Category Archives: 1997 Vol 9 No 1

Role and effectiveness of Elaeidobius kamerunicus, Thrips hawaiiensis and Pyroderces sp. in pollination of mature oil palm in Peninsular Malaysia

A study on the pollination of seven-year old palms in a plantation in Selangor, Malaysia was made between 1983 and 1987 to determine the relative roles of three types of pollinators, Elaeidobius kamerunicus (Coleoptera: Curculionidae), Thrips hawaiiensis (Thysanoptera) and Pyroderces sp. (Lepidoptera: Cosmopterygidae) as well as to examine their effects on oil palm bunches. Samples were collected monthly from anthesising male inflorescences to provide information on the actual and potential populations of pollinators. The activities of pollinators on anthesising female inflorescences were measured by pan-trapping. All anthesising female inflorescences at the time of population sampling were marked and the fruit bunches which formed were later harvested for analysis. The weevil Elaeidobius kamerunicus had not displaced T. hawaiiensis and Pyroderces sp. as was evident from their co-existence. Their pollination activities had sustained the fruit set and fruit to bunch ratios about 60 per cent. Nevertheless, E. kamerunicus had become the most important pollinator, even during the wet season. During dry periods, T. hawaiiensis played a more important role than E. kamerunicus in pollination. The critical threshold of weevil numbers required for pollination could not be determined because the fruit set had not declined to low levels. Furthermore, a high population was not necessarily beneficial because it resulted in the lowering of fruit set. During the period after the introduction of the weevil into Malaysia, there was no significant change on bunch parameters, with one exception: oil to bunch ratio showed a marked depression in 1985, three years after the introduction of the weevil. Three explanations have been suggested, the most important of which was related to a marked increase in the moisture content of the fruit bunches

Effect of first stage dry fractionation on the quality of CBE based on palm oil and sal fat

Palm oil (PO) and sal fat (SL) were dry fractionated separately at 30-33°C to remove the high melting constituents, yielding palm olein (POo), and sal olein (SLo). Acetone fractionation was then conducted on a blend of POo+SL(7:3) to produce CBE1, and on a blend of POo+SLo(7:3) to produce CBE2. Changes in the composition of the fractionated products were monitored from the triacylglycerol profiles and polar lipid content, while physical changes were observed from the DSC melting profile and Jensen cooling curve. The dry fractionation reduced the trisaturated triacylglycerol content of palm oil, but had no profound effect on the triacylglycerol composition of sal fat. Nevertheless, dry fractionation reduced the polar constituents of sal fat, and improved the physical characteristics of the CBE produced.

Determination of antioxidants in palm oil products by high performance liquid chromatography

Tertiary butyl hydroquinone (TBHQ),butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) were found to be the common antioxidants used in the palmoil industry.They are added to palm oil products either singly or in combination products either singly or in combination within the permissible limit of 200 parts per million. A procedure for the determination of the phenolic antioxidants which is based on the AIIBP method using a single step methanolic extraction and reverse phase gradient elution by HPLC was proven to be very simple and reliable.

A local Bacillus thuringiensis, SRBT1 with potential for controlling Metisa plana (WLK).

Most commercial products from Bacillus thuringiensis (B.t.) were ineffective for controlling Metisa plana (WZk.). The effectiveness of a B.t. product against an insect depends on its protoxin composition, and the presence of suitable receptor sites and factors activating the toxic crystals within the insect’s midgut. The pH of the midgut must be suitable for solubilizing crystals prior to activation. The selection of a B.t. strain effective against the target pest is a practical approach. A B.t. strain containing the right toxin which binds to receptors sites present in the pest needs to be identified and selected by screening. This paper reports on the progress made in increasing the potency of a local strain of B.t., SRBT1, selcted after a study of its toxicity.

Alkaline and acidic compounds were added to SRBT1 to enhance the effect of its toxins. The addition of 0.5% tannic acid and 1.5% sodium borate showed a 4 fold increase in mortality of M. plana at 4 days afer treatment (DAT). A Three fold increase in mortality resulted from incorporation of 0.5% magnesium chloride and a two fold increase with 0.5% potassium carbonate and 0.5% sodium borate at 4 DAT. At 6 DAT, SRBT1 containing 1.5% sodium borate caused 94% mortality, as against 70% for the best commercial product tested, Florbac. One hundred percent mortality was observed at 9 DAT when 0.5% sodium borate, 0.5% and 1.5% tannic acid were added separately to SRBT1. SRBT1 with no chemical additive produced 100% mortality at 11 DAT. SRBT1 with or without chemical additives, gave a marked reduction, 98 – 100%, in leaf area damaged (LAD) as compared with the control. This reduction is comparable to that produced by methamidophos 99.4%. Florbac gave only 59.7 % reduction in LAD. The reduction in LAD was more obvious when sodium borate and tannic acid were used. SRBT1 must harbour toxins suitable for the control of M. plana, because the effect on feeding behaviour is very pronounced. Determination of SRBT1 cry genes, cry proteins and exploitation of this isolate should be attempted.

Stability of emulsions of refined palm oil and its low melting point fraction with egg phospholipid

Emulsions of high melting point refined, bleached and deodorized palm oil (P036) and its low melting point fraction (P015) were prepared using egg yolk phospholipid. Their stability after 24 hr storage were compared to that of soybean oil. The low melting point palm oil fraction (P015) formed stable emulsions similar to that of soybean oil. However, emulsions of the high melting point refined palm oil (P036) were unstable and phase separation occurred immediately.