FORAGINGBEHAVIOUR OF CARPENTERBEES, GENUSXYLOCOPA XYLOCOPIDAE HYMENOPTERA, : : AND THE POLLINATION OF SOME INDIAN PLANTS 1 AluriJacob SolomonRaju andC. SubbaReddi2 Key words: Foraging behaviour, pollination, carpenter bees, Xylocopa latipes, X. pubescens Carpenter bees, or species ofXylocopa, are prominent members ofthe Indian bee fauna. They are found throughoutthe year, foraging indaylightand rarely through themoonlithours. Some plant species are adapted specifically to pollination mediated by nectar-seeking carpenter bees. Suchflowersprotectthenectarchamberagainstpiercing.Someofferpollenfromporicidalanthers astheonlyreward.Bytheirflower-foragingbehaviour,carpenterbeesprovideanexcellentservice totheplantsthattheypollinate,especiallyobligateoutcrosserslikeGmelinaandCochlospermum. Thedifferent typesofforaging behaviourexhibited and theroleplayed bycarpenter bees in the pollinationofvariousplantspeciesoccurringinVisakhapatnam,CoringaandGiddalurinAndhra Pradesh are discussed. Introduction While probing the flowers for pollen or nectar, thebeesusuallycontactstigmasandanthers,and Large carpenter bees ofthe cosmopolitan thereby pollinate flowers. Some plant species genus Xylocopa (Family Xylocopidae, with obligate outcrossing ability are exclusively Hymenoptera) are the mostprominentmembers pollinated by carpenterbees, while some others ofthe Indian bee fauna. They are usually black with self- and outcrossing ability are also on the abdomen and variously coloured in the pollinated by other insects. Further, there are thoracic region. They nest in soft dead wood of mutualistic pollinating relationships between various plant species. Male and female vary in carpenter bees and plants (Snow and Roubik size, andgenerallybothhavelongtongues.They 1987, Scott et al. 1993). The carpenter bees feed on the flowers of various plant species exhibitvariousflower-foragingbehaviourssuch blooming at different times of the year. Their as opportunistic, territorial, traplining, buzzing, foraging activity is usually limited to daylight and others forutilising forage efficiently. These hours,butsomeextendtheiractivityintomoonlit behaviour patterns benefit the plants largely in hours as well (Maxwell-Lefroy and Howlett outcrossing.Altogether,theforagingofcarpenter 1971). The male carpenter bees collect only bees provide an excellent service forplants that nectar,whilethefemalesgatherpollenandnectar theypollinate,especiallyforobligateoutcrossers, toprovisionbroodcells.Bothhaveahighenergy and enhances the fecundity and adult expenditure when foraging (Chappel 1982) due maintenance in bees. In view ofthe importance to their large mass, and this expenditure must of foraging behaviours of carpenter bees in bebalancedbyenergyobtainedfromnectarsugar. pollination, this paper aims at describing the Thebeescancarryquantitiesofnectarand floral, structural and functional features of 15 pollen that are large, relative to the amounts plantspeciesandtheiradaptationstopollination usually available in flowers, and thus they visit by carpenter bees Xylocopa latipes and many flowers or plants during a foraging trip. X. pubescens (Table 1). Of these, two are mangroveplantspecies,Acanthus ilicifoliusand 'AcceptedAugust,1999 Caesalpinia nuga occurring in estuarine 2ADnedpharratmUeninvteorsfiEtnyv,iVriosnamkenhtaaplatSnciaemn5ce3s0,003, habitats ofCoringa ,(16° 55' N, 82° 15' E). Two AndhraPradesh,India. others,Anisomelesmalabarica andA. indicaare JOURNAL, BOMBAYNATURAL HISTORYSOCIETY, 97(3), DEC. 2000 381 1 — ' FORAGINGBEHAVIOUROFCARPENTERBEESXYLOGOYA g 8 g? 1 f! | N N oQ. oCL CoL X<)u Q3Q C3Q Hs_ £ 8 c XO <D 0- Cl Oh £ 8 2 Z c Z Z P-Pollen; G-Geitonogamy, ^ £ «« Es£O 2£C>/5 sCQ3-£ XCuQ wmH.XQuQ"?Hm X4CQ xU xU X4pa X4CQ Cf3filT XuCQ" CQ QQ 6cq" ^4 N-Nectar, SPECIES 60 < X-Xenogamy, I E doooo Sb-Sunbirds; D <U ^ c<5U ^ X" X X X X X PLANT