---

Inscçt int’rstation of stored ;
;II causes wcight ;III~~ qualltv Io~ws that ICIJ 10 ;I
reduction 0f commercial v:~
;md sced germiikition. 1‘0 reducé this &II:~+!.
4cvcral control mcasures h;i;
~XXII taken. n,hich mostl> envol\\ t% chcmic~ul ;IIC‘I~I
ods. Synthctic insecticides ;I . net only a drain on the f;lrmcr’h rneager resclurc‘c\\
but arc oticn frequently use ; hcyond perniisaibl~~ sufè Iimits. The incidci;<,2 01
Insccticiclc rcsistance i s a15 .I growing prohler:l. Re\\i,tancc to ont or IINIIY
Insccticidc(5)
ha5 b e e n rep : d i n at least 500 \\pcc~e, OI‘ Insccts and lllltC\\
(Gcorghiou. IYYO). T h i s 5
itlon bas incrcac~~l t h e nxd ter altcrn;ttl\\ c’\\ to
bynthctic pcsticides. Botan
insecticides iii-c ;I It’bs cupensii’e :111d hiod,gr;id
ablc option. The cffectivclj
, of raw pui-ts and plant t*xtracts againt \\ti)rc*tl-
gl-ain insccts bas been dcsc. j:4 hy many authors (Jotuani .~nd Sircar. t 965.
Singh et 4.. lY78; JacobsI.
lY83: Golob and Weble>. lY8i): Graingc .I .II..
IYXS: Lognq ct al., 1991:
,cli et al.. IYYI: fl;iuhrugc ct a1 , IYXY~.
WC invcstigated thc !
ogical acti\\ itj o t
ROJ~.I~I 5r~c:tr(c~1.si.s (I’!,KS.)
LAM. ((‘apparaceae).
a pl:
bat is found throughout north-central
anti north~rn
Senegal (Bille 2nd Poupons
1977). where II is traditionaIl\\ ~XXI h> l;riln~~r\\
against 5tored grain insects
, i addition. ~‘c isolated and idcntified hiolo~ ~~;III)
active componcnts of this 1’
II.
Plant tnatcrial was ri:.
11n1y harvestcd in tht: rcgion 01 l‘hics (SC!IC~,I~>.
Our tnaterial has been idcr;: .ctl and depositcd ;II the Jardin Botanique N;itic>nal
de Belgique (BR) as B. A(‘)
,rl~~z.si.r. Leavcs usc’d f o r trIaI 1 wcrc harve\\:4 111
Novcmhïr IYOO. Fruits ;III!
2ves llscd ti)r triaI\\ 2 ün(l i Mci-c collectcd II! kla\\
IYYI.
Four cxperiments WCI
lnducted with plant part\\ (triaI\\ I and 2,. e\\tr;tcl\\
(tria1 3). and pure molecu!
tria1 4) using five 5torçcl-gr;iin irrt’çt spcscic,,. I’hc
test insccts. C~illosohr~rt~I::.
~rr~ular~.s (F. ) ((‘OI, , Bruchidac I. Sirotrogc, ( ‘(‘II-
trlrllu OLIV. (Lep., Ccl(‘!
lac), Pl.o.sr~,1~12trlrlc.\\ ~n~/~<‘~lril.s HOKN. (Col I<(I~-
tryc~hldac), Trilwlium ctrvr
um HERBSI‘. ((‘01.. Tcnchrionldac).
.G/c,:jkl/~\\
.~<wtt~ui.\\ MOTSCH. (Col.
~~r<ulionidae). M~‘I-c rcarcd undcr controlle~.l <~II-
ditions (32” + 2°C and
k 10% relative humiditt I Bio;lss;Iys w~51~: ;II\\~
carried out undcr these CO!
ans. Al1 chcrnicalx and >olvcnts \\vc’rc of ~II;I > t~~.;ti
grade.
TricrIs / md 2 . Th~.~~
rst t w o trials wc‘rc performed with fresh ground
Icavcs (F(;I,). i‘resh enri!
3ves (FEL). clr‘ Icaf powder- (DLP). ;ml f‘rc41
ground t’rultx (FGF). 1%~
t material5 \\b’crc .klded tc) COM pca 5ecds. l’i,ytrtr
rtrlguic~~ltrr<r
(I..) WALP i\\
Black Eyecl) üt l- 3 2 % for FGI.. FEL, ani: 1)l.f)
in triai 1 : and 0.52% for-
!: and FGL II~ tri;!1 1. F(;I. ad k’(iF wcrc p~~~~p;~r~~l
C_m
--
--

