Camponotus arminius is a large black carpenter ant that occurs in tropical and sub-tropical Africa and has extensive foraging trails both in trees and on the ground. Analysis of excised mandibular glands has confirmed The presence of pentane-2,4-dione, n-hexanal, 4-methyl-3-heptanone, and mellein. Pentane-2,4-dione has not been reported from insects. The postpharyngeal gland contains n-heneicosane, n-tricosene, n-tricosane, n-pentacosene, n-pentacosane, and a significant amount of 11-methyl- n-tricosaneand 11-methyl- n-pentacosane. Dufours glands contain mainly n-undecane, n-tridecane, and two terpenoid compounds that are unknown in the genus Camponotus. These latter two compounds are geranyllinalool and probably geranylfarnesol

Brand, J.M.

Mabinya, L.V.

Morgan, E.D.

English

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140 s. Afr J. Zool. 1999, 34(3) Volatile chemicals in gJands of the carpenter ant, Cllmp()nofus arm in ius J.M. Brand*, L.V. Mabinya Department of Biochemistry, University of Fort Hare, Alice, 5700 South Africa brand@ufhcc.ufh.ac.za E.D. Morgan Department of Chemistry, University of Keele, Staffordshire ST5 5SG, United Kingdom Received 19 March 1999: accepted aiter reV1SlOJJ 2 / Ma.~ j r)t)t) CampDnDtus arminjus is a large black carpenter ant that occurs in tropIcal and sub-tropIcal Africa and has extensive foraging trails both in trees and on the ground. Analysis of excised mandibular glands has confirmed the presence of pentane-2,4-dione, n-hexanal, 4-methyl-3-heptanone, and mellein. Pentane-2,4-dione has not been reported from insects. The postpharyngeal gland contains n-heneicosane, n-tricosene, n-trlcosane, n-pen-tacosene, n-pentacosane, and a significant amount of 11-methyl-n-tricosane and 11-methyl-n-pentacosane. Dufours glands contain mainly n-undecane, n-tridecane, and two terpenoid compounds that are unknown in the genus Camponotus. These latter two compounds are geranyllinalool and probably geranylfarnesol. >II Author to whom correspondence should be (lddre~sed. Introduction The subfamily Formicinac (formicinc ants) has a large num-ber of genera with the genus Campono/us being one of the largest. Many species of this genus are large, dark coloured or black ants that live in galleries in decaying wood, and are therefore commonly known as carpenter ants. Worker ants have no sting and spray a solution of fonn ic acid and Dufours gland contents at attackers. The species Campana/lis arminius occurs in tropical and sub-tropical Africa, where it is found as far south as the south coast of Natal, South Africa. It makes large nests in galleries in trees with major workers often protecting the entrance holes. Workers can be found following long trails both in the trees and on the ground to sources of sugary plant exudates. This species is rather unique amongst fonnicines in that it has naked pupae. whereas, in general, the pupae of formicines are enclosed in cocoons. As ants are social insects. they use volatile chemicals in a variety of \vays for the communication necessary for social existence. Hillen (1994) has counted 39 exocrine glands (i.e. glands secreting externally) in ants that are potential sources of pheromones. We have analysed the compounds present 10 the mandibular gland, the postpharyngeal gland, and the Du-fours gland of C. arm 111 ius. Certain of the compounds have been identified in many other ant species. However, a com-pound (pentane-2,4-dione) previollsly unreported in insects, has been identified in the mandibular gland and the Dufours gland contains two terpenoid compounds (geranyllinalool and probably geranylfarnesol) that have not been reported from this genus. Materials and methods Worker ants were collected from a nest in an old S.vz.vgium cordatum (umdoni) tree in the Margate district of NataJ, South Africa. Glands were dissected under a microscope, placed in a cup made at the end of a 100 III glass pipette, and inserted directly into the modified inlet of a Hew lell Packard 5890 GC as described by Burger. Munro. Smit, Schmidt. W'u & Tien (1990) and modified by Brand & Mpuru (1993) An HP Ultra I column (50 m x 0.2 mm Ld. and 0.33 nun film thickness) was temperature programmed from 50"C to 260:J( at 5ClC min-I. Mass spectra were recorded by a HP 5970 MSD at 70 eY ionisation potential. Chemical standards Llsed were: pentane-2A-dione (Aldrich Chemical Co., Milwaukee, WI). l1-hexanal (Aldrich Chemical Co., Milwaukee, WI), (-10 to C-21 fI-alkanes (Alltech Asso-ciates, Deerfield. IL) and geranylhnaiool (Akros, Loughbor-ough. UK). Results The direct insertion into the (Ie inlet of excised mandibular glands gave chromatograms that always exhibited three peaks corresponding to pentanc-2.4-dione. n-hexanal and mellein Crable I). Peak 4. while oftell present in chromatograms, re-mains unidentified. The compounds identified from the chro-matographic separation of the volatile components in the Table 1 Identified compounds in an excised mandibular gland of C. armimus Peak 110 Ret til11e'! ,\1':0\ 0'0 11 Jdelllit\ h idence' 8 I 21 :i penldlle-::'..-l.-dlolle Gc. \IS 2 8.2 l) ~ n-he"\<lIlZlI (it". MS 12.4 lwce -l.-lllelh~ 1-3-heplanune c.le. \-IS 4 174 118 lIllJ...IW\\11 1\1S :5 246 traLe ~lIb~tlt\lt<:d p~ r:ville .) MS 6 307 ")76 Illelielll I'"IS a. Minutes b. Typical vallle~ for nl1l;' ~1<11ll1 Tr<1ce l11<'ans pre.~ent ill some ChrOlJ1:ltogrmlls c. GC means that all L1utht:llliL ,t;Jnd:-nd \\ ,h .1\ ,lIlabk tt)r cOlllpLlri~Ol1. ()(!Jl"r-v,'isc idcllti ticmioll n: ]1I:d Ull i Illaprelall( 111 (\1 [he: l1la~, ~rectnllil. Reproduced by Sabinet Gateway under licence granted by the Publisher (dated 2009).S. Afr. 1. Zool. 1999, 34(3) postpharyngeal gland and the Dufours gland are listed in Ta-bles 2 and 3. Certain compounds were available as authentic standards for confirmation of identity, while others in the chromatograms were identified on Iy from their mass spectra. As single glands were analysed, the reported area percent is typical of that observed for a single gland, but varies from one gland to another. Therefore, these values provide an indica-tion of those compounds that are major components and those that are minor or trace components in the three glands. Discussion Old ,~vz.vgium corda/um trees seem to be a favoured tree for C. arminius nests in the area where they were collected. The trees secrete sugary secretions and old trees often have de-cayed regions where gallery construction is easy. The nests can be very extensive in the trunk and larger branches and an old established nest will contain many thousands of workers. The mandibular gland of C. arminius contains an interesting variety of compounds (Table I ). Pentane-2,4-dione has been observed in every chromatogram obtained, both of whole Table 2 Identified compounds in an excised postpha-ryngeal gland of C. armin/us Peak no Ret. timea Area %b Identity Evidellcec 437 7 n-hene I cosane Uc. \ItS 2 47.8 8 n-tricosene MS 3 48.5 16 n-tricosane MS 4 495 18 ll-mcthyl-n-tricosanc MS 5 4.2 13 n-pentacosene MS 6 55.2 [race n-pentacosane \1S 7 56.7 30 II-methyl-n-pentacosane \-fS a. Minutes b. Typical values for aile gland. Tmce means present in some chromatograms. c CC mealls [hal all authentic standard was available for compamon. orht!r-wise identitication relied 011 interpretation afthe mass spectrum. Table 3 Identified compounds in an excised Dufours gland of C. arminius Peak no. Ret. timea Area %b Identity Evidencec 15.1 trace n-decane Gc. MS 2 1&.7 67 n-undecanc fiC, MS 3 21.6 1.3 n-dodecane (lC. \-fS 4 24.35 trace n-tridecene MS 5 24.45 trace n-tridecene MS 0 24.