Journal of Chemical Ecology, Vol. 7, No. 2, 1981
D U F O U R ' S G L A N D SECRETION IN THE CELL LININGS OF BEES (HYMENOPTERA: A P O I D E A ) ~
J A M E S H. C A N E 2 Ecological Station of Uppsala University S-38 600 FtJ'rjestaden, Sweden
(Received-December 17, 1979; revised July 19, 1980) Abstract--The volatile chemicals, detectable by coupled capillary gas chromatography-mass spectrometry, in the nest cell linings of four species in the bee genera Colletes, Andrena, and Lasioglossum are identical with, and limited to, the volatile components present in the Dufour's gland of females, suggesting this source for some of their cell-lining constituents. The extractable material that lines the cells of Trachusa byssina, in contrast, is derived from Pinus resin, to which it can be chemically traced. Key Words--Dufour's gland secretion, Colletes, Lasioglossum, Andrena, Trachusa, macrocyclic lactones, nest cell lining.
INTRODUCTION Of those species of bees whose nests are subterranean, most provide m e m b r a n e s or waxen h y d r o p h o b i c linings of variable thickness for their nest cells. Possible exceptions are species of D a s y p o d a (Melittidae) and Perdita (Andrenidae), whose nest cell walls appear uncoated (Michener, 1964; Rozen, 1967). Some nest cell linings are insoluble in most organic solvents (Jakobi, 1964; Batra, 1972) and resist degradation by acidic and basic hydrolyses (May, 1974; Hefetz et al., 1979). The long-suspected origin of this lining material, in the Colletidae, Andrenidae, Halictidae, and some A n t h o p h o r i d a e , is the D u f o u r ' s gland of the sting apparatus. This is evidenced in these bees by correlation of glandular enlargement with nesting activity (Bordas, 1895; Semichon, 1906; Lello, ~Contribution number 1738 from the Department of Entomology, University of Kansas, Lawrence. ~Present address: Department of Entomology, University of Kansas, Lawrence, Kansas 66045, U.S.A. 403 0098-0331/ 81/0300-0403503.00/09 1981PlenumPublishingCorporation
404
CANE
1971a,b; May, 1974), female cell construction behaviors (Batra, 1968; Roberts, 1969; May, 1974), and the potential for ready polymerization of some Dufour's gland exudates, such as the macrocyclic lactones (Bergstr6m, 1974). May (1974), using IR spectrometry, indicated the presence of wax esters in both the Dufour's gland secretion and nest cell lining of Augochlora pura (Halictidae). The nest cell linings of three North American Colletes species are formed from polyesters composed of co-hydroxy acid units derived from the corresponding macrocyclic lactones in the bee's Dufour's gland secretions (Hefetz et al., 1979). The glandular origin and chemistry of secreted cell linings have only been demonstrated for these three species of Colletes, for Anthophora abrupta (Norden et al., 1980), and for Augochlora pura pura (Duffield et al., 1980). Most Megachilidae nest in above-ground substrates, ranging from modified preexisting cavities, especially plant stems, to various fabricated structures of mud, leaves, plant resins, and hairs, etc. (Michener, 1974). Trachusa spp. (Megachilidae) seem intermediate in nesting habits, as they excavate subterranean nests but coat their cell surfaces with plant resins and leaves (Hachfeld, 1926). No megachilid bee is known to use secreted nest cell linings (Michener, 1974), based on morphological and behavioral evidence. METHODS AND MATERIALS
Biological Materials. The bees used in this study were all obtained from the Swedish island of 01and. Dufour's glands were excised from live, chilled, recently collected bees (Bergstrom and Teng6, 1974), whose own nest cell linings were also to be analyzed. Bees were collected directly from their nests. Previously identified Dufour's gland components were in all cases verified (Bergstr6m, 1974; Bergstr6m and Teng6, 1974). Single, whole glands or their extracts were placed in a thermally programmed precolumn and the volatiles were directly analyzed with a combined capillary gas chromatograph-mass spectrometer (Bergstr6m and Tengo, 1974). Nest cell linings were obtained only from unprovisioned cells. Volatile lining components of cells were made available for GC-MS analyses either by precolumn thermolysis of cell lining fragments or by chemical extraction and concentration in either methylene chloride, pentane, or hexane. Additionally, for Andrena marginata, methylene chloride extracts were prepared both from five pollen provision balls and fifty flowers of Campanula rotundifolia (Campanulaceae) at which this species was observed foraging. Instrumentation. Chemical analyses were performed with the aid of a combined GC-MS (Pye Unicam gas chromatograph, LKB-2091 mass spectrometer) modified to receive splitless precolumn injections (Bergstr6m, 1973). An FFAP/OV-17, 25-m-long glass capillary column was selected for the GC-MS system, while an OV-101 25-m-long column in a Perkin-Elmer 900 GC with flame ionization detection provided comparative chromatograms.
