UNIVERSITI PUTRA MALAYSIA

1. THE SYNTHESIS AND BIOLOGI CALACTIVITY OF SOME ESTRAGOLE ANALOGUES TOWARDS OIL PALM POLLINATING WEEVILS

ELAEIDOBIUS KAMERUNICUS FAUST

2. ALKALOID CONSTITUENTS OF BREYNIA CORONATA (EUPHORBIACEAE)

HAZIMAH BTE ABU HASSAN

FSAS 1990 2

1 . THE SYNTHES IS AND B IOLOGICAL ACTIVITY OF SOME ESTRAGOLE ANALOGUES TOWARDS O I L PALM POLLINATING WEEVILS

ELAEIDOBIUS KAMERUNICUS FAUST

2 . ALKALOID CONSTITUENTS OF BREYNIA CORONATA (EUPHORBIACEAE)

By

HAZIMAH BTE ABU HASSAN

Thes i s Submi tted i n Ful fi l ment of the Requi rements for the Degree of Master of Sci ence

i n the Facul ty of Sci ence and Envi ronmental Studi es

Uni vers i ti Pertani an Mal ays i a

August , 1990

DEDICATED TO KAK LONG AND AYIB

PREFACE

Pl ants and i nsects have evol ved together over hundreds of

mill i on years that there exi st between them, the most

i ntri cate i nteracti ons and interdependence. Pl ants are al so

very r i ch in chemi cal s whi ch are apparentl y not di rectly

connected wi th the normal metabol i c process of photosynthesi s ,

respi rat ion and growth . Thi s thes i s consi sts of two stud i es :

the fi rst i nvol ves the 'Synthes i s and B iol ogi cal Act iv ity of

Some Estragol e Anal ogues Towards Oi l Pal m Pol l i nating Weevi l s

El aei dobi us kameruni cus Faust ' and the second study invol ves

the 'Extraction of the Al kal o id Consti tuents of Breyni a

coronata ( Euphorbi aceae) . '

I woul d l i ke to take thi s opportuni ty to express my

s i ncere grati tude and appreci at ion to my supervi sor , Assoc .

Prof. Dr . Md . Nord in Hj . Laji s for hi s pati ence , support ,

gui dance , suggest i ons , advice and di scussi on throughout thi s

research work.

I am al so grateful to my co-supervi sor Dr . Mohd . Aspol l ah

Hj . Sukari for hi s hel p and support , Dr . Abd . Rahman Manas for

di scuss i ons and suggesti ons i n some of the synthet ic work, En .

Atan Mohd . Shari ff for di scuss ions and hel p i n obtai ning some

of the NMR spectra and Dr . Maward; Rahmani and Dr . Si dek

Si1 0ng for thei r hel p , di rectl y or indi rectl y .

iii

I am al so indebted to Puan Nor Akma I brahim (Dept . of

Math . UPM) for her t ime and pati ence dur ing the d i scuss ion of

the stati sti cal anal yses of the data , and Assoc . Prof. Dr.

Mohd . Yussof Husse in (Dept . of Pl ant Protecti on , UPM) for some suggest ions and permi s s ion to use hi s fl owmeter for the

bi oassay tests .

My appreci at ion al so goes to Dr . Wan Mohd . lin Wan Mohd .

Yunus , the Head , Department of Chemi stry, UPM , and to al l the

staff i n the department especi al l y to Puan Habsah , Puan

Noraini , Paul i ne , En . Ihsan , En . Narzari , En . lai nud in and En .

lai nal lahari for the ir ass i stance and cooperati on .

My grati tute i s al so dedi cated to lur ina Mahmud for her

hel p and fri endshi p part i cul arl y dur ing my fi rst semester at

UPM .

Last but not l east , I am very grateful to my fami l y

espec i al l y to my parents , my husband Abd . Ghani Abdul l ah and

my two chi l dren , Nur Suriyana and Ari ff Ehsan for the ir l ove ,

support , sacri fi ces and understanding .

