Journal of Stored Products Research

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1 Journl of Stored Produts Reserh 48 (12) 61e67 Contents lists ville t SiVerse SieneDiret Journl of Stored Produts Reserh journl homepge: Sesonl vritions in hemil omposition nd fumignt tivity of five Eulyptus essentil oils ginst three moth pests of stored dtes in Tunisi Joud Mediouni Ben Jemâ, *, Soumy Houel, Mohmed Bouziz, Mohmed Lri Khouj Lortoire de Protetion des Végétux, Institut Ntionl de l Reherhe Agronomique de Tunisie (INRAT), Rue Hedi Krry, 49 Arin, Tunis, Tunisi Lortoire des Bioproédés Environnementux, Centre de Biotehnologie de Sfx, BP 1177, Sfx 318, Tunisi Lortoire d Eologie et Améliortion Sylvo-Pstorle, INRGREF, 8 Arin, Tunisi rtile info strt Artile history: Aepted 3 Otoer 11 Keywords: Essentil oil Eulyptus Seson Moth Stored dtes Tunisi The present work investigtes sesonl vrition in hemil omposition of essentil oils isolted from leves of five Eulyptus speies (Nmely: Eulyptus mldulensis, Eulyptus stringens, Eulyptus leuoxylon, Eulyptus lehmnnii nd Eulyptus rudis) nd ssesses their fumignt tivity ginst three stored-dte moth pests: Ephesti kuehniell, Ephesti utell nd Etomyelois ertonie. GC nd GCeMS nlyses showed tht hemil omposition vried with Eulyptus speies nd sesons. The five essentil oils ontined 1,8-ineole, -pinene, nd -terpineol s mjor ommon ompounds. Of the other mjor onstituents, -pinene nd p-ymene were only present in E. rudis essentil oil. In ddition, o-ymene ws speifi only to E. mldulensis nd E. rudis essentil oils. Oil yields were the highest nd generlly riher in toxi ompounds during the summer seson. Results demonstrted tht fumignt toxiity vried with seson, inset speies, essentil oil onentrtion nd exposure time. E. mldulensis essentil oil ws more toxi ginst E. utell nd E. kuehniell. LC 5 vlues were respetively 11.7 nd ml/l ir while LT 5 vlues were nd 3.46 h. However, for E. ertonie, E. rudis essentil oil ws more effetive, with LC 5 nd LT 5 vlues of 31.4 ml/l ir nd 36.1 h respetively. For ll pest speies, fumignt tivity ws strongest for the summer seson oils. E. utell ws the most sensitive speies. Ó 11 Elsevier Ltd. All rights reserved. 1. Introdution In Tunisi, dtes re n importnt nd vlule export ommodity, 16% of the totl vlue of griulturl exports oming from the dte industry. Tunisin dtes re rnked 4th in the world in terms of exported quntities nd the first in terms of foreign exhnge ernings (GIFruits, 9). The nnul ntionl prodution ws round 174, tonnes inluding 79, tonnes for export (GIFruits, 1). Nevertheless, high infesttion rtes y pyrlid moth pests, nmely the ro moth Etomyelois ertonie (Zeller), the Mediterrnen flour moth Ephesti kuehniell (Zeller) nd the lmond moth Ephesti utell (Wlker), re using signifint eonomi losses during storge. These insets re reported s mjor pests of stored dtes in Tunisi (Jrry nd Vinson, 198; Dhouii, 1989; Jrry, 3). These devstting insets use loss of weight nd downgrding of the ommeril vlue of the fruit (Dhouii, * Corresponding uthor. Tel.: þ , þ (moile); fx: þ E-mil ddresses: joudmediouni@lyos.om, j_mediouni@hotmil.fr (J. Mediouni Ben Jemâ). ). The ro moth infests % of the hrvestle dte rop nnully (GIFruits, 9). Current ville methods for posthrvest ontrol re sed on fumigtion. Azelmt et l. (6) reported tht hemil ontrol using fumigtion is the most eonomil tool for mnging these stored pests in posthrvest tretment. Moreover, methyl romide is still the primry insetiide of posthrvest inset ontrol for dtes in Tunisi nd in severl other ountries (Zre et l., 2; Jrry, 3). However, the