Pollination Rates Research Articles

Rotating Arrays of Orchid Flowers: A Simple and Effective Method for Studying Pollination in Food Deceptive Plants

Floral deception has been observed in several genera in angiosperms, but is most common in the Orchidaceae. Pollination mechanisms in food deceptive plants are often difficult to assess, as visitation frequency by insects requires numerous hours of field observations to ascertain. Here, for the first time, we describe in detail and validate a simple and effective method that extends previous approaches to increase the effectiveness of pollination studies of food deceptive orchids. We used an orchid of southwest Australia, Diuris brumalis (Orchidaceae), that visually mimics model plants belonging to the genus Daviesia (Faboideae). Arrays of orchid flowers were placed and moved systematically in proximity to model plants, resulting in rapid attraction of the pollinators of D. brumalis. We compared pollinaria removal (as an indicator of pollination success) in naturally growing orchids with pollinaria removal in arrays of orchid flowers in the same sites. We showed that the proposed method greatly enhances pollinator attractiveness in food deceptive systems with very low pollination rates, and we compared its efficiency with other similar methods. The approach can be used for observing pollinator behavioural patterns and confirming effective pollinators for food deceptive species with low insect visitation rates.

It Is Not All About Being Sweet: Differences in Floral Traits and Insect Visitation among Hybrid Carrot Cultivars.

Cytoplasmically male-sterile (CMS) carrot cultivars suffer from low pollination rates. In this study, insect visitation varied more than eightfold between 17 CMS carrot cultivars in a field-based cultivar evaluation trial. The visitation rates of honey bees, nectar scarabs, muscoid flies, and wasps each significantly differed among these cultivars. No significant difference in visitation rates was observed among cultivars of different CMS type (brown-anther or petaloid) or flower colour, but cultivars of Berlicumer root type had significantly higher insect visitation rates than Nantes. Six cultivars were further compared in regard to selected umbel traits: as umbel diameter increased, so did the visitation of soldier beetles, while that of honey bees decreased. Finally, nectar of these six cultivars was analysed for sugar content, which revealed monosaccharides to be the most common sugars in all. There was high variation in the levels of sugars from individual umbellets but no significant difference in nectar sugar composition among cultivars, suggesting that nectar sugar composition is of minor importance regarding pollinator attraction to hybrid CMS carrot umbels.

Variation in the pollinator community visiting invasive Cytisus scoparius L. Link (Fabaceae) along an elevation gradient

Invasive plants are a novel resource for the resident pollinator community, but may not be able to successfully attract pollinators if they have a specialized pollination system or restrictive floral morphology. Pollinator limitation may limit invasion success, but a plant able to attract many pollinators in different conditions will be a successful invasive species. In this study, we measured the pollinator community by capturing pollinators at several timepoints during the flowering season. Captures were made at six field sites along an elevation gradient. Measurements were specific to an invasive shrub with very low self-compatibility and a restrictive floral morphology, Cytisus scoparius (Scotch broom). We found that the pollinator community varies along an elevation gradient, having more Apis mellifera at low elevation sites and more Bombus spp., especially Bombus sitkensis at higher elevations. We saw different higher pollination rates, but lower seed set at higher elevation sites. Although C. scoparius has been able to attract a variety of pollinators, pollen robbing by one species may result in decreased plant fitness.

Pollen limitation in a single year is not compensated by future reproduction

Seed production is critical to the persistence of most flowering plant populations, but may be strongly pollen limited. To what extent long-lived plants can compensate pollen limitation by increasing future reproduction is poorly understood. We tested for compensation in two Dactylorhiza species that differ in reproductive investment by experimentally reducing and increasing pollination in two independent annual cohorts and monitoring demographic responses in the subsequent 2 years for the 2014 cohort and in 1 year for the 2015 cohort. Demographic rates in the second year were significantly affected by pollination treatment in both species, but specific responses differed both between species and years. There was no effect of pollination treatment on demographic responses in the third year. In sum, effects were too weak to make up for the lost reproduction; total fruit production across all 3 years was by far highest in the increased pollination treatment in both species. These results show that long-lived plants do not necessarily compensate for pollen limitation by increasing future reproduction. It further suggests that even periodic declines in pollination rates may have severe demographic consequences, particularly in populations where germination is not density dependent. This has implications for predicting plant population viability in response to changes in pollination intensity.