F inal l y I wi sh to thank Uni vers i ti Pertani an Mal ays i a for

financ i al support through Graduate Ass i stant Programme.

i v

TABLE OF CONTENTS

Page

PREFACE • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 1; ;

LIST OF TABLES . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . • . . • . . ix

L IST OF F IGURES • • . . . • • . • . • . • . . • • • . . • . • • . . • • . • . • • . . . • x

L I ST OF PLATES • • • . • • • • • • • • • . • • • • • . • • • • • • • • . • • • • • • • • • xi

LIST OF ABBREVIATIONS • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • xii

ABSTRACT • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • xi; 1

ABSTRAK • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • xvi

STUDY NO . 1

CHAPTER

1 INTRODUCTION

El aeis guineensis - History, Products and Bi 01 09Y • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 1

Literature Review . . . . . . . . . . . . . . . . . . . . . . . . 3

Pol l ination in El aeis guineensis • • • • • • 3

El aeidobius kamerunicus Faust • • • • • • • • • 5

Pol l ination in Oil Pal m Pl antations in Mal aysia • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 6

History of Introduction • • • • • • • • • • • • • • • 8 Impact of the Weevil s in Mal aysia • • • • • 9

The Chemistry of Pl ant - Insect Interaction in Oil Pal m Pol l ination • • • 10

Objectives of Research • • • • • • • • • • • • • • • • • • • • 12

v

2 THE SYNTHESIS OF ESTRAGOLE AND ITS ANALOGUES

Introducti on • • . • • • • • • • • • . • • . . . • • • • • . • • • • • • . 14

Experimental ............................... 16

General Experimental .................... 16

Preparati on Of

4-Methoxyal l yl benzene ( 1 ) • • • • • • • • • • • • 20

4-Ethoxybromobenzene (2) • • • • • • • • • • • • • 22

4-Ethoxyal l yl benzene (3) • • • • • • • • • • • • • 23

4-Bromophenyl i sopropyl ether (4) • • • • 23

4-lsopropoxyal l yl benzene (5) • • • • • • • • • 24

Pyri d i ni um Chl orochromate (6) • • • • • • • • 25

4- (Methoxyphenyl )acetal dehyde (7) • • • • 25

3- (4-Methoxyphenyl )methyl oxi rane (8) . 26

Isopropyl tri phenyl phosphoni um Brom;de (9) .......................... 27

Ethyl tri phenyl phosphoni um Bromi de ( 10) 28

4- (4-Methoxyphenyl ) -2-Butene ( 12) • • • • 28

4- (4-Methoxyphenyl ) -2-Butanone ( 13 ) .. 30

4- (4-Methoxyphenyl ) -2-Butanol ( 14) • • • 31

Resul ts and Di scuss i on • • • • • • • • • • • • • • • • • • • • • 31

4-Methoxyal l yl benzene ( 1 ) • • • • • • • • • • • • • • • 31

4-Ethoxyal l yl benzene (3) • • • • • � • • • • • • • • • • 33 4-lsopropoxyal l yl benzene (5) • • • • • • • • • • • • 34

vi

4- (Methoxyphenyl ) acetal dehyde (7) • • • • • • • 36

3- (4-Methoxyphenyl )methyl ox; rane (8) • • • • 38

4- (4-Methoxyphenyl ) -2-Butene ( 12) • • • • • • • • 40

Another Approach to the Synthesi s of ( 12) 43

3 B IOASSAYS FOR THE ATTRACTANCY ON ELAEIDOBIUS KAMERUNICUS FAUST

Introducti on • • . . . . . . . . • • • • . . • • • • • • • • • . • • . . • 46

Experimental • • • • • • . . . • . . • • • . • • • • • • • • • . • • • • • 50

Resul ts and Di scuss ion • • • • • • • • • • • • • • • • • • • • • 54

Concl usi on • . . • • • • . . . . . . . . • • • . . . • • . . • • • . • • . . 81

STUDY NO. 2

SECURININE : THE MAJOR ALKALO ID IN BREYNIA CORONATA (EUPHORBIACEAE)

Introducti on . . . . . . • . . • • • . . . . • . . . . • • . . . • • . . . 82

Genus Breyni a • • • • • • • • • • • • • • • • • • • • • • • • • • • 83

Previ ous Work on the Genus Breyn ia • • • • • • 84

Li terature Revi ew on Some of the Al kal oi ds I sol ated From the Fami l y Euphorbi aceae .. 86

