The study compared the impacts of natural weevil pollination versus manual assisted pollination on young mature oil palm in West Kalimantan. Over a 13 month period: - Bunches from palms that received assisted pollination averaged 9.95 kg compared to 7.19 kg for natural pollination, a 39% increase. - Assisted pollination bunches had higher fruit-to-bunch (66.87% vs. 56.14%), kernel-to-bunch (7.01% vs. 5.95%), and oil-to-bunch (29.30% vs. 24.40%) ratios. - Estimated annual revenue increase from assisted pollin

1. 1
+IMPACT OF ASSISTED AND NATURAL WEEVIL POLLINATION IN YOUNG MATURED OIL
PALM IN WEST KALIMANTAN
Mathews J, Barasa R A, Batubara H and Ardiyanto A
joshua.mathews@bumitama.com
husri.batubara@bumitama.com
adhy.ardiyanto@bumitama.com
PT. Bumitama Gunajaya Agro (BGA).
Jl. Melawai Raya No. 10, Kebayoran Baru, Jakarta Selatan 12160, Indonesia.
Phone: 62 21 72798418 Fax: 62 21 72798665.
ABSTRACT
An experiment was conducted from March 2014 to September 2015 on young matured palms of
2011 plantings of P.T.Bumitama Gunajaya Agro, Seriam Jaya Estate, in West Kalimantan for a
comparative study on the impacts of natural weevil and manual assisted pollinated on female
inflorescences and bunches of oil palm. A total of 710 female inflorescences pollinated manually for
a period of 13 months was compared with 709 natural weevil (Elaeidobius kamerunicus) pollinated
female inflorescences of the palms planted in moderately deep Sulfaquepts soil. Measurement
taken in the field for a period of 12 months from October 2014 to September 2015 for harvested
fresh fruit bunches indicated that the average bunch weight in assisted pollinated treatment of 9.95
kg per bunch was about 39.39% higher when compared to the natural weevil pollinated bunches of
7.19 kg per bunch. The fruit to bunch ratio by weight measured in 208 samples of naturally
pollinated bunches was 56.14%, which was 19.12% lower when compared to the same number of
bunches measured in the assisted pollinated bunches, which was 66.87%. The kernel to bunch ratio
of 7.01% in the assisted pollinated treatment was 17.82% higher than the naturally pollinated
bunches of 5.95 %. The overall mean oil to bunch ratio in assisted pollinated bunches was 29.30%
against the natural pollinated bunches of mean 24.40%, an increment of 20.09% in assisted
pollinated bunches was observed. The natural pollinated bunches showed distinct seasonal variation
in the fruit to bunch ratio, from May 2015 to July 2015 bunches exhibited low fruit to bunch ratio.
The experiment indicates that the efficiency of natural pollinator weevils have to be more active to
improve yields in Borneo. An extra expected income of Rp 8.7 juta per hectare per year has been
calculated in assisted pollination with an operation cost of 2.3 juta per hectare. The weevil
population introduced in 1981 in South East Asia, climate in Kalimantan Island, high sex ratio in oil
palm progenies on the pollination at young matured age is also discussed in this paper.
Keywords : Elaeidobius kamerunicus, Assisted pollination, fruit set, and young mature oil palm.
1. INTRODUCTION
The 3000 Elaeidobius kamerunicus weevils were first released in South East Asia on 21st
February
1981 from Africa Pamol du Cameroon Lobe estate to Pamol Plantation in Kluang, Malaysia. The
introduction of weevils had a tremendous impact on the oil palm plantings by improving the fruit
formation on the bunch, kernel and oil extractions, and fresh fruit bunch (FFB) production (Syed et
al., 1982). From thereon, the pollinating weevils were well distributed to a wide range of oil palm
growing countries in Indonesia, Papua New Guinea, India, Thailand, Cambodia and S. America
(Corley and Tinker 2003). The weevil pollinator was a boon to the oil palm industry as it replaced the
tedious manual assisted pollination that was practiced prior to 1981 and which has been described
The paper was presented as poster in the event of 100th
Year
celebration of Indonesian Oil Palm Research Institute and 6th
international seminar IOPRI–MPOB for current research and
Pests, Ganoderma and Pollination for higher productivity held in
Medan on 27th
to 28th
September 2016.