Successful pollen dispersal modulates with flowering phase in field-hybridizing grasses

Gene-flow between intensively and extensively farmed grass populations is an ongoing feature of agroecological landscapes, especially in Atlantic northwestern Europe. Adjoining population boundaries and in-field admixture of grass types via winter forage dispersal facilitates both in-field hybridisation and recruitment of immigrant seedlings. Here we examine the paternal hybridisation of one grass species (Lolium multiflorum, pollen donor) into the population of a second, fully interfertile, grass species (L. perenne, pollen receptor) via pollen-mediated gene-flow in an experimental field plot. Using weekly counts of successful pollination in 470 individual receptor plants based on paternity analysis in 4281 germinated F1 seedlings, we determined the extent of evident hybridisation (hybrid progeny that show some paternal morphology) and silent hybridisation (hybrid progeny that show no paternal morphology) over the course of floral anthesis. Co-dominant morphological traits in F1 progeny underestimated microsatellite-validated genetic hybridisation by approximately 30%, while background pollen competition dampened the overall rate of successful pollen donor pollination. Overall pollination from the donor plot followed a composite decline model. However over the course of floral anthesis the successful pollination pattern was changeable, and showed varying levels of affinity to three tested decline distribution models.

Successful pollen dispersal modulates with flowering phase in field-hybridizing grasses

Gene-flow between intensively and extensively farmed grass populations is an ongoing feature of agroecological landscapes, especially in Atlantic northwestern. Europe. Adjoining population boundaries and in-field admixture of grass types via winter forage dispersal facilitates both in-field hybridisation and recruitment of immigrant seedlings. Here we examine the paternal hybridisation of one grass species (Lolium multiflorum, pollen donor) into the population of a second, fully inter-fertile, grass species (L. perenne, pollen receptor) via pollen-mediated gene-flow in an experimental field plot. Using weekly counts of successful pollination in 470 individual receptor plants based on paternity analysis in 4281 germinated F-1 seedlings, we determined the extent of evident hybridisation (hybrid progeny that show some paternal morphology) and silent hybridisation (hybrid progeny that show no paternal morphology) over the course of floral anthesis. Co-dominant morphological traits in F-1 progeny underestimated microsatellite-validated genetic hybridisation by approximately 30%, while background pollen competition dampened the overall rate of successful pollen donor pollination. Overall pollination from the donor plot followed a composite decline model. However over the course of floral anthesis the successful pollination pattern was changeable, and showed varying levels of affinity to three tested decline distribution models.

Foraging behavior of stingless bee (Geniotrigona thoracica and Heterotrigona itama) on star fruit trees (Averrhoa carambola L.)

Star fruit produce flowers and fruits nearly the whole year round and it require cross- pollination for good fruit set and yields. An inadequate pollination rate is one of the factor that contributes to low yield. One of the effective way of increasing the pollination rate is by having insect pollinators such stingless bees in the star fruit farm. Malaysia is rich with native pollinator such as stingless bee, but there still lack of study related on their foraging behaviour. Therefore, the objectives were to study the foraging behaviour of Geniotrigona thoracica and Heterotrigona itama on star fruit trees. The colonies of G. thoracica and H.itama were selected for observation of activity foraging of stingless bee. Foraging bees was enumerated by using a manual tally counter to determine the number of individuals that flew out and into their hive within a 10 minute period each hour for each colonies. Then 10 of foragers’ G. thoracica and H.itama were selected randomly and marked using insect colouring on their thorax The period for each flower that visited by G. thoracica and H.itama was recorded by using stopwatch. The number offlower visited by G. thoracica and H.itama also recorded in 3 minutes. Result showed the peak time foraging activity of both stingless bees were in between 8.00am until 10.00am The foraging activity for each hours showed there was not significant differences, p > 0.05. Then the highest number flower visited by G.thoracica in 3 minute is 31 flowers while the lowest number flower visited in 3 minute is 7 flowers. However, for H.itama the highest number visited flowers are 27 and lowest number visited flowers are 8, for the longest average visited period for each flower is 14.76 seconds and the shortest period is 3.57 seconds. Meanwhile for G.thoracica longest average visited period for each flower is 12.88 seconds and the shortest average visited period for each flower is 2.72 seconds. In conclusion, this experiment showed that stingless bees have the characteristic for effective pollinator and have the potential to be used as a pollinator for star fruit trees. However, temperature, humidity and weather gave big influence on the foraging activity of stingless bees on star fruit plant.

