CJES Caspian Journal of Environmental Sciences

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1 Cspin J. Env. Sci. 26, Vol. 4 No.1 pp. 31~37 Copyright by The University of Guiln, Printed in I.R. Irn [Article] CJES Cspin Journl of Environmentl Sciences Effects of Thrips (Pseudodendrothrips mori Niw) Infested Mulberry Leves on Silkworm Growth nd Commercil Cocoon Prmeters K. Etebri 1* nd A. R. Bizhnni 2 1- Dept. of Sericulture, Fculty of Nturl Resources, The University of Guiln, Somehe Sr 1144, Irn 2- Irn Sericulturl Reserch Center (ISRC), Psikhn, Rsht, Irn *Corresponding uthor s E-mil: etebri@guiln.c.ir Abstrct In mulberry orchrds in northern prt of Irn, thrips is dominnt pest nd cusing lot of dmge to the mulberry. The effect of pest on bio-chemicl prmeters of mulberry lef of two vrieties viz. Kenmochi nd nd lso the effect of feeding of infested leves on rering performnces hve been studied. For the study, six plots of 2 m 2 re of both the vrieties were selected nd three of them, of ech vriety, were spryed with.5% Metsystox t pek period of occurrence of nymph popultion to obtin the good helthy lef without thrips infesttion. Another 3 plots were left without pesticide spry to obtin infested leves so s effect of infesttion on chemicl prmeters of lef nd effect of infested leves on rering performnce could be studied. During rering, lrve were fed with good qulity of mulberry lef while nother lot were fed with infested leves. The results showed tht there ws decrese in nitrogen, phosphorus, potssium nd protein contents of leves by 2.5, 1.8, 18.7 nd 12.5%, respectively due to infesttion nd the decrese in these prmeters ws more in Kenmochi. There ws lso significnt decrese in totl cocoon production, cocoon weight, pupl weight, nd shell weight due to feeding of infested leves. However, there ws no significnt difference in shell rtio between the lots fed with helthy nd infested leves. Keywords: Bombyx mori, Crop loss ssessment, Mulberry Thrips, Pseudodendrothrips mori, Silkworm Introduction Infesttion of mulberry grden by different species of thrips were reported by different scientists (Etebri et l., 2 b; Mound, 1999; Wn nd Zhng, 1997; Plmer, 199), However, Pseudodendrothrips mori Niw (Thysnopter; Thripide) ws found to be most dominnt species in different prts of world. Thrips, is highly oligophgous pest nd ntive of northern hemisphere (Mound, 1999). It ws first collected in Mrylnd, USA by Crwford in 1937 (Stnnrd, 1968; Woo, 1974) nd noticed in Itly in 1975 s serious pest of mulberry trees (Cppellozz nd Mitto, 1975). It is lso reported from Afric, Austrli, Chin, Indi, Jpn, Kore Sri Lnk, nd Vietnm (Etebri et l., 24; Mound, 1999; Wn nd Zhng, 1997; Plmer, 199). P. mori is introduced s dominnt species in the insect fun of mulberry field in the north of Irn, wheres this species ws dispersed in ll regions of Irn with mulberry orchrds (Etebri et l., 1998). Mulberry, Morus lb L. is the sole food plnt for silkworm, Bombyx mori L. nd is grown under vried climtic conditions rnging from temperte to tropicl. Mulberry lef is mjor economic component in sericulture since the qulity nd quntity of lef produced per unit re hve direct bering on cocoon hrvest (Etebri, et l., 2 ). P. mori feed on fully expnded leves nd young tissue in the bud. Infested leves dry out nd hve stippled or silverflecked ppernce. Smll brownish specks of excrement will usully be noticed on the underside of the leves (Lewis, 1997). Estimtion of crop losses re required to determine the reltive importnce of prticulr pests, nd thus decide upon the level of resources tht should be devoted to reserch nd pest mngement inputs nd provide bsis for understnding the often complex interction between pest nd its host plnt. Attempts were mde to find out the losses due to thrips infesttion on different morpho-physiologicl prmeters of mulberry t West Bengl in few yers Online version is vilble on

