McMullen, Conley K.

English

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OBSERVATIONS ON INSECT VISITORS TO FLOWERING PLANTS OF 
ISLA SANTA CRUZ. 
PART I. THE ENDEMIC CARPENTER BEE 
by 
Conley K. McMullen 
Department of Botany, University 0/ Maryland. College Pork. Maryland 20742 
Within the Galapagos Islands there are few insect pollinators, which maybe the reason that most endemic 
angiosperm species have small flowers (Stewart, 1911). This paucity of in sects is illustrated by the fact thai 
only one species of bee (Xy/ocopa darwini, the endemic carpenter bee) is represented on the islands 
(Cockerell, 1935; Hurd, 1958). Rick (1963, 1966) studied its role as a pollinator of plants on Isla Santa 
Cruz and reported that it made visits to Justicia galapagana (Acanthaceae), Scalesia affinis and S, kelleri 
(Asleraceae), Cordia lutea (Boraginaceae), Opuntio echios (Cactaceae), MormordicQ (charon/fa) 
(Cucurbitaceae), Piscidia (conhagenensis) (Fabaceae), Nolana galapagensis (recorded as Periloba 
ga/apagensis) (Nolanaceae), CryplOcarpus (pyrijormis) (Nyctaginaceae), Cardiospermum galapageium 
(Sapindaceae), Castela ga/apageia (Simaroubaceae), and Lycopersicon cheesmanii (recorded as L 
pimpinelli/olium) (Solanaceae). 
Linsley et al. (1966) recorded Xylocopa darwini as visiting the following additional plants on Santa Cruz 
between January 20 and February 28, 1964: Telramerium nervosum (recorded as T. hispidium) 
(Acanthaceae), Vallesia g/abra (Apocynaceae), Scalesia peduncu/ata (Asteraceae), Bursera graveo/ens 
(Burseraceae). Canna sp. (Cannaceae). Ipomoea pes-caprae (ConvolvuJaceae), Cucurbita pepo 
(Cucurbitaccae), Acacia insulae-iacobi (recorded as A. tortuoso), A. macracanlha, Cassia occidentaJis, 
Crota/aria incana (recorded as C. setijera), Galactea striata (recorded as G. jussiana), Inga edu/is, 
Parkinsonia acu/eata. Prosopis ju/iflora (recorded as P. du/cis), and Rhynchosia minima(Fabaceae), Persea 
americana (recorded as P. gratis.sima) (Lauraceae), MentzeJia aspera (Loasaceae), Abuti/on depauperatum, 
AbeJmoschus manihot (recorded as Hibiscus manihot), Hibiscus ti/iaceus. Malvastrum coromandeJianum, 
Sida acuta and S. spinosa (recorded as S. anguslijo/ia) (Malvaceae), Miconia robinson;ana 
(Melastomaceae), Commicarpus luberosus (recorded as Boerhaavia scandens), Mirabilis jalapa 
(Nyctaginaceae), Passiflora Joelido (Passifloraceae). Portulaca o/eracea (Portulacaceae), ChiococCQ a/ab, 
CoJJea arabica. Psycholr;a rujipes (Rubiaceae), Physalis pubescens (Solanaceae), Waltheria ovata 
(recorded as W. reticulata) (Sterculiaceae), Clerodendrum mol/e, lAntana peduncularis, Slachylarpheta 
cayannensis (Verbenaceae), and Tr;bulus cisloides (Zygophyllaceae). 
From October 1983 through March 1984 the author performed studies to determine the presence of self-
compatibility versus self·jncompatibility in selected angiosperms on Santa Cruz. Plants were tested along 
the southern slope with quadrats established in each of the seven major vegetation zones (Wiggins and 
Porter, 1971; van der Werff, 1979). A secondary objective of this research was to observe natural 
pollination agents. The first of these observations (those pertaining to Xylocopa darwini) are reported in 
Table I, along with information on locations, amount of activity observed, and whether the plants are 
endemic or non-endemic. 
Two of the fourteen species listed by the author are new pollination records for Santa Cruz. These species 
are Cordia leucophlycl;s and Vigna IUleola. Although Sida rhombijolia is not mentioned specifically for 
Santa Cruz in previous studies, Linsley et al. (1966 )do include a photograph of Xylocopa darwini visitinga 