Pollination and resource limitation as interacting constraints on almond fruit set.

Pollination and resource availability are factors determining reproductive success of plants, and in agriculture these factors influence yield of fruit-bearing crops. Our understanding of the importance of crop pollination is fast improving, but less is known about how the interaction between pollination and resources constrains fruit production. We conducted an experiment with almond trees (Prunus dulcis) to examine how the number of flowers, light availability and competition for resources affected nut (fruit) production on individual spurs (fruit-bearing structures) exposed to open-pollination or hand-pollination. We found a positive relationship between flower number and nut number on spurs with up to four flowers, but no further benefit after four flowers, suggesting a resource threshold expressed by individual spurs. Spurs with few flowers increased the conversion rate of flowers to nuts when supplemented with hand-pollination, but spurs with more flowers were more likely to achieve the threshold number of nuts even under open-pollination. Our experiment included a further treatment involving spraying whole trees with pollen. This treatment reduced nut production by spurs with many flowers and high light availability, suggesting competition is experienced by well-resourced spurs when resources need to be shared among developing nuts across the whole tree. Our study supports the hypothesis that excess flower production in fruit trees increases the potential for fruit production when pollinator and resource availability is variable (bet-hedging). Spurs with more flowers typically produce more nuts (within a limited range), but only if both resources and pollen supply increase with flower number. For almond growers, a focus on maintaining high flower numbers, especially in high light regions of the canopy, is the foundation for high levels of production. Strategies to lift flower number and light are complicated by trade-offs inherent in tree architecture and orchard design. However, fruit set would be lifted above that achieved by current practice by an increase in the pollination rate of flowers.

Supplemental and Synchronized Pollination May Increase Yield in Cacao

Artificial pollination management strategies are a potential solution to improving the livelihoods of smallholder cacao farmers by increasing crop productivity in situations when pollination services are limiting. However, field-based research trials evaluating the yield benefits of artificial pollination management strategies within intensified cacao systems are lacking. Thus, in an intensively managed cacao system, we evaluated the effects of artificial pollination condition (i.e., pollen genotype, pollination intensity, and pollination synchrony) on fruit development and yield in three high-yielding cacao clones. Artificial pollination, regardless of intensity, significantly increased fruit set and yield. Pollination synchrony had a significant effect on cherelle survivorship; older cherelles had greater survival rates across all developmental stages than younger cherelles. Yield differed between genotype crosses and varied according to the pollen donor used, highlighting the importance of understanding self- and cross-compatibility when selecting clones for cultivation. Pollination intensity had no significant effect on harvested yield, indicating that more rigorous research is needed to identify the pollination intensity required for optimized yield under artificial pollination conditions. We conclude that strategies to enhance flowering, pollination rates, and pollination synchrony while ensuring adequate tree nutrition may increase productivity in cacao. Future research evaluating numerous cacao clones across multiple years and locations may help us to understand the region-specific effects of intensive management strategies on the long-term sustainability of enhancing cacao tree productivity.

Variation of Pollination Rate on Eucalyptus grandis and E. tereticornis

The most widely used clones were all breed by artificial hybrids steps in China, therefore it is important to research on pollination rate. Three individual trees of E. grandis and E. tereticornis were selected as female while the pollen of hybrid clone DH32-29, E. grandis, E. pellita, E. tereticornis and E. urophylla were collected as male. The results indicated that E. grandis family 4 always had higher pollination rate with different male pollen than other E. grandis families. Family 116 had higher pollination rate with DH32-29 and E. urophylla than family 41 while family 41 had higher pollination rate with E. grandis and E. tereticornis than family 116. Though different families had different pollination rate, the studied E. grandis families all had higher pollination rate (above 75%) with different male pollen. E. tereticornis family 243-1 always had higher pollination rate (nearly 100%) with different male pollen than other E. tereticornis families while E. tereticornis family 238-2 always had lower pollination rate (nearly 60%) with different male pollen than other E. tereticornis families. All the male pollen had similar pollination rate with family 238-1 and 243-1. E. grandis pollen had higher pollination rate with family 238-2 than other male pollens.