2 32 Effects of mulberry thrips on silkworm go. The losses in dry weight nd lef re incresed progressively from 3 rd lef downwrd nd reched highest level in 17 th mounting to nd 58.45% respectively, while losses in fresh weight did not show ny significnt difference in norml nd infested leves (Ds et l., 1994 ). P. mori hs 6-8 genertions per yer in Irn (Etebri et l., 2 ; Jlli et l., 22). In mid-mrch, when there re 2-3 leves on the mulberry trees, the overwintered dults emerge to dmge the leves. In north of Irn mulberry thrips hs high popultion in lte- July to mid-august (Etebri, 22). Jlli et l., (22) reported tht spring crop rering of silkworm is not ffected by thrips but some negtive effects on utumn rering yield were ssumed. In the present study effect of feeding of thrips infested leves on rering performnce nd on biochemicl prmeters of mulberry were studied in utumn seson. Mterils nd Methods Tretment Effect of infesttion on two dominnt mulberry vrieties of the re viz Kenmochi nd were selected t mulberry orchrds of Irn Sericulture Reserch Center (ISRC Rsht, Irn) for the present study. For ech mulberry vriety, six plots of 2m² re in rndomized block design were utilized. Three of them were spryed with.5% Metsystox t the pek period of occurrence of second nymph popultion to obtin helthy lef without ny infesttion while nother three plots of both the vrieties were left without ny spry to obtin the infested leves nd lso to study the effect on chemicl chrcteristics of mulberry. Silkworm Rering Seed of Bivoltine silkworm hybrid ws obtined from ISRC nd rered in the lbortory with stndrd rering technique (Lim et l., 199) under 25ºC with RH of 75 ± 5% nd photoperiod of 16L: 8D. Silkworm lrve were divided in two lots, ech hving 3 lrve. First instr lrve in first lot ws fed with the helthy leves (thrips free) obtined from the grden fter 3 dys of sprying of Metsystox, while nother lot ws fed with infested leves. This experiment ws conducted for both the vrieties seprtely. Dt on lrvl nd cocoon prmeters nd mortlity in lst instr lrve ws recorded. The cocoon weight, cocoon shell weight, cocoon shell rtio nd pupl weight were determined by using stndrd technique in sericulture (Lim et l., 199). Biochemicl nd minerl constituents of mulberry leves The mulberry leves from both the vrieties were collected during silkworm rering period nd the collected leves dried in shdow nd prepred for chemicl nlysis. Totl orgnic nitrogen nd pro-tein were dtermined by Micro-Kjeldl method. Potssium ws mesured by flme photometry uing lithium internl stndrd. Phosphorus ws determined using the Molybdte blue method ccording to Bry nd Kurtz (1945). Sttisticl Anlysis Dt were subjected to sttisticl nlysis of vrince test for significnt differences in the mesured prmeters of the control (thrips free) nd thrips infected groups. For nlysis of vrince the tukey s test in SAS softwre nd the t-test were used (SAS, 1997). Results nd Discussions Mulberry Leves Chemicl Properties The results showed tht the thrips infesttion hs negtive effects on qulity nd nutritive vlue of mulberry leves of both the vrieties (Fig 1). The men mount of Nitrogen, Phosphorus, Potssium nd Protein of the leves showed 2.5, 1.8, 18.7 nd 12.5% decrese, respectively nd this decrese ws much more evident in Kenmochi vriety. The decreses in phosphorus(%) in Kenmochi nd the mount of totl protein in leves of vriety were not significnt fter thrips infesttion (Fig 1). Decrese in Nitrogen content ws more prominent in Kenmochi vriety s there ws 13% decrese. Different uthors reported the reduction of protein content in mulberry leves by 17.8% (Etebri et l., 1998), 12.5% (Pik nd Lee, 1984) nd 75.21% (Ds et l., 1994) due to mulberry thrips infesttion. Decrese in protein content in infested leves my be prtly due to utiliztion by thrips t fster rte for its multipliction. Hydrolysis of protein by proteolytic enzymes secreted by the pest itself my be the other cuse of lowering the protein (Sengupt et l., 1999). Pik nd Lee, (1984) reported tht totl crbohydrte ws reduced more thn 16% in