use of this fumignt is eing restrited nd phsed-out euse of its effets on helth nd the environment, prtiulrly its effet on the ozone lyer (Bell, ). Therefore, reserh on effetive lterntive methods is needed, prtiulrly euse Tunisin dtes re minly exported to the EU mrket (GIFruits, 1). Reently, pest nd disese ontrol progrmmes inluding essentil oils hve shown some promise (Regnult-Roger, 1997; Ismn, ; Bkkli et l., 8; Btish et l., 8). Among essentil oils, Eulyptus oil, in prtiulr, is more useful s it is esily extrtle ommerilly nd possesses wide rnge of desirle properties worth exploiting for pest mngement (Bolnd et l., 1991; FAO, 1995; Brton, ). Fumignt toxiity of essentil oils from Eulyptus speies hs een reported ginst mny Lepidoptern speies inluding the ro X/$ e see front mtter Ó 11 Elsevier Ltd. All rights reserved. doi:1.116/j.jspr

2 62 J. Mediouni Ben Jemâ et l. / Journl of Stored Produts Reserh 48 (12) 61e67 moth E. ertonie (Houel et l., 1) nd the Mediterrnen flour moth, E. kuehniell. Furthermore, in Tunisi, 117 speies of the genus Eulyptus hve een introdued nd limted into 3 roretums distriuted from the north to the south of the ountry sine 1957 (Khouj et l., 1). Vrious studies hve een reported previously onerning sesonl vritions in yield nd hemil omposition of essentil oils from different plnts. In this ontext, Lopes et l. (1997); Dushtzky et l. (1999) nd Moudhirou et l. (1999) showed tht differenes in the yield nd omposition of the essentil oils were influened y the time of hrvest. Moreover, diverse studies hve shown tht for Eulyptus genus the mount nd omposition of lef oil my vry sesonlly nd diurnlly for some plnts, depending on environmentl onditions (Bolnd et l., 1991). Additionlly, sine monoterpenes re mjor omponents of Eulyptus essentil oils (Ohr et l., 1), sesonl vritions in oil omposition ould e ttriuted to the monoterpene omponent. In this respet, Rivol et l. (1) reported tht despite temperture nd light, seson hd strong effet on the overll terpene emission rte, eing signifintly higher in spring nd summer thn in utumn nd winter. Similrly, Roles nd Grzino () reported tht vrition in terpene levels during the yer my e due to severl environmentl prmeters whih re proly used y omintion of sunlight, limte, nutrients nd wter vilility in soil. Furthermore, for Eulyptus speies, mny ftors my influene monoterpene emissions, espeilly sesonl nd diurnl emission tivity yles (He et l., ). Previous studies hve shown tht for Eulyptus spp there is positive reltionship etween monoterpene emission nd lef oil ontent (Ytgi et l., 1995). Kim (1) reported tht hnges in monoterpene emission rtes were due to sesons, tree ges, nd lef moistures, while Simmons nd Prsons (1987) indited tht lef geing ppers to e the most likely ftor explining ptterns of vrition in the voltile lef oils of two Eulyptus speies. Additionlly, Li et l. (1996) indited tht the differenes in lef oils etween dult nd juvenile lef smples from some Tsmnin Eulyptus speies re minly quntittive rther thn qulittive. Our ojetive in the present study is to investigte the sesonl vrition in hemil omposition of five Eulyptus essentil oils (Eulyptus mldulensis (Dehnh), Eulyptus stringens (Miden), Eulyptus leuoxylon (F. Muell), Eulyptus lehmnnii (Shuer) Benth nd Eulyptus rudis (Endl)) nd to ssess their fumignt toxiity ginst three pyrlid speies of stored-dtes: E. kuehniell, E. utell nd E. ertonie. 