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

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. 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

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

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

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

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

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.

7. REFERENCES

Chee K H and Chiu SB (1998) A study of Elaeidobius kamerunicus in Kalimantan oil palm plantations-

A Review, The Planter, Kuala Lumpur, 75 (877) 187-198.

Corley RHV and Tinker PB (2003) The Oil Palm, Fourth Edition, Blackwell Science Ltd.

Syed R.A. Law I H and Corley R H (1982) Insect pollination of oil palm. Introduction establishment

and pollinating efficiency of Elaeidobius kamerunicus in Malaysia, The Planter, 58 (681) 547-561.

Foong L C, Clarence P J and Mathews J (2004) Preliminary Investigations on supplementing and

protecting oil palm pollinating weevils (Elaeidobius kamerunicus, Faust) in young mature palms in

Sabah In proceedings of the International Conference of pests and diseases of importance to the oil

palm industry, Kuala Lumpur .

Mathews J, Ng S.K. and Ip W.M (2009) Inclusion of Parthenocarpic fruitlets in Bunch Analysis

Procedure and its Relevance to Oil palm Breeding Programmes. The Planters, Kuala Lumpur 85

(1005) 739-745.

Prasetyo A. K and Susanto A (2012). Meningkatkan Fruit set Kelapa Sawit dengan Teknik Hatch and

Carry Elaeidobius kamerunicus, Indonesian Oil palm research Institute ISBN 978-602-7539-08-2

Rao V and Law I H (1998) The problem of poor fruit set in parts of East Malaysia. The Planter, Kuala

Lumpur, 74 (870) 463-483.

Sugih W, Heru S., Achmad F and Thiagarajan S (1996) Influence of rainfall, palm age and assisted

pollination on oil palm fruit set in Riau, Indonesia. In proceedings of the (1996) International Palm Oil

Congress (Agriculture) Kuala Lumpur 207-220.

Tuo Y, Koua H K and Hala N. (2011) Biology of Elaeidobius kamerunicus and Elaeidobius plagiatus

(Coleoptera, Curculionidae) Main Pollinators of Oil Palm in West Africa. European Journal of

Scientific Research Vol. 49, No.3 426 432 ISSN 1450-216X.

Turner P.D. and Gillbank R.A. (1974) Oil Palm Cultivation and Management, Chapter 9, Incorporated

Society of Planters, Kuala Lumpur.

9