3 Etebri nd Bizhnni 33 The Percentge of Nitrogen The Percentge of Protein Mulberry Vriety Mulberry Vriety The Percentge of Phosphorus The Percentge of Potsium Mulberry Vriety Mulberry Vriety Fig 1. Effect of thrips infection on biochemicl nd minerl constituents of the leves in two mulberry vrieties infected leves while this mount is vrious in different vrieties of mulberry. It hs been reported tht most of the mulberry vrieties were susceptible for the thrips ttck (Nik, 1997) nd severe ttcks led to different morpho-physiologicl chnges in the leves (Ds et l., 1994). But mulberry thrips show certin host preference in their feeding ctivity. There re lrge numbers of vrition in the numbers of thrips on different mulberry vrieties (Xi nd Zhu, 1991). Plnting the mulberry vrieties tht re less susceptible to P. mori my lso ffect the level of infesttion. Etebri et l., (2b) recorded the number of thrips individuls in one cm 2 of lef re s density index in four vrieties of mulberry. It hs been recorded tht the KM vriety bering n verge of 3.48±.3 insects/cm 2 lef, is significntly different from the other vrieties. The results of recent reserch confirm our pervious study. The nymphs nd dults of the mulberry thrips lcerte the tissue nd suck the oozing cell sp from the upper nd lower surfces of the leves. So, the usul evportion process of the leves is quickened, especilly during high temperture sesons, by dditionl evportion through these wounds (Ye nd Gu, 199). This is most hrmful in dry climtes nd sesons when hevily ttcked plnts lose moisture hevily. In these conditions infesttion cn seriously deplete yields. Pul et l., (1992) reported tht leves moisture is one of the most importnt fctors in silkworm nutrition. Mulberry thrips reduces the moisture by 3.57%, therefore hs negtive impct on the qulity of the leves consumed by silkworm (Etebri et l., 1998). Dmge by mulberry thrips in spring t Chin, my lso be reltively serious due to the region s different climte, 1% decrese

4 34 Effects of mulberry thrips on silkworm the Lrvl Mortlity (%) b Km Mulberry Vriety in the production of mulberry leves ws reported by Xi nd Zhu (1991). Also in Indi, the estimted loss is bout 4-5% of totl lef production (Venugopl nd Krishnswmi, 1983). Venugopl nd Krishnswmi (1983) reported tht mulberry thrips hve cused serious dmge to sericulture in the southern sttes of Indi. The thrips infesttion ffects the qulittive nd quntittive chrcters of mulberry lef. Ds et l., (1991) reported tht chlorophyll /b rtio ws lower in infested leves in most cses. Decrese in chlorophyll nd crotenoid contents in infested leves my hve been due to loss in chlorophyll synthetse ctivity in response to thrips infesttion (Ds et l., 1994 b). Effects on silkworm rering The result showed tht the mortlity rte is high with the feeding of infested Uninfected Fig 2. Effect of feeding thrips infected mulberry leves over the lrvl mortlity of silkworm I mulberry leves. The percentge of mortlity in the lrve fed on thrips infected leves of Kenmochi vriety ws higher thn other vriety (Fig 2). The number of cocoon nd cocoon weight were decresed considerbly in the lot fed thrips infested lef of Kenmochi vriety. However there ws no significnt difference in these prmeters in lrve, which fed on, helthy or infested leves of vriety (Fig 3). The cocoon chrcteristics of silkworm fed on thrips infected mulberry leves showed in Tble 1. As shown in Tble 1 the decrese in mle cocoon weight nd cocoon shell weight ws more thn femle cocoon weight nd cocoon shell weight in