T-Traces, H-Hawkmoth, DIFFERENT Wh-White; OF 3 £ Bu-Butteiflies, O -£ i— © Pu-Puiple, H 1 ’ 1 FORAGERS n <u ss AND X o CQ >- CQ Bi-Blue, Th-Thrips, c l- <ou oj La-Lavendar, An-Ants. FLOWERS <5 « J Jd, J J ~o o o o o OF m Oo O c ° W-Wasps,Buz-Buzzing. DETAILS o,o£i 6eE«0 0ormoatn-^oXoo-0om^Oor (IoI-L s°m(N Cr-Creamy-white,F-Flies, Op-Opportunistic, fX%2 1<oD_ < Oltoir lSiv2L lOot fSijSLl<^CL <CL •CS««L8£3*0Z8>o0* Ye-Yellow, bees, Cb-Carpenter Tr-Traplining, P-Poricidal, B-Bees, L-Longitudinal, Te-Territoriality, A-Autogamy; <3 382 JOURNAL, BOMBAYNATURAL HISTORYSOCIETY, 97(3) DEC. 2000 / FORAGINGBEHAVIOUROFCARPENTERBEESXYLOCOPA inhabitants ofthe foothills ofGiddalurarea (15° consequence,the flowersreceivemultiplevisits, 10' N, 18° 45' E); all others occur in hence cross- or self-pollination is ensured. The Visakhapatnam (17° 42' N, 82° 18' E). bees show fidelity to this plant throughout its Thefloralfeaturesandforagingbehaviour flowering by exhibiting territorial foraging of carpenter bees with reference to pollination behaviour to exploitthe nectar. havebeenreportedbyAluri(1990, 1993);Aluri 2. Alangium salviifolium (Linn. F.) and Subba Reddi (1989, 1994, 1996a, b); Wang. (Alangiaceae): A small deciduous tree, BhaskaraRaoandSubbaReddi(1994a,b);Jyothi itshedsleavesbeforeflowering.Itflowersduring et al. (1990); Subba Reddi and Aluri (1997); February-April. Although the flowers are open Subba Reddi and Bhaskara Rao, (1993); and day and night, they are fora—ged for pollen and Subba Reddi et al. (1996, 1997). The foraging ornectarbydiurnalinsects bees, wasps, flies behaviourofcarpenterbeesandbreedingsystems and butterflies. Of these, carpenter bees show havebeenfurtherstudiedextensivelyinthefield, fidelity to this plant by foraging throughout the where the abovementionedplant species occur. flowering period and largely effecting cross-pollination. The flowers standoutvisually Floral details and foraging behaviour of by their large display and by shedding leaves carpenter bees whichattractthebees.Thecarpenterbeesexhibit 1. Acanthus ilicifolius L. (Acanthaceae): traplining and territorial foraging behaviour. This plant grows in the estuarine habitats of Trapliningisemployedtoforageonthedistantly Coringa and adjoining areas in the Godavari spaced plants intermingled with other plant deltaandflowersduringMay-August.Itsflowers species, andterritoriality to forage on the plants arelarge, blue andnectariferous. The flowerhas aggregated in one place. These two behaviour a cartilaginous corolla tube, terminating in an patterns occur throughout the flowering period, upper lip sheltering stamens and the pistil, and andprobablypromotexenogamy. a lower lip which serves as a landing site for 3 &4.Anisomelesmalabarica R. Br. and foragers.Thestigmaprojectsbeyondtheanthers. A. indica O. Kuntze (Lamiaceae): These two Thepollenreceptacleconsistsoffertileandsterile speciesareherbaceousperennialsandgrowfrom anthers,whicharefirmlyinterlocked. Separation both rootstock and seed. A. malabarica shows of these locules and subsequent liberation of vegetative growth in July, flowers during pollen are possible only by large-bodied mid-OctoberanddisappearsinJanuary.A. indica pollinators. The flowers are visitedby carpenter shows vegetative growth and flowers during bees along with sunbirds for nectar; both are October to mid-January. It exhibits flowering equally efficient in exploiting the nectar and episodesinresponsetowaterstress. Theflowers effecting cross-pollination. While probing the open from 0100-0500 hrs inA. malabarica and flower, the carpenter bee inserts its proboscis from 0530-0730 hrs in A. indica. The flower through the pollen receptacle with much force structureofthetwospeciesissimilar.Theflowers to getatthe nectar. This results inthe separation are purple, showy, large, fragrant, bisexual and of fertile locules from the sterile