2. Mterils nd methods 2.1. Inset rering Etomyelois ertonie ws rered on n rtifiil diet sed on whet rn, yest, surose, slt mixture, vitmin C, ureomyine, methyl pren, lysine, glyerine nd distilled wter (for detils see Mediouni nd Dhouii, 7). The lmond moth, E. utell ws rered on n rtifiil diet sed only on whet rn, yest, surose nd glyerine. However, the Mediterrnen flour moth, E. kuehniell ws rered on red whet flour. For the three speies, rering were onduted in plsti oxes ( m) under photoperiod of 15:9 (L: D) t 25 1 C nd 65 5% reltive humidity (r.h). Adult insets of e24 h old were olleted nd used for iossys Plnt mteril Leves from the five Eulyptus speies were olleted from the roretum of Korous (north Tunisi) respetively during the four sesons (Collet 1: 27 My 9, Collet 2: 25 August 9, Collet 3: 3 Novemer 9 nd Collet 4: Ferury 1). Leves of sme ge were tken from the sme trees in order to get homogeneous smples. The hrvested leves were ir-dried t room temperture (e25 C) for one week nd then stored in loth gs. The roretum of Korous (north-est Tunisi, Ltitude 36 deg N; Longitude 1 deg E.) hd n re of 16 h. The site ws hrterized y n nnul men rinfll of 54 mm. Trees were plnted on soil-rih snd, sndstone nd ly. Temperture reorded during the hottest moth ws out 32.7 C wheres for the oldest moth, it fell to 6.8 C. The re plnted in Eulyptus overed out 37.5% of the totl re of the roretum (6 h). Trees were out fifteen yers old Essentil oils extrtion nd hemil nlysis The essentil oils were extrted y hydrodistilltion of the dried plnt leves (1 g of eh smple in 5 ml of distilled wter) using modified Clevenger-type pprtus for 4 h. The oils were dried over nhydrous sodium sulphte nd stored in seled glss vils t 4e5 C prior to nlysis. Yields were verged over four experiments nd lulted ording to dry weight of the plnt mterils. The essentil oils were nlyzed using n Agilent-Tehnologies 689 N Network GC system equipped with flme ioniztion detetor nd HP-5MS pillry olumn (3 m.25 mm, film thikness.25 mm; Agilent-Tehnologies, Little Flls, CA, USA). The injetor nd detetor tempertures were set t 2 C nd 29 C, respetively. The olumn temperture ws progrmmed from 8 C to 2 C t rte of 4 C/min, with the lower nd upper tempertures eing held for 3 nd 1 min, respetively. The flow rte of the rrier gs (Helium) ws 1. ml/min. A smple of 1. ml ws injeted, using split mode (split rtio, 1:1). All quntifitions were rried out using uilt-in dt-hndling progrm provided y the mnufturer of the gs hromtogrph. The omposition ws reported s reltive perentge of the totl pek re. The identifition of the essentil oil onstituents ws sed on omprison of their retention times to n-lknes, ompred to pulished dt nd spetr of uthenti ompounds. Compounds were further identified nd uthentited using their mss spetr ompred to the Wiley version 7. lirry. Voltile ompounds were rnged into groups (monoterpene hydrorons, oxygented monoterpenes, sesquiterpene oxygented, sesquiterpene hydrorons, other ompounds). Mjor ompounds in eh group were mrked in old form Fumignt toxiity iossys To ssess fumignt toxiity of the five essentil oils olleted during the four sesons, 2 m dimeter filter ppers (Whtmn No. 1) were impregnted with the different oil doses.5, 1, 2, 3, 4 nd 5 ml. Doses were onverted to give equivlent fumignt onentrtions of respetively 13.16, 26.31, 52.63, 78.95, nd ml/l ir. The impregnted filter pper ws then tthed to the srew ps of 38 ml Plexigls ottle. Cps were srewed tightly on the vils, eh of whih ontined 1 unsexed dults (e24 h old). Eh onentrtion nd ontrol ws replited five times. Mortlity ws reorded hourly until deth. When no leg or ntennl movements were oserved, insets were onsidered ded. The mortlity ws lulted using Aott s orretion formul (Aott, 1925) Lethl doses iossys Trils were designed to ssess 5% lethl doses or onentrtions (LC 5 vlues). Ten unsexed dult insets were put into 38 ml