NEST CELL LININGS OF BEES
405
4 6
Cell lining
5
2
225
isothermall3' 0
150
9FO . / ~ 0
210
10
*C
0 min
FIG. 1. Capillary gas chromatogram of 5-min precolumn thermolysis of a cell lining fragment of Colletes cunicularius. Precolumn 175~ 1 = heneicosane;2 = unknown; 3 = tricosane; 4 = 18-octadecanolide; 5 = 18-octadecenolide; 6 = 20-eicosanolide.
Chemical Identification. Identifications of the volatile components of glands, cell linings, and pollen balls were made by comparisons with reference spectra and retention times of previously published or available synthetic compounds (Bergstr6m, 1974; Bergstrom and Teng6, 1974; Teng6 and Bergstr6m, 1975). Two to five glands and cell linings per species were each analyzed independently by GC-MS to determine constancy of chemical constituencies. All chromatograms and spectra are deposited with the Ecological Station at Uppsala University. RESULTS
In each of the following species, the predominant volatile compounds isolated from the nest cell lining were identical with and limited to the chemicals of the Dufour's gland secretion of the respective bee species. Thus, macrocyclic lactones predominate in the Dufour's gland secretion (Bergstrfm, 1974, their Figure 1) and cell linings (Figure 1) of Colletes cunicularius as well as Lasioglossum albipes (Figure 2A and B). Farnesyl derivatives characterize the Andrena haemorrhoa Dufour's gland secretion (Bergstrom and Teng6, 1974, their Figure 11) and nest cell linings (Figure 3). Three farnesene isomers are present in similar proportions for both the nest cell lining and Dufour's gland secretion (Figure 4) of Andrena marginata. The predominant volatile components isolated from the pollen balls of Andrena marginata are identical with and limited to those chemicals present
406
CAN~ 98
7
A Dufour's
gland
9
10
225
isothermal
i
,,,
t?o
1,1o
3o "c
20
10
Omin
FIG. 2. Capillary gas chromatograms of 5-min precolumn thermolyses of the Dufour's gland (A) and pentane extract of the nest cell lining (B) of Lasioglossum albipes. Precolumn 200~ 7 = 16-hexadecanolide; 8 = 18-octadecanolide; 9 = 18-octadecenolide; 10 = 20-eicosanolide. in its D u f o u f s gland reservoir (Figures 4A and B). They are not those volatiles extracted f r o m Campanula rotundifolia nectar or pollen, as judged f r o m the pattern of G C retention times. The origin of the volatiles extracted f r o m the nest cell walls of Trachusa byssina (Megachilidae) was chemically traced b o t h to the resin bails carried by
407
NEST CELL L I N I N G S OF BEES
Cell lining
11 15
225 isothermal J 2'0
13 I
130 1~)
50 ~ ,,,I 0 rain
FIG. 3. Capillary gas chromatogram of 5-rain precolumn injection of a cell lining fragment of Andrena haemorrhoa. Precolumn 200~C. 11, 12, 13 --- farneseneisomers; 14 = farnesol; 15 = farnesyl hexanoate. the females and the exuding bud resin of nearby Pinus sylvestris (Pinaceae). They all contain a-,/3-pinenes, A-3-carene, and limonene in like proportions (Figure 5).
