Survey of flower visiting by aculeate wasps and bees in the semi-arid to arid areas of southern Africa

2006·34.1 MB·English

by  S K Gess

SURVEY OF FLOWER VISITING BY ACULEATE WASPS AND BEES
IN THE SEMI-ARID TO ARID AREAS OF SOUTHERN AFRICA
S.K. GESSandF.W. GESS
MakanaBiodiversity Centre, AlbanyMuseum
Grahamstown, 6139SouthAfrica
e-mail: [email protected]; [email protected]
CONTENTS
ABSTRACT
2
INTRODUCTION
3
METHODS
3
Study area 3
Sampling sites andtimes 5
Sampling methods 5
Database 5
Identifications 5
Classification systems 8
Glossary 8
RESULTSAND SYNTHESIS
8
DIVERSITYOF PLANTTAXAVISITED
8
PLANT FAMILIESAND THEIRVISITORS 9
MONOCOTS
9
EUDICOTS
10
Proteales 10
Proteaceae 10
CORE EUDICOTS
10
Caryophyllales 10
Amaranthaceae 10
Aizoaceae (including Mesembryanthemaceae) 11
Molluginaceae 12
Nyctaginaceae 12
Plumbaginaceae 12
Portuiacaceae 13
Saxifragales 13
Crassulaceae 13
ROSIDS
13
Zygophyllaceae 13
Geraniales 14
Gcraniaceac 14
EUROSIDSI
15
Celastraceae 15
Cucurbitales 15
Cucurbitaceae 15
Fabales 15
Fabaceae (Leguminosae) 15
Mimosoideae 16
Papilionoideae 16
Caesalpinoideae 18
Polygalaceae 19
Malpighiales 19
Euphorbiaceae 19
Rosales 20
Rhamnaceae 20
EUROSIDS
II 20
Brassicales 20
Annals oftheEastern CapeMuseumsVol 5 (October2006): 1-51 1
Brassicaceae (including Capparaceae) 20
Malvales 21
Malvaceae (including Sterculiaceae) 21
Neuradaceae 22
Myrtales 22
Combretaceae 22
ASTERIDS 22
Comales 22
Loasaceae 22
Ericales 22
Ebenaceae 22
EUASTERIDS
I 22
Boraginaceae (including Hydrophyllaceae) 22
Vahliaceae 32
Gentianales 32
Apocynaceae (includingAsclepiadaceae) 32
Lamiales 32
Acanthaceae 32
Lamiaceae (Labiatae) 33
Pedaliaceae 34
Scrophulariaceae 34
Solanales 35
Solanaceae 35
EUASTERIDS II 36
Apiales 36
Apiaceae (Umbelliferae) 36
Asterales 36
Asteraceae (Coinpositae) 36
Campanulaceae 37
Campanuloideae 37
Cyphioideae 37
Lobelioideae 37
DISCUSSION 38
CONCLUSIONS
39
ACKNOWLEDGEMENTS
40
REFERENCES
41
APPENDICES 44
Appendix 1: Classification ofaculeate wasps andbees 44
Appendix 2: Map locating places mentioned in the text and captions to figures 45
INDICES 46
Index 1: Plants 46
Index 2: Insects 49
ABSTRACT
The results ofa survey offlowersvisitedby aculeate wasps andbees inthe semi-arid to arid areas ofsouthern
Africa, i.e. the Karoo Biome andassociated dry fynbos, arid savanna and desert fringes, are presented. Flowers of36
plant families, represented by c 600 species, were recordedas visitedby aculeate wasps andbees. Visitation offlowers
by family is examined and discussed, based on 16,229 records forvisits by 927 species ofsolitary aculeatewasps and
bees: 129 species ofmasarinewasps (pollen wasps); 375 species ofnon-masarinewasps; and423 species ofbees.
Differences in assemblages ofvisitors between families, within families between sub-families, tribes, generaand
species and across geographic gradients are noted. The dependability orlackofdependability ofvisitors based on the
degree ofpolyphagy oroligophagy exhibited is discussed. Thepotential ofvisitors as pollinators is suggested where
sufficient records and observations on flowerfit and visitor behaviourare available.
Keywords: Karoo Biome, Kalahari, Namib desert, dry fynbos, dry savannah, pollination, pollinators, polyphagy,
oligophagy, monophagy, Hymenoptera, behaviour, taxonomic surveys
2 Gess & Gess: Surveyofflowervisitingbyaculeatewasps andbees
by family is examined anddiscussed, based on a catalogue Consequently,pollenwaspshavethepotentialtoobtain
of 16,229 records (supported by voucher specimens) nectar from a wide range offlower forms including many
bfoeresvi(sGitesssby&9G2e7sssp2e0c0i3e)s.oDfifsfoleirteanrcyesaciunleaastseemwbalsapgsesanodf in whichthe nectaris notreadily accessible.
visitors - between families, within families between sub-
families, tribes, genera and species and across geographic METHODS
gradients, from south to north and west to east-are noted.