3 J. Mediouni Ben Jemâ et l. / Journl of Stored Produts Reserh 48 (12) 61e67 63 Plexigls ottles with srew lids. Oil mounts tested were.5, 1, 2, 3, 4 nd 5 ml orresponding to onentrtions of 13.16, 26.31, 52.63, 78.95, nd ml/l ir. Control insets were kept under the sme onditions without ny essentil oil. Eh dose ws replited five times. Mortlity ws evluted y diret oservtion of the insets. The numer of ded nd live insets in eh ottle ws ounted 24 h fter initil exposure. Proit nlysis (Finney, 1971) ws used to estimte LC 5 vlues Lethl time iossys To e effetive, fumigtion trils should e sed on the use of lower fumignt onentrtions leding to high mortlity in short time. Therefore, one series of iossys ws designed to determine medin effetive times (LT 5 ) to use mortlity of 5% of test insets t the lowest dose ml/l ir. The mortlity ws ssessed y diret oservtion of insets. Dt were nlyzed using Finney s method (1971) Sttistil nlysis Dt were nlyzed y one-wy nlysis of vrine using Sttisti (Sttsoft, 1998). A Dunn test ws pplied to the mens to detet signifint differenes t the.5 perent level. 3. Results 3.1. Sesonl vritions in Eulyptus essentil oil yields Results relted to the sesonl vritions in essentil oils yields re shown in Tle 1. Results showed tht essentil oil yields vried ording to Eulyptus speies nd sesons. For ll speies, high yields were otined from leves olleted t the summer seson (Seson 2, Tle 1) though E. stringens gve rther onstnt yields during the four sesons (1.23% for seson 1 nd 1.1% for seson 4). Compred to the other speies, E. lehmnnii gve the highest yields for the four sesons, oilyields vrying from 2.52% for seson 2 to 1.74% for seson 4. E. leuoxylon ws hrterized y the lowest yields. Sttistil nlysis showed signifint differenes in essentil oil yields otined through the four sesons nd mong the five essentil oils for eh seson. For the spring seson (seson 1, Tle 1), results indited signifint differenes etween yield of E. lehmnnii (2.21%), E. stringens (1.23%) nd the three others speies. Conerning the summer seson (seson 2, Tle 1), results showed signifint differenes etween yields of ll speies. Oil yields otined for the utumn nd winter sesons (Sesons 3 nd 4, Tle 1) showed sttistil differenes etween most of the speies Sesonl vritions in Eulyptus essentil oils omposition The men perentges of the min hemil lsses, the others onstituents nd totl identified ompounds of essentil oils olleted through the four sesons nd used in iossys re shown in Tle 2, while the mjor ompounds (5%) re listed in Tle 3. In detil, the five Eulyptus essentil oils showed high perentge of monoterpenes, minly oxygented ompounds, while lower quntities of sesquiterpenes were reorded throughout the four sesons. In E. rudis summer seson oil, 53.29% of the ontents were monoterpenes. Moreover, in E. mldulensis oil, monoterpenes were prevlent (36.89%, 56.34%, 51.31% nd 34.56% respetively for the sesons S1, S2, S3 nd S4) while sesquiterpene hydrorons [14.84% (S1), 6.65% (S2), 16.54% (S3) nd 13.35% (S4)] nd oxygented sesquiterpenes [6.89% (S1), 3.93% (S2), 2.14% (S3) nd 11.6% (S4)] were less represented (Tle 3). Eulyptus leuoxylon essentil oil ontined minly oxygented monoterpenes with prevlene of 1,8 ineole. The essentil oil of E. lehmnnii ws mde up lrgely of monoterpenes (hydrorons nd oxygented (28.36%, 42.83% in S1; 4.33%, in S2; 44.89%, 3.9% in S3 nd 27.59%, 62.75% in S4 respetively), with smller mounts of sesquiterpene hydrorons nd unlike