DISCUSSION It is likely that Dufour's gland secretions are present in the nest cell linings of other burrowing bees. There is a close infrageneric chemical similarity between the nest cell linings described here and the Dufour's gland secretions previously reported for species of Colletes (Bergstr6m, 1974; Hefetz et al., 1979), Andrena (Bergstr6m and Teng6, 1974; Teng6 and Bergstr6m, 1978; Cane, unpublished), and Lasioglossum (sensu lato) (Bergstr6m, 1974; Hefetz et al., 1978). Similar macrocyclic lactones are present in the Dufour's gland secretions of other Halictinae, such as Halictus (Bergstrbm and Tengo, 1979), Agapostemon, and Augochlorella (Hefetz et al., 1978). Thus, the Dufour's gland secretion may be expected in their cell linings too, as Duffield et al. (1980) have shown for Augochlora pura pura. Hachfeld's (1926) observation that Trachusa byssina females visit conifers to obtain resins for cell linings is chemically confirmed. Only Correia (1977) has previously analyzed any other resinous megachilid cell lining chromatographically, using Heriades truncorum. Volatile coniferous leaf oil
408
CAN~
terpenes have been chemosystematically analyzed (Rudloff, 1975) and so can provide evidence for the cell lining origins of other megachilids. Although the secreted cell linings studied here include chemicals derived from the Dufour's gland in Colletes, Andrena, and Lasioglossum, they may not be limited to this glandular source. Suggested origins have included not only the Dufour's gland (Colletes--Hefetz et al., 1979; Andrena--Lello, 22
Dufour's gland
A
17
18
22
20
17
Pollen balls
21
225 isothermaIP
B
18
190 210
'
,,110,,, 10
30 ~ ' Omin
FIG. 4. Capillary gas chromatograms of 5-rain programed precolumn thermolysis of the Dufour's gland (A) and splitless injection of methylene chloride extract of five pollen balls (B) of Andrena marginata. Precolumn 200~ 16 = dihydrofarnesene; 17, 18, 19 = farnesene isomers; 20 = farnesol; 21 = tricosane; 22 = farnesyl hexanoate.
NEST CELL LININGS OF BEES
409 25 24
23
Cell lining
26
f
is~
22s
19o
l~o
J
20
10
30 ~ Omin
FIG. 5. Capillary gas chromatogram of a splitless injection of pentane extract of cell lining fragment of Trachusa byssina. 23 = t~-pinene; 24 = fl-pinene; 25 = A-3-carene; 26 = limonene.
1971a; B e r g s t r 6 m a n d T e n g 6 , 1974; Augochlora--May, 1974;Anthophora-S e m i c h o n , 1906; M a l y s h e v , 1928), b u t a l s o t h e s a l i v a r y g l a n d s (Colletes-C l a u d e - J o s e p h , 1926; B a t r a , 1972; M a l y s h e v , 1968; Andrena--Batra, 1972), a n d i n t e r s e g m e n t a l g l a n d s (Andrena--Altenkirch, 1962).
Acknowledgments--I thank Dr. Jan TengiS, Anna-Karin Borg-Karlsson, and the numerous other scientists and staff at the Ecological Station of the University of Uppsala for their enthusiastically shared biological and chemical knowledge and supportive encouragement, without which this study would have been impossible. Dr. Bertil Kullenberg and the Ax:son Johnson Foundation generously permitted the use of the research facilities and living quarters at the Station. My work there was funded by a Thord-Gray Memorial Fellowship from the American Scandinavian Foundation and a travel grant from the U.S. Fulbright Commission. This manuscript was kindly reviewed by Drs. C.D. Michener and R. Carlson, University of Kansas, and Dr. G. Bergstrbm, University of Gfteborg. Preparation and typing of the manuscript was facilitated by NSF grant DEB 77-23035. REFERENCES ALTENKIRCH, G. 1962. Untersuchungen fiber die Morphologie der abdominalen Hautdr/isen einheimischer Apiden. Zool. Beitr, 7:161-238. BATRA, S.W.T. 1968. Behavior of some social and solitary halictine bees within their nests: A comparative study. Z Kans. Entomol. Soc. 41:120-133. BATRA, S.W.T. 1972. Some properties of the nest-building secretions of Nomia, Anthophora, Hylaeus, and other bees. J. Karts. Entomol. Soc. 45:208-218.