ones and nectariferous. They are bilabiate, with stamens sheddingpollenonto thebackofthe bee andon and style extending beyond the small upper lip the stigma. If the bee carries pollen from the resemblingtheclassicalgullettypeblossom.Day- previously visited flower, it results in flying bees, wasps, ants, thrips, butterflies and cross-pollination or else effects selfing. The sunbirds visit the flowers of both species, of separated anther locules regain their original which only carpenter bees and sunbirds are position with the departure of the bee. In regular and perform efficient and effective JOURNAL. BOMBAYNATURAL HISTORYSOCIETY. 97(3), DEC 2000 383 FORAGINGBEHAVIOUROFCARPENTERBEESXYLOCOPA pollination. Other foragers visit the flowers bypassingthepollinationapparatus, abehaviour occasionally,andsomeofthemdepletethefloral pattern known as side-working. AbouF25% of forage by probing from the side ofthe flowers, the foraging visits relate to side working. bypassing the pollination apparatus. The 6. Caesalpinia nuga Ait. carpenterbees, afterlanding onthe strong lower (Caesalpiniaceae): Itthriveswellintheestuarine lip, probe flowers in an upright position for habitats of Coringa and blooms during nectar, duringwhichthestigmasituatednearthe March-June. Its flowers are large, bisexual, tip of upper lip contacts the residual pollen in protandrous and nectariferous, opening every thedorsalcreviceofthebees.Themalecarpenter morning. The flowers are aromatic, yellow with bees exhibit territorial and traplining foraging nectar guide on the upper petal, and the behaviour and collect only nectar. This dual reproductivestructuresplacednearthelowerpart behaviour greatly profits the taxa in achieving ofthecorolla.XylocopalatipesandX.pubescens outcrossing. Sunbirds are equally important for are the principal pollinators; they are diurnal pollination. Theyfeedonthenectarofflowering foragers and collect only nectar. Guided by the Anisomeles throughout winter. nectarguide,thebeesprobetheflowerinupright 5. Bauhinia purpurea Linn. position and contact anthers and stigma with (Caesalpiniaceae): An evergreen, popular their sternum. They exhibit traplining foraging ornamental tree, flowers during October- behaviour. December;sometreesmayfloweruptoFebruary. 7. Cassia alata L. (Caesalpiniaceae): It is Theflowersopendailyfrom0430-0530hrs.They a herbaceous shrub and blooms in October- are large, purple, showy, bisexual and February. The flowers open daily between nectariferous. The flowers are dichogamous, 0300-0400hrs. Theyarelarge, yellow,bisexual, showingantherdehiscencein 1stdayflowersand nectarless and exhibit heteranthery, having stigmatic receptivity in 2nd day flowers. This feeding pollinating anthers with poricidal floral trait precludes self-pollination. The dehiscence, and enantiostyly having right and availability ofboth phases in different flowers left stylar orientation. Carpenter bees are the on the same plant on a day facilitates exclusiveforagersofthisplant,collectingpollen geitonogamy. The flowers are foraged by bees, by buzzing. While buzzing, the vibration ofthe waspsandbutterflies;beesareregular,consistent bee causes discharge of pollen from the foragers, while wasps and butterflies are pollinating anthers on to the sides of the bee’s occasional and least important in effecting thoraxandabdomen.Atthesametime,thepollen pollination. Among bees, the carpenterbee and grains are transferred to the stigmas oriented to the digger bee Amegilla, are the principal the right or to the left. The intensity ofbuzzing pollinators. The carpenterbee usuallyalights on increases with bee size, resulting in more thestaminalfilamentsandcrawlsintotheflower, effective pollen discharge and pollination. seeking nectar. While taking off, the bee’sbody Heteranthery andenantiostyly, withthebuzzing touches the anthers and the pollen is