in the other oils totl sene of oxygented sesquiterpenes. The hemil hrteristi of E. stringens oil ws lso the undnt quntity of monoterpenes, whih represented more thn 5% of the totl oil mounts for the ll sesons. Reltive mounts were respetively 58.21% (S1), 57.85% (S2), 53.42% (S3) nd 63.55% (S4) Sesonl vritions in fumignt toxiity Even t the lowest onentrtion (13.16 ml/l ir), the five essentil oils were toxi to the three moth speies (Fig. 1). Oils were more toxi to E. utell thn to E. kuehniell nd E. ertonie. Highest mortlities were otined during summer seson (Seson 2) while lowest mortlities were oserved during winter seson (Seson 4). The most effetive essentil oils ginst the three pests were respetively E. mldulensis nd Eulyptus lehmni. At ml/l ir. Eulyptus mldulensis oil led to 48.25, nd 19.81% mortlity respetively for E. utell, E. kuehniell nd E. ertonie fter 24 h of exposure during seson 2. Menwhile, E. lehmni oil hieved respetively oil 44.25, nd 12.25% mortlity ginst E. utell, E. kuehniell nd E. ertonie t this onentrtion fter 24 h of exposure (Fig. 1) Sesonl vrition in lulted LC vlues Sesonl vritions in LC vlues of the five essentil oils re reported in Tle 4. Results indited tht ll five oils exhiited fumignt toxiity ginst the three moths. Proit nlysis showed tht E. utell ws omprtively more suseptile thn either E. kuehniell or E. ertonie to oils from eh speies nd seson (Tle 4). Comprison of LC 5 vlues showed tht E. mldulensis oil ws reltively more toxi to E. utell nd E. kuehniell thn the other oils wheres, E. rudis oil ws more toxi to E. ertonie. Tle 1 Essentil oil yields (%) of the five Eulyptus speies olleted during four sesons (Sesons 1, 2, 3 nd 4 orrespond respetively to spring, summer, utumn nd winter). Eulyptus speies Oil yields (%) Seson 1 Seson 2 Seson 3 Seson 4 E. rudis * *** ** ** E. mldulensis * d** ***.76.2 * E. leuoxylon * e** d* d* E. lehmni ** *** ** * E. stringens ** **** *** * For eh seson, men vlues followed y different letters within olumn re signifintly different using Dunn s multiple rnge test (P < 5%). Between sesons, men vlues followed y different supersripts (*) within row re signifintly different using Dunn s multiple rnge test (P <.5).

4 64 J. Mediouni Ben Jemâ et l. / Journl of Stored Produts Reserh 48 (12) 61e67 Tle 2 Chemil frtions, others onstituents nd totl identified ompounds of the essentil oils otined from leves of five Eulyptus speies olleted during the four sesonl periods (%). Eulyptus speies Seson Chemil lss Others Totl of Monoterpene hydrorons Oxygented monoterpenes Sesquiterpene hydrorons Oxygented sesquiterpenes E. rudis S S S S E. mldulensis S S S S E. leuoxylon S S S S E. lehmni S t S t S t S t E. stringens S S S S t ¼ tres (.5%) S1, S2, S3 nd S4 orrespond respetively to spring, summer, utumn nd winter sesons. identified ompounds Furthermore, lowest LC 5 vlues ourred during seson 2 ompred to sesons 1, 3 nd 4 (Tle 4) suggesting tht oils olleted during this seson displyed the est insetiidl potentil. The respetive LC 5 vlues for E. mldulensis oil were 11.7 nd.46 ml/l ir ginst E. utell nd E. kuehniell respetively, nd 3.55 ml/l ir for E. rudis ginst E. ertonie Sesonl vrition in lethl time vlues Proit nlysis gin showed tht E. utell ws more suseptile to essentil oils from the vrious Eulyptus speies thn E. kuehniell nd E. ertonie t the lowest onentrtion ml/l ir. The LT 5 vlues for E. utell rnged from h for Tle 3 Mjor ompounds (5%) of the essentil oils otined from leves of five Eulyptus speies olleted during the four sesonl periods (%). Eulyptus speies S1 S2 S3 S4 E. rudis -pinene (5.83) -pinene (14.49) -pinene (5.47) -pinene (12.3) O-ymene (16.35) g-terpinene (6.4) O-ymene (3.3) -pinene (8.65) Terpinen-4-ol (7.87) 1,8 ineole (19.87) Aromdendrene (5.86) p-ymene (19.77) Aromdendrene (9.1) Aromdendrene (6.37) Crypton (6.36) Cmphene (7.73) Trns-Cryophyllene (1.1) Vitrenl (7.44) Aromdendrene (9.89) Trns-Cryophyllene (9.75) Spthulenol (6.26) E. mldulensis -pinene (11.74) -pinene (16.49) -pinene (17.75) -pinene (8.7) 1,8 ineole (19.24) 1,8 ineole (.62) g-terpinene (5.63) O-ymene (18.12) Spthulenol (13.37) 1,8 ineole (15.52) Aromdendrene (9.55) Terpinene-4-ol (6.84) Spthulenol (13.35) Spthulenol (12.55) E. leuoxylon -pinene (5.61) -pinene (32.73) -pinene (.51) -pinene (21.77) 1,8 ineole (14.9) 1,8 ineole (17.62) Cmphene (5.22) 1,8 ineole (13.13) Terpinen-4-ol (6.44) Viridiflorol (5.27) 1,8 ineole (15.64) Trns-pinorveol (9.28) Trns-pinorveol (6.14) Gloulol (14.67) -terpineol (6.8) -terpineol (6.7) -terpineol (6.65) Gloulol (14.38) Gloulol (13.95) Isothymol (5.8) -eudesmol (5.85) Aromdendrene (6.9) g-gurjunene (12.16) Viridiflorol (8.13) E. lehmni -pinene (7.22) -pinene (31.61) -pinene (31.88) -pinene (17.8) Cmphene (21.14) Cmphene (8.72) Cmphene (13.1) Cmphene (1.51) 1,8 ineole (18.42) 1,8 ineole (34.56) 1,8 ineole (14.21) 1,8 ineole (54.55) Trns-pinorveol (5.1) -terpineole (6.82) -terpineol (5.11) -terpineole (15.14) E. stringens -pinene (25.13) -pinene (29.83) -pinene (25.39) -pinene (19.63) 1,8 ineole (13.91) 1,8 ineole (17.29) 1,8 ineole (12.21) 1,8 ineole (25.91) Trns-pinorveol (15.6) -terpineol (5.11) Trns-pinorveol (12.3) Trns-pinorveol (8.64) Aromdendrene (5.18) Aromdendrene (5.1) Aromdendrene (5.2) Pinorvone (5.51) Gloulol (12.8) Viridiflorol (11.24) Viridiflorol (8.35) Ledene (8.27) S1, S2, S3 nd S4 orrespond respetively to spring, summer, utumn nd winter sesons.

5 J. Mediouni Ben Jemâ et l. / Journl of Stored Produts Reserh 48 (12) 61e Mortlity (%) Seson 1 E. utell E. kuehniell E. ertonie Seson Seson Seson 4 Fig. 1. Perentge mortlity fter 24 h of exposure of E. utell, E. kuehniell nd E. ertonie dults exposed to the lowest onentrtion (13.16 ml/l ir) of essentil oil from five Eulyptus speies olleted in spring (1), summer (2), utumn (3) nd winter (4). (For eh seson, omprisons were mde etween mortlities of the three pests. Mens followed y different letters re signifintly different using Dunn s multiple rnge test P < 5%). E. mldulensis essentil to 53.6 h for E. lehmnnii oil (Tle 5). With E. kuehniell, the LT 5 vlues rnged from 3.46 h for E. mldulensis to 63.6 h for E. leuoxylon essentil oil. Additionlly, for E. ertonie, the LT 5 vlue rnged from 36.1 h for E. rudis oil to h for E. mldulensis essentil oil (Tle 5). 4. Disussion Results of our study lerly indite the presene of gret sesonl vritions oth for hemil omposition s well s for the insetiidl tivity of the essentil oils. The five Eulyptus speies investigted in the present work showed lrge vrition in their hemil omposition throughout the four sesons. The essentil oils were dominted y few ommon voltile ompounds inluding 1,8-ineole, -pinene, nd -terpineol. Previous studies reported tht the hemil omposition of romti plnts my e influened y sesonl hnges nd tht mostly quntittive rther thn qulittive vritions of the oil omposition were oserved (Kmtou et l., 8). Silvestre et l. (1997) reported tht vrition of essentil oil omposition nd yield of Eulyptus gloulus Lill. ws due to sesonl nd lef ge influenes. Moreover, sesonl influenes were deteted in the Tle 4 LC 5 vlues lulted for mortlity within 24 h of exposure of E. utell, E. kuehniell nd E. ertonie