Objecti ves of Research • • • • • • • • • • • • • • • • • • • • • 91

Experimental . . . . . . . . . . . . . . • . . . . . . • . . . . . . • . . 92

General Experimental ... . ................ 92

Al kal oi d Test . . • • • . . . . . • • • . . . • • . . . • • • • • • 93

Extracti on of the Al kal oid Fracti on • • • • • 93

Isol ati on and Puri fi cati on of the Al kal oi ds • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 95

vi i

Recrystal l i zat ion of the Major Al kal o i d . 95

Puri fi cat i on of the Minor Al kal oi ds • • • • • 97

Preparati on of the Hydrobromi de Sal t • • • • 98

Decol ouri zation of Al kal oi ds wi th Acti vated Charcoal . . . . . . . . . . . . . . . . . . . . . 98

Spectroscopi c Anal yses of BC-B and BC-C 99

Resul ts and Di scuss ion • • • • • • • • • • • • • • • • • • • • • 100

Securin ine (BC26-31 ) • • • • • • • • • • • • • • • • • • • • 100

Previ ous Work and Occurrence of Secur in ine in Other Pl ants • • • • • • • • • • • • • 106

Sampl e BC-B

Sampl e BC-C

. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

109

1 1 1

CQncl us i on • • • • • . . • • • • • • • • • • • • • • • • • • • • • • • • • • 1 15

B IBLIOGRAPHY • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 1 16

APPENDIX • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 128

VITA • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • . • • • • . • • 132

vi i i

LIST OF TABLES

Tabl e Page

1 Actual Number of Weevi l s Responded to Test Compounds Agai nst Water 60

2 Actual Number of Weevi l s Responded to Test Compounds Agai nst Estragol e 6 1

3 Percentage Rel ati ve Attractancy of the Test Compounds Agai nst Water 62

4 Percentage Rel ati ve Attractancy of the Test Compounds Agai nst Estragol e 63

5 Actual Number of Weevi l s Responded i n the Pre-Exposed and Admixture Tests Agai nst Water 64

6 Actual Number of Weevi l s Responded i n the Pre-Exposed and Admixture Tests Agai nst Estragol e 65

7 Percentage Rel ati ve Attractancy of the Pre-Exposed and Admixtures Agai nst Water 66

8 Percentage Rel ati ve Attractancy of the Pre�Exposed and Admixtures Agai nst Estragol e 67

9 Stati sti cal Anal ys i s on the Weevi l s ' Responses Towards Test Compounds and Water 68

10 Stat i st i cal Anal ys i s on the Weevi l s ' Responses Towards Test Compounds and Estragol e 69

1 1 Stati sti cal Anal ys i s on the Weevi l s ' Responses Towards Pre-Exposed , Admi xtures and Water 70

12 Stat i st i cal Anal ysi s on the Weevi l s ' Responses Towards Pre-Exposed , Admixtures and Estragol e 71

ix

LIST OF FIGURES

Fi gure Page

1 Estragol e 1 1

2 Estragol e Rel ated Compounds 15

3 Estragol e Anal ogues Sel ected for Synthesi s Work 17

4 The V-tube Ol factometer Used Throughout the Bi oassay Tests 52

5 The V-tube Ol factometer Used i n the Earl i er Experiments (Other Measurements Simi l ar to Fi g . 4) 55

6 The Attracti on Act i vi ty Index (AAI ) of Test Compounds When Tested Agai nst Water 72

7 The Attracti on Acti vi ty Index (AAI ) of Test Compounds When Tested Against Estragol e 73

8 Tl c of Crude Al kal oi d i n 5% MeOH i n CHC1 3 94

9 1H NMR Spectrum of Secur in ine (BC26-3 1 ) 102

10 Parti al Structure of BC26-31 103

1 1 1H NMR Chemi cal Shi fts Ass i gnments for BC26-31 105

12 13C NMR Ass i gnments for BC26-31 105

13 Mass Spectral Fragmentati ons of Securi ni ne 107

14 Bi osyntheti c Pathway of Secur in ine 108

15 1H NMR Spectrum of BC-B 1 10

1 6 1H NMR Spectrum of BC-C 1 12

17 1H NMR Spectrum of BC-C i n Compari son Wi th Securi n i ne 1 13

x

Pl ate

1

2

3

4

LIST OF PLATES

El aei dobi us kameruni cus Faust

Mal e Infl orescences of �. gui neensi s Jacq .