deposited behaviour ofpollinator carpenterbees promote on the dorsum. Ifthe bee, after its visit to a 1st cross-pollination. dayflower,visitsa2nddayflower, thereceptive 8 Peltophorumpterocarpum Backer ex. . stigma contacts precisely with the pollen K. Heyne (Caesalpiniaceae): Flowers profusely deposited area and results in pollination. They during March-June. The flowers open during forageequallyonmaleandfemalephaseflowers, daylight hours. The large, bright yellow corolla therebypromotinggeitonogamyandxenogamy. is a convenient landing site for the pollinator. Sometimes the bees probe the flowers laterally, Monomorphic anthersreleasepollen all atonce, 384 JOURNAL, BOMBAYNATURAL HISTORYSOCIETY, 97(3) DEC. 2000 A FORAGINGBEHAVIOUROFCARPENTERBEESXYLOCOP along the entire length ofthe anthers, typically gynaecium exhibits enantiostyly. Although the by complete longitudinal stomial slits, filiform flowersopenatnight,theyareforagedbydiurnal styleterminatinginacapitatestigmalyingabove insects. The foragers include bees, ants, wasps, the stamens, andthe nectarproducedintraces is flies andbutterflies. Ofthese,bees are dominant hidden by dense silky structures present at and and among them, honey bees are the major around the basal parts of stamens. The flowers pollinators while carpenter bees act as minor are promiscuous to any visitor species but pollinators.Nectargathering carpenterbees first carpenterbees,CeratinaandTrigonaaretheonly land on the central petal in an upright position, foragers.Amongtheforagingbees, Ceratinaand andtheninsertintothetubularpartofthecorolla. Trigona are small in size, and hence This facilitates simultaneous contact ofthe sex inappropriate for pollination. Further, they are organswiththebee’sback,resultinginnototribic infrequentvisitors. The carpenterbees are large pollination. Although carpenter bees are minor in size, regular and frequent foragers. They are pollinators, their inter-tree flight behaviour theprincipalforagers,effectingpollinationwhile assumes great significance if cross-pollination probing for pollen and/or nectar. The male ofall the pollinator insects is considered. carpenterbeescollectnectarandthefemalesboth 10. Cochlospermum religiosum (L.) nectar and pollen. Both sexes probe the flower Alston (Cochlospermaceae): A deciduous, legitimately for nectar. The pollen feeding tropical tree, itisused commercially and forthe females probe the flower by buzzing. After afforestationofbare,rocky, denudedhills. After landingonthepetalsand/orstamens,theyrapidly sheddingleaves,itflowersduringJanuary-April. contract the indirect flight muscles, producing The large, showy, bright yellow, bisexual, strong vibrations that are transmitted directly to nectarless flowers open daily from 2300-2400 the ant9h.ers, indicatedby the audible buzzing of hrs. The stamens are numerous and arranged in thebees. Thevibrationsrapidlyproduceapollen two whorls, anther dehiscence is poricidal. The cloud from the anthers, which along with the stylewithacapitatestigmaprojects outfromthe stigma, simultaneously strike the ventral side of base of the ovary and stands at the level of thebeeandresultinstemotribicpollination. The anthers. The flowers are foraged for pollen by buzzing is very brief at sunrise and gradually carpenter bees Xylocopa, Amegilla honey bees , increases towards midday. Further, the floral Apis cerana indica, A.florea and stingless bees vibrations are single buzzes in the morning Trigona but only carpenter bees are regular, ; hours, and the bees stay at one position on the consistent and effective inharvesting the pollen flowers. Later in the day, the bees use multiple crop.Theothersareoccasionalforagers,andplay buzzes and rotate on the flowers, depending on a minor role as pollinators. The carpenter bees, theavailabilityofpollen.Thisresultsinthemost upon landing on the anthers, vibrate