Displaying publications 1 - 20 of 41 in total

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  1. Financial risk evaluations in Malaysian stock exchange using extreme-value-theory and component-ARCH model
    Chin WC, Zaidi Isa, Abu Hassan Shaari Mohd Nor
    Sains Malaysiana, 2009;38.
    This study investigates the value-at-risk (VaR) using nonlinear time-varying volatility (ARCH model) and extreme-value-theory (EVT) methodologies. Similar VaR estimation and prediction are observes under the EVT and heavy-tailed long-memory ARCH approaches. The empirical results evidence the EVT-based VaR are more accurate but only at higher quantiles. It is also found that EVT approach is able to provide a convenient framework for asymmetric properties in both the lower and upper tails which implies that the risk and reward are not equally likely for the short- and long-trading positions in Malaysian stock market.
    Matched MeSH terms: Reward
  2. Fulltext Feedback-related potentials in a gambling task with randomised reward
    Mushtaq F, Guillen PP, Wilkie RM, Mon-Williams MA, Schaefer A
    Data Brief, 2016 Mar;6:378-85.
    PMID: 26862585 DOI: 10.1016/j.dib.2015.11.060
    Event-related potentials (ERPs) time-locked to decision outcomes are reported. Participants engaged in a gambling task (see [1] for details) in which they decided between a risky and a safe option (presented as different coloured shapes) on each trial (416 in total). Each decision was associated with (fully randomised) feedback about the reward outcome (Win/Loss) and its magnitude (varying as a function of decision response; 5-9 points for Risky decisions and 1-4 points for Safe decisions). Here, we show data demonstrating: (a) the influence of Win feedback in the preceding outcome (Outcome t-1) on activity related to the current outcome (Outcome t ); (b) difference wave analysis for outcome expectancy- separating Expected Outcomes (consecutive Loss trials subtracted from consecutive reward) from Unexpected Outcomes (subtracting Loss t-1Win t trials from Win t-1Loss t trials); (c) difference waves separating Switch and Stay responses for Outcome Expectancy; (d) the effect of magnitude induced by decisions (Risk t vs. Safe t ) on Outcome Expectancy; and finally, (e) expectations reflected by response switch direction (Risk to Safe responses vs. Safe to Risk t ) on the FRN at Outcome t .
    Matched MeSH terms: Reward
  3. Fulltext Contemporary issues in coach education and learning coaching in modern society – a review
    Oleksandr Krasilshchikov
    Jurnal Sains Sukan & Pendidikan Jasmani, 2015;4(1):0-0.
    MyJurnal
    Sports coaching and especially high performance coaching has long existed in some sort of duality. On one hand, sport coaching has been regarded by many as a prestigious and rewarding job, whereas on the other, sport coaching still lacks a reputation as a career opportunity mostly due to the fact that coaching is yet to receive its full professional recognition in the society. Given the vast variety of coaching qualifications, coaching roles and coaching occupations available within sport infrastructure in the society, the situation has got progressively complicated with the recognition of coaching qualifications. In addition, the growing popularity of high performance and participation sports in the society started drawing more attention from the public to the issues of coach education, competence and qualifications. Malaysian scenario on the issue is quite complicated as well, and growing demand to uplift the country’s performance in SEA, Asian, Commonwealth and Olympic Games requires interference from the higher education institutions and NGOs.
    Matched MeSH terms: Reward
  4. Fulltext Conditional Learning Deficits in Children with ADHD can be Reduced Through Reward Optimization and Response-Specific Reinforcement
    De Meyer H, Tripp G, Beckers T, van der Oord S
    Res Child Adolesc Psychopathol, 2021 09;49(9):1165-1178.
