the other biological properties (pheromonal, repellent, repugnant) already demonstrated and as such, have no direct usage in the life of the colony.
ant, Calomyrmcx Tierpsychol.,
I wish to thank Dr. A. A. Holland for allowing me the use of his microbiology laboratory and for his advice.
REFERENCES E. J. 1976. Notes on the ecology of an Australian desert species of Calomyrmex (Hymenoptera: Formicidae). J. Austrul. Ent. Sot., 15,
BROUGH,
(Hymenoptera:
Formicidae).
Z.
46, 279-297.
M. W., AND MOORE, B. P. 1979. Volatile secretory products of an Australian formicine ant of the genus Calomyrmex (Hymenoptera: Formicidae).
BROWN,
Insect
ACKNOWLEDGMENT
311
SECRETION
Calomyrmex
Biochem.,
9, 45 I-460.
T. A., BOCH, R., AND MARGETTS. V. J. 1979. Inhibition of Ascosphaeru upis by citral and geraniol. .I. Invertebr. Pathol., 34, 57-61. LILLY, V. G.. AND BARNETT. H. L. 1951. “Physiology of Fungi.” McGraw-Hill, New York.
GOCHNAUER,
MASCHWITZ.
U.
1967. Eine
neuartige
wehr von Mikroorganismen wissenschaften,
Form
der
Ab-
bei Insekten. Nutur-
54, 649.
E. J. 1977. The morphology and histology of the mandibular gland of an Australian species of C’alomyrrnex (Hymenoptera: Formicidae). Zoomor-
U., KOOB, K., AND SCHILDKNECHT, H. 1970. Ein Beitrag sur Funktion der Metathoracald&e der Ameisen. /. Insect Physiol., 16, 387-404. PAVAN, M. 1958. Significato chimico e biologica di alcuni veleni di insetti. Inst. Anaf. Camp. Unit,. Pavia, l-75.
phologie.
VALCURONE,
339-346. BROUGH,
87, 73-86.
E. J. 1978. The multifunctional role of the mandibular gland secretion of an Australian desert
BROUGH,
MASCHWITZ,
M.
L.,
AND
sostanze antibatteriche Boll.
Inst.
Sieroter.
Milan.,
BAGGINI.
A.
1957.
Sulle
di origine entomologica. 36, 283-305.