Femal e Infl orescences of �. gui neens i s Jacq .

Breyni a coronata ( Euphorbi aceae)

xi

Page

128

129

130

131

q m d t h s b C H M Hz hr Li t mi n ppm mol no . tl c b . p . m . p . Ld . mmol THF NMR TMS BMS I R HPLC PORIM MCPBA PCC EtOH Et 0 CH�1 3 KOH CH2C1 2 SOC1 2 n-Bu[i NaHC03 NaBH4 HCl NaOH MgS04 MeOH CDC1 3 CrOa Si

LIST OF ABBREVIATIONS

quartet mul t i pl et doubl et tr i pl et heptet s i ngl et broad carbon hydrogen mol ar Hertz hour l i terature mi nute parts per mi l l i on mol e number thi n l ayer chromatography boi l i ng poi nt mel t ing poi nt i nternal di ameter mi l l i mol e tetrahydrofuran nucl ear magneti c resonance tetramethyl s i 1 ane borane methyl sul phi de i nfra red hi gh performance l i qui d chromatography Pal m Oi l Research Insti tute of Mal ays i a m-chl oroperbenzoi c aci d pyr idi ni um ch1 0rochromate ethanol di ethy1 ether chl oroform potass i um hydroxi de di ch1 0romethane thi ony1 chl ori de n-butyl l i th i um sodi um hydrogen carbonate sod i um borohydri de hydrochl ori c aci d sod i um hydroxi de magnes i um sul fate methanol deuterated chl oroform chromi um tri oxi de s11 i ca

xi i

Abstract of thes i s submi tted to the Senate of Uni vers i ti Pertani an Mal ays i a i n ful fi l ment of the requi rements for the degree of Master of Sci ence .

STUDY NO . 1

THE SYNTHESI S AND B IOLOGICAL ACTIVITY OF SOME ESTRAGOLE ANALOGUES TOWARDS O I L PALM POLLINATING WEEVILS

ELAEIDOBIUS KAMERUNICUS FAUST

STUDY NO . 2

ALKALOID CONSTITUENTS OF BREYNIA CORONATA (EUPHORBIACEAE)

By

HAlIMAH BTE ABU HASSAN

August , 1990

Supervi sor : Assoc . Prof. Md . Nordi n Hj . Laj i s , Ph . D .

Facul ty : Facul ty of Sci ence and Envi ronmental Stud ies .

STUDY NO . 1

Estragol e i s an attractant for the weevi l s E1 aei dobi us

kameruni cus Faust . The weevi l s were recentl y i denti fi ed as an

effi ci ent pol l i nator of the oi l palm , E1 aei s gui neens i s Jacq .

Four organ i c compounds , anal ogous to estrago1 e , namely :

4-ethoxya1 1 y1 benzene , 4- i sopropoxya1 1 y1 benzene , 3 - (4-methoxy

pheny1 }methy1 0xi rane and (4-methoxypheny1 } aceta1 dehyde were

prepared i n the l aboratory.

xi i i

Bi oassay usi ng a Y-tube ol factometer was carri ed out for

each anal ogue i n order to test i ts act i vi ty as an attractant

for the weevi l s �. kameruni cus . Attractancy tests aga inst

water i ndi cated that none of the anal ogues were acti ve except

for 4-ethoxyal l yl benzene .

However an i ntri gui ng resul t was observed when the

act i vi ty of the compounds was tested agai nst estragol e .

3 - (4-Methoxyphenyl )methyl oxi rane showed stronger act iv ity when

tested agai nst estragol e whereas al l others were l ess

attracti ve . I t was thought that synergi sm was i nvol ved ,

however further tests carri ed out d id not seem to i nd i cate

thi s was so .