-
,--__
- _......-L

---

using a \\mall laboratoq :
<Moulinex) l’or 5 Illin. 1)l.I) W;I~ slmilarl> 1. I.OLI~I~
and thcn passed through L~
)-mesh laboratoq SI~~C. f-‘~~llowing this proc :durm:.
2 0 g of’ cowpzas werc 1’
,ughly mixcd M’II~I plant inatcr-ial at thc t!lbslrcd
concentrations In Petri tl
(6 90 mm) antl inftistetl !L i t h 10 unscxc~i I tlaj-
oid C. I/I<I(.U/U~US adu1t.x
reatcd cowpea ~L:~(IS wcrc similarly int’cst~~~l wlth
10 insczts. flash trcatnlc,:
Including thc contr-ol. V+;I~ replicateci fi\\ c‘ IIICKS
Mortality assessment u’::
de aticr ont t o t\\!o dayh. Twcnty-two du:, ‘~ I;lt:r
whcn F, adults started tl
:rge. insccts wcrc removcd daily ancl cou1t1~~d I~N
10 days. Numbers of 11~1
,nd unholed sced\\ wcrc also countcd and l~~~rcc’nt
damage was calculated.
Data werc subjcctc,&’
thc mcans (Duncan’s mi!:
Trid 3. Fifty grall:
a Waring blcnder and k,.
thcn liltcrcd ami concet)::
a U. srvlc,quicvrsi.s acctor.
by volu11~t2 of water.
BlcKlssays were Gll i,
ut in 82%ml scai~4 glass desiccators in \\\\ :II~,II 5
m l ot‘ B A F E wcre depo
Five millilitcrs 01 ,icetonc werc’ similarly j~,i~~‘ttlld
in anothcr dcsiccator us\\”
.ontrol. Aftcr 3 hr ;tt roorn tzmpt*raturc. thc xoI\\cnt
cvaporatcd colnpletcly /’
control. One huntlrcd adults 01’ difl’crcnt ‘~CCIC!,
wcrc thc,ri introduced il.
.lèsiccat«rs. whlcll wcrc ~~loscd :md plac~tl undcr
ercpcrimcntal condition\\
r vurious time cxposurc5. tram 1 .S to 12 hi. inor-
tality rc;ldings were rec
lor cach trcatment. ‘fhc iillle rcquircd to ki ! 50’;
(LT-,,) of’ t h e insects V.
.‘n dctcrmined h> transti)rming monality \\:,1t;l to
probita ;md calculating ’
‘lia1 times ( L T ) (Sncdccor ;md (‘ochran. I’J(,?).
Atwlysi.s r~/‘voluti/~~
f%oscia scncgalcn\\ls ~<Y~QJ.\\. Frcshly grounci jt’avt‘s
(100 g) wcrc 5tcam-di
f o r 35 m i n and Ihc: aqucous distillate (‘)(Y) ml)
cxtractccl thrcc timcs u ,’
K) ml dicthvtethcr Thc éther solution \\\\‘a\\ &Ii!-
dratccl with anhydrous
11 sull’ate, conccntr-3ted to 4 1111 hy clistill.i!ioii 01‘
thc solLent at 78°C. an
ty analyzed by ga>--liquid chronlatograph>
(i1.c’)
ubing two types o f col\\
inder the followinu condltlons: Thc polar i ~~lunin
was a C‘P-Wau S2CB i
long. 0 . 3 2 m m II). 0 . 2 /LIN film thickncsxl Irc~~m
C’hrompack: carrier ga‘
icliurn at 100 kf’:l. tcmp~~I:rrurc program 11.~11 30
to 240^(’ ;it IO”C/min:
‘on-colunin”
in,lector and I9D dctector iiia:i::a~~i+v.l
al 250°C: apparatus: f+
f%dwd HP SXXO Thc ;Ipolar c~olurnn wa‘r ;t (‘P
Si1 8 CB (25 m long; (!
~m I D , 0 . 2 prn tilin thickncss) t‘rom Chroi~.pa~~k:
carrier gas was heliun!
kPa; temperaturc” propr;irn: from 3 0 10 241 C‘ :it
S”C/min: cold “on-co’
ir!jcctor and Fil) detcc‘tor malntainccl at ~~)OU~:‘:
apparatus: Carlo Erba ‘%
5160.
‘J.). T h c glucosincliatcs MCI.C analyzed i n 11 \\VI,<’
:E hy rcver\\c-pha\\e
HPI .(‘ al’ic-r cn/> mt111. :IC:~I