    PMID: 33792820 DOI: 10.1007/s10802-021-00781-5
    When children with ADHD are presented with behavioral choices, they struggle more than Typically Developing [TD] children to take into account contextual information necessary for making adaptive choices. The challenge presented by this type of behavioral decision making can be operationalized as a Conditional Discrimination Learning [CDL] task. We previously showed that CDL is impaired in children with ADHD. The present study explores whether this impairment can be remediated by increasing reward for correct responding or by reinforcing correct conditional choice behavior with situationally specific outcomes (Differential Outcomes). An arbitrary Delayed Matching-To-Sample [aDMTS] procedure was used, in which children had to learn to select the correct response given the sample stimulus presented (CDL). We compared children with ADHD (N = 45) and TD children (N = 49) on a baseline aDMTS task and sequentially adapted the aDMTS task so that correct choice behavior was rewarded with a more potent reinforcer (reward manipulation) or with sample-specific (and hence response-specific) reinforcers (Differential Outcomes manipulation). At baseline, children with ADHD performed significantly worse than TD children. Both manipulations (reward optimization and Differential Outcomes) improved performance in the ADHD group, resulting in a similar level of performance to the TD group. Increasing the reward value or the response-specificity of reinforcement enhances Conditional Discrimination Learning in children with ADHD. These behavioral techniques may be effective in promoting the learning of adaptive behavioral choices in children with ADHD.
    Matched MeSH terms: Reward
  5. Fulltext Randomised prior feedback modulates neural signals of outcome monitoring
    Mushtaq F, Wilkie RM, Mon-Williams MA, Schaefer A
    Neuroimage, 2016 Jan 15;125:868-879.
    PMID: 26497268 DOI: 10.1016/j.neuroimage.2015.10.046
    Substantial evidence indicates that decision outcomes are typically evaluated relative to expectations learned from relatively long sequences of previous outcomes. This mechanism is thought to play a key role in general learning and adaptation processes but relatively little is known about the determinants of outcome evaluation when the capacity to learn from series of prior events is difficult or impossible. To investigate this issue, we examined how the feedback-related negativity (FRN) is modulated by information briefly presented before outcome evaluation. The FRN is a brain potential time-locked to the delivery of decision feedback and it is widely thought to be sensitive to prior expectations. We conducted a multi-trial gambling task in which outcomes at each trial were fully randomised to minimise the capacity to learn from long sequences of prior outcomes. Event-related potentials for outcomes (Win/Loss) in the current trial (Outcomet) were separated according to the type of outcomes that occurred in the preceding two trials (Outcomet-1 and Outcomet-2). We found that FRN voltage was more positive during the processing of win feedback when it was preceded by wins at Outcomet-1 compared to win feedback preceded by losses at Outcomet-1. However, no influence of preceding outcomes was found on FRN activity relative to the processing of loss feedback. We also found no effects of Outcomet-2 on FRN amplitude relative to current feedback. Additional analyses indicated that this effect was largest for trials in which participants selected a decision different to the gamble chosen in the previous trial. These findings are inconsistent with models that solely relate the FRN to prediction error computation. Instead, our results suggest that if stable predictions about future events are weak or non-existent, then outcome processing can be determined by affective systems. More specifically, our results indicate that the FRN is likely to reflect the activity of positive affective systems in these contexts. Importantly, our findings indicate that a multifactorial explanation of the nature of the FRN is necessary and such an account must incorporate affective and motivational factors in outcome processing.
    Matched MeSH terms: Reward*
  6. Electroencephalography-detected neurophysiology of internet addiction disorder and internet gaming disorder in adolescents - A review
    Sharifat H, Suppiah S
    Med J Malaysia, 2021 05;76(3):401-413.
    PMID: 34031341
    INTRODUCTION: Internet Addiction Disorder (IAD) is an umbrella term for various types of Internet-based behavioural addiction, whereas Internet Gaming Disorder (IGD) addresses a specific type of IAD that is postulated to be due to a lack of control in impulse inhibition. IGD is an area of concern in the Diagnostic and Statistics Manual of Mental Disorders (DSM-5), which can be objectively assessed by dysfunctional behaviour and the increasing time of being online, particularly during the COVID-19 pandemic. Electroencephalography (EEG) identifies amplitude changes in the evoked response potential (ERP) among IGDs, correlated with underlying comorbidities.