Low soil temperature reducing the yield of drip irrigated rice in arid area by influencing anther development and pollination

Drip irrigation can produce high rice yields with significant water savings; therefore, it is widely used in arid area water-scarce northern China. However, high-frequency irrigation of drip irrigation with low temperature well water leads to low root zone temperature and significantly reduce the rice yield compared to normal temperature water irrigated rice, for example, reservoir water. The main purpose of this paper is to investigate the effects of low soil temperature on the yield reduction of drip irrigated rice in the spike differentiation stage. The experiment set the soil temperatures at 18°C, 24°C and 30°C under two irrigation methods (flood and drip irrigation), respectively. The results showed that, at the 30°C soil temperature, drip irrigation increased total root length by 53% but reduced root water conductivity by 9% compared with flood irrigation. Drip irrigation also increased leaf abscisic acid and proline concentrations by 13% and 5%, respectively. These results indicated that drip irrigated rice was under mild water stress. In the 18°C soil temperature, drip irrigation reduced hydraulic conductivity by 58%, leaf water potential by 40% and leaf net photosynthesis by 25% compared with flood irrigation. The starch concentration in male gametes was also 30% less in the drip irrigation treatment than in the flood irrigation treatment at soil temperature 18°C. Therefore, the main reason for the yield reduction of drip irrigated rice was that the low temperature aggravates the physiological drought of rice and leads to the decrease of starch content in male gametes and low pollination fertilization rate. Low temperature aggravates physiological water deficit in drip irrigated rice and leads to lower starch content in male gametes and low pollination fertilization rate, which is the main reason for the reduced yield of drip irrigated rice. Overall, the results indicated that the low soil temperatures aggravated the water stress that rice was under in the drip irrigated environment, causing declines both in the starch content of male gametes and in pollination rate. Low temperature will ultimately affect the rice yield under drip irrigation.

Limited Cross Plant Movement and Non-Crop Preferences Reduce the Efficiency of Honey Bees as Pollinators of Hybrid Carrot Seed Crops.

Pollination rates in hybrid carrot crops remain limited after introduction of honey bee hives. In this study, honey bee foraging behaviour was observed in commercial hybrid carrot seed crops. Significantly more visits were made to male-fertile (MF) rather than cytoplasmically male-sterile (CMS) flowers. Pollen was collected from bees returning to a hive, to determine daily variation in pollen loads collected and to what level the bees were foraging for carrot pollen. Honey bees visited a wide range of alternative pollen sources and made relatively few visits to carrot plants throughout the period of flowering. Visitation rates to other individual floral sources fluctuated but visitation to carrot was consistently low. The underlying rate of carrot pollen visits among collecting trips was modelled and estimated to be as low as 1.4%, a likely cause of the limited success implementing honey bee hives in carrot crops.

Pollination ecology of Tetratheca species from isolated, arid habitats (Banded Iron Formations) in Western Australia