The dependability or lack of dependability of visitors - STUDYAREA
based on the degree ofpolyphagy or oligophagy exhibited
- is discussed. The potential of visitors as pollinators is The study area is constituted of the Karoo Biome of
Rutherford (1997) together with the Fynbos fringe in the
suggested where sufficient records and observations on
southwest and the Desert and Savanna fringes in the north
flowerfit andvisitorbehaviourare available.
The records are supported by voucher specimens. (Figure 1).
The vegetation of the entire area is characterized by
For further details on the database associated with these
low scrub with taller shrubs and/or trees mainly restricted
records, seepage 3 (under ‘Database’).
The majority of specimens, those collected by the to drainage channels and hill slopes (Plates 1-16). The
authors, are linked by note numbers which further link scrubvegetationvaries accordingtoregionalrainfall, from
them to fieldnotes. The published catalogue (Gess & mspmarse(overmostofthearea, whichreceivesfrom 100-500
Gess 2003) gives approximate localities; however, exact precipitation per annum) to extremely sparse (along
localities, in most cases with co-ordinates, are recorded tmhme fringes of the Namib which receives less than 100
on the specimen labels and, in the case ofthe bees, in an precipitation per annum). Succulence is particularly
electronic relational database held at theAlbany Museum, associated with the winter rainfall region, resulting in this
Grahamstown, by the African Pollinator Initiative (API) part oftheKaroo Biomebeingtermedthe Succulent Karoo
and the South African Biodiversity Information Facility Biome (Rutherford & Westfall 1986). The summerrainfall
(SABIF). The sexes ofthe insect specimens are given in region oftheKaroo-witha lowerlevelofsucculence and
the catalogue and bee database, however. a higher grassy element - is known as the Nama Karoo
When collecting specimens, distinction betweenpollen Biome (Rutherford & Westfall 1986).
andnectarcollectionwasnotalwaysmadeandthus,except Detailed reviews of the climate, topography, geology
where specifically referred to, the present discussion and vegetation ofthe study area are presented by various
encompasses both types of visits indiscriminately. Those authors in Cowling et al. (1997) and Dean & Milton
species visiting flowers of taxonomically-divers plants (1999).
are termed polyphagous (sensu Struck 1994). Degrees The aculeate wasp and bee fauna of the southern
of polyphagy from narrow to broad are recognized. The Karoo is polarized into two main faunal groups, one
term oligophagous is limited in the present paper to centered in the west andthe other in the east. Between the
species visiting flowers of plants belonging to a single two extremes lies a transition of overlapping subtraction
family, subfamily, tribe or genus. Few monophagous margins ofthe eastern and western faunas corresponding
species, i.e. thoserestrictedto single species ofplant, were with the interface between the winterrainfall and summer
encountered. rainfall regions (Gess & Gess 1993). To the north there are
In order to facilitate ease of reading, in the present strong affinities with the arid savanna fauna. Sampling in
paper all solitary aculeate wasps that visit flowers for theNamib Desertwas principallyin the drainage channels
Annals oftheEastern CapeMuseums Vol 5 (October2006): 1-51 3
Fig. 1. SouthernAfrica. Distributions ofFynbos (F), Succulent Karoo (SK), Nama Karoo (NK),
Desert (Namib) (N) and Savanna (S) biomes, afterRutherford (1997). Digits 3-18 denote areas
illustrated in figures 3-18.
4 (Jess & Gess: Surveyofflowervisitingbyaculeate wasps andbees
1
where there is a recognizable desert faunal element, with species in all. Ofthese records, 98.2% were derived from
penetration by savanna species from the east and coastal deliberatesamplingbytheauthors(assistedatvarioustimes
species from the west. Pollen wasps show their highest and sites by D.W. Gess, H.W. Gess and R.W. Gess). The
species diversity in southernAfrica and in particular in the remaining records have been assembled from label data
west, species diversity falling off markedly from west to from the Albany Museum collection, mostly concurrently
east (Gess 1992a, 1996). collectedmaterial fromtheeasternkarroidareas(C.F.Jacot
Guillarmod, 219 records; J.G.H.Londt, 66 records; A.J.S
SAMPLING SITESAND TIMES Weaving, 30 records). Published records by other authors
are taken into account in the discussion but have not been
The distribution ofthe sampling sites within the semi-
included in the database foranalysis.
arid to arid areas ofsouthernAfrica is shown in Figure 2. The records are supported by voucher specimens. The
Each dot covers a quarter degree square in which majority of specimens - those collected by the authors
is included one or more sampling sites. Sampling to the - are linked by note numbers that further link them to
east and south has taken place during the past thirty years, fieldnotes. The catalogue gives approximate localities.