    MATERIALS AND METHODS: A scoping review was performed to elaborate on the research regarding resting-state EEG and task-based EEG, particularly for Go/No-go paradigms pertaining to subjects with IAD or specifically IGD. The role of EEG was identified in its diagnostic capability to identify the salient changes that occurred in the response to reward network and the executive control network, using restingstate and task-based EEG. The implication of using EEG in monitoring the therapy for IAD and IGD was also reviewed.

    RESULTS: EEG generally revealed reduced beta waves and increased theta waves in addicts. IGD with depression demonstrated increased theta and decreased alpha waves. Whereas increased P300, a late cognitive ERP component, was frequently associated with impaired excessive allocation of attentional resources of the IAD towards addiction-specific cues. IGD had increased whole brain delta waves at baseline, which showed significant reduction post therapy.

    CONCLUSION: EEG can identify distinct neurophysiological changes among Internet Addiction Disorder and Internet Gaming Disorder that are akin to substance abuse disorders.

    Matched MeSH terms: Reward*
  7. Fulltext Altmetrics: A new paradigm for scholarly communication
    Shekhawat KS, Chauhan A
    Indian J Dent Res, 2019 3 23;30(1):125-126.
    PMID: 30900670 DOI: 10.4103/ijdr.IJDR_27_17
    Counting citations have been the usual norm to determine the impact of any research and/or scholar. However, with majority of the scholarly activities happening on the World Wide Web, traditional counting of citations is now being termed "slower." The recent explosion of online data storage for many articles may serve as a pool which uses social media sites to navigate. Altmetrics has been proposed as the new entity which aims to change the focus of the scholarly reward system to value and encourage web-native scholarship. This paper makes an attempt to understand altmetrics.
    Matched MeSH terms: Reward
  8. Pollination biology in a lowland dipterocarp forest inSarawak, Malaysia. I. Characteristics of the plant-pollinator communityin a lowland dipterocarp forest
    Momose K, Yumoto T, Nagamitsu T, Kato M, Nagamasu H, Sakai S, et al.
    Am J Bot, 1998 Oct;85(10):1477-501.
    PMID: 21684899
    Flowerings and flower visitors were observed continuously in alowland dipterocarp forest in Sarawak, Malaysia, for 53 mo in1992-1996. Flower visitors of 270 plant species were observed orcollected, and pollinators were assessed by observing body contact tostigmas and anthers. We recognized 12 categories of pollination systems.Among them, plants pollinated by social bees included the largest numberof species (32%) and were followed by beetle-pollinated species(20%). Pollination systems were significantly related with somefloral characters (flowering time of day, reward, and floral shape), butnot with floral color. Based on the relationships between pollinatorsand floral characters, we described pollination syndromes found in alowland dipterocarp forest. The dominance of social bees and beetlesamong pollinators is discussed in relation to the general floweringobserved in dipterocarp forests of West Malesia. In spite of high plantspecies diversity and consequent low population densities of lowlanddipterocarp forests, long-distance-specific pollinators were uncommoncompared with theNeotropics.
    Matched MeSH terms: Reward
  9. The impact of cognitive load on reward evaluation
    Krigolson OE, Hassall CD, Satel J, Klein RM
    Brain Res, 2015 Nov 19;1627:225-32.