Pollination and reproductive ecology of arid zone species in Australia are neglected topics. This is particularly true of rare species, some of which are threatened by mining operations. The bee community at Windarling Range in southern Western Australia and the pollination ecology of four rare Tetratheca taxa with distributions restricted to Banded Iron Formation inselbergs in the arid south-west were examined in winter and spring to understand if pollination rate was affecting the reproductive ecology of the plants. The bee fauna on the Windarling Range was sampled using coloured pan traps at three landscape positions of ridge (where Tetratheca paynterae subsp. paynterae occurs), slope and flats and the insect visitors to T. paynterae subsp. paynterae were quantified by direct observation. The bee fauna varied over the two years with average richness higher in 2010 than 2011 and was higher on the ridge compared with the slope and flats below the inselberg. The Tetratheca species are buzz pollinated and T. paynterae subsp. paynterae is only visited by a subsection of the bee fauna, mainly Lasioglossum species, which were shown to be relatively faithful to the species in terms of the pollen they carried. Flowering mainly occurs after the winter wet season, but may occur at other times when there has been substantial rain. This may not coincide with bee activity. In the winter flowers may be poorly serviced if maximum daytime temperatures are below 20°C. However, in spring when temperatures are higher the majority of flowers were pollinated and there was no significant difference in proportion of pollinated flowers between the four taxa examined. As T. paynterae is outcrossing the propensity for bees to attend few flowers on a visit to each plant, often on the outer part of the plant canopy, will likely ensure a high success rate for seed formation. High seed set in such an arid environment with few suitable sites for seedling establishment is essential so some propagules can find safe sites for establishment to maintain population numbers.

EFFECTS OF POLLEN CONTAMINATION AND KERNEL WEIGHT ON KERNEL STRUCTURE OF MAIZE IN OPEN AND SELF POLLINATION TREATMENTS

In small plot experiments conducted in maize, the mostly used pollination methodsare open and self-pollination treatments. Comparative studies using thesetreatments are abundant in scientific literature; however studies on the effect ofcross pollination and kernel weight on kernel biochemical properties in differenttreatments are limited. In this study, we conducted a comparative experiment toinvestigate the effect of pollen contamination and mean kernel weight on kernelbiochemical composition of ten different maize genotypes by using two differentpollination methods.Open and self-pollination treatments were applied aspollination methods. Eight different traits; kernel weight, cross pollination rate,protein, oil, carbohydrate, oleic acid linoleic acid and carotenoid content weremeasured. Regression analyses were performed to understand the effects of crosspollination and mean kernel weight on biochemical constituents of maize kernel indifferent treatments. Results showed that the major biochemical traits, such asprotein, oil and carbohydrate content were significantly affected by pollencontamination but minor traits were not. When data were combined (n=60) theeffect of pollen contamination in different treatments was not clearly understood.When data (n=30) of each treatment were separately analyzed, it was found thatcross pollination rate had significant effect on the most of biochemical constituentsin open pollination. Overall, results suggested that pollen contamination had aneffect on major biochemical traits in maize and hand pollination could be used forpreventing of unwanted effect of pollen contamination in small plot experiments.However, it should be considered that the effects of hand pollination on kernelweight affect the some biochemical traits in maize.

Frequent Insect Visitors Are Not Always Pollen Carriers in Hybrid Carrot Pollination.

Insect crop visitations do not necessarily translate to carriage or transfer of pollen. To evaluate the potential of the various insects visiting hybrid carrot flowers to facilitate pollen transfer, this study examines insect visitation rates to hybrid carrot seed crops in relation to weather, time of day and season, pollen carrying capacity, inter-row movement, and visitation frequency to male-fertile and male-sterile umbels. The highest pollen loads were carried by nectar scarabs, honey bees, and the hover fly Eristalis tenax (Linnaeus). Honey bees and muscoid flies were observed to forage mostly within the male fertile carrot row while nectar scarabs and E. tenax foraged across rows, carrying equal pollen loads regardless of their distance from the pollen source. All observed insect taxa were more frequently seen visiting male-fertile than male-sterile umbels. In contrast to other visiting insects, honey bees were abundant and frequent visitors and were observed carrying high pollen loads. Consequently, we suggest both optimizing honey bee management and improving the attraction of carrot lines to honey bees to improve pollination rates for hybrid carrot seed crops.

Mating patterns and pollen dispersal in a Japanese larch (Larix kaempferi) clonal seed orchard: a case study.

