ViewApril1994 metadata, citation and similar papers at core.ac.uk brought to you by CORE NOTICIAS DE GALÁPAGOS 25 provided by Aquatic Commons R.I. pacifîc Bowman, M. Buson &A.E. Leviton. lished Report, Estación Cientffica Charles Dar- Division of the AAAS. pp 539-568. win. Patton, J.L., Yang, p.lg7S. S.Y. & Myers, Genetic Snow, D. L964. Untitled note. Noticias de Galápa- and morphologic divergence among introduced gos. 3: p 20. rat populations (Ranus rattus) of the Galápagos S teadman, D.W. & Ray, C .8. 1982. The relationships Archipelago, Ecuador. Syst. Zool. 2 4(3):296-310. of Megaoryzomys curioi, an extinct Cricetine ro- Peterson, R.I. 1966. Recent mammal records from dent (Muroidea: Muridae) from the Galápagos the Galápagos tA5. islands. Mammalia. 30(3):441- Islands, Ecuador. Smithsonian Contributions to Sivinta-Mena" Byron. 1 988. Ecologia de la rata norue- Paleobiology. No.51. ga Rattus norvegicus, especie de reciente Trillmich, F. 1 986. The future of rhe Fernandina rice establecimiento Puerto en Ayora, Santa Cruz, rats: extinction or captive breeding? Noticias de Galápagos. Unpublished thesis, UniversidadTéc- Galápagos. M:15-16. nica de Ambato, Ecuador. Gillian Key Biological Sciences, Manchester Met- Snell, H., p. Snell, H. & Stone, 1993. Accelerated ropolitan Universit¡ Manchester MlsGD, UK. mortality plaza of Opuntia on Isla Sur: Another EdgarMuñoz Heredia, Charles Darwin Research Threat from an Introduced Vertebrate? Unpub- Station,Isla Santa Cruz, Galápagos, Ecuador.

POLLINATION OF SCALESIA BAURT SSP. HOPKINSII (ASTERACEAE) ON PINTA ISLAND

By: Conley K. McMullen and Sandra J. Naranjo

Previous studies in the genusScalesiahave shown this genus, Scalesia baurii Robinson & Greenman that,S. affinis Hooker f., S. helleri Robinson, S. pe- ssp. hopkinsii (Robinson) Eliasson, were conducted dunculata Hooker f., and S. asperaAndersson can on Pinta Island from 28 June - 20 July 1990 (Fig. l). reproduce by aurogamy (automatic self-pollination) Pintais one of the northern islands in the archipelago (Rick 1966; McMullen 1987, 1990). In addition, the that the carpenter bee does not inhabit. Fifteen indi- first three of these, as well as an unidentified species viduals, located between 15-67 maltitude on pinta's thought to be S. reffoflexaHemsley, a¡e known to be southem sþe, were selected for this study. One pollinated by the endemic carpentff bee Xylocopa hundredinfl orescences were bagged before theirflow- darwini Cockerell (Hymenoptera: Apidae) (Linsley ers had opened to determine if the plants could et al. 1966; Rick 1966; Eliasson 1974; McMullen reproduce autogamously. One hundred open-polli- 1985). The flowers of S. pedunculata onsanra Cruz nated inflorescences were marked as well, and then Island are alsovisitedbythe Galápagos fritillary but- covered after being exposed for one week. All polli- terfly Agraulis vanillae galapagensjs Holland nation bags werecollectedon the lastday of the study (: Nymphalidae) (personal observation). and fruit counts were made. Flower observations Pollination studies on an additional member of were conducted to discover what made visits No.53 26 NOTICIAS DE GALAPAGOS

Figure 1. Inflorescence and leaves of Scalesia baurií ssp. hopkinsü on Pinta Island.

to these plants and might act as pollinators. These and one inflorescence was actually obsewed being this visits were timed and recorded. The maximum stay eaten. Ten of the bags were not recove¡ed after listed for any one was 15 minutes. After this, study. One explanation for this might be that they Howev- the insectwas eithercaptured, or anotherobservation were overlooked during the final collection. weredesEoyed was begun so as not to spend an excessive amount of er, anotherpossibility is thatthese bags time watching one individual. by the Galápagos hawk (Buteo galapagoensis). This Table 1 shows the results of the bagging studies' hawk removed and tore apart pollination bags from Flower counts were not made, so an actual percent- other plant species that were being studied during the age of fruit set cannot be given. Eliasson (1974) same period. mentions that approximately 50 bisexual disc-flow- Theprimary insectvisitors to theseplants arenoted (Diptera: Bom- ers are typically found in an inflorescence, although in Table 2. A species of Mythenteles with 5 1 visits as many as 100 or more may be present' Ray-flowers byliidae) was most fiequently observed, are also present, but these are sterile. In any case, and a total of 28,49 4 seconds spent on infl orescences. both treatmentsproduced numerous fruits. The mean These bee flies wouldoftenvisitmore than one flow- number for bagged inflorescences was 45.2, while er per inflorescence, and appeared to be probing for its thatforopen-pollinatedinflorescences was 38.2. The nectar. In fact, one was observed trying to force reason for the latter having a lower fruit set is prob- way down into a corolla tube. Pollen was clearly ably because of their exposue to predators before visible on its wings andthorax during this visit. Second Thomas being bagged. Finches wereoften seen attheseplants, in occurrence was Lepidanthrax tinctus April 1994 NOTICIAS DE GALÁPAGOS 27

Table 1. Bagging experiment results, in number of fruits produced per inflorescence.