the lrve fed with thrips infested groups in both vrieties. While the percentge of decrese in femle pup weight of thrips infected tretment is more thn mle pup. So, it is cler tht the reduction in qulity of mulberry leves due to thrips infection in both vrieties hd negtive effects on femle reproductive system. Also the mle lrv of silkworm is susceptible to feeding of thrips infested leves, s there were decreses in their cocoon nd shell trits. Infesttion of thrips ws more prominent in Kenmochi thn since depletion in chemicl properties ws more in Kenmochi nd lso there were significnt differences on rering performnce. The decrese in cocoon prmeters ws more in the lrve fed with Kenmochi leves. However, s fr s shell rtio is concerned there ws no significnt difference between two vrieties (Fig 4). There re no sufficient informtion vilble on the effects of thrips dmge on silkworm rering but Pik nd Lee (1984) reported tht mulberry thrips cused 12% reduction in cocoon weight. In current Tble 1. The cocoon chrcteristics of Bombyx mori fed on thrips infected mulberry leves Tretment Mulberry vrieties Femle Mle FCW FPW FSW MCW MPW MSW KM b.945 b b KM 1.14 b.815 b b Differences (%) (-11.5) (-13.7) (-13.9) (-12.2) (-11.5) (-15.) I I b.913 b b Differences (%) (-4.5) (-4.5) (-4.2) (-17.2) (-.1) (-7.3) F-vlue P C.V

5 Etebri nd Bizhnni 35 Number of Best Cocoon b Totl Best Cocoon Weight (g) b Mulberry Vriety Mulberry Vriety Fig 3. Effect of mulberry thrips infection on cocoon prmeters of silkworm fed on two vrieties of mulberry There re no significnt differences in ech column which shown with sme letter in ech vrieties reserch the cocoon weight decresed more thn 31% in the lrve fed with Kenmochi infested leves. It ws ssumed tht in Irn nd some countries in Europe nd Americ tht the production of silk is very limited; the dmge of pest could be reduced with some nonchemicl methods, which re economiclly tolerble (Etebri nd Mtindoost, 24). But in some sub-tropicl regions like south of Indi, plnning n ccurte IPM for this pest nd utilizing ll the mngement methods of pest control is very importnt (Singh nd Srtchndr, 22). Misr et l. (23) hve reported the effective control of thrips with Shell Rtio (%) Km Mulberry Vriety Uninfected Fig 4.The effect of mulberry thrips infection on shell rtio chrcteristics of silkworm fed on two vrieties of mulberry I the usge of Quinlphos (.2%) nd found no dverse effect on rering of silkworms with the treted mulberry leves. With respect to our current results we recommend the using of non-susceptible vrieties of mulberry for development of sericulture s one of most importnt tools in integrted pest mngement. The evlution of host preferences of P.mori in different regions is very useful study to develop suitble pckge for pest mngement. Acknowledgments This work ws supported by The University of Guiln nd hs been finnced with the reserch projects of Deprtment of Sericulture. The uthors re thnkful to L. Mtindoost for her technicl ssistnce. References Bhttchry, S. S., Chkrborty, N., Ro, K. M. nd Shkundu (1993) Thrips of mulberry in West Bengl & the record of thrips infecting mulberry in Indi. Environ. Ecol. 11, Bry, R.H. nd Kurtz, L.T., Determintion of totl, orgnic nd vilble forms of phosphorus in soils. Soil Sci, 59, Cppellozz, A. nd Mitto, F. (1987) Observtions on the bio-ethologicl behviour of Pseudodendrothrips mori Niw (Thysnopter: Terebrnti) in some zones of Itly. Redi. 7, Chen, L. S. (198) Thrips ssocited with

