The Pollination Biology and Breeding System of Nepenthes Macfaklanei (Nepenthaceae)
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Journal of Tropical Forest Science 12(4) :635-642 (2000) THE POLLINATION BIOLOGY AND BREEDING SYSTEM OF NEPENTHES MACFAKLANEI (NEPENTHACEAE) L. S. L. Chua Forest Research Institute Malaysia, Kepong, 52109 Kuala Lumpur, Malaysia Received October 1998_______________________________________________ CHUA, L. S. L. 2000. The pollination biology and breeding system of Nepenthes macfartanei (Nepenthaceae). Nepenthes macfarlanei xenogamoua s ha s breeding system exhibitd an sgeneralisa t entomophilous pollination syndrome. Potential pollinators include member Dipterf so a (Calliphoridae, Muscida Syrphidae)d ean frequencw .Lo y of insect visits could be a limiting factor to successful pollination, but the species ma e ablyb offseo e t limitatio e th t employiny nb g strategies suc lons ha g periodf so stigmata receptivit synchronoud yan s receptivit pistillate th n yi e inflorescence. Stigmata receptivit visualls ywa y observe occuo dt r abou rate fo r f day th e0 o t 3 t sbu pollination succes highess swa t durin weekfirse o gth tw treceptivityf so . Keywords : Flower morphology - flower visitors - Diptera - pollination - xerogamy CHUA, L. S. L. 2000. Biologi pendebungaan dan sistem pembiakan Nepenthes macfarlanei (Nepenthaceae). Pembiakan Nepenthes macfarlanei ialah jenis pembiakan luar dan spesies ini diperhatikan mengamalkan pendebungaan serangga. Pendebunga- pendebunganya tidak spesifi antarn kda a serangga yang mungkin memainkan peranan penting dalam pendebungaan ialah Diptera (Calliphoridae, Muscida Syrphidae)n eda . Frekuensi lawatan serangga yang rendah mungkin merupakan penghalang kepada kejayaan pendebungaan. Namun demikia dapana i t mengatasi masala dengai hin n melanjutkan jangkamasa kepekaan stigmanya serta memastikan semua stigma pada jambak bunga peka pada masa yang sama panjang. Walaupun stigma diperhatikan peka selam hari0 a3 , kejayaan pendebungaan adalah paling tinggi dala mingga mdu u yang pertama. Introduction genue Th s Nepenthes dioeciouss i . Kaul (1982), Ada . (1989)al mt e , Kato (1993), Moran (1993), Phillipps and Lamb (1996), and Adam (1998) have suggested insect pollinatins sa g agents based largelpresence th n y o nectaf o e foetid an r d odour in the flowers and the regular encounter of insects on the inflorescences. Adam (1989. al t e ) recorded Dipter mose th s ta frequent visitorflowere th n o ss of Nepenthes X kinabaluensis, N. villosa and N. rajah, while Hymenoptera were most frequently seen visitin e flower . greinwardtianath N f o s . affN . d fusca.an Other observed visitors were from Coleopter d Lepidopteran a frod e familan amth y Formicidae. Diptera (Stomorhina spp. d Lepidopteran ) a (Herpetogramma sp., Pleuroptya sp., Pagyda sp., Ambia sp. and Pycnarmon sp.) have been recorded on N. gracilis (Kato 1993). Most of the visits took place between early evening and midnight, the time coinciding with maximum nectar production (Kato 1993). 635 636 Journal of Tropical Forest Science 12 (4) :635-642 (2000) Chrysomelid beetles were the most frequent visitors to N. rafflesiana (Moran 1993), while small flies were frequen rajah. N n o t(Phillipp Lam& s b 1996). This study provides information on the pollination syndrome and breeding syste . macfarlanei,N f mo montana e species endemi Peninsulao ct r Malaysia. Materials and methods Geographic and physical details of the study site, the weather patterns and the floral biology observation methods employed on the sampled population at Mt Purun, Genting Highlands, Peninsular Malaysia e givear , n Chui n a (2000). Seven pistillate inflorescences from five plant seved san n staminate inflorescences from six plants were observed. These inflorescences were observed for fifteen days fro Decembe0 m3 r Apri2 1992 o 3lt 1994, between 090 r timed 160fo 0 an , 0,h frequency and duration of insect visits. Daily observation and trapping were conducted for four days from 12 to 15 January 1994 and the remaining eleven days were staggered up to 22 April 1994. Direct observations were made for foraging feedind an g behaviour f floweso r mode visitorth f polled eo san n transfero T . determine night visitors, observations were also carriesever fo t n dconsecutivou e nights, from 1900 to 0700 h. Samples of flower visitors were captured for species determination and they were examined under the light microscope for the presenc pollef eo n grains . (score0) r o d+ Pollination manipulations were done to determine the breeding system of this species. Pistillate inflorescences bearing mature buds were isolated using nylon bags of 0.2-mm mesh size. Treatments used, each having five inflorescence replicates, were open pollination, control baggin hand gan d pollination open .I n pollination selectee ,th d inflorescences wer t baggedeno , whil contron ei l bagging inflorescencee th s were bagged t manipulatedno t ,bu . Inflorescences selecter dfo hand pollination were bagge theid dan r