Pollination dynamics highly determines the genetic quality of seed orchard crops. However, there is less research about the effect of mating patterns on seed productivity of orchard crops. So far, clonal seed orchards have been producing genetically improved seedlings used for most Japanese larch (Larix kaempferi (Lamb.) Carr.) plantations in China. In the present study, a total of 17 highly variable simple sequence repeat (SSR) markers were used for genotyping a progeny trial population consisting of 647 open-pollinated progenies germinated from seeds which were collected from 63 maternal clones with 140 potential paternal clones in a Japanese larch clonal seed orchard in China. Paternity analysis was used in the present case study in order to evaluate the level of paternal gametic contribution, estimate pollen contamination and selfing rates, and investigate pollination patterns, pollen dispersal patterns and the impact of mating patterns on seed productivity of orchard crops. We observed 93.7% of the success rate of the parental assignment, unequal paternal gametic contribution (0-12.4%) with 6.3% of the progenies derived from pollen contamination or unsampled pollen donors, and absence of evidence for selfing. We also found that pollination rate highly depended on the distance between pollen donors and maternal parents, the majority of the identified crossing (65.7%) occurred between clones within a 150-m radius, and large variations in growth performance existed among the paternal half-siblings. Progeny growth performance (diameter at breast (DBH) and height (HGT)) was measured at Age-20 in order to investigate the impact of mating patterns on timber production of orchard crops. As either the paternal or maternal, two clones (i. e., clones Z38 and Z62) were identified to have produced progenies with higher average stem volume breeding values than that of all of the progenies. Specifically, the genetic gains for volume were 3.53% for the two clones as paternal parents, and 8.26% as the maternal parents at Age-20. Thus, both elite clones were ideal candidates for the construction of next-generation clonal seed orchards due to their synchronous reproductive phenology with greater crossing rate and higher genetic gain. These results improved the pedigree information to provide solid evidence of mating patterns for future design and effective management of seed orchards and for the development of viable long-term breeding strategies for other coniferous species.

Effect of Honey Bee (Apis mellifera L.) Density on Pollination and Fruit Set of Avocado (Persea americana Mill.) Cv. Hass.

Abstract The objective of this research was to determine the effect of honeybee density on pollination and fruit set of the Hass avocado. The research was carried out in the municipality of Popayán, Colombia. Three avocado orchards were selected, each one with an area of one hectare and trees with an age of six years. The treatments were: 1) four hives/ha, 2) six hives/ha, and 3) control without hives. Treatments of six and four hives/ha presented significant differences with respect to the control, with a honeybee density per tree of 7.72, 6.04 and 2.72, pollination rate of 60, 55 and 50%, pollination efficiency of 7.57, 6.04 and 5.98 grains of pollen per stigma, 6.11, 4.13 and 3.54% fruit set initial, 0.058, 0.048 and 0.028% fruit set final, 231, 212 and 137 of fruits per tree, 46.2, 38.2 and 21.6 kg fruit per tree, respectively. The results obtained show an increase of honey-bee density per tree, pollination rate, pollination efficiency, % fruit set, % fruit set final, number of fruits per tree and total fruit weight per tree when six and four bee hives/ha are introduced in the avocado crop.

Polinização e frutificação da pereira ‘Rocha’ em Vacaria, RS, Brasil

Representing only 10% of consumption, Brazilian pear production has been stagnating for more than 20 years, at around 20 thousand tons per year, the results of the low cultivated area due to low productivity and consequent low profitability. One of the main causes of the low production of pear orchards is a low fruit set, due to problems in the process of pollination and fertilization of flowers. The objective of this work is to evaluate the natural fruiting process of ‘Rocha’ pear, identifying the rate of open pollination, natural parthenocarpic and self-pollination, as well as to evaluate potential techniques to increase the fruit set of ‘Rocha’ pear, under the climatic conditions in Vacaria, RS. ‘Rocha’ pear trees grafted on the ‘BA 29’ quince rootstock with 'Packham's Triumph' pollinator cultivated in whole rows were used in the proportion of one row of pollinator for three of Rocha cultivar. The effect of controlled pollination with ‘Packham’s Triumph’ and Pyrus calleryana pollen, the effect of the GA3, GA4+7 + BA, TDZ, AVG, plant growth regulators on the fruit set, productivity and fruit quality of ‘Rocha’ pears were studied. It was found that the self-pollination and natural parthenocarpy rates of ‘Rocha’ pear tree and the implanted arrangement do not provide commercially profitable production. The climatic conditions during the flowering, although not favorable, allow the fecundation and fruiting of ‘Rocha’ pear tree in the conditions of study. 20 mg L-1 sprays of TDZ increase fruit set and the productivity of ‘Rocha’ pear trees.