principally from 1972 to 1985; that in the west north of However,exact localities-inmostcaseswith co-ordinates
the Olifants River Mountains to the southern Richtersveld - are recorded on the specimen labels, and in the case of
principallyfrom 1985to 1996;thatinnorthernRichtersveld thebees inan electronicrelationaldatabase initiatedby the
principally from 1996 to 1998; and that in Namibia authors and held at the Albany Museum, Grahamstown,
principally from 1997 to 2000.
by the African Pollinator Initiative (API) and the South
Apart from the area in which the authors are resident African Biodiversity Information Facility (SABIF). The
(Grahamstown, Eastern Cape) it has not been possible to sexes of the insect specimens are given in the catalogue
sample throughout the year. Seasonal timing ofsampling
and bee database.
by the authors has been based on experience and the
The great majority ofthe insect specimens are housed
generalrainfall andtemperaturepatterns ofdifferentareas. in the terrestrial insect collection ofthe Albany Museum,
The distribution and magnitude of rainfall events, and
Grahamstown. Specimensofmany,butnotall,oftheplants
therefore offlowerpatches in the semi-arid and arid areas have been deposited in the Schonland Herbarium, Albany
ofsouthernAfrica,isunpredictable.Thus,althoughgeneral Museum. Duplicatesofspecimens fromNamibiaare inthe
samplingareasandsamplingtimeshavebeenpurposefully
National Herbarium ofNamibia, Windhoek.
selected,thechoiceofsampling siteshas ofnecessitybeen
opportunistic. IDENTIFICATIONS
In the southeast and south the peaks ofrainfall are in
SeptemberandMarchandthesummerisrarelyexcessively The majority of specimens ofboth insects and plants
hot and dry. Thus sampling has been principally from late were identified to species and the remainder to genus or
Octoberthrough to March. In the winter rainfall region of family.
the southwest, north to Liideritz and Aus, sampling has The greatmajority ofthe specimens ofwasps and bees
been fromAugust,when temperatures startto rise, through wereidentifiedbythesecondauthor. Otherhymenopterists
to December, when most flowering is over and the land who were undertaking generic revisions were responsible
as a general rule becomes parched. North of the Orange forsome ofthe identifications as follows:
River in the southern Kalahari, southeastern Namibia and •AlexanderAntropov, Moscow Lomonosov State
in westernNamibia to the north ofthe winterrainfall area, University, Russia- Gessus Antropov (Crabronidae:
samplinghasbeeninMarchandApril, whichiswhenrains Crabroninae);
are expectedand the excessive heat ofsummer is over. • Connal Eardley, PPRI,ARC Pretoria-Anthophorini
andEucerini (Apidae: Apinae)priorto 1985,
SAMPLING METHODS Ammobatini (Apidae: Nomadinae) priorto 1991,
Lithurgus Berthold (Megachilidae: Megachilinae) prior
Solitary aculeate wasps and bees visiting flowers were
to 1987, andScrapterLepeletier(Colletidae) priorto
collectedusing a handnet.All plants in flowerat the study
1991;
sites were observed for visitors and, when possible, were • Michael Kuhlmann, University ofMunster, Germany-
sampled over periods throughout the day. In effect, wasps
Colletes Latreille (Colletidae);
and bees in an area were all being offered the choice of • Wojciech Pulawski, CaliforniaAcademy ofSciences-
visiting all those plants in flower. Each site sampled TachysphexKohl (Crabronidae: Larrinae).
therefore represented a ‘choice chamber’, in which all the
The identifications of the specimens of plants were
wasps and bees were offered the same choice ofplants in
undertaken by the following botanists: Grace Britten
flower.
and Estelle Brink, Herbarium, Albany Museum (various
DATABASE groups); Coleen Mannheimer, National Herbarium,
Windhoek (the majority of the plants from Namibia);
The database used for the analysis is A catalogue of SabeneAusthallerandPatriciaCraven,NationalHerbarium,
flower visiting recordsfor aculeate wasps andbees in the Windhoek (some plants from Namibia); Jo Beyers, then
semi-arid to arid areas ofsouthern Africa (Gess & Gess of Stellenbosch Herbarium (especially Wahlenbergia and
2003). It is constitutedof16,229 records ofvisits to c 600 Microcodon); JanVlok, then ofSaarsveld ForestryCentre,
species ofplants by solitary aculeate wasps and bees, 927 George Aspalathusspinescens Thunberg); Sue Dean, then
(
Annals oftheEastern CapeMuseums Vol 5 (October2006): 1-5 5
Table 1. Numbersandpercentagesofspeciesofwasps,pollenwaspsandbeesrecordedvisitingflowersofthelistedplant
families, togetherwith the Index ofDiversity ofChoice1 at the specific level for each major group (wasps, pollen wasps
and bees). Asterisks draw attention to the six families attracting the highest numberofspecies.