    PMID: 26431993 DOI: 10.1016/j.brainres.2015.09.028
    The neural systems that afford our ability to evaluate rewards and punishments are impacted by a variety of external factors. Here, we demonstrate that increased cognitive load reduces the functional efficacy of a reward processing system within the human medial-frontal cortex. In our paradigm, two groups of participants used performance feedback to estimate the exact duration of one second while electroencephalographic (EEG) data was recorded. Prior to performing the time estimation task, both groups were instructed to keep their eyes still and avoid blinking in line with well established EEG protocol. However, during performance of the time-estimation task, one of the two groups was provided with trial-to-trial-feedback about their performance on the time-estimation task and their eye movements to induce a higher level of cognitive load relative to participants in the other group who were solely provided with feedback about the accuracy of their temporal estimates. In line with previous work, we found that the higher level of cognitive load reduced the amplitude of the feedback-related negativity, a component of the human event-related brain potential associated with reward evaluation within the medial-frontal cortex. Importantly, our results provide further support that increased cognitive load reduces the functional efficacy of a neural system associated with reward processing.
    Matched MeSH terms: Reward
  10. Designing a neurofeedback device to quantify attention levels using coffee as a reward system
    Cheng KS, Lee JX, Lee PF
    Int J Occup Saf Ergon, 2021 Mar;27(1):258-266.
    PMID: 29658406 DOI: 10.1080/10803548.2018.1459348
    Purpose. Work performance is closely related to one's attention level. In this study, a brain-computer interface (BCI) device suitable for office usage was chosen to quantify the individual's attention levels. Methods. A BCI system was adopted to interface brainwave signals to a coffee maker via three ascending levels of laser detectors. The preliminary test with this prototype was to characterize the attention level through the collected coffee amount. Here, the preliminary testing was comparing the correlation between the attention level and the participants' cumulative grade point average (CGPA) and scores from the 21-item depression, anxiety, and stress scale (DASS-21) and the attentional control scale (ACS) using ordinal regression. It was assumed that a greater CGPA would generate a greater attention level. Result. The generated coffee amount from the BCI system had a significant positive correlation with the CGPA (p = 0.004), mild depression (p = 0.019) and mild and extremely severe anxiety (p = 0.044 and p = 0.019, respectively) and a negative correlation with the ACS score (p = 0.042). Conclusion. This simple and cost-effective prototype has the potential to enable everyone to know their immediate attention level and predict the possible correlation to their mental state.
    Matched MeSH terms: Reward
  11. Value, drug addiction and the brain
    Loganathan K, Ho ETW
    Addict Behav, 2021 05;116:106816.
    PMID: 33453587 DOI: 10.1016/j.addbeh.2021.106816
    Over the years, various models have been proposed to explain the psychology and biology of drug addiction, built primarily around the habit and compulsion models. Recent research indicates drug addiction may be goal-directed, motivated by excessive valuation of drugs. Drug consumption may initially occur for the sake of pleasure but may transition to a means of escaping withdrawal, stress and negative emotions. In this hypothetical paper, we propose a value-based neurobiological model for drug addiction. We posit that during dependency, the value-based decision-making system in the brain is not inactive but has instead prioritized drugs as the reward of choice. In support of this model, we consider the role of valuation in choice, its influence on pleasure and punishment, and how valuation is contrasted in impulsive and compulsive behaviours. We then discuss the neurobiology of value, beginning with the dopaminergic system and its relationship with incentive salience before moving to brain-wide networks involved in valuation, control and prospection. These value-based neurobiological components are then integrated into the cycle of addiction as we consider the development of drug dependency from a valuation perspective. We conclude with a discussion of cognitive interventions utilizing value-based decision-making, highlighting not just advances in recalibrating the valuation system to focus on non-drug rewards, but also areas for improvement in refining this approach.
    Matched MeSH terms: Reward
  12. Associations Between Delay Discounting and Connectivity of the Valuation-control System in Healthy Young Adults
    Loganathan K, Lv J, Cropley V, Ho ETW, Zalesky A
    Neuroscience, 2021 01 01;452:295-310.