The overal l experiments showed that a s l i ght change i n the

structure of the estragol e caused some reducti on i n act i vi ty.

The resul ts al so i ndi cated that estragol e is sti l l the best

attractant for the weevi l s El aei dobi us kameruni cus Faust .

STUDY NO . 2

Secur ini ne , a yel l ow needl e-shaped crystal , was

successful l y i sol ated from the l eaves of Breynia coronata

( Euphorbi aceae) . A sUbstanti al amount was obtai ned and i t was

xi v

eas i ly puri fi ed by recrystalli zat ion from petroleum ether

( b.p . 68-80oC) . The structure eluci dati on was obtai ned from

spectroscopi c data and compari son wi th the li terature.

The other two mi nor components were i solated and pur i fi ed

from 5i gel chromatography. However thei r structures could not

be unambi guously determi ned due to thei r i nstabi li ty.

Nevertheless , some of the spectroscopi c analyses carri ed out

i nd i cated that they were also alkal oi ds of the

securi ni ne-type.

xv

Abstrak tes i s yang di kemukakan kepada Senat Uni vers i ti Pertani an Mal ays i a bag; memenuh; syarat untuk mendapatkan Ijazah Master Sai ns .

KAJ IAN PERTAMA

SINTESIS DAN KEAKTIFAN BIOlOGI BEBERAPA TERBITAN ESTRAGOlE TERHADAP KUMBANG PENDEBUNGA KElAPA SAWIT

ElAE IDOBIUS KAMERUNICUS FAUST

KAJ IAN KEDUA

KANDUNGAN ALKALOID BREYNIA CORONATA (EUPHORB IACEAE)

Ol eh

HAZIMAH BTE ABU HASSAN

Ogos , 1990

Penyel i a: Prof. Madya Md . Nord i n Hj . laj i s , Ph . D .

Fakul t i: Fakul t i Sai ns dan Pengaj i an Al am Seki tar .

KAJ IAN PERTAMA

Estragol e adal ah bahan penari k bagi kumbang El aei dobi us

kameruni cus Faust . Kumbang i ni tel ah di kenal pasti sebagai agen

pendebungaan yang berkesan bagi tanaman kel apa sawi t dari

spes i es El aei s gui neensi s Jacq .

Empat sebati an organi k yang mempunyai struktur menyerupai

estragol e tel ah d i sedi akan di makmal , i ai tu 4-etoks i al i l -

benzena , 4- i sopropoks i al i l benzena , 3- (4-metoksi feni l )meti l

oks i rana dan (4-metoksi feni l ) asetal dehi d .

xvi

Kaj i an bi oceraki nan tel ah d i jal ankan ke atas

sebati an-sebati an i ni dengan menggunakan al at ol faktometer

t i ub-Y untuk mengkaj i keakti fan bi ol ogi nya sebagai penari k

terhadap kumbang f. kameruni cus . Kaj i an perbandi ngan dengan

ai r menunjukkan anal og yang l ai n t i dak akti f kecual i

4-etoks i al i l benzena .

Keputusan yang agak mengel i rukan tel ah d i dapati apabi l a

uj i an perband i ngan bagi semua sebat i an i ni d i l akukan terhadap

estragol e . Wal aupun kesemua sebati an termasuk

4-etoks i al i l benzena menunjukkan keakti fan penari kan yang l eb ih

rendah , tetapi terbi tan epoks i da dari pada estragol e

menunjukkan keakti fan yang l ebi h . Kaj i an l anjut tel ah

d i jal ankan untuk memasti kan kesan s i nergi sm berl aku . Keputusan

yang d i perol ehi bagaimanapun menunjukkan hi potes i s i ni t i dak

benar .

Keputusan kesel uruhannya menunjukkan sedi ki t perubahan

yang d i l akukan terhadap estragol e , tel ah mengurangkan

keakti fannya sebagai penari k. Keputusan juga menunjukkan yang

estragol e tetap merupakan penari k yang bai k untuk kumbang

El aei dobi us kameruni cus Faust .

xvi i

KAJIAN KEDUA

Sekuri n i na , habl ur kun ing yang berbentuk jejarum, tel ah

berjaya d i as i ngkan dar; daun Breyni a coronata ( Euphorbi aceae) .