Wasps Pollen Bees Totals Percentage
Planttaxa Wasps w+pw+b w+pw+b
(375spp) (129spp.) (423spp.) (927spp.)
no. % no. % no. % no. %
MONOCOTS
Asparagales
Asparagaceae 10 2.67 10 1.08
Asphodelaceae 1 0.78 12 2.84 13 1.40
Iridaceae 2 1.55 12 2.84 14 1.51
EUDICOTS
Proteaceae 15 4.00 8 1.89 23 2.48
COREEUDICOTS
Caryophyllales
Aizoaceae* 76 20.27 60 46.51 98 23.17 234 25.24
Amaranthaceae 42 11.20 1 0.78 24 5.67 67 7.23
Molluginaceae 46 12.27 5 3.88 19 4.49 70 7.35
Nyctaginaceae 2 0.53 2 1.55 3 0.71 7 0.76
Plumbaginaceae 3 0.08 3 2.33 2 0.47 8 0.83
Portulacaeae 3 0.08 3 0.32
Saxifragales
Crassulaceae 2 1.55 7 1.65 9 0.97
ROSIDS
Zygophyllaceae* 51 13.6 17 13.18 71 16.78 139 14.99
(Aramaics
Geraniaceae 5 1.33 8 6.20 6 1.42 19 2.05
EUROSIDSI
Celastraceae 40 10.67 7 1.65 47 5.06
Cucurbitales
Cucurbitaceae 7 1.65 7 0.76
Fabales
Fabaceae* 147 39.2 11 8.53 164 38.77 322 34.74
Polygalaceae 9 2.13 9 0.97
Malpighiales
Euphorbiaceae 15 4.0 1 0.78 3 0.71 19 2.05
Rosales
Rhamnaceae 35 9.33 1 0.24 36 3.88
EUROSIDSII
Brassicales
Brassicaeae 2 0.53 3 2.33 32 7.57 37 3.99
Malvales
Malvaceae 5 1.33 8 6.20 54 12.77 67 7.23
Neuradaceae 1 0.27 1 0.78 10 2.36 12 1.29
Sapindales
Rutaceae 1 0.27 1 0.24 2 0.22
ASTERIDS
Cornales
Loasaceae 2 0.47 2 0.22
EUASTERIDS
I
Boraginaceae 13 3.47 5 3.88 50 11.82 68 7.34
Vahliaceae 1 0.27 1 0.78 7 1.65 9 0.97
Gentianales
Apocynaceae 48 12.80 31 7.33 79 8.52
Lamiales
Acanthaceae 14 3.73 2 1.55 52 12.29 68 7.34
Lamiaceae 10 2.67 2 1.55 65 15.37 77 8.31
Pedaliaceae 9 2.13 9 0.97
Scrophulariaceae* 27 7.20 33 25.58 38 8.98 98 10.57
Solanales
Convolvulaceae 1 0.24 1 0.08
Solanaceae 8 2.13 11 2.60 19 2.05
EUASTERIDSII
Apiales
Apiaceae* 161 42.93 27 6.38 188 20.28
Asterales
Asteraceae* 116 30.93 56 43.41 157 37.12 329 35.49
Campanulaceae 9 2.40 19 14.73 33 7.80 61 6.58
IndexofDiversity
ofChoice 141.60 88.37 144.21
'Seepage 9 fordefinition ofIndex ofDiversity ofChoice
6 Gess & Gess: Surveyofflowervisitingbyaculeatewaspsandbees
Table2.Numbers ofspecies ofbees,byfamily,recordedvisitingflowersofthe listedplantfamiliestogetherwiththeIndex of
DiversityofChoice1 atthespecificlevelforeachbeefamily.
Planttaxa Andrenidae Apidae Colletidae Halictidae Megachilidae Melittidae
(9spp.) (123spp.) (46spp.) (69spp.) (146spp.) (30spp.)