their body efficient extraction of pollen, promoting to discharge pollen through the apical pore of outcrossing. theanthers.Theentirebodyofthecarpenterbees Tamarindus indica Linn. is sprinkled with pollen, but most ofthe pollen (Caesalpiniaceae): A tall tree that has become is deposited on the ventral side ofthe bee. The indigenous,nowcommonlyfoundinthetropics. pollen ladenbees when foraging onthe same or It flowers from April to August. The small, other inflorescences on the same plant effect creamy,bisexual,nectariferousflowersopeneach geitonogamy and on flowers of different night between 2300-0400 hrs. The corolla is conspecificplantseffectxenogamy. tubularatthebaseandhasonesmallcentralpetal 11. Couroupita guianensis Aubl. rolled upwards, and two large lateral ones. The (Lecythidaceae): Flowers almostthroughoutthe JOURNAL, BOMBAYNATURAL HISTORYSOCIETY, 97(3), DEC 2000 385 FORAGINGBEHAVIOUROFCARPENTERBEESXYLOCOPA year with heavy flowering in Febraary-March. overarches the stamens. The flowers are visited It exhibits cauliflory. The flowers are inverted, by Xylocopa (Family Xylocopidae) Trigona yellow on the abaxial face and purple on the (Apidae) and Ceratina (Anthophoridae). adaxial face, nectarless but produce abundant Xylocopidbeesarelarge,abundantandRegularly pollen. The androecium is characterized by forage for nectar, while the other two bees are stamens of the ring and hood which are small, foraging occasionally for pollen and connectedbyastamen-freeligularstructure.The nectar. Their foraging behaviour, coupled with ring stamens serve as pollinating stamina, and floral features such as spacious, strong corolla, hood stamens as feeding stamina, exhibiting light colour, and nectar hidden by the staminal heteranthery. The stigma has a star-like fissure tube,indicatethatcarpenterbeesaretheprincipal and becomes receptive after anther dehiscence. pollinators, while the other bees are incidental The flowers open daily around dawn. Their pollinators. Carpenter bees forage in sunlight. fragranceisreleasedthroughosmophorespresent They probe the flowers in upright position and in the corolla and at the top ofthe filaments of make regular contact with stamens and stigma thehoodanthers. Carpenterbees,honeybeesand sternotribically. The flowering trees stand out the stingless bee are attracted to this fragrance. visuallyandappearconspicuoustothebeesfrom Consideringtheirfrequency,foragingbehaviour, a distance because oftheir large floral display, efficiency in harvesting pollen and effective which enables the carpenter bees to exhibit pollination, carpenter bees assume principal traplining. Towards the end of the flowering pollinator status. period, floral density is reduced, compelling the The carpenter bees, while entering the carpenterbeestoforageopportunisticallyonthis flower, pushthe hooddown, causing the release taxon and on the nearby Peltophorum ofpollen (tetrads) that simultaneously adhere to pterocarpumforpollenand/ornectar, andCassia the ventral part ofthe bee and are accessible for speciesforpollen, whichis available atthesame grooming. Afterenteringtheflower, theycollect time. pollen from the hood, and during pollen 13. GmelinaasiaticaLinn.(Verbenaceae): collection they rub their dorsal parts against the A deciduous, perennial, straggling shrub, ring anthers and the stigma, detaching several floweringfromMarch-October.Theflowersopen ringanthersintheprocess,resultinginnototribic between0500-0600hrseveryday.Theyarelarge, pollination. The bees opportunistically visit the yellow, bisexual and nectariferous. The corolla plant for pollen and other plants like Gliricidia is tubular at the base and its free end is inflated sepium andPeltophorumpterocarpum fornectar into,a bilippedbell-like structure with the upper during the same period. lipenlargedandthelowerlipwithalargecentral 12. Gliricidia