Hasi l yang d i perol ehi agak menggal akkan dan i anya mudah

d i tu l enkan dengan kaedah penghabl uran semul a , menggunakan

petrol eum eter ( s . d . 60-BOoC) . Penentuan strukturnya

d i perol ehi dari pada data spektroskopi dan membandi ngkannya

dengan l aporan l i terature

Dua komponen keci l nya d i as i ngkan dengan menggunakan kaedah

kromatografi gel Si . Strukturnya t i dak dapat d i past i kan kerana

sebati an i ni t i dak stabi l e Beberapa anal i s i s spektroskopi

berjaya d i jal ankan dan dari data yang d i perol ehi , menunjukkan

kedua-dua komponen i ni jeni s al kal oi d yang mempunyai rangka

seperti sekuri n i na .

xvi i i

STUDY NO . 1

THE SYNTHESIS AND B IOLOGICAL ACTIVITY OF SOME ESTRAGOLE ANALOGUES TOWARDS O IL PALM POLLINATING WEEVILS

ElAE IOOBIUS KAMERUHICUS FAUST

CHAPTER 1

INTRODUCTION

El aei s gui neens i s - Hi story, Products and Bi ol ogy

Long before i ts i ntroducti on to Mal ays i a , the oi l

palm , El aei s gui neens i s Jacq . was abundantl y found i n the

tropi cal Afri ca under natural cond i t i ons . The oi l pal m

fi rst entered thi s country through Si ngapore Botani cal

Gardens , but i ts fi rst commerci al pl ant ing began in 1917 at

Tennamaran Estate i n Kual a Sel angor (Mohamad , 1966) .

Mal ays i a exported 4 . 6 mi l l i on tonnes of pal m oi l

products i n 1986 , earni ng 3 . 5 bi l l i on r i nggi t of forei gn

exchange i n the process . Thi s pl aced the commodi ty as the

thi rd important forei gn exchange earner after petrol and

t imber products . I t has certain ly repl aced rubber and t i n

a s the country's outstandi ng export (Lim, 1987) .

Pal m oi l i s used i n the manufacture of soap , candl es

and edi bl e products such as cocoa and mi l k ( i n the form of

cocoa butter equi val ents and the cocoa butter substi tutes ) .

1

2

In add i t i on to bei ng a val uabl e shorteni ng ( frying oi l ) , i t i s

al so a source of val uabl e i ngredi ent i n the making of

i ce-cream , confecti ons and condiments .

Palm oi l i s al so used extens ivel y i n the pl ati ng

process , and to a smal l extent i n the manufacture of heavy

grease and l ubri cants . Its use as a fuel for i nternal

combusti on engi nes i s sti l l at the experi mental stage .

El aei s , Jacq . i s a smal l genus of the fami l y Palmae .

They are found natural l y i n tropi cal Afr ica , where El aei s

gui neens i s Jacq . has a wide di stri but ion . El aei s mel anococca

Gaertn . , occurs wi del y i n tropi cal Ameri ca . The genus i s

cl osel y al l i ed to Cocos ( Burki l l , 1966).

El aei s gui neens i s Jacq . i s a l arge palm havi ng a

sol i tary col umnar stem wi th a short i nternode . It i s unarmed

except for short spi nes on the l eaf whi ch g ive the palm i ts

characteri st i c appearance (Hartl ey, 1967) .

The palm i s normal l y monoeci ous wi th mal e or femal e , but

sometimes hermaphori d i te , wi th i nfl orescences devel opi ng i n

the axi l s o f the l eaves . The fru i t i s a drupe whi ch i s borne

on a l arge compact bunch . Bei ng a monoeci ous pl ant , 1 n whi ch

the mal e and femal e fl owers occur separately , the palm tree

3

has d i st i nct mal e and femal e i nfl orescences and i n thi s case

on the same pl ant .