MONOCOTS
Asparagales
Asparagaceae
Asphodelaceae 2 1 1 8
Iridaceae 3 1 4 2 2
EUDICOTS
Proteaceae 3 3 1 1
COREEUDICOTS
Caryophyllales
Aizoaceae 4 35 10 21 21 7
Amaranthaceae 5 3 10 5 1
Molluginaceae 4 7 4 2 2
Nyctaginaceae 1 1 1
Plumbaginaceae 1 1
Portulacaeae
Saxifragales
Crassulaceae 2 2 2 1
ROSIDS
Zygophyllaceae 3 22 10 23 10 3
Geraniales
Geraniaceae 3 1 2
EUROSIDSI
Celastraceae 1 1 5
Cucurbitales
Cucurbitaceae 4 1 1 1
Fabalcs
Fabaceae 6 41 3 22 80 12
Polygalaceae 2 7
Malpighiales
Euphorbiaceae I 2
Rosales
Rhamnaceae 1
EUROSIDSII
Brassicales
Brassicaeae 17 1 6 7 1
Malvales
Malvaceae 1 21 10 19 3
Neuradaceae 2 1 2 4 1
Sapindales
Rutaceae *
ASTERIDS
Cornales
Loasaceae 1 1
EUASTERIDSI
Boraginaceae 2 29 6 13
Vahliaceae 4 1 2
Gentianales
Apocynaceae 9 1 5 15 1
Laniiales
Acanthaceae 28 4 20
Lamiaceae 2 31 7 25
Pedaliaceae 4 2 3
Scrophulariaceae 1 12 4 15 4 2
Solanales
Convolvulaceae 1
Solanaceae 8 3
EUASTERIDSII
Apiales
Apiaceae 8 6 9 4
Asterales
Asteraceae 1 51 19 29 53 4
Campanulaceae 8 3 7 7 8
IndexofDiversity
ofChoice 177.77 195.93 50.00 202.90 117.81 70.00
'See page 9 fordefinition ofIndex ofDiversity ofChoice
Annals oftheEastern CapeMuseums Vol 5 (October2006): 1-51 7
ofthe Karoo Biome Research Station (somemesems), and withtheflowersunderconsideration,can beexpectedtobe
the first author(various). visitors ofthose flowers.
Foreaseofreading,genericandspecificnamesaregiven Legitimate visitors: flower visitors that, in terms of
withoutauthors inthetextbutarelistedwithauthors inthe theirsize and behaviour, have the potential to pollinate the
indexes to insects andplants atthe endofthispublication. flowers beingvisited.
Thieves: visitors that are able to and do remove nectar
CLASSIFICATION SYSTEMS and/orpollenwithoutpollinatingtheflowers.Thesevisitors
are saidto stealthe nectarand/orpollen.
The classification of flowering plants follows that of
‘The Angiosperm Phylogeny Group1 (APG 1998). This is Trip (tripping): in papilionate ‘pea flowers’, the stamens
based on recent cladistic analyses, which have established and gynoecium are enclosed by the two lower petals in
many of the elements of the major branching sequence what is termed the keel. Avisitor ofa suitable weight and
of flowering plant phylogeny. Most of the families have size landing on the wing petals to the sides ofthe keel or
been grouped into putatively monophyletic orders and the standardpetal atthe“top” oftheflower, when reaching
monophyletic, informal, higher groups. Under these for the nectar enclosed in the basal part of the flower,
informal groups (monocots, commelinoids, eudicots, core causes the keel petals to open and the stamens and style to
eudicots, rosids including eurosids I and II, and asterids protrude. Thisiscalled ‘tripping1theflower. Somevisitors,
including euasterids I and II) are also listed some of the such as honeybees. Apis mel/ifera, reach the nectar from
familiesnotassignedtoanyorder.Atthe endofthe system the side ofthe baseofthe floweranddo nottripthe flower.
areplacedthe remainder ofthe families, forwhichno firm Thus, they ‘steal1the nectar.
data existed regarding their placement in the system. A
-phagous
simplifiedcladogram-basedprincipally on thatpresented
in APG (1998), but including only families recorded from Polyphagous: visiting flowers ofa wide range offamilies.
southern Africa - is presented in Leistner (2000). The Broadlypolyphagous: visiting flowers of a large number of
classification in Tables 1 and 2 are further simplified to families.
includeonlythosefamiliesthatreceivedvisitsfromwasps, Narrowlypolyphagous: visiting flowers ofa small number
pollen wasps orbees during the present survey. offamilies.
Following Hartmann (1991), Aizoaceae with petaloid Oligophagous: visiting a limited range of flowers of
staminodes-infactthoseplantscommonlytermed‘mesems1 species ofplants all belonging to one family orgenus.
andpreviouslyclassified as Mesembryanthemaceae - are Monophagous: visiting flowers ofone species ofplant.
referred to by the collective term Mesembryanthema. Pollinium: a mass of cohering pollen grains, produced
Those Aizoaceae not included in this informal group are by such plants as asclepiads and orchids, transported as a
referred to asAizoaceae: non-Mesembryanthema. whole duringpollination.
The classification of wasps and bees at superfamily
level and of wasps at family level follows that used by RESULTS AND SYNTHESIS
Goulet & Huber (1993), and that ofMichener (2000) for DIVERSITY OF PLANT TAXAVISITED
bees below superfamily level. (Appendix 1).