sepium (Jacq.) Walp lobe and two small lateral lobes. Stamens are (Fabaceae): It is widely cultivated in the tropics didynamous and epipetalous. The stigma is for shade and as an ornamental tree. It sheds simple and stretched beyond the anthers. The leavesbeforefloweringandflowersfromJanuary flowers are foragedexclusivelyby day-foraging to mid-March. Its flowers open between 0730- bees, e.g. Xylocopa Amegilla, Trigona and , 1600 brs. The flowers are lavender, large, Ceratina. Effective pollination in this shrub is bisexual,odourlessandnectariferous.Thecorolla by carpenterbees, which forage fornectar only. is characteristically papilionaceous and has a They approach the flower in upright position, light greenish-yellow glistening spot serving as land on the lower corolla lip and crawl into the anectarguide. Stamens arediadelphous, andthe tubular part, stretching their proboscis to full style springs through the staminal tube and length. In doing so, the dorsal surface of their 386 JOURNAL, BOMBAYNATURAL HISTORYSOCIETY, 97(3) DEC. 2000 FORAGINGBEHAVIOUROFCARPENTERBEESXYLOCOPA body makes initial contact with the stigma and manipulating the flower. Carpenter bees gather then with the dehisced anthers, effecting only nectar; while doing so, they alight on the nototriby. If the bees carry on their back reflexedpetalsandprobefornectarduringwhich conspecific pollen from previously foraged the sex organs brush against their dorsal side, flowers, they effect cross-pollination by their effectingnototriby.Theytravellongdistancesto initial contact with the stigma. The other bees forage on widely dispersed conspecific plants. areofnousetotheplantaspollinators,butnectar This inter-tree movement promotes xenogamy. depletionbyAmegillaindirectlyforcescarpenter The bees are also opportunistic in that they use beestopaymultiplevisitstotheflowerstosatisfy other nectariferous plants in the study area. their energy requirement. Further, the carpenter bees exhibit traplining, which promotes cross- DiscussionandConclusions pollination. 14. Martynia annua L. (Martyniaceae): Most of the plant species described are An annual that normally flowers during July- zygomorphic, large, showy and bisexual; some October. Flowers openeverydaybetween0400- have long tubes and others short, all perfectly 0500hrs. Theflowers arelarge, showy,bisexual adaptedtopollinationbycarpenterbees. Species and nectariferous. The corolla is pendant and with the sex organs placed near or along the tubular, with its mouth containing nectarguides upper lip are adapted to nototriby. Caesalpinia directed laterally. The stamens are epipetalous, and Gliricidia havetheirsexorgans inthe lower withsyngeneciousanthers.Thestylewithbilobed partofthecorollaandareadaptedtostemotriby. stigmaoverarchestheanther.Flowersareforaged The anthesis timings in different plant species by carpenter bees, digger bees and hawkmoths are different, some at night, others during the during the day. The hawkmoth is an inefficient day and one, i.e. Alangium both day and night; , pollinator, but may compel the bees to make but the flowers of all the species are foraged multiplevisitstotheflowersbydepletingnectar. diumally. Anisomeles andAcanthus are foraged The two bee species are equally efficient in by insects as well as sunbirds. Caesalpinia and pollination of the taxon. While probing the Cassia are outcrossers, exclusively foraged and flowers, they land on the large lip andpenetrate pollinatedbycarpenterbees. Someplantspecies intothe corollatube followingthenectarguides. are foraged by different groups of insects and In doing so, their dorsal side touches the sex othersexclusivelybybees,butcarpenterbeesare organs and pollination results. themainpollinators, alsoAmegilla forMartynia 15. Moringa oleifera Lam. and sunbirds for Acanthus and Anisomeles. (Moringaceae): Popularly known as the