410
CANE
BERGSTRt~M,G. 1973. Use of a precolumn tube for the quantitative isolation of natural, volatile compounds for gas chromatography/mass spectrometry. Chem. Scr. 4:135-138. BERGSTR6M, G. 1974. Macrocyclic lactones in the Dufour gland secretion of the solitary bees Colletes cunicularius L. and Halictus calceatus Scop. Chem. Scr. 5:39-46. BERGSTROM, G., and TENGO, J. 1974. Farnesyl- and geranyl-esters as main volatile constituents of the secretion from Dufour's gland in 6 species of Andrena (Hymenoptera, Apidae). Chem. Scr. 5:28-38. BEROSTR6M, G., and TENG6, J. 1979. C24-, C22-, C2o-, and Clrmacrocyclic lactones in halictid bees. Acta Chem. Scand. B 1979:390. BORDAS, M.L. 1895. Apparel glandulaire des Hymenopteres, Ann. Sci., Nat. ZooL /9:1-362. CLAUDE-JOSEPH, F. 19~26. Recherches biologiques sur les Hymenopteres du Chili (melliferes). Ann. Sci. Nat. Zool. 9:113-268. CORRE1A, M. 1977. Sur l'origine des resines employees par Heriades truncorum L. (Hym., Megachilidae) pour la construction ses nids. Apidologie 8:101-109. DUFFIELD, R.M., FERNANDES, A., LAMB, C., WHEELER,J.W., and EICKWORT, G.C. 1980. Macrocyclic lactones and isopentenyl esters in the Dufour's gland secretion of halictine bees (Hymenoptera: Halictidae). J. Chem. Ecol. In press. HACHFELD, G. 1926. Zur Biologie der Trachusa byssina Pz. (Hymenoptera, Apidae, Megachilidae). Z. Wiss. Insektenbiol. 21:63-84. HEFETZ, A., BLOM, M.S., EICKWORT, G.C., and WHEELER,J.W. 1978. Chemistry of the Dufour's gland secretion of halictine bees. Comp. Biochem. PhysioL 61B: 129-132. HEFETZ, A., FALES, H.M., and BATRA, S.W.T. 1979. Natural polyesters: Dufour's gland macrocyclic lactones form brood cell laminesters in Colletes bees. Science 204:415-417. JAKOBI,H. 1964. 0bet die Lfschlichkeit des Brutzellenwasches yon Wildbienen. Z. Bienenforsch. 7:72-76. LELLO, E. DE. 1971a. Adnexal glands of the sting apparatus of bees: Anatomy and histology, I (Hymenoptera: Colletidae, and Andrenidae). J. Kans. Entomol. Soc. 44:5-13. LELLO, E. DE. 1971b. Adnexal glands of the sting apparatus of bees: Anatomy and histology, II (Hymenoptera: Halictidae). d. Kans. Entomol. Soc. 44:14-20. MALYSHEV, S. 1968. Genesis of the Hymenoptera and the Phases of Their Evolution. Methuen and Co., London, 319 pp. MAY, D.K.G. 1974. An investigation of the chemical nature and origin of the waxy lining of the brood cells of a sweat bee, Augochlora pura. J. Kans. Entomol. Soc. 74:504-516. MICHENER, C.D. 1964. Evolution of the nests of bees. Am. Zool. 4:227-239. MICHENER, C.D. 1974. The Social Behavior of the Bees. A Comparative Study. Harvard University Press, Cambridge, Massachusetts, 404 pp. NORDEN, B., BATRA,S.W~ FALES, H.M., HEFETZ, A., and SHAW, G.J. 1980. Anthophorabees: Unusual glycerides from maternal Dufour's glands serve as larval food and cell lining. Science 207:1095-1096. ROBERTS, R.B. 1969. Biology of the bee genus Agapostemon (Hymenoptera: Halictidae). Univ. Kansas Sci. Bull. 48:689-719. ROZEN, J.G., Jr. 1967. Review of the biology of panurgine bees, with observations on North American forms (Hymenoptera, Andrenidae). Am. Mus. Novit. 2297:1-44. RUDLOFF, E. VON. 1975. Volatile leaf oil analysis in chemosystematic studies of North American conifers. Biochem. Syst. Ecol. 2:131-169. SEMICHON, M.L. 1906. Recherches morphologiques et biologiques sur quelques melliferes solitaires. Bull. Sci. Fr. Belg. 40:281-442. TENGO, J., and BERGSTROM,G. 1975. All-trans-farnesyl hexanoate and geranyl octanoate in the Dufour gland secretion of Andrena (Hymenoptera: Apidae). J. Chem. Ecol. 1:253-268. TENO6, J., and BEaGSTRbM,G. 1978. Identical isoprenoid esters in the Dufour's gland secretions of North American and European Andrena bees (Hymenoptera: Andrenidae). J. Kans. Entomol. Soc. 51:521-527.