GLOSSARY Flowersof36familiesoffloweringplantswererecorded
asreceiving visits fromaculeatewasps and bees. Ofthe 36
Aculeates: an acceptable word used to mean Aculeate plantfamilies, 34 receivedvisits from bees, 29 from wasps
Hymenoptera.Inthepresentcontextitshouldbeunderstood and 21 from pollen wasps (Table 1).
tobe a collective term foraculeatewasps andbees only, as Visits were by 927 species ofwasps, pollen wasps and
bees(375 speciesofwasps, 129speciesofpollenwaspsand
antswere not includedin the survey.
423 species ofbees). The two families not receiving visits
Cyathium: in Euphorbiaceae, a subunit of a cymose from bees - which, however, received visits from wasps
inflorescence, that is flower-like in appearance. It is - were Asparagaceae (previously included in Liliaceae)
composed of a female and several male flowers, lacking and Portulacaceae.
petals and sepals, which are united within a cup-like Cowling & Hilton-Taylor (1999, Table 4.1) list the
structure surrounded by bacts that are colouorfi.il in most 10 largest plant families from each of five domains
(Namaqualand-Namib semi-arid, Namaqualand-Namib
species.
arid. Southern Karoo, Eastern Karoo and Damaraland-
Flowervisiting Kaokoveld) of the Karoo-Namib Region (15 families
Casual visitors', visitors that are commonly associated in all) namely Asteraceae, Aizoaceae, Acanthaceae,
with flowers ofother taxa but are very occasionally found Asclepiadaceae (included in Apocynaceae in APG
onthe flowers underconsideration. 1998), Chenopodeaceae, Capparaceae, Crassulaceae,
Dependable visitors: visitors that are oligophagous Euphorbiaceae, Fabaceae, Geraniaceae, Scrophulariaceae,
and can therefore be depended upon to visit flowers of Sterculiaceae (included in Malvaceae in APG 1998),
cetain taxa even when other taxa in flower may be more Iridaceae,Liliaceaeand Poaceae. The 36 familiesrecorded
abundant. in the present survey as visited by solitary aculeate wasps
Expectedvisitors: visitors that, based on the nature of and bees include all the above-listed families except
the flowers visited or the frequency of their association Poaceae and Chenopodiaceae.
Gess & Gess: Surveyofflowervisitingbyaculeate wasps andbees
When consideringthe 10 familiesreceiving visits from PLANT FAMILIES AND THEIR VISITORS
the highest numbers ofspecies ofwasps, pollen wasps and MONOCOTS
bees (Table one finds six of the Cowling and Hilton-
1 ),
Taylor families included, namely Asteraceae (visited by In the study areas, at the times ofyear when sampling
329 species), Fabaceae (visitedby 322 species),Aizoaceae took place, relatively few monocots attracting solitary
(visited by 234 species), Scrophulariaceae (visited by 98 aculeate wasps and bees were encountered. Indeed, many
species),Asclepiadaceae(includedinApocynaceae)(visited ofthe showy species forming spectacularexpanses, which
by 79 species), and Acanthaceae (visited by 68 species). areafeature ofmarshygroundand ‘rockgardens'in spring
The remaining four families were Apiaceae (visited by and early summer in the southwest, are not patronized by
188 species), Zygophyllaceae (visited by139 species), aculeate wasps and solitary bees but by flies and beetles
Lamiaceae (visited by 77 species) and Boraginaceae (Goldblatt& Manning2000a,2000b;Goldblattetai 1995,
(visited by 68 species). Although these are not amongst 2002; Manning & Goldblatt 2001 ).
the10 largest plant families, they are nonetheless amongst Despite the small number ofmonocot species sampled
the families that characterise the Karoo-Namib Region. in the present survey, visits were recorded for all bee
Specific flower visitors show varying degrees of families exceptAndrenidae, whichare, however, known to
diversity of choice, i.e. of oligophagy and polyphagy. visit some Gladiolus (Goldblatt et al. 1998a, 1998 b). No
In order to make comparisons between groups of flower species restricted to monocots were found.
visitors constituted of unequal numbers of species Gess Goldblatt and his co-workers have established
(1992b, unpublished) developed an Index ofDiversity of that solitary bees contribute to the pollination of some
Choice at the specific level, using the formula: Iridaceae, speciesofMoraea(Goldblatt& Bernhardt 999;
D = a-b/bx 100 Goldblatt et al. 1989), Nivenia (Goldblatt & Bernh1ardt
where a = the sum of the number of species recorded 1990), Romulea (Goldblatt et al. 2002), Lapeirousia
visiting each of the flower families and b = the number (Goldblatt et al. 1995) and Gladiolus (Goldblatt
ofspecies offlower visitors (published in Gess 1996 page & Manning 1998; Goldblatt et al. 1998a, 1998 b).