Carpenter bees effect pollination through drumstick tree, it thrives best under a tropical nototriby and stemotriby; the former is a more insular climate. The tree is valued forthe tender advancedmechanisminwhichpollendeposition pods used as vegetables. This tree blooms twice is very precise and not accessible for grooming a year, during February-May and again during bythebees. It ensurespollinationsuccess,while September-November; the former blooming is instemotriby,pollenwastagetakesplaceduring more intense. The flowers open between 0500- grooming of the bee and in flight, and is thus 0900 hrs. They are creamy white, large, showy, not economical. bisexual andnectariferous. They are foragedby Carpenterbees exhibitbuzzing behaviour avarietyofinsectsbutcarpenterbeesanddigger while collecting pollen ofthe nectarless Cassia beesarethemainpollinators. Evenamongthese, andCochlospermum, inwhichantherdehiscence carpenter bees are the most appropriate for is poricidal, and of Peltophorum flowers with JOURNAL, BOMBAYNATURAL HISTORYSOCIETY, 97(3), DEC. 2000 387 : FORAGINGBEHAVIOUROFCARPENTERBEESXYLOCOPA longitudinally dehiscent anthers. Buzzing is faithful to one flowering plant species, greatly typical in pollinators of poricidal flowers that promoting outcrossing, whereas opportunistic exhibit heteranthery and enantiostyly as in behaviour facilitates the use of available Cassia, or without these devices as in flowering species in the biotope, depending on Cochlospermum (Buchmann 1983), while the floral density or intensity offlowering. Peltophorum with firmly adhered oily pollen is All the plant species except Cassia , alsobuzz-pollinated. Onsomeplantspecies, the Cochlospermum and Couroupita are carpenterbees exhibitterritoriality ortraplining nectariferous, withnectarvolumesrangingfrom or both, and on others, opportunistic foraging 0.8 to 80 jj.1 and sugar concentrations from 5 to behaviour. Territoriality means that the bees 48% (authors’ data). The foraging ofcarpenter select a population offlowers rich in nutrients, bees on these plant species indicates that they usually from one plant species, and obtain food make use of variously concentrated sugars as within the same population throughout the available at different times ofthe year for their flowering season. When exhibiting territorial sustenance. Nectarless plant species provide behaviour, male bees alternately defend the pollen rich in nutrients to carpenter bees. The selected flower population by chasing away floral structural and functional devices, coupled intruders and forage on the flowers. Traplining with variously coloured corolla: yellow, purple, isaforagingbehaviourinwhichbeesmakelong creamy-white, sometimes lavender, are evolved distance flights and remember images of the for foraging by carpenter bees exclusively or whole region visited on their regular rounds. preferentially. Opportunisticbehaviouriswhenthebeesexploit Both plants and carpenter bees mutually floralresources, mainlynectar, fromthe flowers benefit each other, and thereby ensure of various plant species co-occurring and perpetuationofbothintheirrespectivebiotopes. blooming simultaneously, in order to obtain Thereisunequivocalevidenceoftheimportance forageforthemselvesandfortheiroffspring(Pijil ofcarpenterbeesinthereproductionofdifferent 1954,Janzen 1964,Frankie 1976,Barrows 1980, species ofplants, and thus for the production of Frankie et al. 1983, Aluri and Subba Reddi plant biomass ofterrestrial ecosystems, and for 1989). Ofthese types ofbehaviour, territoriality generating and maintaining genetic diversity of and traplining impose fidelity in bees to remain the plants. ReferEnces Aluri,J.S.R.(1990):Observationsonthefloralbiologyof (Caesalpiniaceae).J.Nat. Conserv.8:99-100. certain mangroves. Proc. Indian Nat. Sci. Acad. 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