2. 2
by Turner and Gillbank in 1974. However, the weevil pollination and its effect on bunches with
parthenocarpic fruits has been reported in young matured palms, the effect varied depending on
locality, planting age, new planting material of high sex ratio, large scale new plantings and seasonal
behaviour (Suigh et al., 1996, Rao and Law 1998, Chee and Chiu 1998 and Foong et al., 2004).
Method of introducing and increasing weevil population by distributing oil palm male inflorescences
spent in new plantings in Kalimantan has been mentioned by Chee and Chiu 1998. Protecting the
male inflorescence with weevil eggs and larvae, followed by its hatching and morphing in wooden
boxes to improve pollination during monsoon seasons in Sabah were documented by Foong et al.,
2004. In Kalimantan again, hatch and carry system in boxes and hatch and carry by mobile net
system were introduced and practiced for improved pollination in oil palm (Prasetyo and Susanto
2012).
Field visits to young plantings of 2011 plantings in West Kalimantan on February 2014 showed
parthenocarpic fruit formation which prompted the current research authors to test assisted
pollination. The objective of the current study is to understand whether there can be an
improvement in fruit formation by a round of manual or assisted pollination on female
inflorescences in addition to the natural pollination on the same flower of the young mature palm.
The extra fruit formation by an additional assisted pollination will provide the extent of efficiency of
the weevil’s performance in the pollination in young plantings. The study was conducted for a period
of 13 months. The comparative differences in treatments and cost effectiveness of natural and
assisted pollination are discussed further in the present paper.
2. MATERIALS AND METHODS
About 1.30 hectare plot of 2011 planted palms (3 years old) grown in moderately deep Sulfaquept
soil (recent alluvium soil) were selected on March 2014 for the assisted pollination trial at Seriam
Jaya Estate in West Kalimantan. The palms with opened inflorescences of three lobed white creamy
stigmatic female flowers undergoing anthesis were pollinated by assisted pollination using preserved
pollen. After assisted pollination the inflorescences were marked with date of pollination at the base
of its subtending frond with a pointed iron nail. If there are female inflorescences that have just
completed anthesis with natural pollination that is, visually stigmas appeared pinkish lobed, they are
marked as control (without assisted pollination). Thus, 710 female inflorescences from 1.3 hectare
palms were treated by assisted pollination, while 709 flowers were treated as control pollinated
naturally by weevils from March 2014 to March 2015. The assisted pollination was done by the
puffing method approximately 0.3g pollen plus 1.2g talcum powder was used per flower and each
flower was pollinated only once by puffing thrice from the puffing bottle to puff approximately 1.5g
of pollen and talcum powder mixture. The plot of 1.3 hectares was pollinated twice in a week i.e. at
3 days interval. After about 5 ½ to 6 months, the ripe bunches of assisted pollinated and control
natural bunches were harvested and weighed in the field at seventh day harvesting intervals.
Samples of fresh fruit bunches of both treatments were also collected and analysed for oil in the
bunch by the method specified by Mathews J et al., 2009. The bunch weighing in the field was
carried out from September 2014 to September 2015 and analysis in the lab was carried out from
October 2014 to September 2015.

3. 3
3. RESULTS
The monthly fresh fruit bunch (FFB) weight measured in the field from September 2014 to
September 2016 is shown in Table 1 and the bunch analysis carried out in the laboratory for the
period from October 2014 to September 2015 is shown in Table 2.
Table 1. FFB Weighed from September 2014 to September 2015
Months
No. of FFB weighed
Average FFB weight
(Kg)
Control Natural
Pollination
Assisted pollination
Control Natural
Pollination
Assisted pollination
September’14 27 39 6.88 8.64
October’14 85 82 6.65 8.67
November’14 40 42 7.01 9.25
December’14 37 43 7.03 9.92
January’15 38 30 6.38 9.31
February’15 72 60 7.88 9.58
March’15 117 111 7.58 11.02
April’15 45 43 7.68 10.98
May’15 59 66 6.97 10.15
June’15 21 21 6.40 9.26
July’15 45 50 6.36 9.75
August’15 47 52 7.37 9.79
September’15 76 71 7.76 11.10
TOTAL 709 710
7.19
(100)
9.95
(138)
Note: Parenthesis value given is the assisted pollination bunch weight increment over control
Overall the average monthly FFB weight in assisted pollination was significantly higher by 38% than
the natural weevil pollinated bunches (Table 1). Such difference indicates that the weevil population
in young palms is yet to be maximized for the natural pollination of the female inflorescences. The
consequence of FFB weight increment is the increase of crop in the field on per unit area basis as
well.