    PMID: 33242540 DOI: 10.1016/j.neuroscience.2020.11.026
    The process of valuation assists in determining if an object or course of action is rewarding. Delay discounting is the observed decay of a rewards' subjective value over time. Encoding the subjective value of rewards across a spectrum has been attributed to brain regions belonging to the valuation and executive control systems. The valuation system (VS) encodes reward value over short and long delays, influencing reinforcement learning and reward representation. The executive control system (ECS) becomes more active as choice difficulty increases, integrating contextual and mnemonic information with salience signals in the modulation of decision-making. Here, we aimed to identify resting-state functional connectivity-based patterns of the VS and ECS correlated with value-setting and delay discounting (outside-scanner paradigm) in a large (n = 992) cohort of healthy young adults from the Human Connectome Project (HCP). Results suggest the VS may be involved in value-setting of small, immediate rewards while the ECS may be involved in value-setting and delay discounting for large and small rewards over a range of delays. We observed magnitude sensitive connections involving the posterior cingulate cortex, time-sensitive connections with the ventromedial and lateral prefrontal cortex while connections involving the posterior parietal cortex appeared both magnitude- and time-sensitive. The ventromedial prefrontal cortex and posterior parietal cortex could act as "comparator" regions, weighing the value of small rewards against large rewards across various delay duration to aid in decision-making.
    Matched MeSH terms: Reward
  13. Fulltext Adolescent’s strategies and reverse influence in family food decision making
    Othman, M., Boo, H.C., Wan Rusni, W.I.
    International Food Research Journal, 2013;20(1):131-139.
    MyJurnal
    The role of adolescents in family decision making related to food consumption in Malaysia has received comparatively little or no attention by researchers although there were evidences of differences in influences found in other countries. This study addressed the research gap by testing adolescents’ bilateral strategies in influencing their family decision using family power theory. A survey of 500 adolescents from urban area was conducted to investigate their influence based on their involvement in family consumer tasks. Key findings include strong relationship between perception of influence and rewards thus indicate the existence of strategies in adolescents influence attempt.
    Matched MeSH terms: Reward
  14. Fulltext Issues on trust management in wireless environment
    Sirageldin, Abubakr, Baharum Baharudin, Low, Tang Jung
    Pertanika Journal of Science & Technology, 2013;21(1):183-192.
    MyJurnal
    Developing a trust management scheme in mobile computing environment is increasingly important,
    and the effective trust management model is a challenging task. Business, education, military, and
    entertainment have motivated the growth of ubiquitous and pervasive computing environments, which are always available due to the widespread of portable and embedded devices. Wireless and mobile computing are good example of ubiquitous and pervasive computing environments. Due to the uncertainty and mobility in such environments, the issue of trust has been regarded as an important security problem. Malicious nodes are a major threat to these networks; the trust system can monitor the behaviour of nodes and accordingly rewards well-behaved nodes and punishes misbehaving ones. At present, there are a lot of endeavours on the trust model of the pervasive computing environment. In this paper, a trust management framework for mobile computing is presented. The hybrid framework is based on a fusion of the support vector machine (SVM) and fuzzy logic system. From the results, it can be stated that the framework is effective, dynamic, lightweight, and applicable.
    Matched MeSH terms: Reward
  15. Fulltext Public health inspectors enforcement in Selangor, Malaysia
    Sharifa Ezat, A., Aljunid, S.M.
    Malaysian Journal of Public Health Medicine, 2005;5(1):56-61.
    MyJurnal
    A cross·sectional study was done to determine the capacity of Public Health Inspectors in Selangor using a seh administered questionnaire and universal sampling, to determine the enforcement of public health legislation and its influencing factors. A total of 99 respondents from the District Health Offices and 100 respondents from the Local Health Departments participated. The level of enforcement is generally low in all the units except for the Food Unit and Sanitary and Hygiene Units. Factors influencing enforcement of Public Health Legislations are the unit where the respondents worlc and the length of service with the unit. Further analysis using multiple logistic regression, found that respondents from the Food Unit (OR ZZ; 95% C1: 7 .9-58.9 ) , being in the
    U8 category (OR 5; 95% C1: l.4» 17.6), service offour years and above in the same unit (OR 6; 95% C1: 2.2»13.8) , received service rewards (OR 3; 95% C1 : 1.2· 6.9); low exposure to bribery (OR 46; 95% C1: 2.3·100.0) and offered bribes while on the field (OR 3; 95% C1: 1.02» 4.8) have higher kvel enforcement performance. Attention must be given to the enforcement organization with respect to duration of service, service awards and monitoring of bribes exposure to help develop the enforcement of public health legislations.