MEAN RANGE Ð N

Bagged Inflorescences 45.20 0-76 18.06 99

Open-Pollinated Inflorescences 38.1 8 o-67 16.78 91

Thble 2. Insect visitation times, in seconds, based on 24 hours of observation (6:00 A.M. - 6:00 p.M, 9 & tO July 1990).

TOTAL MEAN RANGE Ð N DIPTERA Mythenteles sp. (Bombyliidae) 28,494 5s8.71 30-900 349.26 51 Lepidanthrax tinctus (Bombyliidae) 1,061 32.r5 2-r39 3r.63 33

LEPIDOPTERA Atteva hysginiella (Yponomeutidae) r,664 208,00 12-405 155.68 Pyralid (þralidae) 568 189.33 60-274 1t3.78

(Diptera: Bombyliidae) with 33 visits, and a total ing the observation studies was apyralid moth (Lep- time of 1,061 seconds. A moth, Atteva hysginiella idoptera: Pyralidae). This single individual visited Wallengen (Iæpidoptera Yponomeutidae), w as the third inflorescences three times, for a total of 568 seconds. most common insect with eight visits. However, its In addition, two untimed visits were made by a spe- total visitation time was 1,664 seconds. Thus, its cies of Rhinacloa (Hemiptera: Miridae). mean stay (208 seconds) was approximately 6.5 times Most of the insects made their visits throughout longer than that of L. tinctus. Both of these insects the day, although the pyralid morh did not appear appeared to probe for nectar just as the species of until after 4:00 P.M. Only Mythenr¿l¿s individuals Mythenteles. The least frequent visitor recorded dur- were observed spending more than 15 minutes on an 28 NOTICIAS DE GALAPAGOS No.53 inflorescence during the timed studies. Peck and B.J. Sinclair of Carleton University, Otta- Insufficient nectar was produced by the flowers wa, Canada; and N.L. Evenhuis of the Bemice P. for micropipet collection. Howeve¡, the fact that all Bishop Museum, Honolulu, Hawaii for insect iden- of the insect visitors had mouthparts adapted for suck- tif,rcations. As always,I would like to thank the staffs ing rather than chewing suggests that a small nectar of the CDRS and GNP for thei¡ gtacious assistance. reward presumably is present. This work was supported by National Geographic These results indicate that S. baurii ssp. hopkinsü grant4327-90. is capable of autogamous reproduction, just as the other members of this genus that have been studied. LITERATURE CITED In addition, even though the carpenter bee is absent on Pinta, there afe other visitors that may promote Eliasson, U. 1 974. Studies in Galápagos plants. XIV. self- o¡ cross-pollination. Insects spending longer The genus Scalesia Arn. Opera Botanica 36:1- periods of time on each inflorescence are probably rt7. more important for selfing, since this behavior re- Linsley, E.G., C.M. Rick, and S.G. Stephens. 1966. sults in fewer visits to other plants. If this scena¡io is Observations on the floral relationships of the correct, then t. t inc tus may be more important in the Galápa gos c arpenter bee. Pan-Pacific Entomolo- cross-pollination of this plant than the other visitors gist 42:1-18. listed in Table2. McMullen, C.K. 1985. Observations on insect vis- The breeding strategy of S. baurii ssp. hopkinsii itors to flowering plants of Isla Santa Cruz. I. The appears reasonable for a plant inhabiting an oceanic endemic carpenter bee. Noticias de Galápagos island. Autogamy would promote initial establish- 42:24-25. ment, while visits by available insects might lead to McMullen, C.K. 1 987. Breeding systems of selected outcrossing. The flowers of this species a¡e well suited Galápagos Islands angiosperms. American Jour- to the small generalist insects found on Pinta Island' nal of Botany 74:1694-L7O5. Wind pollination, which demands profuse pollen McMullen, C.K. 1990. Reproductive biology of production, would be of little value, especially dur- Galápagos Islands angiosperms. Monographs in ing thecolonization period when only a few individuals Systematic Botany from the Missouri Botanical presumably would be present (McMullen and Close Garden 32:35-45. 1993). McMullen, C.K., andD.D. Close. 1993. Wind pol- lination in the Galápagos Islands. Noticias de ACKNOWLEDGMENTS Galápagos 52:12-17. Rick, C.M. 1966. Some plant- relations on We wish to thank the following individuals for the Galápagos Islands. Pp.215-224 in R.L Bow- their assistance: Daniel Evans, Aracelly Fajardo, man (ed.)The Galápagos. Universityof California Fernando Hurtado, Gayle Davis-Merlen, Godfrey Press, Berkeley. Merlen, Cecilia Solis, Hugo Valdebenito, and Fion- Contey K. McMullen, Department of Biology and nuala Walsh. Appreciation is also extended to T.J. Chemistr¡ West Liberty State College, West Lib' Henry, R.W Hodges, and M. Lacey-Theisen of the erty, West Virginia, 26074, USA. Sandra J. Systematic Entomology Laboratory United States Naranjo, Escuela de Biologia, Universidad Cen- Department ofAgriculture, Beltsville, Maryland; S.B. tral del Ecuador, Quito, Ecuador.