The femal e i nfl orescence reaches a l ength of 30 cm or

more before ri pen ing . The spi kel ets are thi ck and fl eshy and

devel oped i n the axi 1 s of a spi nous bract . The fl owers are

arranged spi ral l y around the spi kel ets wi th a sharp sp ine at

the end of each spi kel et . The i nfl orescence thus contai ns

several thousands of fl owers .

The mal e i nfl orescence i s borne on a l onger peduncl e and

contai ns l ong fi nger- l i ke cyl i ndri cal spi ke1 ets , whi ch i s not

spi ney. The spi kel et has bracts and termi nal projecti ons but

the s i ze are much reduced . The spi kel ets are between 10-20 cm

i n l ength (Hartl ey, 1967) .

Li terature Revi ew

Pol l i nati on i n El aei s gui neens i s

The process of pol l i nati on i nvol ves the transfer of

pol l en from the mal e part of the pl ant to the recepti ve sti gma

of the femal e. How thi s occur i n the oi l palm pl antati ons has

been a matter of debates for sometimes (Kevan , 1983) .

Oi l pal m pol l i nati on was bel i eved to be anemophi l ous

(wi nd-associ ated) rather than entomophi l ous (Jagoe , 1934; Gray

4

and Bevan , 1966; Wood , 1968; Hardon , 1 973; Turner and

Gi l l banks, 1 974) . The bel i ef stemmed from the supposedl y l ack

of effective i nsect pol l i nators and thi s seemed to be

substanti ated by the hi gh atmospher i c pol l en dens i ti es

observed over consi derabl e d i stances from the mal e

i nfl orescences (Hardon and Turner , 1967) . Hartl ey ( 1967)

stated that the l ack of pol l ens i s a major cause in bunch

fai l ure and Hardon and Turner ( 1967) al so observed that the

producti on of the fru it bunch was greatl y reduced dur ing rai ny

seasons .

These observati ons l ed some pl anters i n Cameroon , to

suspect the i nvol vement of other pol l en di spersal agents , i n

vi ew o f the pol l i nati on i n that country despi te the wet

seasons at whi ch t ime rai n occurs frequentl y.

Based on hi s work in Cameroon , Syed ( 1 978, 1 979 , 1981a)

has shown concl us ivel y that i nsects are v ital to effi ci ent

pol l en transfer i n oi l pal m pl antati ons . The weevi l s

El aei dob i us kameruni cus Faust was found to be one of the

effi ci ent oi l pal m ( El aei s gui neens i s ) pol l i nators and wi th

thi s di scovery, Syed had di sputed the concept of wi nd as a

major pol l i nati ng agent and the rol e of i nsects was fi nal l y

acknowl edged .

El aei dobi us kameruni cus Faust

5

In West Afr ica , the natural habi tat of oi l palm , there

are several pol l i nati ng i nsects (de Chenon , 1982) among whi ch

E1 aei dobi us , a speci es of smal l weevi l s are the most abundant .

El aei dob i us kameruni cus , the most i mportant oi l pal m

pol l i nator i n Cameroon bel ongs t o the sub-fami l y of

Derel omi nae of the fami l y Ci rcul i oni dae (Syed , 1979) . The

d i stri but ions and host of the genus El aei dobi us are remarkabl y

restri cted to El aeis i n West Afr ica . Thi s i s a good i n i t i al

i nd i cat ion of the speci al i zed nature of the sub-fami ly .

The members of Derel omi nae i n Cameroon i ncl ude

El aei dob i us kamerunicus , f. pl agi atus , f . si ngul ari s , f .

bi l i neatus , f . subvi ttatus and rarel y f . spatul i fer . They

vi si t both mal e and femal e i nfl orescences of the oi l palm , but

El aei dobi us kameruni cus i s the most abundant and effi c ient .

The femal es f . kameruni cus l ai d thei r eggs i n the spent

and pol l en shedd i ng mal e fl owers , which were borne on the

spi kel ets of the mal e i nfl orescence . When the eggs hatched the

l arvae fed on the dryi ng , spent mal e fl owers fol l owed by

pupat i ng stage and l ater emerged as adul ts . Thi s process takes

about 10-13 days depend i ng on the sex . Other speci es take

e i ther l onger or shorter per iod to devel op .