47). This is an index by which to compare the degree of In addition toApis mellifera visitors to Moraea in the
oligophagy or polyphagy exhibited by taxa of differing present survey, included anumbe,roftaxa, listedbelow.
numbers ofspecies. ‘D’wouldequal 0 ifeach species only • Melittidae: Rediviva longimanus which obtains
visited one species ofplant; the higherthe value of‘D’the oils fromthe long spurs ofDiascia longicornis
greaterthe degree ofpolyphagy. (Scrophulariaceae), andan undescribed
When this formula is applied to the database (Gess & polyphagous species ofMelitta.
Gess 2003) as summarized in Table 1 the following values • Halictidae: species ofLasioglossum andPatellapis
ofD are obtained: wasps 141.60; pollen wasps 88.37; and which more commonlyvisitedHerrea (Aizoaceae:
bees 144.21. These values indicate a markedly narrower Mesembryanthema).
diversity ofchoice offlowers by pollen wasps overall than •Apidae: Anthophora (Heliophila) wartmanni
bywasps orbees. (Anthophormi), which was most commonlyvisiting
Marked variations in diversity of flower visiting Asteraceae.
between families ofbees are apparent (Table 2 and Gess • Megachilidae: twopolyphagous species-
& Gess 2004b). The following 'D' values were calculated Plesianthidium (Spinanthidium) neli (Anthidiini)
forindividual bee families:Andrenidae 177.77; Colletidae and a species ofHop/itis (Anthocopa) (Osmiini).
50.00; Halictidae 200.00; Melittidae 66.67; Megachilidae One ofthe most widespread bee-pollinated species of
117.81; Apidae (excluding Apis mellifera 195.93. These nectar-producing Gladiolus in the study area is Gladiolus
)
values indicate a similarly low diversity of choice for orchidiflorus, which is found from the Cape Peninsula in
Colletidae and Melittidae and a greater diversity ofchoice the south to southern Namibia in the north and eastwards
for Megachilidae, Andrenidae, Apidae and Flalictidae, in across Bushmanland and the Karoo to Kimberley and
that order. The low diversity ofchoice for Colletidae and Fauresmith, butnot in the southeast (Goldblatt& Manning
Melittidae is comparable with that (88.37) obtained for 1998). During the present study, at a site in Namaqualand,
pollen wasps. it was found to be repeatedly visited by females of two
With the exception of Colletidae, the present values polyphagous species ofAmegilla: A. obscuriceps and A.
spi/ostoma (Apidae: Anthophorini). Both these species
are higher than those obtained in an earlier analysis (Gess
1992b), even if recalculated using the presently-used were recorded by Goldblatt et al. as being visitors to
Gladiolus but not G. orchidiflorus, for which they
classifications. Taking into account that the 1992 database ,
recorded only Anthophora (Pygnanthophora) diversipes
excluded the Richtersveld National Park and the southern
(Anthophorini). Struck (1994) made observations on
and western arid areas ofNamibia, this could be indicative
visitors to G. orchidiflorus near Springbok, Namaqualand,
ofa number ofpossible factors: an overall higher degree
where he recorded Amegilla niveata (Anthophorini) and
of polyphagy; a higher degree of opportunistic foraging
Plesianthidium (Spinanthidium) calvini (Anthidiini). It
to the north, where rainfall is more unpredictable; seems likelythatawiderangeofAmegillaandAnthophora
a shift in plant families visited along ecological can be expected to visit this species ofGladiolus to obtain
gradients in the case of widely-distributed species; or nectar.
a combination of these factors (Gess & Gess 2004a). Othermonocots visited by bees are listed below:
Annals oftheEastern Cape Museums Vol 5 (October2006): 1-51 9
• someAlbuca spp. (Hyacinthaceae)by polyphagous The apids were Apis mellifera which were abundant
,
Megachilidae; visitors, and - uncommonly - Amegilla spilostoma, a
• Wachendorfici sp. (Haemodoraceae) by polyphagous polyphagous species (recorded from 15 plant families)
Apidae; withawidedistributionfromtheeasternlimitsoftheNama
• Balbinella latifolia (Asphodelaceae) by Apis mellifera\ Karoo through to the west. The tiphiids - four species of
• andBulbinefrutescens (Asphodelaceae)by Mesaandone ofTipliiaatNieuwoudtville, andone species
polyphagous Megachilidae, most frequently of Mesa at the Clanwilliam site - can be expected to be
Megachile (Crieghtonella) dorsata. polyphagous.