---

3 x0
SI (‘h 1 , \\,
fation according ICI thc c~lli~~i;~l EEC rncthod I Iluropc;rn Economie C‘c~rnrnunit~.
1990). Identification of B;\\l;ti glucosinolates \\\\ as perforind hy (K-MS ;II~
yses of’ trimcttlylsilylatctl r~roI~‘cuIcs and h> t~\\irmin;rtion of’ thcir tl~~ladatiort
products liberated enzymatrdly uriJcr contr~~ll~~l anclitions. For (K-MS iri\\~e-
tigations. glucosinolalc5 v.crt’ en/> rnatiall> tr~~nsti~r-r~ieJ to clesulli~gl~r~~~~x1r10
lates and trimcthyl-silj IatcJ I~I‘ 20 m
i
n

;II I iO”c’ with 50 111 ot ;I ~rc:rg~*n~
containing N-tnethyl-N-tr~r~~~ctl~yl~ilyltrill~ro~~~~~~~~~
ramidc. 51 rnethqlirllr~la/~~l~,
in acetone ad trimcth> I~hiorosil~nc 30 : 15 .i iviv: VI. ‘l‘hc ~hr-onr~ttc~:l~~~~~l~r~
conditions were as I’ollow:~: (Iolur1in SE-53 (75 iii long. 0.35 rnm If>. 0.2 jln
film thickness) M:I~ from MachcrIS-Nagcl; carric‘r: hcliurrt at 50 I\\F%: tetnpatturc
program: SO-780°C ;II 2O“Ciniin: cold “or~-~olu~~~~i” inlcction. ‘l‘hc IKI~ +Y
tra werc rcconl~d in thc fil m~dc on il h‘cr~i~;ig K IO- lO(’ 5pcctrometcr i 70 CV
source üt 130°C. interi’;icc at 2XO”(‘. rxiss rxrigc scanned fi-om 100 10 X00 ~III~ I
coupled to a Delsi Dl-700 gab chrornato~~rf’ti.
For enzymatic dcgrdrtion ol‘/I. sclr(,~~rr/c,,r.\\i.~ gluco~~nolate~. 0. I 1111 aictt;ltr’
butfer (pH 4.5) and SO ~11 t,~f’ 10 rng/ml bufl~rcti solution of thiogltr~c)sid;rx~
il’(’
3.7.3. 1 ). puriliccl f‘rorn Si~rq~rs tr//>cl 1. ;ii~i~~)rJ~ri~ to Appelqvist and J~~sc~txoir
(1967). ucre atldetl to 0. I 1111 ot’ raidual ;rquc~~us ph:rsc trc~rn BAI-E or 10 ;I
aolution of pure mcth“l’lluc~,>rrlolare (tluc,c)c,apl);rr-in.
Koth rci‘. 73X51 AI~L.~ 2-r
hr. the degradation prociucrx wcrc cxtractetl u 1111 2 ml di<thylether- and an;~l>/a!
hy GLC on polar and apol;ir stationary ph:le\\. Mcthylisothioc)anat~ t Mi IKC)
f’rom BAFE and glucocapparirl \\~CI% idcntilicd Ily compar-ison 01‘ thcrr rc’tcrrtron
times with that of’ a pure I-C~‘CI-CI~CL~ tSigma ~-et’ hlXh32)
‘Tt-id 4
.

‘TO study the close-riiortalit~ r-csp~~rise to Lz. ,sc~/r~~,~~rlc~~r.\\/.\\ ti\\\\ue\\
and MITC. various amounts 01‘ FGF ad I-Cl. I‘rorn (1 t o X gilitcr tw!v) ;II~
pure MI’I‘C from 0 to 3 mg.:litçr (w/ v) u’cre tlepcl\\itcJ in 750-ml glas\\ &~~i<~;~tc~r\\
contarriing 25 üdultb ot c;ich inscct spccic’\\. iii t’our rqlicatic>rl5. Al’tcr- Z-1 ht-
under the experimental clirnatic <~onditiorls,
irrsccts Lvt:r-c tran5t’crrcd to ~.li’;tli
Petri dishes and rnaintaincd in controllcd Con&tions until thc ncxt da> MOI- I~I~I
tality readings as inJisateJ tq Busvinc t 19x1 ). D a t a were suh,jectcd to prohrt
analysis (Finney. 1964). I,og clos+probit III~~ M’;IS analyzcd li)r ~~KK~IKYS of II~
hy the chi-syuarc test (I~us\\ inc‘. 19X I ). l’~~ll~~w~d b‘ ct)rnputatrc~n ot l,Ci,, \\;II~I~‘\\
f’or cach m;rtcrial.