The FFB samples collected from 208 bunches from each treatment as shown in Table 2 indicates that
the bunch weight, fruit to bunch, kernel to bunch and oil to bunch were significantly higher in the
assisted pollinated bunches than natural weevil pollination. This again shows that the natural
pollination alone may not be sufficient to improve bunch weight in young matured palms. Moreover,
the natural weevil pollinated inflorescences exhibits monthly variation and fluctuations in the
production of fertile fruits as shown in Figure 1 and thereby the oil to bunch varied on a monthly
basis in natural pollination. Highest peak in fruit to bunch formation was observed around January to
April and with an eventual decline in May to August and gradually increased again in September. In
assisted pollination although the similar monthly variation was observed, the fluctuation was not as

4. 4
extreme as natural pollination. The correlation between the fruit to bunch percent was calculated
and oil to bunch percent and the value was 0.88.
Table 2. Sampled Fresh Fruit Bunch Analysis of Natural and Assisted Pollinated Bunches
(October 2014 to September 2015)
Parameter Natural
pollination
Assisted
pollination
Difference
in %
Statistical significance
differences between
treatments P=0.001
No. of samples
analysed
208 208 - -
Bunch weight (kg) 8.82 10.38 17.69 Highly Significant
Fruit to bunch (%) 56.14 66.87 19.12 Highly Significant
Mesocarp to fruit
(%)
80.99 80.88 0.14 Not Significant
Oil to mesocarp
(%)
54.01 54.87 1.60 Not Significant
Kernel to bunch
(%)
5.95 7.01 17.82 Highly Significant
Kernel to Fruit (%) 10.67 10.52 1.41 Not Significant
Oil to bunch (%) 24.40 29.30 20.09 Highly Significant
Figure 1. Monthly fluctuation of fruit to bunch% and oil to bunch % in assisted and natural
pollinations
The expected yield increment in terms of fresh fruit bunch and palm products are given in Table 3.
Based on the data in Tables 1 and 2, the expected potential yield increment by fresh fruit bunch and
crude palm oil and kernel are extrapolated in Table 3. The data indicates that in young mature oil
palm the increment of yield on FFB by assisted pollination can be 38% by bunch weight alone.
However, the crude oil yield by assisted pollination appeared to be 65.70% and kernel 61.90% higher
than the natural pollination.
17.00
19.00
21.00
23.00
25.00
27.00
29.00
31.00
45.00
50.00
55.00
60.00
65.00
70.00
75.00
O
i
l
t
o
b
u
n
c
h
%
F
r
u
i
t
t
o
b
u
n
c
h
%
Assisted pollination Fruit to
bunch %
Natural pollination fruit
to bunch%
Natural pollination oil to
bunch %
Assisted pollination oil to bunch %

5. 5
Table 3. Expected Palm Products Production by Assisted and Natural Pollination
If naturally
pollinated
If assisted
pollinated
Expected yield
increment over
control
The expected total bunch number per
hectare per year 1/
978 978
Average Bunch weight (Kg) per year
(Table 1)
7.19 9.95 38.38%
Potential Fresh fruit bunch tons per
hectare per year
7.03 9.73 38.41%
Potential Crude Palm Oil tons per
hectare per year (Oil to bunch from
Table 2)
1.72 2.85 65.70%
Potential Kernel tons per hectare per
year (Kernel to bunch from Table 2)
0.42 0.68 61.91%
Note:
1/
Proportion of the total bunches of the 1.3 hectare of Table 1 converted to 1 hectare and annualized per year
(September 2014 to August 2015).