Visits by pollen wasps to monocots are unusual, in The Leucadendron species (described above) was also
fact only Aloe striata (Asphodelaceae) and Ferraria cf visited by a polyphagous cleptoparasitic bee, Sphecodes
divaricata (Iridaceae) were recorded as receiving visits sp. (Halictidae), and 10 species of wasps of the families
fromthesewasps. AloestriatainthesouthernGreatKaroo Pompilidae, Crabronidae, Philanthidae, Scoliidae and
was visited abundantly by Quartinia antigone (a sample Tiphiidae. Thecrabronidwaspswere Oxybelusperingueyi,
of24 females and five males having been taken in a half Oxybelusruficaudis,DasyproctusimmitusandDasvproctus
hour), a species forwhich no otherflowervisiting records ruficaudis. They were probably casual visitors as the last
are known. three,atleast,arepolyphagousandwidespreadspecies.The
Ferrariaisgenerallyconsideredtobeattractiveonlyto scoliid, Cathimeris (Cathimeris) capensis and the tiphiids
,
flies (Cowling & Pierce 1999; Manning & Goldblatt 2001; -twospeciesofMesa,sharedwithParanomusbracteolaris
Scott-Elliot 1891;Vogel 1954)orfliesandsmallbeetles(de - can be expected to be polyphagous. The records of
Vos 1979). However, in thepresent study, F cf. divaricata, a single male each for the pompilids Paracyphononyx
at two widely separated sites, was being visited solely frustratus andPsammoderes mimicus and foraphilanthid,
and repeatedy by female pollen wasps: in the foothills Philanthuscapensis, areprobably oflittle consequence.
of the Kamiesberg by Celonites capensis, a widespread Rebelo(1995)statesthatsomespeciesofLeucadendron
Karoo species; and in the Richtersveld by Jagurtia “are visited by a number ofbeetles; and that most ofthe
koeroegabensis a narrowly endemic species. Neither of genera(ofProteaceae)withsmallerflowerheadsarevisited
,
these wasps is restricted to Ferraria. Both are unusually by a variety ofbeetles, flies and wasps”. It is clearthat, in
polyphagous for pollen wasps, C. capensis having been the light ofthe findings reported in the present survey, this
recorded from flowers of six additional families and J. statementcan be expandedto include bees.
koeroegabensis from four.
Few species of wasps were found to visit any CORE EUDICOTS
species of monocots, apart from Asparagus suaveolens
Caryophyllales
(Asparagaceae), which they visit abundantly in the
southeast. Five species of pompilids, three species of Inthestudyarea,plantsofsixfamiliesofCaryophyllales,
tiphiids,andonespecieseachofscoliidsandsphecidswere Aizoaceae,Amaranthaceae,Molluginaceae,Nyctaginaceae,
recordedvisitingA. suaveolens. Plumbaginaceae and Portulacaceae, were recorded as
receivingvisits from aculeates.
EUDICOTS
Aniaranthaceae
Proteales
Amaranthaceae form a notable component
Proteaceae of the vegetation of northern Namaqualand and
Proteaceae are not well represented within the study Namibia. Preliminary palyonological evidence from
area, being Fynbos rather than Karoo plants. However, in Eksteenfontein in the Richtersveld suggests that they
the Clanwilliam andNieuwoudtville areas, at the interface were a previously predominant element beforeAizoaceae
betweenkarroidandfynbosscrubtwospeciesofProteaceae (Mesembryanthema) took over in the early Holocene
(in fynbos) were sampled for flower visitors. One was the (Scottetal. 1997).
dusky-pink flowered Paranomus bracteolaris, growing Several species of Hermbstaedtia - most notably H.
west ofNieuwoudtville near the edge of the escarpment glauca in the Richtersveld and H. odorata in Namibia
and inthe hills tothe westofClanwilliam. The otherwasa - are attractive to wasps and bees. They were recorded as
species of Leucadendron, with relatively large brilliantly receiving visits from 7% of the total number of species:
yellow female ‘cones’heldwithinbroadyellowinvolucral 42 wasps and 24 bees. One species of pollen wasp was
leaves, growing west ofClanwilliam nearGraafwater. recorded. Itsvisitswere occasional and casual.
InthepresentstudyP. bracteolariswasbeingvisited,at Amongst the wasps the most numerous species were
both ofthe above-mentioned sites, by bees ofthe families Nyssonidae, of which 17 species were recorded: five
Apidae and Colletidae and wasps ofthe family Tiphiidae. species ofBembecinus and one each ofBembix and Stizus
Ofparticularinterestarethecolletids,Scraptererubescens from FI. glauca\ and three species ofBembecinus, six of
(Clanwilliam andNieuwoudtville), also recorded from the Bembix and one each ofHandlirschia, Stizus andStizoides
Leucadendron (described above), and Scrapterfilliginatus fromH. odorata.
(Clanwilliam). These are the only known records offlower A number ofother other wasps were recorded visiting
visitingforthesebees(Eardley 1996),suggestingthatthere Hermbstaedtia spp.: seven species of Sphecidae and two
may be an association between these bees andProteaceae. species each of Chrysididae, Eumeninae (Vespidae),
10 Gess & Gess: Surveyofflowervisitingbyaculeatewasps andbees