& 19 n-tridecane (iC. MS 7 302 1.5 n-pentadecane CC \1~ 8 35.2 trace n-he ptadecane Gt'. \-fS 9 422 7 geranyllinalool GC :v1S 10 54.6 3 geranylfarnesul? MS a. Minutes b. Typical valLle~ for one gland. Trace means present in some chromato-grams. c. GC means that an authentic standard was available for cOlTIpari~on. other-wise idenlitic::1lion relied on interpretation of the mass spectrum. 141 heads and of excised mandibular gland tissue. The retention time and mass spectrum of an authentic standard has con-firmed this structure and it is reported from an insect source for the first time. n-Hexanal. also confirmed by comparison with an authentic standard. has been found in the mandibular gland of another formicine ant, Oecophylla longinada. the African weaver ant (Bradshaw\ Raker & Howse 1975). On ly trace amounts of 4-methyl-3-heptanone were detected. \NthiJe this ketone occurs in a number of ant species. it is more com-monly found in mynnicine and doryl ine secretions (Oldham, Morgan, Goblin. Schoeters & B i lien 1994) than in form icine secretions. Certain chromatograms of mandibular glands showed peak 4. which remains unidentified. and a very minor peak 5, the mass spectrum of which suggested a substituted pyrazine. Mellein occurs in the mandibular gland of males of Camp()I1()/Us pel1l1syh'onicu.\', C. herclI/eonus and C. /1()\'e/J-oroce17sis (Brand, Fales. Sokoloski. Mac Connell, Blum & Duffield J 973) and In the hindgut of a number of Campol1o-tus, Lasius and Formica species where it acts as a trail phe-romone for certain specie~ (Bestmann. Kern, Schafer & Witschel 1992; Obler. Kern. Bestl11ann, Hblldobler & Attyg-aile 1995; Bestmann. Obler & Hblldobler 1997). The postpharyngeal gland of C. Llrminius workers contains, hydrocarbons in the C-21 to C-26 range with two l1-methyl branched alkanes being major components (Table 2). The only authentic standard available for GC and MS identifica-tion was n-heneicosane. Structural identifications of the other hydrocarbons in this gland are based on the interpretation of their mass spectra. Th is gland is reported to have al i phati c hy-drocarbons similar to those found on the cuticle (Bagneres & Morgan 1991) but we have been unable to obtain chromato-grams showing any significant peaks from the direct insertion technique of the cuticle from one complete abdomen. One must therefore conclude that the cuticle contains very little in the way of hydrocarbons of any kind. The Dufours gland of ants is one of the best studied insect glands and the identi fled alkanes. especially C-II and C- 13 (Table 3). are commonly found in this gland of many for-micines. While milny ants have appreciable amounts, of alkenes. often corresponding in chain length to the alkanes present, this species only has barely detectable trace amounts of two tridecenes. However. the presence or geranyllinalooL confirmed by comparison with ,111 authentic standard, is unique among formicines. as is the likely presence of geranyl-farnesol. In chromatograms of some glands these two COI11-pounds accounted for more than 20% of the total area. Other structurally related terpenoids have been reported