6 36 Effects of mulberry thrips on silkworm mulberry plnt (Morus sp) in Tiwn. Proceedings of the Ntionl Science Council ROC. 4, Ds, C. Shivnth nd Sinh, S.S. (1994 ) Thrips (Tysnopter) infesttion losses in mulberry (Morus lb). Ann. Entomol. 12, 1-4. Ds, C., Shivnth nd Ro, K.M. (1994 b) An investigtion on morpho-physiologicl chnges due to thrips infesttion in mulberry (Morus lb L.). Geobios. 21, Ds, C., Shivnth, Ro, K.M. nd Gltosh, P. (1991) Biochemicl chnges due to thrips infection in mulberry. Proceedings of Ntionl Symposium: Plnt Sciences in the nineties, K.U., pp Etebri, K. (22) Determintion of efficiency of sprinkler irrigtion for non- chemicl control of mulberry thrips Pseudodendrothrips mori (Thys., Thripide) Proceeding of 15th Irnin Plnt Protection Congress. Kermnsh. pp Etebri, K. nd Mtindoost, L. (24) Evlution of effects of sprinkler irrigtion & spring prunning on density of mulberry thrips Pseudodendrothrips mori Niw (Thys., Thripide) J. Entomol. Soc. Irn. 23, Etebri, K., Mtindoost, L. nd Singh, R.N. (24) Decision tools for mulberry thrips Pseudodendrothrips mori mngement in sericulturl regions; n overview. Entomologi Sinic, 11, Etebri, K., Jlli, J. nd Tksokhn, M. (1998) First report on the presence of mulberry thrips Pseudodendrothrips mori Niw (Thys., Thripide) s new species for insect fun of mulberry field of north of Irn. J. Entomol. Soc. Irn, 18, 26. Etebri, K., Jlli, J. nd Tksokhn, M. (2 ) Investigtion on host preference of Psuedodendrothrips mori Niw (Thy; Thripide) on four vrieties of mulberry in the field & lbortory. Irn. J. Agric. Sci. 31, Etebri, K., Jlli, J. nd Tksokhn, M. (2 b) Thrips (Thysnopter) fun of mulberry fields in Guiln province. Proceeding of 14th Irnin Plnt Protection Congress. Isfhn. pp Jlli, J., Hshemini, M., Etebri, K. nd Shojee, M. (22) The Lbortory biology & sesonl popultion vritions of mulberry thrips Pseudodendrothips mori Niw (Thys., Thripide) in Guiln province. J. Entomol. Soc. Irn. 21, Lewis, T. (1997) Thrips s Crop Pests. CAB interntionl publiction, pp. 74. Lim, S. H., Y. T. Kim, S. P. Lee, I. J. Rhee, J. S. Lim nd Lim, B. H. (199) Sericulture trining mnul. FAO, Agriculturl Services Bulletin, Rome. Misr S., C. R. Reddy, V. Sivprsd, K. D. Reddy & Chndrshekhrih. (23) Effect of certin insecticides in controlling Pseudodendrothrips mori in mulberry. Int. J. Indust. Entomol. 7, Mound, L. A. (1999) Slttoril lef-feeding Thysnopter (Thripide: Dendrothripine) from Austrli & New Cledoni, with newly recorded pests of ferns, figs nd mulberries, Aust. J. Entomol. 38, Nik, S. L. (1997) Bio-ecology of thrips infesting mulberry. M.Sc. Thesis, University of Agriculture Sciences, Bnglore, Indi. Pik, H. J. nd Lee, W.C. (1984) Efficcy of severl insecticides to the mulberry thrips. Seri. J. Kore. 25, Plmer, J. M. (199) Identifiction of the common thrips of tropicl Afric (Thysnopter: Insect) Trop. Pest Mng. 36, Pul, D. C., Ro, G. S. nd Deb, D. C. (1992) Impct of dietry moisture on nutritionl indices nd growth of Bombyx mori nd concommitnt lrvl durtion. J. Insect Physiol. 38, SAS institute (1997) SAS/STAT User s Guide for personl computers, Cry, NC: SAS Institute. Sengupt, T., Misr, A. K., Ds, C., Ds, K. K., Sen, S. K. nd Srtchndr, B. (1999) Physiochemicl chnges in thrips infected mulberry leves. Sericologi. 39, Singh, R. N. nd Srtchndr, B. (22) An Integrted Approch in the Pest Mngement in Sericulture. Int. J. Indust. Entomol. 5, Stnnrd, L. J. (1968) The thrips, or Thysnopter, of Illinois. Illinois Nturl History Surv. Bull. 29, Venugopl, S. nd Krishnswmi, S. (1983) Popultion of mulberry thrips, Pseudodendrothrips mori (Niw), in reltion to wether fctors. Indin J. Seric. 21, Woo, K. S. (1974) Thysnopter of Kore. Koren J. Entomol. 4, 1-9. Wn, R. X. nd Zhng, X.W. (1997)

7 Etebri nd Bizhnni 37 Investigtion of the distribution of Belothrips mori Niw on mulberry trees nd its nturl enemies Ningxi Jour. Agric. Forestry Sci. Tech. 6, Xi, T. Z, nd Zhu, J. (1991) The regulr pttern of occurrence of mulberry thrips & the control strtegies. Sichun Sericulture 2, Ye, Y.B. nd Gu, Z.F. (199) Chemicl control of the mulberry thrips Pseudodendrothrips mori. Sericologi. 3, (Received: Apr. 5, Accepted Jun. 1, 26)