dults on filter pper impregnted with Eulyptus essentil oils olleted during the four sesons. Seson Eulyptus Speies LC5, (ml/l ir) E. utell E. kuehniell E. ertonie 1 E. rudis (15.86e21.94) (.73e25.29) 36.1 (5.319e72.83) E. mldulensis (16.36e21.49) (19.45e25.7) (7.69e72.65) E. leuoxylon (15.1e19.84) (33.23e42.55) (4.21e49.17) E. lehmni (15.23e.34) (37.63e47.11) (49.89e61.94) E. stringens 18.2 (15.e.75) (1.81e57.49) (32.52e51.63) 2 E. rudis (1.97e19.65).83 (4.2e42.36) 3.55 (6.42e55.35) E. mldulensis 11.7 (7.63e12.92).46 (17.75e23.22) 34.8 (21.7e48.26) E. leuoxylon (57.76e13.99) (21.15e28.41) (15.16e51.76) E. lehmni (11.73e17.68) 27.9 (22.8e32.2) (49.67e6.21) E. stringens (8.71e14.78) (8.29e65.8) (27.8e41.71) 3 E. rudis (21.55e31.24) (22.46e32.36) (38.66e5.76) E. mldulensis 14.1 (1.97e16.61) 27.2 (1.1e5.7) (4.6e56.1) E. leuoxylon (1.99e34.48) 43.7 (39.97e47.3) 51.6 (18.69e112.14) E. lehmni (11.79e52.66) (48.46e55.32) (59.67e64.89) E. stringens (17.97e47.72) (3.36e37.89) (34.7e96.88) 4 E. rudis (15.95e.11) (18.59e49.58) (41.34e5.11) E. mldulensis (14.21e18.98) (.13e35.79) (19.49e135.5) E. leuoxylon 3.8 (.83e39.83) 4.31 (1.18e11.16) (49.89e57.41) E. lehmni.88 (11.8e29.39) 65.6 (.24e1.27) 63.9 (61.23e65.64) E. stringens (15.53e31.81) 4.47 (35.67e44.32) (34.26e44.68) Units LC 5 ¼ ml/ir, pplied for 24 h t 25 C. 95% lower nd upper onfidene limits re shown in prenthesis.

6 66 J. Mediouni Ben Jemâ et l. / Journl of Stored Produts Reserh 48 (12) 61e67 Tle 5 Sesonl vritions of LT 5 vlues of the five Eulyptus essentil oils ginst E. utell, E. kuehniell nd E. ertonie for the lowest tested onentrtion ml/l ir. Seson Eulyptus Speies LT5 (h) E. utell E. kuehniell E. ertonie 1 E. rudis (3.248e6.65) (49.83e64.93) 49.9 (4.96e55.6) E. mldulensis 19.4 (7.39e32.11) (1.33e85.81) (6.25e7.7) E. leuoxylon (.25e3.5) 46.7 (38.e55.55) 52.7 (49.59e56.) E. lehmni.497 (15.887e27.35) (13.41e14.7) (48.45e65.52) E. stringens (26.92e39.63) (4.35e55.82) 7.15 (65.41e75.82) 2 E. rudis (14.97e21.75) (3.9e43.3) 36.1 (29.31e43.88) E. mldulensis (9.871e17.24) 3.46 (25.22e35.93) (3.439e6.32) E. leuoxylon 18.1 (15.79e.97) (25.15e41.67) (41.8e53.57) E. lehmni (25.46e33.64) 37.5 (3.75e44.67) (37.36e6.17) E. stringens (14.52e18.99) 41.1 (33.67e49.2) (58.4e71.84) 3 E. rudis 39.5 (32.73e47.4) (39.9e57.78) 5.17 (47.61e52.57) E. mldulensis (17.26e38.21) (43.78e56.4) (73.73e12.97) E. leuoxylon 33.9 (27.21e4.75) (4.12e52.) (46.41e55.7) E. lehmni (45.33e61.97) 5.37 (41.72e58.46) 66.5 (59.1e72.61) E. stringens (23.94e32.48) (16.219e94.6) (5.18e75.89) 4 E. rudis (38.6e55.3) (48.39e6.) (46.53e91.66) E. mldulensis (26.77e39.6) (45.722e61.) (16.7e124.45) E. leuoxylon (4.8e56.65) 63.6 (56.67e7.58) (58.35e71.97) E. lehmni 53.6 (44.79e62.91) (5.85e65.62) (46.43e152.8) E. stringens (38.78e5.) 68.7 (38.45e98.95) (42.97e16.74) 95% lower nd upper onfidene limits re shown in prenthesis. essentil oil yield with higher vlues in My nd lower ones in Deemer (Hernández et l., 1988). Additionlly, Btish et l., (6) showed tht there re mny onstrints suh s inonsisteny in the mount of oil tht vries with seson, hnging limte, speies nd even with ge. Similrly, Ismn (, 6) pointed out tht the qulity of the essentil oils vries with seson, limte, ge, geogrphil region, nd geneti mkeup of the plnt. Chemil nlysis showed tht the profile of monoterpenes vries mong the Eulyptus speies nd seson. E. lehmni essentil oil hs een shown to ontin high (7e9%) monoterpene perentges during ll sesons (85.17% inluding oxygented monoterpenes during summer seson, Tle 2) wheres most other speies exhiited high monoterpene