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
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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 .