Floral Trait Variations Among Wild Tobacco Populations Influence the Foraging Behavior of Hawkmoth Pollinators

Most pollinators visit flowers in the search of nectar rewards. However, as the floral nectar can often not be directly detected by pollinators, many flower visitors use secondary metabolites such as odor- or taste-proxies to anticipate nectar quantity and quality. Plants might exploit these sensory inferences of the pollinator to increase their pollination rates without increasing their caloric investment into their floral rewards. Here we investigated the effects of natural variation in certain primary and secondary floral metabolites in three populations of the wild tobacco, Nicotiana attenuata, on the pollination behavior of the hawkmoth Manduca sexta. Although offering the same caloric value per flower, the plants of these populations differ in the compositions and concentrations of sugars within the nectar. Moreover, the flowers of these plants emitted highly contrasting levels of attractive floral volatiles (benzyl acetone), but did not differ in the amounts of defensive nectar metabolites (nicotine). In wind tunnel assays with M. sexta moths, plants from those populations that released the largest amount of benzyl acetone as well as those that had a higher ratio of nectar sucrose were more frequently visited and re-visited by the hawkmoth. High emissions of benzyl acetone additionally correlated with a higher time investment of the moths into individual flowers on each visit, leading to the largest foraging success of the moths on those flowers that were most strongly scented. We propose that it is the variation of flower metabolites and their detection by the pollinator rather than the actual caloric value of the nectar, which determines pollinator visitations to a certain flower population. Hence, plants could potentially create a specialist pollinator community by altering their floral signals, either by producing volatiles that pollinators prefer or by providing nectar sugars that pollinators are most sensitive to, while at the same time keeping the caloric value of their nectar rewards at a constant level. These findings highlight the importance of variations among floral signals and their detection by specific pollinators for plant diversification as well as for the evolution of specific plant-pollinator interactions.

Population structures and seasons affected flowering, pollination and reproductive outputs of sandalwood in Gunung Sewu, Java, Indonesia

Ratnaningrum YWN, Indrioko S, Faridah E, Syahbudin A. 2018. Population structures and seasons affected flowering, pollination and reproductive outputs of sandalwood in Gunung Sewu, Java, Indonesia. Nusantara Bioscience 10: 12-26. Sandalwood was the origin to the south-eastern islands of Indonesia, but is recently occurred as new landraces in Gunung Sewu Geopark, Java, Indonesia. This study compared flowering and pollination, and their effect on reproductive outputs, among sandalwood populations in Gunung Sewu, during the dry and rainy season of 2016 flowering period. Flowering and pollination rate differed significantly between seasons but were similar among sites. Oppositely, reproductive outputs differed significantly among sites, but were similar between seasons. The rainy season produced more flowers and pollination. Pollination was less correlated to flowers abundance, but more affected by population size. The higher and cooler population visited more by Dipterans (31.8% to 32.6%) and Hymenopterans (28.2% to 30%), while the warmer, lower sites dominated by Lepidopterans (37.2% to 43%) and Dipterans (32.9% to 38.2%). Higher population received fewer visits, but more visitors diversity (28 families). In contrast, lower sites received more visits, but with less diversity (20 families). Most insect families were considered “Rare” and “Occasional”. However, pooled altogether, the whole families of Lepidopterans and Dipterans considered “Frequent” and “Effective”. The Hymenopterans considered “Frequent” and “Effective” at Nglanggeran and Wanagama. The Cicadellidae of Coleopterans, along with arachnids and grasshoppers, were considered robbers. All of the agents were diurnal. However, the time of activity was varied. Rainy season gained more flowers and visits, but in contrast, resulted in fewer fruits at all sites. Both flowers abundance and pollination were negatively correlated to the reproductive parameters. Populations might gain more flowers and visits, but the reproductive outputs were significantly lower. Particularly in the clonalized and lower heterozygosity populations, more flowers increased geitonogamy which may lead to inbreeding depression.