flowers were hand-pollinated with pollen grains from freshly dehisced anthers. Where possible, different plants were selected as replicates for a treatment, but occasionally a plant may be used more than once for the same treatment. In such cases, different inflorescences in the plant were used as replicates for the treatments. Buds in the pistillate inflorescence mature synchronously. The treatments were staggered throughout 17 months because it wa possiblt sno haveeo t singl a t ,a e perio timef do inflorescence5 ,1 samplee th n si d populatio pollinatior nfo n work. Upon reaching receptivity, the stigmatic surface remained visibly unchanged for about three weeks (Chua 2000) experimenn a n I . determino t e whethee rth stigma is receptive to pollen transfer throughout this duration, between 18 and 20 budinflorescencn a n si e were randomly selecte pollea r dfo n application afte, 14 r controa day5 d 3 san d l an wit 21 polle8 o ,2 h n n application. Five inflorescences were used in this experiment The treatments were staggered throughout 17 months and hand pollinatio dons nwa e around mid-day scorematurityt s . a Fruid wa t dan te se th , number of mature seeds was counted. The results were analysed using single factor ANOVA (model I) with unequal number of replicates (Sokal & Rohlf 1995). 7 63 Journal of Tropical Forest Science :635-64) (4 2 1 2 (2000) Results Flower morphology The flower morphology of N. macfarlanei is designed to facilitate insect visits. At anthesis, the tepals, where nectar production is concentrated, are fully reflexed, providing a convenient landing and feeding platform for insects to forage. The diamete flowee th f thit ro ra staminat e s stagth n I e. measureecm flower1 o t p ,du the anthers are held well above the tepals by an elongated androphore, while in the pistillate flower, the pistil, which is without style, is about 0.5 cm in height. This specie typicaa s sha l dish-shaped flowerpistillate th n I . e inflorescencee th , synchronous receptivit closd yan e arrangemen flowere th f to s enable flowee dth r visitor o forag t s man a n eo y flower possibles sa . Similar floral morphologs yha been documented in other Nepenthes sp. (Danser 1928, Jebb & Cheek 1997). Flower visitors During the fifteen-day observation period, the total number of visits recorded on both pistillate and staminate inflorescences was 21 (Table 1). The staminate inflorescences had fifteen visits which were spread over ten days. All staminate inflorescences were visited at least once during the observation period but none was visited dail flowey yb fifteee r th visitors f o n t visitsOu . , eleven were mady eb potential pollinators pistillate Th . e inflorescence visitsx si d ; thessha e visits were sprea fiveo t o ,d afte tw fro y rm da whic h there wer longeo en visitsy an r , although there were still display of floral rewards (Table 1). Like its opposite sex, the pistillate inflorescences were visited at least once during the observation period t nonbu e were visited dail flowevisitsy x yb si e ,r fivth visitors f eo wert Ou .e made by potential pollinators. This timing of visits coincided with the anthesis period sample inth e population, which peaked durin monte gth h of January 1994 (Chua 2000) e absenc.Th flowef eo r visitors fro pistillate mth e inflorescences durine gth observatioe th res f o t attributee nb day n lowee sca th o rdt numbe f openeo r d flowers. staminate Th e inflorescences were visite varieta y db flowef yo r visitors, ranging from flies, wasps, bees and plant hoppers to ants, cockroaches, spiders and crabs (Table 1). Formicidae (ants) were the most frequent visitor but in this study their number of visits was not recorded as their foraging behaviour and the dioecious nature of N. macfarlanei do not make them a potential pollinator. Diptera was the second most common visitor; members from Muscidae (brown houseflies), Syrphidae (flower flies Calliphoridad an ) e (carrion flies) made onee ,on foud ran visit respectively totae , th totallin f l o numbe % visitx 40 gsi visits r f sro o . Halictidae (bees) made three visits, two of which took place on the same day, while Dictyopharidae (plant hopper) and Tiiphidae (tiiphid wasp) made one visit each (Table 1). Although cockroaches, spiders and crabs visited the flowers, they are unlikely to be potential pollinators. g Table 1. The frequency and number of flower visitors to the staminate and pistillate flowers of Nepenthes macfarlanei during a fifteen-day observation period from 30 December 1993 to 22 April 1994. (C* = Calliphoridae, D = Dictyopharidae, Halictidae= H Muscidae= * M , Syrphidae = S* , Tiiphidae= T , crabcockcroach= = h b C C , mosquito= o M , , Sr = spider; the number indicates the number of visits made on that day) i 8. •S, I *Member Dipterf so a group. to "fo Journal of Tropical Forest Science 12(4):635-642 (2000) 639 In comparison, only ants, Muscidae fly and mosquitoes visited the pistillate inflorescences (Tabl . Once1) e again, ants wer mose eth t frequent visitore Th .