D U F O U R ' S G L A N D SECRETION IN THE CELL LININGS OF BEES (HYMENOPTERA: A P O I D E A ) ~
J A M E S H. C A N E 2 Ecological Station of Uppsala University S-38 600 FtJ'rjestaden, Sweden
(Received-December 17, 1979; revised July 19, 1980) Abstract--The volatile chemicals, detectable by coupled capillary gas chromatography-mass spectrometry, in the nest cell linings of four species in the bee genera Colletes, Andrena, and Lasioglossum are identical with, and limited to, the volatile components present in the Dufour's gland of females, suggesting this source for some of their cell-lining constituents. The extractable material that lines the cells of Trachusa byssina, in contrast, is derived from Pinus resin, to which it can be chemically traced. Key Words--Dufour's gland secretion, Colletes, Lasioglossum, Andrena, Trachusa, macrocyclic lactones, nest cell lining.
INTRODUCTION Of those species of bees whose nests are subterranean, most provide m e m b r a n e s or waxen h y d r o p h o b i c linings of variable thickness for their nest cells. Possible exceptions are species of D a s y p o d a (Melittidae) and Perdita (Andrenidae), whose nest cell walls appear uncoated (Michener, 1964; Rozen, 1967). Some nest cell linings are insoluble in most organic solvents (Jakobi, 1964; Batra, 1972) and resist degradation by acidic and basic hydrolyses (May, 1974; Hefetz et al., 1979). The long-suspected origin of this lining material, in the Colletidae, Andrenidae, Halictidae, and some A n t h o p h o r i d a e , is the D u f o u r ' s gland of the sting apparatus. This is evidenced in these bees by correlation of glandular enlargement with nesting activity (Bordas, 1895; Semichon, 1906; Lello, ~Contribution number 1738 from the Department of Entomology, University of Kansas, Lawrence. ~Present address: Department of Entomology, University of Kansas, Lawrence, Kansas 66045, U.S.A. 403 0098-0331/ 81/0300-0403503.00/09 1981PlenumPublishingCorporation
404
CANE
1971a,b; May, 1974), female cell construction behaviors (Batra, 1968; Roberts, 1969; May, 1974), and the potential for ready polymerization of some Dufour's gland exudates, such as the macrocyclic lactones (Bergstr6m, 1974). May (1974), using IR spectrometry, indicated the presence of wax esters in both the Dufour's gland secretion and nest cell lining of Augochlora pura (Halictidae). The nest cell linings of three North American Colletes species are formed from polyesters composed of co-hydroxy acid units derived from the corresponding macrocyclic lactones in the bee's Dufour's gland secretions (Hefetz et al., 1979). The glandular origin and chemistry of secreted cell linings have only been demonstrated for these three species of Colletes, for Anthophora abrupta (Norden et al., 1980), and for Augochlora pura pura (Duffield et al., 1980). Most Megachilidae nest in above-ground substrates, ranging from modified preexisting cavities, especially plant stems, to various fabricated structures of mud, leaves, plant resins, and hairs, etc. (Michener, 1974). Trachusa spp. (Megachilidae) seem intermediate in nesting habits, as they excavate subterranean nests but coat their cell surfaces with plant resins and leaves (Hachfeld, 1926). No megachilid bee is known to use secreted nest cell linings (Michener, 1974), based on morphological and behavioral evidence. METHODS AND MATERIALS
Biological Materials. The bees used in this study were all obtained from the Swedish island of 01and. Dufour's glands were excised from live, chilled, recently collected bees (Bergstrom and Teng6, 1974), whose own nest cell linings were also to be analyzed. Bees were collected directly from their nests. Previously identified Dufour's gland components were in all cases verified (Bergstr6m, 1974; Bergstr6m and Teng6, 1974). Single, whole glands or their extracts were placed in a thermally programmed precolumn and the volatiles were directly analyzed with a combined capillary gas chromatograph-mass spectrometer (Bergstr6m and Tengo, 1974). Nest cell linings were obtained only from unprovisioned cells. Volatile lining components of cells were made available for GC-MS analyses either by precolumn thermolysis of cell lining fragments or by chemical extraction and concentration in either methylene chloride, pentane, or hexane. Additionally, for Andrena marginata, methylene chloride extracts were prepared both from five pollen provision balls and fifty flowers of Campanula rotundifolia (Campanulaceae) at which this species was observed foraging. Instrumentation. Chemical analyses were performed with the aid of a combined GC-MS (Pye Unicam gas chromatograph, LKB-2091 mass spectrometer) modified to receive splitless precolumn injections (Bergstr6m, 1973). An FFAP/OV-17, 25-m-long glass capillary column was selected for the GC-MS system, while an OV-101 25-m-long column in a Perkin-Elmer 900 GC with flame ionization detection provided comparative chromatograms.