Economics of assisted pollination is given in Table 4. The expected economic impacts are the
increment in crude palm oil and kernel productions. An annual additional 1.13 tons of crude palm oil
and 0.26 tons of kernel on per hectare are expected by carrying out additional assisted pollination
on young bunches. The expected extra revenue from crude palm oil is about Rp 9,322,500 per
hectare per year, while from kernel was Rp 1,716,000 per hectare per year. The total extra revenue
per hectare per year from both palm products was close to Rp 11.04 million. The expected annual
cost of operation for assisted pollination for collecting pollen, drying, storing it, and the labour for
field application is about Rp2.62 million per hectare. An additional earning of Rp 8.42 million per
hectare per year is expected after deducting total cost of Rp 2.62 million per hectare per year for
assisted pollination operation.
4. DISCUSSION
In large scale new planting of oil palm in parts of Borneo Island, high percent of parthenocarpic fruit
on bunches was evident in young mature palms. Seasonal variations of fruit formation on the fresh
fruit bunches of young mature palms were also reported (Foong et al., 2004). The decision to
experiment assisted pollination was mooted after field visit to the estate showed that many bunches
exhibits poorly pollinated inspite of introducing the male inflorescence spents for the multiplication
of weevils in the region before the maturity of the palms. The current study was conducted on 2011
plantings- 3 year old palms vulnerable to poor pollination by natural means and the estate was
planted mainly with large scale 2010 and 2011 plantings. There could be other factors too for high
parthenocarpic fruit formation in young plantings. Firstly, most of the current planting materials are
catered for early high sex ratio or precocious yield. Secondly, the soil of recent alluvium could have
favoured early high sex ratio with limited male inflorescences per unit area resulting in high
parthenocarpic fruit formation in bunches at the early stage of maturity.

6. 6
Table 4. Economics of Assisted Pollination
A. Expected Revenue from Palm Products after Assisted Pollination.
Potential crude palm oil expected from natural
pollination
1.72 tonnes per hectare
Potential crude palm oil expected from assisted
pollination
2.85 tonnes per hectare
Difference in crude palm oil production 1.13 tonnes per hectare
Price (Rp) of Crude palm oil per tonne1/
9,322,500
Extra revenue (Rp) from Crude palm oil 9,157,500 per hectare
Potential kernel expected from natural
pollination
0.42 tonnes per hectare
Potential kernel expected from assisted
pollination
0.68 tonnes per hectare
Difference in kernel production 0.26 tonnes per hectare
Price (Rp) of Kernel per tonne 6,600,000
Extra revenue in Kernel 1,716,000 per hectare
Potential total extra revenue from crude palm oil
and kernel (Rp)
11,038,500 per hectare “ A”
B. Expected Cost of Production
Male inflorescence collection@ 7 flowers per
day x 30g per = 210g of pollen.
Rp 90,000/-
210g pollen drying, preparation and storing in
refrigerator.
Rp 90,000/-
Pollen required per hectare @ 0.3g per
inflorescence x 978 inflorescences (Table 3) per
hectare per year.
313g per hectare per year
Cost of 313g of pollen per year (collection,
drying, preparation and storage)
Rp 268,290/-
Cost of Talcum powder @ 1.2g per pollination x
1041 inflorescences per hectare = 1.25 kg x Rp
10,000 per kg
Rp 12,500/-
Labour for pollination per hectare @ 104 times
of pollination per hectare per year, productivity
based on 4 hectares per day per worker and
worker’s daily pay at Rp 90,000/- per day
Rp2,340,000/- per hectare per year
Total Cost of Production Rp 2,620,790/- per hectare per year “B”
Extra additional expected profit by assisted
pollination alone (A-B)
Rp 8,417,710/- per hectare per year.
1/
Conversion rate at MYR to Rp at 3300
Some approaches to improve fruit formation on the bunches were implemented in Borneo island.
Methods by protecting weevil’s eggs and larvae that morphed to weevils in the shelter boxes during
monsoon in Sabah had improved fruit to bunch by about 18% after 5 to 6 months of monsoon
(Foong 2004). A similar system in terms of ‘hatch and carry’ was implemented throughout every
season of the year was reported to have 30% increment in production (Presetyo and Susanto 2012).
All operations implemented in addition to the routine operations required utmost regimental
attention on details of work. The additional methods when used on large scale in the fields of
planting, where high sex ratio planting material is used and the soils and climate favoured for high
sex ratio of female inflorescence, will end up with lack of sufficient male inflorescences and weevil
population, which in turn will have to depend on the assisted pollination, with the purchase of pollen

7. 7
from an external supplier. Nevertheless, one should bear in mind that in implementing assisted
pollination there is the need for a holistic approach in managing the operation.