    Matched MeSH terms: Reward
  16. Chronic mitragynine (kratom) enhances punishment resistance in natural reward seeking and impairs place learning in mice
    Ismail NIW, Jayabalan N, Mansor SM, Müller CP, Muzaimi M
    Addict Biol, 2017 Jul;22(4):967-976.
    PMID: 26990882 DOI: 10.1111/adb.12385
    Kratom (Mitragyna speciosa) is a widely abused herbal drug preparation in Southeast Asia. It is often consumed as a substitute for heroin, but imposing itself unknown harms and addictive burdens. Mitragynine is the major psychostimulant constituent of kratom that has recently been reported to induce morphine-like behavioural and cognitive effects in rodents. The effects of chronic consumption on non-drug related behaviours are still unclear. In the present study, we investigated the effects of chronic mitragynine treatment on spontaneous activity, reward-related behaviour and cognition in mice in an IntelliCage® system, and compared them with those of morphine and Δ-9-tetrahydrocannabinol (THC). We found that chronic mitragynine treatment significantly potentiated horizontal exploratory activity. It enhanced spontaneous sucrose preference and also its persistence when the preference had aversive consequences. Furthermore, mitragynine impaired place learning and its reversal. Thereby, mitragynine effects closely resembled that of morphine and THC sensitisation. These findings suggest that chronic mitragynine exposure enhances spontaneous locomotor activity and the preference for natural rewards, but impairs learning and memory. These findings confirm pleiotropic effects of mitragynine (kratom) on human lifestyle, but may also support the recognition of the drug's harm potential.
    Matched MeSH terms: Reward*
  17. Brain activity elicited by reward and reward omission in individuals with psychopathic traits: An ERP study
    Salim MA, van der Veen FM, van Dongen JD, Franken IH
    Biol Psychol, 2015 Sep;110:50-8.
    PMID: 26188154 DOI: 10.1016/j.biopsycho.2015.07.001
    Psychopathy has been associated with behavioral adaptation deficits, which might be associated with problems in feedback and reward processing. In the present study, we examined the relation between psychopathic traits and reward processing in a passive gambling task. A total of 39 male participants who scored high (HP) and 39 male participants who scored low (LP) on the Triarchic Psychopathy Measure (TriPM), total score were tested. Feedback-related Event-Related Potentials (ERPs; i.e., P2, FRN, and P3) on predicted and unpredicted rewards and reward omissions were compared between both groups. It was found that in HP individuals, the P2 was enhanced for predicted rewards and reward omissions, but not for unpredicted stimuli. Moreover, HP individuals as compared to the LP individuals demonstrated a generally reduced P3 amplitude. The FRN amplitude, however, did not differ between the two groups. In addition, HP individuals showed enhanced reward sensitivity on the self-report level. Taken together, these findings suggest that HP individuals show enhanced sensitivity to early and reduced sensitivity to later markers of processing reinforcement learning signals, which points in the direction of compromised behavioral adaptation.
    Matched MeSH terms: Reward*
  18. Fulltext Rajyoga meditation induces grey matter volume changes in regions that process reward and happiness
    Babu MGR, Kadavigere R, Koteshwara P, Sathian B, Rai KS
    Sci Rep, 2020 09 30;10(1):16177.