NEST CELL LININGS OF BEES
405
4 6
Cell lining
5
2
225
isothermall3' 0
150
9FO . / ~ 0
210
10
*C
0 min
FIG. 1. Capillary gas chromatogram of 5-min precolumn thermolysis of a cell lining fragment of Colletes cunicularius. Precolumn 175~ 1 = heneicosane;2 = unknown; 3 = tricosane; 4 = 18-octadecanolide; 5 = 18-octadecenolide; 6 = 20-eicosanolide.
Chemical Identification. Identifications of the volatile components of glands, cell linings, and pollen balls were made by comparisons with reference spectra and retention times of previously published or available synthetic compounds (Bergstr6m, 1974; Bergstrom and Teng6, 1974; Teng6 and Bergstr6m, 1975). Two to five glands and cell linings per species were each analyzed independently by GC-MS to determine constancy of chemical constituencies. All chromatograms and spectra are deposited with the Ecological Station at Uppsala University. RESULTS
In each of the following species, the predominant volatile compounds isolated from the nest cell lining were identical with and limited to the chemicals of the Dufour's gland secretion of the respective bee species. Thus, macrocyclic lactones predominate in the Dufour's gland secretion (Bergstrfm, 1974, their Figure 1) and cell linings (Figure 1) of Colletes cunicularius as well as Lasioglossum albipes (Figure 2A and B). Farnesyl derivatives characterize the Andrena haemorrhoa Dufour's gland secretion (Bergstrom and Teng6, 1974, their Figure 11) and nest cell linings (Figure 3). Three farnesene isomers are present in similar proportions for both the nest cell lining and Dufour's gland secretion (Figure 4) of Andrena marginata. The predominant volatile components isolated from the pollen balls of Andrena marginata are identical with and limited to those chemicals present
406
CAN~ 98
7
A Dufour's
gland
9
10
225
isothermal
i
,,,
t?o
1,1o
3o "c
20
10
Omin
FIG. 2. Capillary gas chromatograms of 5-min precolumn thermolyses of the Dufour's gland (A) and pentane extract of the nest cell lining (B) of Lasioglossum albipes. Precolumn 200~ 7 = 16-hexadecanolide; 8 = 18-octadecanolide; 9 = 18-octadecenolide; 10 = 20-eicosanolide. in its D u f o u f s gland reservoir (Figures 4A and B). They are not those volatiles extracted f r o m Campanula rotundifolia nectar or pollen, as judged f r o m the pattern of G C retention times. The origin of the volatiles extracted f r o m the nest cell walls of Trachusa byssina (Megachilidae) was chemically traced b o t h to the resin bails carried by
407
NEST CELL L I N I N G S OF BEES
Cell lining
11 15
225 isothermal J 2'0
13 I
130 1~)
50 ~ ,,,I 0 rain
FIG. 3. Capillary gas chromatogram of 5-rain precolumn injection of a cell lining fragment of Andrena haemorrhoa. Precolumn 200~C. 11, 12, 13 --- farneseneisomers; 14 = farnesol; 15 = farnesyl hexanoate. the females and the exuding bud resin of nearby Pinus sylvestris (Pinaceae). They all contain a-,/3-pinenes, A-3-carene, and limonene in like proportions (Figure 5).