rtes in the summer seson only (53.29% for E. rudis, 56.34% for E. mldulensis) or in oth summer nd utumn sesons (55.5 nd 56.98% for E. leuoxylon) while E. stringens ws similr to E. lehmni ut showed generlly lower (53.42e63.55%) sesoneindependent profile for monoterpenes. The two monoterpenes 1,8 ineole nd -pinene whih support the pestiidl tivity of Eulyptus oils (Btish et l., 6), were well represented in the five oils minly during the summer seson (Tle 3). These results my e ompred with previous reports inditing tht in spring nd summer higher monoterpene emission rtes were found ompred with utumn nd winter emissions (Kim et l., 5; Rivol et l., 1). Furthermore, terpene emissions re speies-speifi nd influened y vrious ioti nd ioti ftors, in prtiulr light nd temperture. Terpene levels show qulittive nd quntittive vriility ording to seson, generlly with mxim in spring nd summer (Llusi nd Peñuels, ; Angelopoulou et l., 2). Sine the iotivity of the essentil oils depends upon the type nd nture of the onstituents nd their individul onentrtion levels (Btish et l., 8), we ould ttriute the sesonl vritions oserved in insetiidl iossy effiy to vritions in the oil omposition. Indeed, highest mortlities were oserved during summer seson during whih 1,8 ineole nd -pinene were t or ner their mximum rtes. Essentil oil from E. mldulensis nd E. lehmni ontining respetively 16.49% nd 31.61% of -pinene nd.62% nd 34.56% of 1,8 ineole during summer hieved the highest mortlities of the three inset pests (Fig. 1). Lower LC vlues (Tle 4) were thus otined for the three pests during summer, suggesting tht insetiidl effiy of ll oils ws optiml during this seson. A hemil omposition nd insetiidl-tivity reltionship dedued from our results demonstrtes tht the insetiidl tivity of E. mldulensis, E. lehmni, E. stringens nd E. leuoxylon is relted to high mounts of 1,8-ineole nd -pinene, lthough other onstituents of the essentil oils hve previously showed noteworthy tivity (eg. -terpineol nd romdendrene: Prtes et l., 1998; Ojimelukwe nd Adler, 1999; Cimng et l., 2; Btish et l., 6; Su et l., 6; Liu et l., 8).For E. rudis, highest tivity ws reveled during summer seson when 1,8 ineole ws present, ut the orreltion etween the insetiidl tivity nd the hemil omposition ould e due to the high perentge of some other mjor ompounds suh s romdendrene, p-ymene, O-ymene, terpinen-4-ol, trns-ryophyllene nd spthulenol. Some of them, suh s terpinen-4-ol (Kordli et l., 6); romdendrene (Btish et l., 8) nd p-ymene (Regnult-Roger nd Hmroui, 1995) hve previously een reported s toxi to severl inset speies. To summrize, we propose tht vritions in insetiidl tivity n e relted to hnges in the mounts of the tive omponents present in eh Eulyptus speies t different sesons. The essentil oils displyed their strongest fumignt toxiity during summer seson. These dt re very muh needed y frmers in order to determine whih seson of the yer would provide the Eulyptus oils with the most promising iologil tivity in the serh for possile lterntives to syntheti fumignts. Our results lerly demonstrte tht for use in pest ontrol, summer is generlly the est time of the yer for hrvesting Eulyptus leves. Strong fumignt toxiity ws oserved during this seson, providing dt to support the use of Eulyptus essentil oils s n lterntive to the fumignt methyl romide for treting stored-dte ommodities in Tunisi. Therefore further investigtions, inluding the impt of Eulyptus essentil oil extrts t the dose levels needed for ontrol of pests on dte qulity, re wrrnted. 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