In oil palm biology, the time period of female inflorescences for anthesis is about 36 to 48 hours. The
flowers are carried on the spikelets of inflorescences and the female flowers at the base of the
inflorescence open first for pollination as compared to the top. Likewise, the flower at the base of
the spikelet opens first as compared to the top spikelets. When the three lobed stigmas of the
female flower turns from pale creamy to purple colour, the flower losses it ability for pollination
(Corley and Tinker 2003). Assisted pollination carried out when the upper flowers where visually
seen in the anthesis stage. It must be taken note that the assisted pollination per inflorescence was
carried out only once. This means that knowing the pattern of the opening of the flowers that
underwent assisted pollinated could have been pollinated by natural weevil visitations to the flowers
as well. However, the bunch weight increment in assisted pollination was 39% as compared to
natural pollination and the fertile fruit formed on the bunches harvested in assisted pollinated
inflorescences analysed through bunch analysis were 19% higher than the natural pollination. Data
leads to understand that the weevil pollination may not be efficient or sufficient enough to have
good pollination of female inflorescences.
The seasonal variation of fruit formation on bunches appeared to be lessened in assisted pollination
whereas in natural pollination a large peak and trough cycles of fruit formation occurred. The
seasonal variation of poor fruit formation in Borneo Island was due to the monsoon season 5 to 6
months prior to bunch harvesting, whereby the weevil activities or its flights were hampered by
heavy down pour during day time that coincides with the weevil’s diurnal flight activities (Foong et
al., 2004). However, it must be noted that in the current study, even if the natural pollination was at
its peak for the fruit bunch formation and oil to bunch from January 2015 to April 2015, the assisted
pollination still produced higher fruit to bunch and oil to bunch than the natural pollination (Figure
1). With higher pollination by assisted pollination as compared with natural pollination in the peak
season of fruit formation may raise the question of efficiency of weevils in pollinating young bunches
of the oil palm. Is there a need to introduce new group Elaeidobius kamerunicus from its centre of
origin Cameroon? The current population of weevils in general was derived from 3000 insects in
1981 in Pamol Kluang, Malaysia. If calculated at a sex ratio of 50% of male and 50% of female in the
weevil population at the time of introduction, with a life cycle of 24-37 days the weevils bred
themselves for 35 years for about 420 generations. Was there any inbreeding set in the first
population introduced in Malaysia? With inbreeding, whether the weevils are weak in terms of flight
distance even in favourable climatic condition and preferred to stay on male inflorescence? We may
have to rethink whether new species pollinators in additional to Elaeidobius kamerunicus need to be
introduced in the oil palm plantation e.g. Elaeidobius plagiatus, which is considered as another
potential pollinator of oil palm in West Africa (Tuo et al., 2011).
Economically, it appears the assisted pollination provides extra early income from young palms
through improved palm products production namely crude palm oil and kernels. The fruit formation
on the bunch was low during certain months in natural pollination, the assisted pollination helped to
increase fruit formation. For the early yield of young palms, it may be necessary to look into the
possibility to increase yield by a pollination. It must be noted that areas like Haplohumods and deep
quartzipsamment soils in general have low yields due to high water deficits. In such cases, it is
worthwhile to increase the bunch weight with available bunches and thereby the yield per unit area.

8. 8
5. CONCLUSIONS
The present study of the assisted pollination in young plantings improves palm products yield of
crude palm oil and kernel. There is a high possibility to increase early yields of young planted oil
palm by assisted pollination if the operation is carried out in an orderly manner with sufficient work
force. The efficiency of weevil population in the early stage of maturity of palms may have to be
looked into. The possibility of introducing new gene pool of Elaeidobius kamerunicus from its centre
of origin Cameroon or a new species should be viewed at governmental level.
6. ACKNOWLEDGEMENT
The authors wish to thank Bumitama Gunajaya Agro (BGA) management for their support to publish
this paper as poster paper. The field and laboratory executives and staff who conducted monthly
sampling and bunch analysis are gratefully acknowledged.
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9. 9