flower of this plant near Bella Vista. Therefore, from these studies it appears that the Galapagoscarpenter 
bee, which is polylectic and visits many different plants for pollen and nectar, continues to be a major 
pollinator on Isla Santa Cruz, especially for non-endemic members of the flora. Part II of this paper will 
outline observations on other insect visitors to plants on Santa Cruz including butterflies, moths, flies, 
and ants. 
ACKNOWLEDGEMENTS 
During a study of six months one receives assistance in one form or another from more individuals than 
can be mentioned in this short space. However, the author would like to indicate those few without whose 
contributions this study would have been much more difficult if not impossible. These are Marsha Cox, 
Jose Villa, LUong Tan Tuoc, Basilio Toro, Friedemann Koster, GUnther Reck, Miguel Cifuentes, and 
Fausto Cepeda, as well as the many other members of the Charles Darwin Research Station and National 
Park Service Staff, 
Noticias de Galapagos, vol. 42 1985
LITERATURE CITED 
Cockerell, T.O.A. (1935) The Templeton Crocker Expedition of the California Academy of Sciences, 
1932. The carpenter bees of the Galapagos Islands. Proc. Calif. Acad. Sci., ser. 4, 21: 379-382. 
Hurd, P.O. (1958) The carpenter bees of the eastern Pacific oceanic islands. J. Kansas Ent. Soc. 31: 249-
255. 
Linsley, E.G., Rick, C.M. and Stephens, S.G. (1966) Observations on the floral relationships of the 
Galapagos carpenter bee. The Pan-Pacific Entomologist 42: 1-18. 
Rick, CM. (1963) Biosystematic studies on Galapagos tomatoes. Occas. Papers Calif. Acad. Sci. 44: 59-
17. 
Rick, eM. (1966) Some plant-animal relations on the Galapagos Islands. In: R.1. Bowman (ed.), The 
Galapagos, pp. 215-224. Univ. Calif. Press, Berkeley and Los Angeles. 
Stewart, A. (l91l) A botanical survey of the Galapagos Islands. Proc. Calif. Acad. Sci., serA, I: 7-288. 
van der Werff, H. (1979) Conservation and vegetation of the Galapagos Islands. In: O. Bmmwell(ed.), 
Plants and Islands, pp. 391-404. Academic Press, London. 
Wiggins, I.L. and Porter, O.M. (1971) Flora of the Galapagos Islands. Stanford University Press, 
Stanford. 
Table I. Summary of flower records for X)'locopa darwini from October 1983-March 1984. 
Family 
Acanthaceac 
Asteraceac 
Boraginaceae 
Fabaceae 
Malvaceae 
Passifloraceae 
Rubiaceae 
Vcrbcnaccae 
Zygopllyllaceae 
...... 
Just/cia ga/apagana (E) 
Sco/e$ia peduncukua 
val. p4rVifloro (El 
Cordia /eucophlycIi$ (E) 
Cordia /UIN (N) 
Cassia occidt"talb (N) 
Parkinsonio acu/tota (N) 
Pro$opis juJiflora (N) 
Vigna 'uteo/a (N) 
&mardla viscose (N) 
Sido rhombl/olia (I) 
Pam flora foetida 
var. galopagen$i$ (E) 
Coffta orabico (C) 
Clerodendrum ma/lt 
var. mollt (N) 
Tribu/U$ ci$loides (I) 
(E) endemic (N) native 
Locali • Acth·ity 
Sca/tna Zonc, 10w 
near Los Gemel05 
Sca/uia Zone, moderate 
near Los Gemel05 
Arid Zone, high 
Darwin Station 
Arid Zone, 10w 
Darwin Station 
Transition Zone ~w 
3.5km n. Puerto AyOQ 
Arid Zone, high 
Darwin Station 
Littoral Zone, high 
Tortuga Bay 
Pampa Zone, 10w 
3 km. n. Media Luna 
Arid Zone, 10w 
Darwin Station 
Zanthoxylum Zone, moderate 
near Santa Rosa 
Arid Zone, moderate 
Darwin Station 
ScaleSia Zone, 10w 
near los Gemel05 
Arid Zone, 10w 
Darwin Station 
Arid Zooe, moderate 
Darwin Station 
(I) introduced weed (C) cultivated escape 
" 
Noticias de Galapagos, vol. 42 1985


Observations on insect visitors to flowering plants of Isla Santa Cruz. Part 1. The endemic carpenter bee

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Observations on insect visitors to flowering plants of Isla Santa Cruz. Part 1. The endemic carpenter bee

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