in the Du-fours gland of Fornm;a species (Bergstrom & Lofqvist 1973) and geranyllinalool has been identified as a minor component in the Dufours gland of New V'/orld army allts (Keegans, 8il-len, Morgan & Gokcen 1993). The identification of the major components of the three glands of C arminills offers an opportunity to study the behavioural roles of their secretions As worker ants follow long trails both in trees and along the ground. and also exhibit some alarm behaviour when provoked. these two behavioural characteristics are probably the 1110st likely to yield results from bioassays of glandular contents. Complex behaviour Reproduced by Sabinet Gateway under licence granted by the Publisher (dated 2009).142 often relies on complex mixtures, but as some of the identi-fied compounds will not be obtained readily, it will be diffi-cult to test mixtures made up of pure compounds. References BAGNCRES. A-Ci. & t'v10RCiAN, E.D. 1991. The postpharyngeal glands and the cuticle of formicidae contain the same characteristic hydrocarbons. Experientia 47: 106-111. BERGSTROM, G. & LOfQVIST, J. 1973. Chemical congruence of the complex odoriferous secretions from the Dufollrs gland in three species of am of the genus Formica. J Insect PhYSlOf. 19: 877-907. BESTMANN, I U., KERN, F., SCHAFER, D. & WITSCHEL. f\,tc. 1992. 3 A-Dihydroi socoumari n~, a new class of ant trai I pheromones. Angew Chem. Int. Ed Fng/. 31: 330-33 I. BESTMANN. II.L UBLER. E. & HOLLDOBLER, B. 1997. First biosynthelic studies on trial pheromones in ants. Ange ... r. Chem. Int Ed Eng/. 36: 395-397. BILLEN . .I. 1994. Morphology of exocrine glands in social insects: an update 100 years after eh. Janet. P. 2 14. In A. Lenoir. G Arnold & M. Lepage (eds.) Les rnsectes Socisux Publications. lJniversitc Paris Nord, Paris. BRADSHAW,.I.W S .. BAKER, R. & HOWSE. P.E. 1975. Multicomponent alarm pheromones of the v ..'caver ant. Nature 25R: 230-23 I. S. Afr. 1. Zoo!. 1999.34(3) BRAND. lM .. FALES. H.M , SOKOLOSKI. E.1\., MAC CONNELL. J.G .. BUJ\1. M.S. & DI,I]-'I'11-:1.0. R.M. 1973. Identification of mellein In [he mandibular gland secretions of carpenter ants. Life Sciences 13. 201-21 I. BRAND, 1M. & MPURU, S.P. 1993. Dufour's gland and poison gland chemistr), of the rnyrmlcme ant. J/essor capensis (Mayr). J. Chern. Feo/. 19: 1315 1321. BURGER, B.V., MUNRO, Z. S\1IT. D., SCI I \1 lOT. U .. WU. C-L. & TIEN, F-C. 1990. Sample II1troductlon III gas chromatography: simple method for the solve1Hles~ introduction of crude samples uf biological origln . .J C'hronwtogr. 518: 207-214. KEEGANS. S.L BILLEN. L MORGAN, I-:.D. & GOKe'EN. O.A. 1993. Volatile glandular secretIOns of three species ofNe"" World army ants, EClfOIl burchelli. Labldw COCCIIS. and Labldus praedator, J. Chem F,co/. Il): 2705-27 [l). OLDHAM, N.L MORGAN, E.D., GOBIN, B.. SCHOETERS. E. & B1LLEN,.I. 1994. Volatile secretions of old \\.orld army ant Aenictus rolul1datlts and chcmotaxol1omic unplications of army ant Dufour gland chemistry . .J Chem j·;co/. 20. 3297-3305. OBLER, E .. KERN. F., BESTMA]\N. H.l, HOLLDOBLER. B. & ATrYGALLE, A B. 1995. Trail pheromone oft\>wo formicme ants, CampOI/o/ILl' Silvlco/a and C r/!/!j)('.\' (llymenoptera: Formicidae). ,'y'alllrwi.'isel1sci1affl'n R2: 523-525. Reproduced by Sabinet Gateway under licence granted by the Publisher (dated 2009).

Volatile chemicals in glands of the carpenter ant, Camponotus arminius

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Volatile chemicals in glands of the carpenter ant, Camponotus arminius

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