---

fCkSl!l.‘fS

---

FGL significantly reduccd C‘. I~I~I~~UI~IIU.S pqcny. comparctl to FEL and 1)I.f’
(Figure 1).
Damqe. FGL gave 100% protection at 2 4 and 23 7 damagc ;it 1 % In
the same conditions. ti:~ma~e was %).Y-64.X”c l’or FEL and 30.X-67.5’:; ter
DLP (Table 1).
Tria1 2
Morta1if.v. Afier 72 hr ai concentration OI’ ?Si, mortality was Y3.6D ter
FGF and 24.8%. for FGL. Al‘tcr 4X hr. it ranged f’ronl 3.X to 7Y.804 [t)r I:[;F
compared to O-24.2 5% tiv FCL. Af’ter 24 hr, mortality rrmged tram 3.X to 72.89;
for FGF and from 0 to H ‘5 ti)r f:GL (Tablé 2).
Progrny. A t 2%‘, F(;I; showzd n o adult émergence
v,hile 7.x 2nd 13.1 s
adults emerged, respectivcly,
in FGL and the control treatment. At 1 ‘i; . 12
adults emerged from FGF comparcd to 104 for FGL (Tablc 3).
Dm~uge. A t 1 O/c conccntT;ltion. damage \\v;ib 8.7 % for FGF and (,.?!; t’or
FGL. At 2%‘ concentration. FGfz g:rvv IOO% pr’o(cctIon. wh~lc h. I dan~acc M’;I~
L
noted in the FGI. treatmcnt (TabIc 3).

---

---

GLC andysis of thc volatiles f‘rom FGL d~owd ont: major pcak (92 ‘3 I)I
the total area) at retention tirries of’ Y.3 I~I~I ancl 6.5 min, rexpectivcl> on ~OIJI-
and apolar columns. w h i c h corrcaponded
to thox ot‘ an authcntx ~nplc OI
MITC. The detection of hl ITC‘ front B. .s~,tlc~~rrlctl.si.s leaves (Figure 2) suggc~tt~l
that t7lethylglucosinolatc (~luc~ocappat-in) may bc thc rttain prccurhor of’thc lI1>ci
tiçidal c o m p o u n d . Glucosinolate enzymatic dcgradation Icads to sc‘vc~.i~i 13‘
products among which isothiocyanata predominatc (Tookey et d.. 1980). TO
test t h e aforementioned hypothesis, WC: analy& t h c rcsidual water phaac 01
BAFE f’ollowing a three-step procedurc (HPLC. identilication of glucos~nola~~~
by-product. and GC-MS). Thtt HPL-C retcntion time of pure desulfon~eth~lgl~l.
cosinolate (2 min) correq~~nd~:d to that of thc ma,lor peak detected in HAFt.
On the othcr hard. the elution profiles libcratcd cnzymattcally from 13AFt:
--

---

residual aqueous phaac and methyl~lu~oinolate are practicdly identical: MITC
ia dlstinguishable on the two chn.)mato~rams but is absent on thc blank. Thc
identiticntion of’ glucocnpparin in RA.Ff< was tinallq validatecl by CC-MS A
typicai mass spectra is shown in Figure 3. The mass fragments at /ll/c -= 103.
117. 137. 169. 204, 243. 771. 361 (bac pcuk). and 451 wcrc gcneratal bh thc
gluc~cl~c moiety of tht: moleculc and ivcrc not of‘ intcrcst ti)r thc idcntificatic~n
of the aglycone. Nevertheless. t h c ion> recordcd a t 11fic := OI.3 (M) ’ . 59X
(M-CH \\) ’ , 524 ( M - C H , - T M S ) and SOX (M-CH,ThlSOH) indicated clearl>
;i glucosinolate hearing a methyl radical. As for dl othcr alkylglu~osinol~~t~s.
the intensities of thesr: characteristic mass fragments were low The methylglu-
cosinolate content of R. .rf~ll~‘~(~I<‘~f.~i.\\ niatcrial testeci In tria1 4 rrpresented 73.6
t 0.X pmol/g fresh leavcs 2nd 3X + 1 .7 ~molig t’resh fruits (HPL(’ detcrm-
nation with sinigrin as internai standard). Hcadspace ampling conductcci uncler
the sarnc conditions as tria1 3 and trapping the volatiles in dicthq i cther at -- 70”(
Ied to detection of MITC from the vapor pha.se. The total ion current (Figure
4) showcd scvcral pcaks, among which wus MITC (K, = 1h.h min). Thc II~~I-
cculc wus unambiguously identified by comparison of’ its ~nass spectrometric
pnttcrn with EPA-NIH and Wilcy Iibrarics and also on thc basis ofG1.c’ retcntion
liilltt.
I)ISCl!SSION
This research has dcmonstrateci ;i signilicant biologd eitcct 01’ N. .S~IIO-
,f$e~f.sis plant parts and extracts. I‘he ecidcnce in support 01’ thesc rcsults wil\\
obtaincd from four experimcnts. First. B. ,scr~c~u/~~r.si.s FGL (when adcled to
cowpeas at 4% wiw) completelq killcti C’. r77u1d~~ru.~ dults within 74 hr. inhib-
itcd thc production of F,, progai) ard prevented bruchid clamagc. Under thc
same conditions. FEL and DLP had almost no cfl’cct. Second, comparative