DISCUSSION It is likely that Dufour's gland secretions are present in the nest cell linings of other burrowing bees. There is a close infrageneric chemical similarity between the nest cell linings described here and the Dufour's gland secretions previously reported for species of Colletes (Bergstr6m, 1974; Hefetz et al., 1979), Andrena (Bergstr6m and Teng6, 1974; Teng6 and Bergstr6m, 1978; Cane, unpublished), and Lasioglossum (sensu lato) (Bergstr6m, 1974; Hefetz et al., 1978). Similar macrocyclic lactones are present in the Dufour's gland secretions of other Halictinae, such as Halictus (Bergstrbm and Tengo, 1979), Agapostemon, and Augochlorella (Hefetz et al., 1978). Thus, the Dufour's gland secretion may be expected in their cell linings too, as Duffield et al. (1980) have shown for Augochlora pura pura. Hachfeld's (1926) observation that Trachusa byssina females visit conifers to obtain resins for cell linings is chemically confirmed. Only Correia (1977) has previously analyzed any other resinous megachilid cell lining chromatographically, using Heriades truncorum. Volatile coniferous leaf oil
408
CAN~
terpenes have been chemosystematically analyzed (Rudloff, 1975) and so can provide evidence for the cell lining origins of other megachilids. Although the secreted cell linings studied here include chemicals derived from the Dufour's gland in Colletes, Andrena, and Lasioglossum, they may not be limited to this glandular source. Suggested origins have included not only the Dufour's gland (Colletes--Hefetz et al., 1979; Andrena--Lello, 22
Dufour's gland
A
17
18
22
20
17
Pollen balls
21
225 isothermaIP
B
18
190 210
'
,,110,,, 10
30 ~ ' Omin
FIG. 4. Capillary gas chromatograms of 5-rain programed precolumn thermolysis of the Dufour's gland (A) and splitless injection of methylene chloride extract of five pollen balls (B) of Andrena marginata. Precolumn 200~ 16 = dihydrofarnesene; 17, 18, 19 = farnesene isomers; 20 = farnesol; 21 = tricosane; 22 = farnesyl hexanoate.
NEST CELL LININGS OF BEES
409 25 24
23
Cell lining
26
f
is~
22s
19o
l~o
J
20
10
30 ~ Omin
FIG. 5. Capillary gas chromatogram of a splitless injection of pentane extract of cell lining fragment of Trachusa byssina. 23 = t~-pinene; 24 = fl-pinene; 25 = A-3-carene; 26 = limonene.
1971a; B e r g s t r 6 m a n d T e n g 6 , 1974; Augochlora--May, 1974;Anthophora-S e m i c h o n , 1906; M a l y s h e v , 1928), b u t a l s o t h e s a l i v a r y g l a n d s (Colletes-C l a u d e - J o s e p h , 1926; B a t r a , 1972; M a l y s h e v , 1968; Andrena--Batra, 1972), a n d i n t e r s e g m e n t a l g l a n d s (Andrena--Altenkirch, 1962).
Acknowledgments--I thank Dr. Jan TengiS, Anna-Karin Borg-Karlsson, and the numerous other scientists and staff at the Ecological Station of the University of Uppsala for their enthusiastically shared biological and chemical knowledge and supportive encouragement, without which this study would have been impossible. Dr. Bertil Kullenberg and the Ax:son Johnson Foundation generously permitted the use of the research facilities and living quarters at the Station. My work there was funded by a Thord-Gray Memorial Fellowship from the American Scandinavian Foundation and a travel grant from the U.S. Fulbright Commission. This manuscript was kindly reviewed by Drs. C.D. Michener and R. Carlson, University of Kansas, and Dr. G. Bergstrbm, University of Gfteborg. Preparation and typing of the manuscript was facilitated by NSF grant DEB 77-23035. REFERENCES ALTENKIRCH, G. 1962. Untersuchungen fiber die Morphologie der abdominalen Hautdr/isen einheimischer Apiden. Zool. Beitr, 7:161-238. BATRA, S.W.T. 1968. Behavior of some social and solitary halictine bees within their nests: A comparative study. Z Kans. Entomol. Soc. 41:120-133. BATRA, S.W.T. 1972. Some properties of the nest-building secretions of Nomia, Anthophora, Hylaeus, and other bees. J. Karts. Entomol. Soc. 45:208-218.
410
CANE
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