    PMID: 32999361 DOI: 10.1038/s41598-020-73221-x
    Studies provide evidence that practicing meditation enhances neural plasticity in reward processing areas of brain. No studies till date, provide evidence of such changes in Rajyoga meditation (RM) practitioners. The present study aimed to identify grey matter volume (GMV) changes in reward processing areas of brain and its association with happiness scores in RM practitioners compared to non-meditators. Structural MRI of selected participants matched for age, gender and handedness (n = 40/group) were analyzed using voxel-based morphometric method and Oxford Happiness Questionnaire (OHQ) scores were correlated. Significant increase in OHQ happiness scores were observed in RM practitioners compared to non-meditators. Whereas, a trend towards significance was observed in more experienced RM practitioners, on correlating OHQ scores with hours of meditation experience. Additionally, in RM practitioners, higher GMV were observed in reward processing centers-right superior frontal gyrus, left inferior orbitofrontal cortex (OFC) and bilateral precuneus. Multiple regression analysis showed significant association between OHQ scores of RM practitioners and reward processing regions right superior frontal gyrus, left middle OFC, right insula and left anterior cingulate cortex. Further, with increasing hours of RM practice, a significant positive association was observed in bilateral ventral pallidum. These findings indicate that RM practice enhances GMV in reward processing regions associated with happiness.
    Matched MeSH terms: Reward*
  19. A new pollination system: dung-beetle pollination discovered in Orchidantha inouei (Lowiaceae, Zingiberales) in Sarawak, Malaysia
    Sakai S, Inoue T
    Am J Bot, 1999 Jan;86(1):56-61.
    PMID: 21680345
    Lowiaceae, a family of the Zingiberales, comprise 11 species in the single genus Orchidantha. Here we present the first report on the pollination of Lowiaceae and describe a new system of dung-beetle pollination from Sarawak, Borneo. Orchidantha inouei has a zygomorphic flower located just above the ground. Observations revealed that the plant is visited frequently and is pollinated by scarabaeid dung beetles, mainly members of the genus Onthophagus. All four species of Onthophagus collected on O. inouei have also been caught using traps baited with dung or carrion in Borneo. Onthophagus was presumably attracted to the dung-like odor of the flower. Pollination of O. inouei is different from other examples of beetle pollination in that its flower provides neither reward nor protected space. Dung beetles are excellent at following a particular dung scent. Orchidantha is the only genus that includes species lacking floral nectar. It is interesting that this deception pollination using dung beetles was found in Zingiberales, in which all known species have mutual and specialized relationships with their long-distance, but costly, pollinators-bees, birds, and bats.
    Matched MeSH terms: Reward
  20. Beetle pollination of Shorea parvifolia (section Mutica, Dipterocarpaceae) in a general flowering period in Sarawak, Malaysia
    Sakai S, Momose K, Yumoto T, Kato M, Inoue T
    Am J Bot, 1999 Jan;86(1):62-9.
    PMID: 21680346
    Pollination ecology of an emergent tree species, Shorea (section Mutica) parvifolia (Dipterocarpaceae), was studied using the canopy observation system in a lowland dipterocarp forest in Sarawak, Malaysia, during a general flowering period in 1996. Although the species has been reported to be pollinated by thrips in Peninsular Malaysia, our observations of flower visitors and pollination experiments indicated that beetles (Chrysomelidae and Curculionidae, Coleoptera) contributed to pollination of S. parvifolia in Sarawak. Beetles accounted for 74% of the flower visitors collected by net-sweeping, and 30% of the beetles carried pollen, while thrips accounted for 16% of the visitors, and 12% of the thrips carried pollen. The apical parts of the petals and pollen served as a reward for the beetles. Thrips stayed inside the flower almost continuously after arrival, and movements among flowers were rare. Fruit set was significantly increased by introduction of beetles to bagged flowers, but not by introduction of thrips. Hand-pollination experiments and comparison of fruit set in untreated, bagged, and open flowers suggested that S. parvifolia was mainly outbreeding.
    Matched MeSH terms: Reward
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