---

.,(.?,
,-
C0n1Kll
cvaluation of’ FGF and FGL revcalcd that fruits uere more toxic to C‘. IPU(I~~UU.S
and reduced both progeny and damagc to a grcater c.xtcnt. than clid lea\\c\\
Third, BAFE exhibited a high f’umigant efkct on threc atored-grain
inscct spc-
cies. which had a differential time-mortality response. Finally, we quantiticd
the acute toxicity of B. .serwgalcrz.sis fresh ground fruits and leaves as well as
pure MITC and obtained dose-mortality responses for three stored-grain
bcetles.
B. s~n~gulensi.s is a shrub, growing up to 3 m high. that is frequently tound
on abandoned tennite mounds and on barren and fire-scorched
soi1 01‘ thc Sahel.
it is distributed from Mauritanie to Niger. northem Nigeria. the northwest C’am-
eroons, and across Aftica to Sudan and Ethiopia (Booth and Wickens. 1988).

---

3x7
i..
i
Leaves ad fruits are used as human food ad animal fodder (Bernus. 1979:
Baumer. 1981; Maydell, 1983: Burkill, 198.5: Becker. 19X.3). The 1eave.s. bark.
and mots are widely used in northem Senegal for thcir medicinal properta
(Kerharo and Adam, 1973; Hooth and Wickens, 1988).

---

Alzouma and Bo~~bacar t 1X-3) rcported on thc toxicitk of‘ H. .sc~r~c,gu/~~r~.\\i.\\
leaves from Niger. which :II~ rcduced B~-~(V~irlir~ Or-olirrrnrus Pic. ;III~ I‘.
mu~ubr~.s oviposition. but they gave no details about thc active co~~qxment~.
Kjaer et al. (1973) reported that B. .s~ll(>glll<~)l.si.s Iwfless twigs contnincd methh 1
and isopropyl glucosinoiatt3.
Our bioassay5, pert‘ornlcd b> wmparing Ht~(.itl tlshucs ad MITC‘. indiiatc
that H. .srrrc,,ytrlcn.si.s
fruit,. IC;I\\~. and MII’C wre toxic to insects ;II marlous
le~els, according to thc \\pwics 2nd the plant tissue. They also indicatc. con-
sidering LC,,, values l’or FGF. FGL. and pure MlTC on thc one hand. and thc
amounts of glucocapparin
found in the plant tissues on the other hand, that
Bct,scio
fruits and leaves containcd sufficient glucoc~appar-in to libcratc MIT(‘ ;it
levels comparable to thc I,C?,, ot’ thc pure ~nolcculc.
These results indicatc that in addition to its mccli~inal propcrtia (I>al/~el.
1 9 4 8 ) a n d utilization ah ;I f’;.mine food (Beckcr. IYXh: Salih ct ;II.. 1391). H.
.serwgalrn.ri.s also has potential in stored-grain
protection due to a potcnt t‘unii~‘rnt
effect on different insect species. B. .sCtlc~~L~lPtz.si.s has hecn traditionaIl> used h!
African fat-mers as a gram protectant, but thc basis 01‘ its ctfèctivencss
hns ne\\cr
been explained. WC bave shown that B. .sc,tlc~,~alrtt.si.s
biological activity IS I~nkccl
to the liberation of’ mcth>,l isothiocyanatc t’rorrl a glucosinolate
prccursor. glu-
cocapparin,
contained in its fruits and leaves. As thc plant frocs spontancou~l!
in somc of the poorest arws of the world (mainly in thc arid sahelian rcgion).
this research suggests a natural insccticicle t‘rom B. .,(~tI(~,~~tIptt.si.~ as an alternatl\\‘c
to synthctic pcsticidcs In dcveloping Countr-ics.

---